bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2024–03–17
75 papers selected by
Viktor Korolchuk, Newcastle University
  1. Coronavirus hijacks STX18-ATG14 axis-regulated lipophagy to evade an anti-viral effect.
  2. Discrete Mechanistic Target of Rapamycin Signaling Pathways, Stem Cells, and Therapeutic Targets.
  3. The nutrient-sensing Rag-GTPase complex in B cells controls humoral immunity via TFEB/TFE3-dependent mitochondrial fitness.
  4. The multiple roles of autophagy in uveal melanoma and the microenvironment.
  5. Quantitative analysis of the spatial distance between autophagy-related membrane structures and the endoplasmic reticulum in Saccharomyces cerevisiae.
  6. MoAti1 mediates mitophagy by facilitating recruitment of MoAtg8 to promote invasive growth in Magnaporthe oryzae.
  7. Subversion of selective autophagy for the biogenesis of tombusvirus replication organelles inhibits autophagy.
  8. GRAF1 Acts as a Downstream Mediator of Parkin to Regulate Mitophagy in Cardiomyocytes.
  9. Emerging Role of Autophagy in Governing Cellular Dormancy, Metabolic Functions, and Therapeutic Responses of Cancer Stem Cells.
  10. Autophagy as a new player in the regulation of clock neurons physiology of Drosophila melanogaster.
  11. AMPK-upregulated microRNA-708 plays as a suppressor of cellular senescence and aging via downregulating disabled-2 and mTORC1 activation.
  12. How does the neuronal proteostasis network react to cellular cues?
  13. Multidimensional autophagy nano-regulator boosts Alzheimer's disease treatment by improving both extra/intraneuronal homeostasis.
  14. Pathogenesis of Parkinson's disease: from hints from monogenic familial PD to biomarkers.
  15. Potential role of modulating autophagy levels in sensorineural hearing loss.
  16. Preclinical evaluation of the third-generation, bi-steric mechanistic target of rapamycin complex 1-selective inhibitor RMC-6272 in NF2-deficient models.
  17. Impaired TFEB-mediated autophagy-lysosome fusion promotes tubular cell cycle G2/M arrest and renal fibrosis by suppressing ATP6V0C expression and interacting with SNAREs.
  18. Loss of FoxO1 activates an alternate mechanism of mitochondrial quality control for healthy adipose browning.
  19. Lysosomes in Cancer-At the Crossroad of Good and Evil.
  20. Yeast Bxi1/Ybh3 mediates conserved mitophagy and apoptosis in yeast and mammalian cells: convergence in Bcl-2 family.
  21. TRIM44 promotes autophagy through SQSTM1 oligomerization in the response to oxidative stress induced by Arsenic Trioxide in cancer cells.
  22. Late-Life Alcohol Exposure Does Not Exacerbate Age-Dependent Reductions in Mouse Spatial Memory and Brain TFEB Activity.
  23. Activation of the lysosomal damage response and selective autophagy: the coordinated actions of galectins, TRIM proteins, and CGAS-STING1 in providing immunity against Mycobacterium tuberculosis.
  24. Loss of chaperone-mediated autophagy does not alter age-related bone loss in male mice.
  25. Membrane atg8ylation in canonical and noncanonical autophagy.
  26. Discovery of SQSTM1/p62-dependent P-bodies that regulate the NLRP3 inflammasome.
  27. Human cytomegalovirus degrades DMXL1 to inhibit autophagy, lysosomal acidification, and viral assembly.
  28. BAG3 localizes to mitochondria in cardiac fibroblasts and regulates mitophagy.
  29. ALKBH1 promotes HIF-1α-mediated glycolysis by inhibiting N-glycosylation of LAMP2A.
  30. Immunological regulation and the role of autophagy in preeclampsia.
  31. Research Progress of Mitophagy in Alzheimer's Disease.
  32. Deficiency of Nuclear Receptor Coactivator 3 Aggravates Diabetic Kidney Disease by Impairing Podocyte Autophagy.
  33. Targeted Degradation of Cell-Surface Proteins via Chaperone-Mediated Autophagy by Using Peptide-Conjugated Antibodies.
  34. Mitophagy defect mediates the aging-associated hallmarks in Hutchinson-Gilford progeria syndrome.
  35. The role of HDAC6 in enhancing macrophage autophagy via the autophagolysosomal pathway to alleviate legionella pneumophila-induced pneumonia.
  36. Role of protein degradation systems in colorectal cancer.
  37. Epigenetic Regulation of Autophagy in Bone Metabolism.
  38. Real-Time Autophagic Flux Measurements in Live Cells Using a Novel Fluorescent Marker DAPRed.
  39. Endoplasmic reticulum stress, autophagy, neuroinflammation, and sigma 1 receptors as contributors to depression and its treatment.
  40. Cisplatin Nephrotoxicity Is Critically Mediated by the Availability of BECLIN1.
  41. Utilizing Extracellular Vesicles for Eliminating 'Unwanted Molecules': Harnessing Nature's Structures in Modern Therapeutic Strategies.
  42. Theileria parasites sequester host eIF5A to escape elimination by host-mediated autophagy.
  43. GLA Mutations Suppress Autophagy and Stimulate Lysosome Generation in Fabry Disease.
  44. mTOR Signaling: Recent Progress.
  45. The Potential of Targeting Autophagy-Related Non-coding RNAs in the Treatment of Alzheimer's and Parkinson's Diseases.
  46. From homeostasis to defense: Exploring the role of selective autophagy in innate immunity and viral infections.
  47. Role of PTEN-Induced Protein Kinase 1 as a Mitochondrial Dysfunction Regulator in Cardiovascular Disease Pathogenesis.
  48. The Ubiquitin Ligase RBX2/SAG Regulates Mitochondrial Ubiquitination and Mitophagy.
  49. Role of β-cell autophagy in β-cell physiology and the development of diabetes.
  50. Targeting cuproplasia and cuproptosis in cancer.
  51. Autophagy and Symbiosis: Membranes, ER, and Speculations.
  52. Pyrimethamine upregulates BNIP3 to interfere SNARE-mediated autophagosome-lysosomal fusion in hepatocellular carcinoma.
  53. microRNA-125b-1-3p mediates autophagy via the RRAGD/mTOR/ULK1 signaling pathway and mitigates atherosclerosis progression.
  54. TDCPP and TiO2 NPs aggregates synergistically induce SH-SY5Y cell neurotoxicity by excessive mitochondrial fission and mitophagy inhibition.
  55. Pathogenic mutations in UBQLN2 exhibit diverse aggregation propensity and neurotoxicity.
  56. SQSTM1 downregulates avian metapneumovirus subgroup C replication via mediating selective autophagic degradation of viral M2-2 protein.
  57. Lysine specific demethylase 1 inhibits sodium arsenite activation of HSCs by regulating SESN2/AMPK/ULK1 signaling pathway activity.
  58. Investigating the role of an immediate early gene FOS as a potential regulator of autophagic response to hypoglycemia in embryonic hypothalamic neurons.
  59. Myocardial glycophagy flux dysregulation and glycogen accumulation characterize diabetic cardiomyopathy.
  60. Biallelic USP14 variants cause a syndromic neurodevelopmental disorder.
  61. Ferritinophagy: Assessing the Selective Degradation of Iron by Autophagy in Human Fibroblasts.
  62. Toosendanin induces hepatotoxicity by restraining autophagy and lysosomal function through inhibiting STAT3/CTSC axis.
  63. mTORC1 accelerates osteosarcoma progression via m6A-dependent stabilization of USP7 mRNA.
  64. Autophagy inhibition-induced cytosolic DNA sensing combined with differentiation therapy induces irreversible myeloid differentiation in leukemia cells.
  65. NME3 is a gatekeeper for DRP1-dependent mitophagy in hypoxia.
  66. Quercetin Enhances 5-fluorouracil Sensitivity by Regulating the Autophagic Flux and Inducing Drp-1 Mediated Mitochondrial Fragmentation in Colorectal Cancer Cells.
  67. Lamin B1 curtails early human papillomavirus infection by safeguarding nuclear compartmentalization and autophagic capacity.
  68. RNF135 promotes cell proliferation and autophagy in lung adenocarcinoma by promoting the phosphorylation of ULK1.
  69. Influence of Cigarette Aerosol in Alpha-Synuclein Oligomerization and Cell Viability in SH-SY5Y: Implications for Parkinson's Disease.
  70. HES1 induces ITPR1-mediated autophagy to exert anti-metastatic effects in pituitary adenomas.
  71. The Janus-faced functions of Apolipoproteins L in membrane dynamics.
  72. Targeting PARP14 with lomitapide suppresses drug resistance through the activation of DRP1-induced mitophagy in multiple myeloma.
  73. CircFOXO3 mediates hypoxia-induced autophagy of endometrial stromal cells in endometriosis.
  74. Mitochondrial damage and clearance in retinal pigment epithelial cells.
  75. Inhibition of HSP20 ameliorates steatotic liver disease by stimulating ERK2-dependent autophagy.
  1. Autophagy. 2024 Mar 13.
    Coronavirus hijacks STX18-ATG14 axis-regulated lipophagy to evade an anti-viral effect.
    Zhen Yuan, Binbin Ding.
      ATG14 is a core subunit of the class III phosphatidylinositol 3-kinase complex I (PtdIns3K-C1) for macroautophagy/autophagy initiation and also binds to the STX17 to promote autophagosome-lysosome fusion. Our recent work found that ATG14 also targets lipid droplets (LDs) and interacts with mammalian Atg8-family proteins (ATG8s) to mediate lipophagy (selective autophagic degradation of lipid droplets). We also demonstrated that STX18 (syntaxin 18) acts as a negative regulator that disrupts the interactions of ATG14-ATG8s and the formation of the PtdIns3K-C1 through binding to ATG14. Furthermore, we found that knockdown of STX18 induces LD-associated anti-viral protein RSAD2/Viperin degradation dependent on ATG14-mediated lipophagy. Additionally, coronavirus M protein hijacks STX18 to induce lipophagy and degrade RSAD2, facilitating virus production. In summary, our findings reveal new roles of ATG14 in lipid metabolism and viral replication as an autophagic receptor.
    Keywords:  ATG14; SARS-CoV-2; STX18; Viperin; lipid droplets; selective autophagy
    DOI:  https://doi.org/10.1080/15548627.2024.2330039
  2. Cells. 2024 Feb 27. pii: 409. [Epub ahead of print]13(5):
    Discrete Mechanistic Target of Rapamycin Signaling Pathways, Stem Cells, and Therapeutic Targets.
    Meena Jhanwar-Uniyal, Sabrina L Zeller, Eris Spirollari, Mohan Das, Simon J Hanft, Chirag D Gandhi.
      The mechanistic target of rapamycin (mTOR) is a serine/threonine kinase that functions via its discrete binding partners to form two multiprotein complexes, mTOR complex 1 and 2 (mTORC1 and mTORC2). Rapamycin-sensitive mTORC1, which regulates protein synthesis and cell growth, is tightly controlled by PI3K/Akt and is nutrient-/growth factor-sensitive. In the brain, mTORC1 is also sensitive to neurotransmitter signaling. mTORC2, which is modulated by growth factor signaling, is associated with ribosomes and is insensitive to rapamycin. mTOR regulates stem cell and cancer stem cell characteristics. Aberrant Akt/mTOR activation is involved in multistep tumorigenesis in a variety of cancers, thereby suggesting that the inhibition of mTOR may have therapeutic potential. Rapamycin and its analogues, known as rapalogues, suppress mTOR activity through an allosteric mechanism that only suppresses mTORC1, albeit incompletely. ATP-catalytic binding site inhibitors are designed to inhibit both complexes. This review describes the regulation of mTOR and the targeting of its complexes in the treatment of cancers, such as glioblastoma, and their stem cells.
    Keywords:  4E-BP1; GBM; S6K; mTOR; mTORC1; mTORC2
    DOI:  https://doi.org/10.3390/cells13050409
  3. bioRxiv. 2024 Mar 01. pii: 2024.02.26.582122. [Epub ahead of print]
    The nutrient-sensing Rag-GTPase complex in B cells controls humoral immunity via TFEB/TFE3-dependent mitochondrial fitness.
    Xingxing Zhu, Yue Wu, Yanfeng Li, Xian Zhou, Jens O Watzlawik, Yin Maggie Chen, Ariel L Raybuck, Daniel Billadeau, Virginia Shapiro, Wolfdieter Springer, Jie Sun, Mark R Boothby, Hu Zeng.
      During the humoral immune response, B cells undergo rapid metabolic reprogramming with a high demand for nutrients, which are vital to sustain the formation of the germinal centers (GCs). Rag-GTPases sense amino acid availability to modulate the mechanistic target of rapamycin complex 1 (mTORC1) pathway and suppress transcription factor EB (TFEB) and transcription factor enhancer 3 (TFE3), members of the microphthalmia (MiT/TFE) family of HLH-leucine zipper transcription factors. However, how Rag-GTPases coordinate amino acid sensing, mTORC1 activation, and TFEB/TFE3 activity in humoral immunity remains undefined. Here, we show that B cell-intrinsic Rag-GTPases are critical for the development and activation of B cells. RagA/RagB deficient B cells fail to form GCs, produce antibodies, and generate plasmablasts in both T-dependent (TD) and T-independent (TI) humoral immune responses. Deletion of RagA/RagB in GC B cells leads to abnormal dark zone (DZ) to light zone (LZ) ratio and reduced affinity maturation. Mechanistically, the Rag-GTPase complex constrains TFEB/TFE3 activity to prevent mitophagy dysregulation and maintain mitochondrial fitness in B cells, which are independent of canonical mTORC1 activation. TFEB/TFE3 deletion restores B cell development, GC formation in Peyer's patches and TI humoral immunity, but not TD humoral immunity in the absence of Rag-GTPases. Collectively, our data establish Rag-GTPase-TFEB/TFE3 pathway as an mTORC1 independent mechanism to coordinating nutrient sensing and mitochondrial metabolism in B cells.
    DOI:  https://doi.org/10.1101/2024.02.26.582122
  4. J Cancer Res Clin Oncol. 2024 Mar 11. 150(3): 121
    The multiple roles of autophagy in uveal melanoma and the microenvironment.
    Bo Liu, Xueting Yao, Yu Shang, Jinhui Dai.
       PURPOSE: Uveal melanoma (UM) is the most common primary malignant intraocular tumor in adults, and effective clinical treatment strategies are still lacking. Autophagy is a lysosome-dependent degradation system that can encapsulate abnormal proteins, damaged organelles. However, dysfunctional autophagy has multiple types and plays a complex role in tumorigenicity depending on many factors, such as tumor stage, microenvironment, signaling pathway activation, and application of autophagic drugs.
    METHODS: A systematic review of the literature was conducted to analyze the role of autophagy in UM, as well as describing the development of autophagic drugs and the link between autophagy and the tumor microenvironment.
    RESULTS: In this review, we summarize current research advances regarding the types of autophagy, the mechanisms of autophagy, the application of autophagy inhibitors or agonists, autophagy and the tumor microenvironment. Finally, we also discuss the relationship between autophagy and UM.
    CONCLUSION: Understanding the molecular mechanisms of how autophagy differentially affects tumor progression may help to design better therapeutic regimens to prevent and treat UM.
    Keywords:  Autophagy; Drug target; Microenvironment; Uveal melanoma
    DOI:  https://doi.org/10.1007/s00432-023-05576-3
  5. Autophagy. 2024 Mar 13.
    Quantitative analysis of the spatial distance between autophagy-related membrane structures and the endoplasmic reticulum in Saccharomyces cerevisiae.
    Yang Shi, Kuninori Suzuki.
      Macroautophagy/autophagy is the process by which cells degrade their cytoplasmic proteins or organelles in vacuoles to maintain cellular homeostasis under severe environmental conditions. In the yeast Saccharomyces cerevisiae, autophagy-related (Atg) proteins essential for autophagosome formation accumulate near the vacuole to form the dot-shaped phagophore assembly site/pre-autophagosomal structure (PAS). The PAS then generates the phagophore/isolation membrane (PG), which expands to become a closed double-membrane autophagosome. Hereinafter, we refer to the PAS, PG, and autophagosome as autophagy-related structures (ARSs). During autophagosome formation, Atg2 is responsible for tethering the ARS to the endoplasmic reticulum (ER) via ER exit sites (ERESs), and for transferring phospholipids from the ER to ARSs. Therefore, ARS and the ER are spatially close in the presence of Atg2 but are separated in its absence. Because the contact of an ARS with the ER must be established at the earliest stage of autophagosome formation, it is important to know whether the ARS is tethered to the ER. In this study, we developed a rapid and objective method to estimate tethering of the ARS to the ER by measuring the distance between the ARS and ERES under fluorescence microscopy, and found that tethering of the ARS to the ER was lost without Atg1. This method might be useful to predict the tethering activity of Atg2.
    Keywords:  Autophagy-related 2 (Atg2); Endoplasmic reticulum exit sites (ERES); Fluorescence microscopy; Morphological analysis; Phagophore; Yeast
    DOI:  https://doi.org/10.1080/15548627.2024.2330033
  6. Mol Plant Pathol. 2024 Mar;25(3): e13439
    MoAti1 mediates mitophagy by facilitating recruitment of MoAtg8 to promote invasive growth in Magnaporthe oryzae.
    Huanbin Shi, Shuai Meng, Jiehua Qiu, Shuwei Xie, Nan Jiang, Chaoxi Luo, Naweed I Naqvi, Yanjun Kou.
      Mitophagy is a selective autophagy for the degradation of damaged or excessive mitochondria to maintain intracellular homeostasis. In Magnaporthe oryzae, a filamentous ascomycetous fungus that causes rice blast, the most devastating disease of rice, mitophagy occurs in the invasive hyphae to promote infection. To date, only a few proteins are known to participate in mitophagy and the mechanisms of mitophagy are largely unknown in pathogenic fungi. Here, by a yeast two-hybrid screen with the core autophagy-related protein MoAtg8 as a bait, we obtained a MoAtg8 interactor MoAti1 (MoAtg8-interacting protein 1). Fluorescent observations and protease digestion analyses revealed that MoAti1 is primarily localized to the peripheral mitochondrial outer membrane and is responsible for recruiting MoAtg8 to mitochondria under mitophagy induction conditions. MoAti1 is specifically required for mitophagy, but not for macroautophagy and pexophagy. Infection assays suggested that MoAti1 is required for mitophagy in invasive hyphae during pathogenesis. Notably, no homologues of MoAti1 were found in rice and human protein databases, indicating that MoAti1 may be used as a potential target to control rice blast. By the host-induced gene silencing (HIGS) strategy, transgenic rice plants targeted to silencing MoATI1 showed enhanced resistance against M. oryzae with unchanged agronomic traits. Our results suggest that MoATI1 is required for mitophagy and pathogenicity in M. oryzae and can be used as a target for reducing rice blast.
    Keywords:  Atg8; fungal pathogen; pathogenicity; rice blast; selective autophagy
    DOI:  https://doi.org/10.1111/mpp.13439
  7. PLoS Pathog. 2024 Mar 14. 20(3): e1012085
    Subversion of selective autophagy for the biogenesis of tombusvirus replication organelles inhibits autophagy.
    Yuanrong Kang, Wenwu Lin, Peter D Nagy.
      Elaborate viral replication organelles (VROs) are formed to support positive-strand RNA virus replication in infected cells. VRO formation requires subversion of intracellular membranes by viral replication proteins. Here, we showed that the key ATG8f autophagy protein and NBR1 selective autophagy receptor were co-opted by Tomato bushy stunt virus (TBSV) and the closely-related carnation Italian ringspot virus. Knockdown of ATG8f or NBR1 in plants led to reduced tombusvirus replication, suggesting pro-viral function for selective autophagy. BiFC and proximity-labeling experiments showed that the TBSV p33 replication protein interacted with ATG8f and NBR1 to recruit them to VROs. In addition, we observed that several core autophagy proteins, such as ATG1a, ATG4, ATG5, ATG101 and the plant-specific SH3P2 autophagy adaptor proteins were also re-localized to TBSV VROs, suggesting that TBSV hijacks the autophagy machinery in plant cells. We demonstrated that subversion of autophagy components facilitated the recruitment of VPS34 PI3 kinase and enrichment of phospholipids, such as phosphatidylethanolamine and PI3P phosphoinositide in the VRO membranes. Hijacking of autophagy components into TBSV VROs led to inhibition of autophagic flux. We also found that a fraction of the subverted ATG8f and NBR1 was sequestered in biomolecular condensates associated with VROs. We propose that the VRO-associated condensates trap those autophagy proteins, taking them away from the autophagy pathway. Overall, tombusviruses hijack selective autophagy to provide phospholipid-rich membranes for replication and to regulate the antiviral autophagic flux.
    DOI:  https://doi.org/10.1371/journal.ppat.1012085
  8. Cells. 2024 Mar 04. pii: 448. [Epub ahead of print]13(5):
    GRAF1 Acts as a Downstream Mediator of Parkin to Regulate Mitophagy in Cardiomyocytes.
    Qiang Zhu, Matthew E Combs, Dawn E Bowles, Ryan T Gross, Michelle Mendiola Pla, Christopher P Mack, Joan M Taylor.
      Cardiomyocytes rely on proper mitochondrial homeostasis to maintain contractility and achieve optimal cardiac performance. Mitochondrial homeostasis is controlled by mitochondrial fission, fusion, and mitochondrial autophagy (mitophagy). Mitophagy plays a particularly important role in promoting the degradation of dysfunctional mitochondria in terminally differentiated cells. However, the precise mechanisms by which this is achieved in cardiomyocytes remain opaque. Our study identifies GRAF1 as an important mediator in PINK1-Parkin pathway-dependent mitophagy. Depletion of GRAF1 (Arhgap26) in cardiomyocytes results in actin remodeling defects, suboptimal mitochondria clustering, and clearance. Mechanistically, GRAF1 promotes Parkin-LC3 complex formation and directs autophagosomes to damaged mitochondria. Herein, we found that these functions are regulated, at least in part, by the direct binding of GRAF1 to phosphoinositides (PI(3)P, PI(4)P, and PI(5)P) on autophagosomes. In addition, PINK1-dependent phosphorylation of Parkin promotes Parkin-GRAF1-LC3 complex formation, and PINK1-dependent phosphorylation of GRAF1 (on S668 and S671) facilitates the clustering and clearance of mitochondria. Herein, we developed new phosphor-specific antibodies to these sites and showed that these post-translational modifications are differentially modified in human hypertrophic cardiomyopathy and dilated cardiomyopathy. Furthermore, our metabolic studies using serum collected from isoproterenol-treated WT and GRAF1CKO mice revealed defects in mitophagy-dependent cardiomyocyte fuel flexibility that have widespread impacts on systemic metabolism. In summary, our study reveals that GRAF1 co-regulates actin and membrane dynamics to promote cardiomyocyte mitophagy and that dysregulation of GRAF1 post-translational modifications may underlie cardiac disease pathogenesis.
    Keywords:  GRAF1; PINK1-Parkin pathway; cardiomyocytes; metabolism; mitophagy
    DOI:  https://doi.org/10.3390/cells13050448
  9. Cells. 2024 Mar 04. pii: 447. [Epub ahead of print]13(5):
    Emerging Role of Autophagy in Governing Cellular Dormancy, Metabolic Functions, and Therapeutic Responses of Cancer Stem Cells.
    Meenakshi Tiwari, Pransu Srivastava, Sabiya Abbas, Janani Jegatheesan, Ashish Ranjan, Sadhana Sharma, Ved Prakash Maurya, Ajit Kumar Saxena, Lokendra Kumar Sharma.
      Tumors are composed of heterogeneous populations of dysregulated cells that grow in specialized niches that support their growth and maintain their properties. Tumor heterogeneity and metastasis are among the major hindrances that exist while treating cancer patients, leading to poor clinical outcomes. Although the factors that determine tumor complexity remain largely unknown, several genotypic and phenotypic changes, including DNA mutations and metabolic reprograming provide cancer cells with a survival advantage over host cells and resistance to therapeutics. Furthermore, the presence of a specific population of cells within the tumor mass, commonly known as cancer stem cells (CSCs), is thought to initiate tumor formation, maintenance, resistance, and recurrence. Therefore, these CSCs have been investigated in detail recently as potential targets to treat cancer and prevent recurrence. Understanding the molecular mechanisms involved in CSC proliferation, self-renewal, and dormancy may provide important clues for developing effective therapeutic strategies. Autophagy, a catabolic process, has long been recognized to regulate various physiological and pathological processes. In addition to regulating cancer cells, recent studies have identified a critical role for autophagy in regulating CSC functions. Autophagy is activated under various adverse conditions and promotes cellular maintenance, survival, and even cell death. Thus, it is intriguing to address whether autophagy promotes or inhibits CSC functions and whether autophagy modulation can be used to regulate CSC functions, either alone or in combination. This review describes the roles of autophagy in the regulation of metabolic functions, proliferation and quiescence of CSCs, and its role during therapeutic stress. The review further highlights the autophagy-associated pathways that could be used to regulate CSCs. Overall, the present review will help to rationalize various translational approaches that involve autophagy-mediated modulation of CSCs in controlling cancer progression, metastasis, and recurrence.
    Keywords:  autophagy; cancer stem cells; chemotherapy; metabolic functions; mitophagy; quiescence; radiotherapy
    DOI:  https://doi.org/10.3390/cells13050447
  10. Sci Rep. 2024 03 13. 14(1): 6085
    Autophagy as a new player in the regulation of clock neurons physiology of Drosophila melanogaster.
    Kornel Szypulski, Aleksandra Tyszka, Elzbieta Pyza, Milena Damulewicz.
      Axonal terminals of the small ventral lateral neurons (sLNvs), the circadian clock neurons of Drosophila, show daily changes in their arborization complexity, with many branches in the morning and their shrinkage during the night. This complex phenomenon is precisely regulated by several mechanisms. In the present study we describe that one of them is autophagy, a self-degradative process, also involved in changes of cell membrane size and shape. Our results showed that autophagosome formation and processing in PDF-expressing neurons (both sLNv and lLNv) are rhythmic and they have different patterns in the cell bodies and terminals. These rhythmic changes in the autophagy activity seem to be important for neuronal plasticity. We found that autophagosome cargos are different during the day and night, and more proteins involved in membrane remodeling are present in autophagosomes in the morning. In addition, we described for the first time that Atg8-positive vesicles are also present outside the sLNv terminals, which suggests that secretory autophagy might be involved in regulating the clock signaling network. Our data indicate that rhythmic autophagy in clock neurons affect the pacemaker function, through remodeling of terminal membrane and secretion of specific proteins from sLNvs.
    Keywords:  Circadian clock; Neuroplasticity; Sleep; The fruit fly
    DOI:  https://doi.org/10.1038/s41598-024-56649-3
  11. MedComm (2020). 2024 Mar;5(3): e475
    AMPK-upregulated microRNA-708 plays as a suppressor of cellular senescence and aging via downregulating disabled-2 and mTORC1 activation.
    Jian Zhang, Hui Gong, Tingting Zhao, Weitong Xu, Honghan Chen, Tiepeng Li, Yu Yang, Ming Yang, Ning Huang, Chuhui Gong, Fangfang Wang, Cuiying Zhang, Jin Liu, Hengyi Xiao.
      Senescence-associated microRNAs (SA-miRNAs) are important molecules for aging regulation. While many aging-promoting SA-miRNAs have been identified, confirmed aging-suppressive SA-miRNAs are rare, that impeded our full understanding on aging regulation. In this study, we verified that miR-708 expression is decreased in senescent cells and aged tissues and revealed that miR-708 overexpression can alleviate cellular senescence and aging performance. About the molecular cascade carrying the aging suppressive action of miR-708, we unraveled that miR-708 directly targets the 3'UTR of the disabled 2 (Dab2) gene and inhibits the expression of DAB2. Interestingly, miR-708-caused DAB2 downregulation blocks the aberrant mammalian target of rapamycin complex 1 (mTORC1) activation, a driving metabolic event for senescence progression, and restores the impaired autophagy, a downstream event of aberrant mTORC1 activation. We also found that AMP-activated protein kinase (AMPK) activation can upregulate miR-708 via the elevation of DICER expression, and miR-708 inhibitor is able to blunt the antiaging effect of AMPK. In summary, this study characterized miR-708 as an aging-suppressive SA-miRNA for the first time and uncovered a new signaling cascade, in which miR-708 links the DAB2/mTOR axis and AMPK/DICER axis together. These findings not only demonstrate the potential role of miR-708 in aging regulation, but also expand the signaling network connecting AMPK and mTORC1.
    Keywords:  AMP‐activated protein kinase (AMPK); Disabled 2 (DAB2); aging; mammalian traget of rapamycin coplex 1 (mTORC1); miR‐708
    DOI:  https://doi.org/10.1002/mco2.475
  12. Biochem Soc Trans. 2024 Mar 15. pii: BST20230316. [Epub ahead of print]
    How does the neuronal proteostasis network react to cellular cues?
    Ki Hong Nam, Alban Ordureau.
      Even though neurons are post-mitotic cells, they still engage in protein synthesis to uphold their cellular content balance, including for organelles, such as the endoplasmic reticulum or mitochondria. Additionally, they expend significant energy on tasks like neurotransmitter production and maintaining redox homeostasis. This cellular homeostasis is upheld through a delicate interplay between mRNA transcription-translation and protein degradative pathways, such as autophagy and proteasome degradation. When faced with cues such as nutrient stress, neurons must adapt by altering their proteome to survive. However, in many neurodegenerative disorders, such as Parkinson's disease, the pathway and processes for coping with cellular stress are impaired. This review explores neuronal proteome adaptation in response to cellular stress, such as nutrient stress, with a focus on proteins associated with autophagy, stress response pathways, and neurotransmitters.
    Keywords:  ISR; UPR; autophagy; neurons; nutrient stress; proteome
    DOI:  https://doi.org/10.1042/BST20230316
  13. Acta Pharm Sin B. 2024 Mar;14(3): 1380-1399
    Multidimensional autophagy nano-regulator boosts Alzheimer's disease treatment by improving both extra/intraneuronal homeostasis.
    Yixian Li, Peng Yang, Ran Meng, Shuting Xu, Lingling Zhou, Kang Qian, Pengzhen Wang, Yunlong Cheng, Dongyu Sheng, Minjun Xu, Tianying Wang, Jing Wu, Jinxu Cao, Qizhi Zhang.
      Intraneuronal dysproteostasis and extraneuronal microenvironmental abnormalities in Alzheimer's disease (AD) collectively culminate in neuronal deterioration. In the context of AD, autophagy dysfunction, a multi-link obstacle involving autophagy downregulation and lysosome defects in neurons/microglia is highly implicated in intra/extraneuronal pathological processes. Therefore, multidimensional autophagy regulation strategies co-manipulating "autophagy induction" and "lysosome degradation" in dual targets (neuron and microglia) are more reliable for AD treatment. Accordingly, we designed an RP-1 peptide-modified reactive oxygen species (ROS)-responsive micelles (RT-NM) loading rapamycin or gypenoside XVII. Guided by RP-1 peptide, the ligand of receptor for advanced glycation end products (RAGE), RT-NM efficiently targeted neurons and microglia in AD-affected region. This nano-combination therapy activated the whole autophagy-lysosome pathway by autophagy induction (rapamycin) and lysosome improvement (gypenoside XVII), thus enhancing autophagic degradation of neurotoxic aggregates and inflammasomes, and promoting Aβ phagocytosis. Resultantly, it decreased aberrant protein burden, alleviated neuroinflammation, and eventually ameliorated memory defects in 3 × Tg-AD transgenic mice. Our research developed a multidimensional autophagy nano-regulator to boost the efficacy of autophagy-centered AD therapy.
    Keywords:  Alzheimer's disease; Autophagy-lysosome pathway; Cascade dual-targeting; Gypenoside XVII; Multi-target therapy; Neuroinflammation; Proteostasis; Rapamycin
    DOI:  https://doi.org/10.1016/j.apsb.2023.10.009
  14. J Neural Transm (Vienna). 2024 Mar 13.
    Pathogenesis of Parkinson's disease: from hints from monogenic familial PD to biomarkers.
    Nobutaka Hattori, Manabu Funayama, Yuzuru Imai, Taku Hatano.
      Twenty-five years have passed since the causative gene for familial Parkinson's disease (PD), Parkin (now PRKN), was identified in 1998; PRKN is the most common causative gene in young-onset PD. Parkin encodes a ubiquitin-protein ligase, and Parkin is involved in mitophagy, a type of macroautophagy, in concert with PTEN-induced kinase 1 (PINK1). Both gene products are also involved in mitochondrial quality control. Among the many genetic PD-causing genes discovered, discovering PRKN as a cause of juvenile-onset PD has significantly impacted other neurodegenerative disorders. This is because the involvement of proteolytic systems has been suggested as a common mechanism in neurodegenerative diseases in which inclusion body formation is observed. The discovery of the participation of PRKN in PD has brought attention to the involvement of the proteolytic system in neurodegenerative diseases. Our research group has successfully isolated and identified CHCHD2, which is involved in the mitochondrial electron transfer system, and prosaposin (PSAP), which is involved in the lysosomal system, in this Parkin mechanism. Hereditary PD is undoubtedly an essential clue to solitary PD, and at least 25 or so genes and loci have been reported so far. This number of genes indicates that PD is a very diverse group of diseases. Currently, the diagnosis of PD is based on clinical symptoms and imaging studies. Although highly accurate diagnostic criteria have been published, early diagnosis is becoming increasingly important in treatment strategies for neurodegenerative diseases. Here, we also describe biomarkers that our group is working on.
    Keywords:   PARK2 ; Autophagy-lysosome pathway; Biomarker; Lysosome; Mitochondria; Mitophagy; Parkin; Ubiquitin–proteasome pathway
    DOI:  https://doi.org/10.1007/s00702-024-02747-5
  15. Biochem Pharmacol. 2024 Mar 07. pii: S0006-2952(24)00098-4. [Epub ahead of print]222 116115
    Potential role of modulating autophagy levels in sensorineural hearing loss.
    Ting Zou, Renwei Xie, Sihan Huang, Dingkun Lu, Jun Liu.
      In recent years, extensive research has been conducted on the pathogenesis of sensorineural hearing loss (SNHL). Apoptosis and necrosis have been identified to play important roles in hearing loss, but they cannot account for all hearing loss. Autophagy, a cellular process responsible for cell self-degradation and reutilization, has emerged as a significant factor contributing to hearing loss, particularly in cases of autophagy deficiency. Autophagy plays a crucial role in maintaining cell health by exerting cytoprotective and metabolically homeostatic effects in organisms. Consequently, modulating autophagy levels can profoundly impact the survival, death, and regeneration of cells in the inner ear, including hair cells (HCs) and spiral ganglion neurons (SGNs). Abnormal mitochondrial autophagy has been demonstrated in animal models of SNHL. These findings indicate the profound significance of comprehending autophagy while suggesting that our perspective on this cellular process holds promise for advancing the treatment of SNHL. Thus, this review aims to clarify the pathogenic mechanisms of SNHL and the role of autophagy in the developmental processes of various cochlear structures, including the greater epithelial ridge (GER), SGNs, and the ribbon synapse. The pathogenic mechanisms of age-related hearing loss (ARHL), also known as presbycusis, and the latest research on autophagy are also discussed. Furthermore, we underscore recent findings on the modulation of autophagy in SNHL induced by ototoxic drugs. Additionally, we suggest further research that might illuminate the complete potential of autophagy in addressing SNHL, ultimately leading to the formulation of pioneering therapeutic strategies and approaches for the treatment of deafness.
    Keywords:  Age-related hearing loss; Autophagy; Cochlear development; Ototoxicity; Sensorineural hearing loss
    DOI:  https://doi.org/10.1016/j.bcp.2024.116115
  16. Neurooncol Adv. 2024 Jan-Dec;6(1):6(1): vdae024
    Preclinical evaluation of the third-generation, bi-steric mechanistic target of rapamycin complex 1-selective inhibitor RMC-6272 in NF2-deficient models.
    Srirupa Bhattacharyya, Janet L Oblinger, Roberta L Beauchamp, Lili Kosa, Francis Robert, Scott R Plotkin, Long-Sheng Chang, Vijaya Ramesh.
       Background: NF2-associated meningiomas are progressive, highly morbid, and nonresponsive to chemotherapies, highlighting the need for improved treatments. We have established aberrant activation of the mechanistic target of rapamycin (mTOR) signaling in NF2-deficient tumors, leading to clinical trials with first- and second-generation mTOR inhibitors. However, results have been mixed, showing stabilized tumor growth without shrinkage offset by adverse side effects. To address these limitations, here we explored the potential of third-generation, bi-steric mTOR complex 1 (mTORC1) inhibitors using the preclinical tool compound RMC-6272.
    Methods: Employing human NF2-deficient meningioma lines, we compared mTOR inhibitors rapamycin (first-generation), INK128 (second-generation), and RMC-6272 (third-generation) using in vitro dose-response testing, cell-cycle analysis, and immunoblotting. Furthermore, the efficacy of RMC-6272 was assessed in NF2-null 3D-spheroid meningioma models, and its in vivo potential was evaluated in 2 orthotopic meningioma mouse models.
    Results: Treatment of meningioma cells revealed that, unlike rapamycin, RMC-6272 demonstrated superior growth inhibitory effects, cell-cycle arrest, and complete inhibition of phosphorylated 4E-BP1 (mTORC1 readout). Moreover, RMC-6272 had a longer retention time than INK128 and inhibited the expression of several eIF4E-sensitive targets on the protein level. RMC-6272 treatment of NF2 spheroids showed significant shrinkage in size as well as reduced proliferation. Furthermore, in vivo studies in mice revealed effective blockage of meningioma growth by RMC-6272, compared with vehicle controls.
    Conclusions: Our study in preclinical models of NF2 supports possible future clinical evaluation of third-generation, investigational mTORC1 inhibitors, such as RMC-5552, as a potential treatment strategy for NF2.
    Keywords:  4E-BP1; NF2; RMC-6272; mTORC1; meningioma
    DOI:  https://doi.org/10.1093/noajnl/vdae024
  17. Int J Biol Sci. 2024 ;20(5): 1905-1926
    Impaired TFEB-mediated autophagy-lysosome fusion promotes tubular cell cycle G2/M arrest and renal fibrosis by suppressing ATP6V0C expression and interacting with SNAREs.
    Xiang Ren, Jing Wang, Huizhi Wei, Xing Li, Yiqun Tian, Zhixian Wang, Yisheng Yin, Zihao Guo, Zhenliang Qin, Minglong Wu, Xiaoyong Zeng.
      Increasing evidence suggests that autophagy plays a major role during renal fibrosis. Transcription factor EB (TFEB) is a critical regulator of autophagy- and lysosome-related gene transcription. However, the pathophysiological roles of TFEB in renal fibrosis and fine-tuned mechanisms by which TFEB regulates fibrosis remain largely unknown. Here, we found that TFEB was downregulated in unilateral ureteral obstruction (UUO)-induced human and mouse fibrotic kidneys, and kidney-specific TFEB overexpression using recombinant AAV serotype 9 (rAAV9)-TFEB in UUO mice alleviated renal fibrosis pathogenesis. Mechanically, we found that TFEB's prevention of extracellular matrix (ECM) deposition depended on autophagic flux integrity and its subsequent blockade of G2/M arrest in tubular cells, rather than the autophagosome synthesis. In addition, we together RNA-seq with CUT&Tag analysis to determine the TFEB targeted gene ATP6V0C, and revealed that TFEB was directly bound to the ATP6V0C promoter only at specific site to promote its expression through CUT&Run-qPCR and luciferase reporter assay. Interestingly, TFEB induced autophagic flux integrity, mainly dependent on scaffold protein ATP6V0C-mediated autophagosome-lysosome fusion by bridging with STX17 and VAMP8 (major SNARE complex) by co-immunoprecipitation analysis, rather than its mediated lysosomal acidification and degradation function. Moreover, we further investigated the underlying mechanism behind the low expression of TEFB in UUO-induced renal fibrosis, and clearly revealed that TFEB suppression in fibrotic kidney was due to DNMT3a-associated TFEB promoter hypermethylation by utilizing methylation specific PCR (MSP) and bisulfite-sequencing PCR (BSP), which could be effectively recovered by 5-Aza-2'-deoxycytidine (5A-za) to alleviate renal fibrosis pathogenesis. These findings reveal for the first time that impaired TFEB-mediated autophagosome-lysosome fusion disorder, tubular cell G2/M arrest and renal fibrosis appear to be sequentially linked in UUO-induced renal fibrosis and suggest that DNMT3a/TFEB/ATP6V0C may serve as potential therapeutic targets to prevent renal fibrosis.
    Keywords:  Renal fibrosis; V-ATPase; autophagy; cell cycle; methylation; transcription factor EB
    DOI:  https://doi.org/10.7150/ijbs.91480
  18. Clin Sci (Lond). 2024 Mar 20. 138(6): 371-385
    Loss of FoxO1 activates an alternate mechanism of mitochondrial quality control for healthy adipose browning.
    Limin Shi, Jinying Yang, Zhipeng Tao, Louise Zheng, Tyler F Bui, Ramon L Alonso, Feng Yue, Zhiyong Cheng.
      Browning of white adipose tissue is hallmarked by increased mitochondrial density and metabolic improvements. However, it remains largely unknown how mitochondrial turnover and quality control are regulated during adipose browning. In the present study, we found that mice lacking adipocyte FoxO1, a transcription factor that regulates autophagy, adopted an alternate mechanism of mitophagy to maintain mitochondrial turnover and quality control during adipose browning. Post-developmental deletion of adipocyte FoxO1 (adO1KO) suppressed Bnip3 but activated Fundc1/Drp1/OPA1 cascade, concurrent with up-regulation of Atg7 and CTSL. In addition, mitochondrial biogenesis was stimulated via the Pgc1α/Tfam pathway in adO1KO mice. These changes were associated with enhanced mitochondrial homeostasis and metabolic health (e.g., improved glucose tolerance and insulin sensitivity). By contrast, silencing Fundc1 or Pgc1α reversed the changes induced by silencing FoxO1, which impaired mitochondrial quality control and function. Ablation of Atg7 suppressed mitochondrial turnover and function, causing metabolic disorder (e.g., impaired glucose tolerance and insulin sensitivity), regardless of elevated markers of adipose browning. Consistently, suppression of autophagy via CTSL by high-fat diet was associated with a reversal of adO1KO-induced benefits. Our data reveal a unique role of FoxO1 in coordinating mitophagy receptors (Bnip3 and Fundc1) for a fine-tuned mitochondrial turnover and quality control, underscoring autophagic clearance of mitochondria as a prerequisite for healthy browning of adipose tissue.
    Keywords:  FoxO1; adipose browning; metabolism; mitochondrial quality control; mitophagy
    DOI:  https://doi.org/10.1042/CS20230973
  19. Cells. 2024 Mar 05. pii: 459. [Epub ahead of print]13(5):
    Lysosomes in Cancer-At the Crossroad of Good and Evil.
    Ida Eriksson, Karin Öllinger.
      Although it has been known for decades that lysosomes are central for degradation and recycling in the cell, their pivotal role as nutrient sensing signaling hubs has recently become of central interest. Since lysosomes are highly dynamic and in constant change regarding content and intracellular position, fusion/fission events allow communication between organelles in the cell, as well as cell-to-cell communication via exocytosis of lysosomal content and release of extracellular vesicles. Lysosomes also mediate different forms of regulated cell death by permeabilization of the lysosomal membrane and release of their content to the cytosol. In cancer cells, lysosomal biogenesis and autophagy are increased to support the increased metabolism and allow growth even under nutrient- and oxygen-poor conditions. Tumor cells also induce exocytosis of lysosomal content to the extracellular space to promote invasion and metastasis. However, due to the enhanced lysosomal function, cancer cells are often more susceptible to lysosomal membrane permeabilization, providing an alternative strategy to induce cell death. This review summarizes the current knowledge of cancer-associated alterations in lysosomal structure and function and illustrates how lysosomal exocytosis and release of extracellular vesicles affect disease progression. We focus on functional differences depending on lysosomal localization and the regulation of intracellular transport, and lastly provide insight how new therapeutic strategies can exploit the power of the lysosome and improve cancer treatment.
    Keywords:  LMP; exocytosis; extracellular vesicles; lysosomal positioning; lysosome
    DOI:  https://doi.org/10.3390/cells13050459
  20. Biol Chem. 2024 Mar 12.
    Yeast Bxi1/Ybh3 mediates conserved mitophagy and apoptosis in yeast and mammalian cells: convergence in Bcl-2 family.
    Yuying Wang, Zhiyuan Hu, Maojun Jiang, Yanxin Zhang, Linjie Yuan, Ziqian Wang, Ting Song, Zhichao Zhang.
      The process of degrading unwanted or damaged mitochondria by autophagy, called mitophagy, is essential for mitochondrial quality control together with mitochondrial apoptosis. In mammalian cells, pan-Bcl-2 family members including conical Bcl-2 members and non-conical ones are involved in and govern the two processes. We have illustrated recently the BH3 receptor Hsp70 interacts with Bim to mediate both apoptosis and mitophagy. However, whether similar pathways exist in lower eukaryotes where conical Bcl-2 members are absent remained unclear. Here, a specific inhibitor of the Hsp70-Bim PPI, S1g-10 and its analogs were used as chemical tools to explore the role of yeast Bxi1/Ybh3 in regulating mitophagy and apoptosis. Using Om45-GFP processing assay, we illustrated that yeast Ybh3 mediates a ubiquitin-related mitophagy pathway in both yeast and mammalian cells through association with Hsp70, which is in the same manner with Bim. Moreover, by using Bax/Bak double knockout MEF cells, Ybh3 was identified to induce apoptosis through forming oligomerization to trigger mitochondrial outer membrane permeabilization (MOMP) like Bax. We not only illustrated a conserved ubiquitin-related mitophagy pathway in yeast but also revealed the multi-function of Ybh3 which combines the function of BH3-only protein and multi-domain Bax protein as one.
    Keywords:  Bxi1/Ybh3; Hsp70; mitophagy; ubiquitin
    DOI:  https://doi.org/10.1515/hsz-2023-0359
  21. Res Sq. 2024 Feb 20. pii: rs.3.rs-3951960. [Epub ahead of print]
    TRIM44 promotes autophagy through SQSTM1 oligomerization in the response to oxidative stress induced by Arsenic Trioxide in cancer cells.
    Nami McCarty, Yuqin Wang, Lin Lyu, Trung Vu.
      Tripartite motif containing 44 (TRIM44), a deubiquitinase, plays a pivotal role in connecting proteotoxic stress response to autophagic degradation in cancer and neurological diseases. While numerous studies have reported the upregulation of TRIM44 as a prognostic maker in various cancers, the detailed molecular mechanisms through which TRIM44 promotes autophagic degradation remain unclear. Here, we reported that TRIM44 can promote autophagy in response to oxidative stress which results in decreased cytotoxicity in Arsenic Trioxide treated cancer cells. The study focuses on the posttranslational modification of sequestosome-1 (SQSTM1) and its role in enhancing sequestration function during autophagic degradation. We discovered that TRIM44 significantly promotes SQSTM1 oligomerization in PB1 domain-dependent and oxidation-dependent manners. Furthermore, TRIM44 enhances the interaction between protein kinase A (PKA) and oligomerized SQSTM1, leading to increased phosphorylation of SQSTM1 at S349 and subsequent activation of NFE2L2 in response to oxidative stress. Collectively, our data support the potential roles of TRIM44 in the sensitivity of SQSTM1-mediated autophagy in the context of cancer, ageing and ageing-associated diseases, as well as neurodegenerative diseases.
    DOI:  https://doi.org/10.21203/rs.3.rs-3951960/v1
  22. bioRxiv. 2024 Feb 28. pii: 2024.02.23.581774. [Epub ahead of print]
    Late-Life Alcohol Exposure Does Not Exacerbate Age-Dependent Reductions in Mouse Spatial Memory and Brain TFEB Activity.
    Hao Chen, Kaitlyn Hinz, Chen Zhang, Yssa Rodriguez, Sha Neisha Williams, Mengwei Niu, Xiaowen Ma, Xiaojuan Chao, Alexandria L Frazier, Kenneth E McCarson, Xiaowan Wang, Zheyun Peng, Wanqing Liu, Hong-Min Ni, Jianhua Zhang, Russell H Swerdlow, Wen-Xing Ding.
      Alcohol consumption is believed to affect Alzheimer's disease (AD) risk, but the contributing mechanisms are not well understood. A potential mediator of the proposed alcohol-AD connection is autophagy, a degradation pathway that maintains organelle and protein homeostasis. Autophagy is in turn regulated through the activity of Transcription factor EB (TFEB), which promotes lysosome and autophagy-related gene expression. To explore the effect of alcohol on brain TFEB and autophagy, we exposed young (3-month old) and aged (23-month old) mice to two alcohol-feeding paradigms and assessed biochemical, transcriptome, histology, and behavioral endpoints. In young mice, alcohol decreased hippocampal nuclear TFEB staining but increased SQSTM1/p62, LC3-II, ubiquitinated proteins, and phosphorylated Tau. Hippocampal TFEB activity was lower in aged mice than it was in young mice, and Gao-binge alcohol feeding did not worsen the age-related reduction in TFEB activity. To better assess the impact of chronic alcohol exposure, we fed young and aged mice alcohol for four weeks before completing Morris Water and Barnes Maze spatial memory testing. The aged mice showed worse spatial memory on both tests. While alcohol feeding slightly impaired spatial memory in the young mice, it had little effect or even slightly improved spatial memory in the aged mice. These findings suggest that aging is a far more important driver of spatial memory impairment and reduced autophagy flux than alcohol consumption.
    DOI:  https://doi.org/10.1101/2024.02.23.581774
  23. Crit Rev Microbiol. 2024 Mar 12. 1-20
    Activation of the lysosomal damage response and selective autophagy: the coordinated actions of galectins, TRIM proteins, and CGAS-STING1 in providing immunity against Mycobacterium tuberculosis.
    Asrar Ahmad Malik, Mohd Shariq, Javaid Ahmad Sheikh, Sheeba Zarin, Yashika Ahuja, Haleema Fayaz, Anwar Alam, Nasreen Z Ehtesham, Seyed E Hasnain.
      Autophagy is a crucial immune defense mechanism that controls the survival and pathogenesis of M. tb by maintaining cell physiology during stress and pathogen attack. The E3-Ub ligases (PRKN, SMURF1, and NEDD4) and autophagy receptors (SQSTM1, TAX1BP1, CALCOCO2, OPTN, and NBR1) play key roles in this process. Galectins (LGALSs), which bind to sugars and are involved in identifying damaged cell membranes caused by intracellular pathogens such as M. tb, are essential. These include LGALS3, LGALS8, and LGALS9, which respond to endomembrane damage and regulate endomembrane damage caused by toxic chemicals, protein aggregates, and intracellular pathogens, including M. tb. They also activate selective autophagy and de novo endolysosome biogenesis. LGALS3, LGALS9, and LGALS8 interact with various components to activate autophagy and repair damage, while CGAS-STING1 plays a critical role in providing immunity against M. tb by activating selective autophagy and producing type I IFNs with antimycobacterial functions. STING1 activates cGAMP-dependent autophagy which provides immunity against various pathogens. Additionally, cytoplasmic surveillance pathways activated by ds-DNA, such as inflammasomes mediated by NLRP3 and AIM2 complexes, control M. tb. Modulation of E3-Ub ligases with small regulatory molecules of LGALSs and TRIM proteins could be a novel host-based therapeutic approach for controlling TB.
    Keywords:  Autophagy; CGAS; E3-Ub ligase; STING1; galectin
    DOI:  https://doi.org/10.1080/1040841X.2024.2321494
  24. FASEB Bioadv. 2024 Mar;6(3): 73-84
    Loss of chaperone-mediated autophagy does not alter age-related bone loss in male mice.
    James A Hendrixson, Alicen James, Nisreen S Akel, Dominique J Laster, Julie A Crawford, Stuart B Berryhill, Melda Onal.
      Chaperone-mediated autophagy (CMA) is a lysosome-dependent degradation pathway that eliminates proteins that are damaged, partially unfolded, or targeted for selective proteome remodeling. CMA contributes to several cellular processes, including stress response and proteostasis. Age-associated increase in cellular stressors and decrease in CMA contribute to pathologies associated with aging in various tissues. CMA contributes to bone homeostasis in young mice. An age-associated reduction in CMA was reported in osteoblast lineage cells; however, whether declining CMA contributes to skeletal aging is unknown. Herein we show that cellular stressors stimulate CMA in UAMS-32 osteoblastic cells. Moreover, the knockdown of an essential component of the CMA pathway, LAMP2A, sensitizes osteoblasts to cell death caused by DNA damage, ER stress, and oxidative stress. As elevations in these stressors are thought to contribute to age-related bone loss, we hypothesized that declining CMA contributes to the age-associated decline in bone formation by sensitizing osteoblast lineage cells to elevated stressors. To test this, we aged male CMA-deficient mice and controls up to 24 months of age and examined age-associated changes in bone mass and architecture. We showed that lack of CMA did not alter age-associated decline in bone mineral density as measured by dual x-ray absorptiometry (DXA). Moreover, microCT analysis performed at 24 months of age showed that vertebral cancellous bone volume, cortical thickness, and porosity of CMA-deficient and control mice were similar. Taken together, these results suggest that reduction of CMA does not contribute to age-related bone loss.
    Keywords:  CMA; age‐related bone loss; aging; cellular stress; chaperone‐mediated autophagy; skeletal aging
    DOI:  https://doi.org/10.1096/fba.2023-00133
  25. J Mol Biol. 2024 Mar 11. pii: S0022-2836(24)00119-0. [Epub ahead of print] 168532
    Membrane atg8ylation in canonical and noncanonical autophagy.
    Vojo Deretic, Thabata Duque, Einar Trosdal, Masroor Paddar, Ruheena Javed, Prithvi Akepati.
      Membrane atg8ylation is a homeostatic process responding to membrane remodeling and stress signals. Membranes are atg8ylated by mammalian ATG8 ubiquitin-like proteins through a ubiquitylation-like cascade. A model has recently been put forward which posits that atg8ylation of membranes is conceptually equivalent to ubiquitylation of proteins. Like ubiquitylation, membrane atg8ylation involves E1, E2 and E3 enzymes. The E3 ligases catalyze the final step of atg8ylation of aminophospholipids in membranes. Until recently, the only known E3 ligase for membrane atg8ylation was ATG16L1 in a noncovalent complex with the ATG12-ATG5 conjugate. ATG16L1 was first identified as a factor in canonical autophagy. During canonical autophagy, the ATG16L1-based E3 ligase complex includes WIPI2, which in turn recognizes phosphatidylinositiol 3-phosphate and directs atg8ylation of autophagic phagophores. As an alternative to WIPIs, binding of ATG16L1 to the proton pump V-ATPase guides atg8ylation of endolysosomal and phagosomal membranes in response to lumenal pH changes. Recently, a new E3 complex containing TECPR1 instead of ATG16L1, has been identified that responds to sphingomyelin's presence on the cytofacial side of perturbed endolysosomal membranes. In present review, we cover the principles of membrane atg8ylaton, catalog its various presentations, and provide a perspective on the growing repertoire of E3 ligase complexes directing membrane atg8ylation at diverse locations.
    DOI:  https://doi.org/10.1016/j.jmb.2024.168532
  26. Cell Rep. 2024 Mar 07. pii: S2211-1247(24)00263-8. [Epub ahead of print]43(3): 113935
    Discovery of SQSTM1/p62-dependent P-bodies that regulate the NLRP3 inflammasome.
    Elizabeth R Barrow, Evelina Valionyte, Chris R Baxter, Yi Yang, Sharon Herath, William A O'Connell, Justyna Lopatecka, Alexander Strachan, Waldemar Woznica, Holly N Stephenson, Gyorgy Fejer, Vikram Sharma, Boxun Lu, Shouqing Luo.
      Autophagy and ribonucleoprotein granules, such as P-bodies (PBs) and stress granules, represent vital stress responses to maintain cellular homeostasis. SQSTM1/p62 phase-separated droplets are known to play critical roles in selective autophagy; however, it is unknown whether p62 can exist as another form in addition to its autophagic droplets. Here, we found that, under stress conditions, including proteotoxicity, endotoxicity, and oxidation, autophagic p62 droplets are transformed to a type of enlarged PBs, termed p62-dependent P-bodies (pd-PBs). p62 phase separation is essential for the nucleation of pd-PBs. Mechanistically, pd-PBs are triggered by enhanced p62 droplet formation upon stress stimulation through the interactions between p62 and DDX6, a DEAD-box ATPase. Functionally, pd-PBs recruit the NLRP3 inflammasome adaptor ASC to assemble the NLRP3 inflammasome and induce inflammation-associated cytotoxicity. Our study shows that p62 droplet-to-PB transformation acts as a stress response to activate the NLRP3 inflammasome process, suggesting that persistent pd-PBs lead to NLRP3-dependent inflammation toxicity.
    Keywords:  ASC/PYCARD; CP: Molecular biology; LLPS; NLRP3 inflammasome; P-bodies; RNP granules; SQSTM1/p62; autophagy; liquid-liquid phase separation; stress granules
    DOI:  https://doi.org/10.1016/j.celrep.2024.113935
  27. Cell Host Microbe. 2024 Mar 05. pii: S1931-3128(24)00055-6. [Epub ahead of print]
    Human cytomegalovirus degrades DMXL1 to inhibit autophagy, lysosomal acidification, and viral assembly.
    Hanqi Li, Alice Fletcher-Etherington, Leah M Hunter, Swati Keshri, Ceri A Fielding, Katie Nightingale, Benjamin Ravenhill, Luis Nobre, Martin Potts, Robin Antrobus, Colin M Crump, David C Rubinsztein, Richard J Stanton, Michael P Weekes.
      Human cytomegalovirus (HCMV) is an important human pathogen that regulates host immunity and hijacks host compartments, including lysosomes, to assemble virions. We combined a quantitative proteomic analysis of HCMV infection with a database of proteins involved in vacuolar acidification, revealing Dmx-like protein-1 (DMXL1) as the only protein that acidifies vacuoles yet is degraded by HCMV. Systematic comparison of viral deletion mutants reveals the uncharacterized 7 kDa US33A protein as necessary and sufficient for DMXL1 degradation, which occurs via recruitment of the E3 ubiquitin ligase Kip1 ubiquitination-promoting complex (KPC). US33A-mediated DMXL1 degradation inhibits lysosome acidification and autophagic cargo degradation. Formation of the virion assembly compartment, which requires lysosomes, occurs significantly later with US33A-expressing virus infection, with reduced viral replication. These data thus identify a viral strategy for cellular remodeling, with the potential to employ US33A in therapies for viral infection or rheumatic conditions, in which inhibition of lysosome acidification can attenuate disease.
    Keywords:  autophagy; human cytomegalovirus; lysosome; pH; proteomics; systems virology; viral assembly; viral replication
    DOI:  https://doi.org/10.1016/j.chom.2024.02.013
  28. Am J Physiol Heart Circ Physiol. 2024 Mar 15.
    BAG3 localizes to mitochondria in cardiac fibroblasts and regulates mitophagy.
    Thomas G Martin, Laura A Sherer, Jonathan A Kirk.
      The co-chaperone BAG3 is a central node in protein quality control in the heart. In humans and animal models, decreased BAG3 expression is associated with cardiac dysfunction and dilated cardiomyopathy. While previous studies focused on BAG3 in cardiomyocytes, cardiac fibroblasts are also critical drivers of pathologic remodeling. Yet, BAG3's role in cardiac fibroblasts is almost completely unexplored. Here, we show BAG3 is expressed in primary rat neonatal cardiac fibroblasts and preferentially localizes to mitochondria. Knockdown of BAG3 reduces mitophagy and enhances fibroblast activation, which is associated with fibrotic remodeling. Hsp70 is a critical binding partner for BAG3 and inhibiting this interaction in fibroblasts using the drug JG-98 decreased autophagy, decreased mitofusin-2 expression, and disrupted mitochondrial morphology. Together, this data indicates that BAG3 is expressed in cardiac fibroblasts, where it facilitates mitophagy and promotes fibroblast quiescence. This suggests that depressed BAG3 levels in heart failure may exacerbate fibrotic pathology, thus contributing to myocardial dysfunction through sarcomere-independent pathways.
    Keywords:  BAG3; cardiac fibroblasts; heart; mitophagy
    DOI:  https://doi.org/10.1152/ajpheart.00736.2023
  29. Cell Mol Life Sci. 2024 Mar 12. 81(1): 130
    ALKBH1 promotes HIF-1α-mediated glycolysis by inhibiting N-glycosylation of LAMP2A.
    Yanyan Liu, Mengmeng Li, Miao Lin, Xinjie Liu, Haolin Guo, Junyang Tan, Liubing Hu, Jianshuang Li, Qinghua Zhou.
      ALKBH1 is a typical demethylase of nucleic acids, which is correlated with multiple types of biological processes and human diseases. Recent studies are focused on the demethylation of ALKBH1, but little is known about its non-demethylase function. Here, we demonstrate that ALKBH1 regulates the glycolysis process through HIF-1α signaling in a demethylase-independent manner. We observed that depletion of ALKBH1 inhibits glycolysis flux and extracellular acidification, which is attributable to reduced HIF-1α protein levels, and it can be rescued by reintroducing HIF-1α. Mechanistically, ALKBH1 knockdown enhances chaperone-mediated autophagy (CMA)-mediated HIF-1α degradation by facilitating the interaction between HIF-1α and LAMP2A. Furthermore, we identify that ALKBH1 competitively binds to the OST48, resulting in compromised structural integrity of oligosaccharyltransferase (OST) complex and subsequent defective N-glycosylation of LAMPs, particularly LAMP2A. Abnormal glycosylation of LAMP2A disrupts lysosomal homeostasis and hinders the efficient degradation of HIF-1α through CMA. Moreover, NGI-1, a small-molecule inhibitor that selectively targets the OST complex, could inhibit the glycosylation of LAMPs caused by ALKBH1 silencing, leading to impaired CMA activity and disruption of lysosomal homeostasis. In conclusion, we have revealed a non-demethylation role of ALKBH1 in regulating N-glycosylation of LAMPs by interacting with OST subunits and CMA-mediated degradation of HIF-1α.
    Keywords:   N-glycosylation; ALKBH1; Chaperone-mediated autophagy; HIF-1α ; Lysosome
    DOI:  https://doi.org/10.1007/s00018-024-05152-z
  30. Am J Reprod Immunol. 2024 Mar;91(3): e13835
    Immunological regulation and the role of autophagy in preeclampsia.
    Akitoshi Nakashima, Atsushi Furuta, Mihoko Yoshida-Kawaguchi, Kiyotaka Yamada, Haruka Nunomura, Keiko Morita, Ippei Yasuda, Satoshi Yoneda, Akemi Yamaki-Ushijima, Tomoko Shima, Sayaka Tsuda.
      Autophagy is a bulk degradation system that maintains cellular homeostasis by producing energy and/or recycling excess proteins. During early placentation, extravillous trophoblasts invade the decidua and uterine myometrium, facing maternal immune cells, which participate in the immune suppression of paternal and fetal antigens. Regulatory T cells will likely increase in response to a specific antigen before and during early pregnancy. Insufficient expansion of antigen-specific Treg cells, which possess the same T cell receptor, is associated with the pathophysiology of preeclampsia, suggesting sterile systemic inflammation. Autophagy is involved in reducing inflammation through the degradation of inflammasomes and in the differentiation and function of regulatory T cells. Autophagy dysregulation induces protein aggregation in trophoblasts, resulting in placental dysfunction. In this review, we discuss the role of regulatory T cells in normal pregnancies. In addition, we discuss the association between autophagy and regulatory T cells in the development of preeclampsia based on reports on the role of autophagy in autoimmune diseases.
    Keywords:  FOXP3; autophagy; hydroxychloroquine; preeclampsia; regulatory T cells
    DOI:  https://doi.org/10.1111/aji.13835
  31. Curr Alzheimer Res. 2024 Mar 12.
    Research Progress of Mitophagy in Alzheimer's Disease.
    Jinglin Yao, Bohong Kan, Zhengjia Dong, Zhenyu Tang.
      The prevalence of Alzheimer's disease (AD) is increasing as the elderly population, which hurts elderly people's cognition and capacity for self-care. The process of mitophagy involves the selective clearance of ageing and impaired mitochondria, which is required to preserve intracellular homeostasis and energy metabolism. Currently, it has been discovered that mitophagy abnormalities are intimately linked to the beginning and progression of AD. This article discusses the mechanism of mitophagy, abnormal mitophagy, and therapeutic effects in AD. The purpose is to offer fresh perspectives on the causes and remedies of AD.
    Keywords:  Alzheimer's disease (AD); PINK1; mitochondrial damage; mitophagy; parkin; treatment.
    DOI:  https://doi.org/10.2174/0115672050300063240305074310
  32. Adv Sci (Weinh). 2024 Mar 14. e2308378
    Deficiency of Nuclear Receptor Coactivator 3 Aggravates Diabetic Kidney Disease by Impairing Podocyte Autophagy.
    Yaru Xie, Qian Yuan, Xinyi Cao, Yang Qiu, Jieyu Zeng, Yiling Cao, Yajuan Xie, Xianfang Meng, Kun Huang, Fan Yi, Chun Zhang.
      Nuclear receptors (NRs) are important transcriptional factors that mediate autophagy, preventing podocyte injury and the progression of diabetic kidney disease (DKD). However, the role of nuclear receptor coactivators that are powerful enhancers for the transcriptional activity of NRs in DKD remains unclear. In this study, a significant decrease in Nuclear Receptor Coactivator 3 (NCOA3) is observed in injured podocytes caused by high glucose treatment. Additionally, NCOA3 overexpression counteracts podocyte damage by improving autophagy. Further, Src family member, Fyn is identified to be the target of NCOA3 that mediates the podocyte autophagy process. Mechanistically, NCOA3 regulates the transcription of Fyn in a nuclear receptor, PPAR-γ dependent way. Podocyte-specific NCOA3 knockout aggravates albuminuria, glomerular sclerosis, podocyte injury, and autophagy in DKD mice. However, the Fyn inhibitor, AZD0530, rescues podocyte injury of NCOA3 knockout DKD mice. Renal NCOA3 overexpression with lentivirus can ameliorate podocyte damage and improve podocyte autophagy in DKD mice. Taken together, the findings highlight a novel target, NCOA3, that protects podocytes from high glucose injury by maintaining autophagy.
    Keywords:  autophagy; diabetic kidney disease; nuclear receptor coactivator; peroxisome proliferator-activated receptor -γ; podocyte
    DOI:  https://doi.org/10.1002/advs.202308378
  33. Angew Chem Int Ed Engl. 2024 Mar 12. e202319232
    Targeted Degradation of Cell-Surface Proteins via Chaperone-Mediated Autophagy by Using Peptide-Conjugated Antibodies.
    Jinning Shao, Xuefen Lin, Haoting Wang, Chuhan Zhao, Shao Q Yao, Jingyan Ge, Su Zeng, Linghui Qian.
      Cell-surface proteins are important drug targets but historically have posed big challenges for the complete elimination of their functions. Herein, we report antibody-peptide conjugates (Ab-CMAs) in which a peptide targeting chaperone-mediated autophagy (CMA) was conjugated with commercially available monoclonal antibodies for specific cell-surface protein degradation by taking advantage of lysosomal degradation pathways. Unique features of Ab-CMAs including cell-surface receptor-/E3 ligase-independent degradation, feasibility towards different cell-surface proteins (e.g., epidermal growth factor receptor (EGFR), programmed cell death ligand 1 (PD-L1), human epidermal growth factor receptor 2 (HER2)) by a simple change of the antibody, and successful tumor inhibition in vivo, make them attractive protein degraders for biomedical research and therapeutic applications. As the first example employing CMA to degrade proteins from the outside in, our findings may also shed new light on CMA, a degradation pathway typically targeting cytosolic proteins.
    Keywords:  Antibody-Peptide Conjugates; Cell-Surface Proteins; Chaperone-Mediated Autophagy; Lysosomal Degradation; Targeted Protein Degradation
    DOI:  https://doi.org/10.1002/anie.202319232
  34. Aging Cell. 2024 Mar 14. e14143
    Mitophagy defect mediates the aging-associated hallmarks in Hutchinson-Gilford progeria syndrome.
    Yingying Sun, Le Xu, Yi Li, Shunze Jia, Gang Wang, Xufeng Cen, Yuyan Xu, Zhongkai Cao, Jingjing Wang, Ning Shen, Lidan Hu, Jin Zhang, Jianhua Mao, Hongguang Xia, Zhihong Liu, Xudong Fu.
      Hutchinson-Gilford progeria syndrome (HGPS) is a rare and fatal disease manifested by premature aging and aging-related phenotypes, making it a disease model for aging. The cellular machinery mediating age-associated phenotypes in HGPS remains largely unknown, resulting in limited therapeutic targets for HGPS. In this study, we showed that mitophagy defects impaired mitochondrial function and contributed to cellular markers associated with aging in mesenchymal stem cells derived from HGPS patients (HGPS-MSCs). Mechanistically, we discovered that mitophagy affected the aging-associated phenotypes of HGPS-MSCs by inhibiting the STING-NF-ĸB pathway and the downstream transcription of senescence-associated secretory phenotypes (SASPs). Furthermore, by utilizing UMI-77, an effective mitophagy inducer, we showed that mitophagy induction alleviated aging-associated phenotypes in HGPS and naturally aged mice. Collectively, our results uncovered that mitophagy defects mediated the aging-associated markers in HGPS, highlighted the function of mitochondrial homeostasis in HGPS progression, and suggested mitophagy as an intervention target for HGPS and aging.
    Keywords:  HGPS; UMI-77; aging; mitophagy
    DOI:  https://doi.org/10.1111/acel.14143
  35. Virulence. 2024 Dec;15(1): 2327096
    The role of HDAC6 in enhancing macrophage autophagy via the autophagolysosomal pathway to alleviate legionella pneumophila-induced pneumonia.
    Minjia Chen, Xiuqin Cao, Ronghui Zheng, Haixia Chen, Ruixia He, Hao Zhou, Zhiwei Yang.
      Legionella pneumophila (L. pneumophila) is a prevalent pathogenic bacterium responsible for significant global health concerns. Nonetheless, the precise pathogenic mechanisms of L. pneumophila have still remained elusive. Autophagy, a direct cellular response to L. pneumophila infection and other pathogens, involves the recognition and degradation of these invaders in lysosomes. Histone deacetylase 6 (HDAC6), a distinctive member of the histone deacetylase family, plays a multifaceted role in autophagy regulation. This study aimed to investigate the role of HDAC6 in macrophage autophagy via the autophagolysosomal pathway, leading to alleviate L. pneumophila-induced pneumonia. The results revealed a substantial upregulation of HDAC6 expression level in murine lung tissues infected by L. pneumophila. Notably, mice lacking HDAC6 exhibited a protective response against L. pneumophila-induced pulmonary tissue inflammation, which was characterized by the reduced bacterial load and diminished release of pro-inflammatory cytokines. Transcriptomic analysis has shed light on the regulatory role of HDAC6 in L. pneumophila infection in mice, particularly through the autophagy pathway of macrophages. Validation using L. pneumophila-induced macrophages from mice with HDAC6 gene knockout demonstrated a decrease in cellular bacterial load, activation of the autophagolysosomal pathway, and enhancement of cellular autophagic flux. In summary, the findings indicated that HDAC6 knockout could lead to the upregulation of p-ULK1 expression level, promoting the autophagy-lysosomal pathway, increasing autophagic flux, and ultimately strengthening the bactericidal capacity of macrophages. This contributes to the alleviation of L. pneumophila-induced pneumonia.
    Keywords:  Histone deacetylase 6 (HDAC6); Legionella pneumophila; autophagy; autophagyolysosomal pathway; macrophages
    DOI:  https://doi.org/10.1080/21505594.2024.2327096
  36. Cell Death Discov. 2024 Mar 14. 10(1): 141
    Role of protein degradation systems in colorectal cancer.
    Zihan Cui, Mingqi Cong, Shengjie Yin, Yuqi Li, Yuguang Ye, Xi Liu, Jing Tang.
      Protein degradation is essential for maintaining protein homeostasis. The ubiquitin‒proteasome system (UPS) and autophagy-lysosome system are the two primary pathways responsible for protein degradation and directly related to cell survival. In malignant tumors, the UPS plays a critical role in managing the excessive protein load caused by cancer cells hyperproliferation. In this review, we provide a comprehensive overview of the dual roles played by the UPS and autolysosome system in colorectal cancer (CRC), elucidating their impact on the initiation and progression of this disease while also highlighting their compensatory relationship. Simultaneously targeting both protein degradation pathways offers new promise for enhancing treatment efficacy against CRC. Additionally, apoptosis is closely linked to ubiquitination and autophagy, and caspases degrade proteins. A thorough comprehension of the interplay between various protein degradation pathways is highly important for clarifying the mechanism underlying the onset and progression of CRC.
    DOI:  https://doi.org/10.1038/s41420-023-01781-8
  37. Function (Oxf). 2024 ;5(2): zqae004
    Epigenetic Regulation of Autophagy in Bone Metabolism.
    Yazhou Zhang, Qianqian Wang, Hongjia Xue, Yujin Guo, Shanshan Wei, Fengfeng Li, Linqiang Gong, Weiliang Pan, Pei Jiang.
      The skeletal system is crucial for supporting bodily functions, protecting vital organs, facilitating hematopoiesis, and storing essential minerals. Skeletal homeostasis, which includes aspects such as bone density, structural integrity, and regenerative processes, is essential for normal skeletal function. Autophagy, an intricate intracellular mechanism for degrading and recycling cellular components, plays a multifaceted role in bone metabolism. It involves sequestering cellular waste, damaged proteins, and organelles within autophagosomes, which are then degraded and recycled. Autophagy's impact on bone health varies depending on factors such as regulation, cell type, environmental cues, and physiological context. Despite being traditionally considered a cytoplasmic process, autophagy is subject to transcriptional and epigenetic regulation within the nucleus. However, the precise influence of epigenetic regulation, including DNA methylation, histone modifications, and non-coding RNA expression, on cellular fate remains incompletely understood. The interplay between autophagy and epigenetic modifications adds complexity to bone cell regulation. This article provides an in-depth exploration of the intricate interplay between these two regulatory paradigms, with a focus on the epigenetic control of autophagy in bone metabolism. Such an understanding enhances our knowledge of bone metabolism-related disorders and offers insights for the development of targeted therapeutic strategies.
    Keywords:  autophagy; bone homeostasis; bone metabolism; bone-related diseases; epigenetics; miRNA
    DOI:  https://doi.org/10.1093/function/zqae004
  38. Bio Protoc. 2024 Mar 05. 14(5): e4949
    Real-Time Autophagic Flux Measurements in Live Cells Using a Novel Fluorescent Marker DAPRed.
    Arnold Sipos, Kwang-Jin Kim, Juan R Alvarez, Edward D Crandall.
      Autophagy is a conserved homeostatic mechanism involved in cellular homeostasis and many disease processes. Although it was first described in yeast cells undergoing starvation, we have learned over the years that autophagy gets activated in many stress conditions and during development and aging in mammalian cells. Understanding the fundamental mechanisms underlying autophagy effects can bring us closer to better insights into the pathogenesis of many disease conditions (e.g., cardiac muscle necrosis, Alzheimer's disease, and chronic lung injury). Due to the complex and dynamic nature of the autophagic processes, many different techniques (e.g., western blotting, fluorescent labeling, and genetic modifications of key autophagy proteins) have been developed to delineate autophagy effects. Although these methods are valid, they are not well suited for the assessment of time-dependent autophagy kinetics. Here, we describe a novel approach: the use of DAPRed for autophagic flux measurement via live cell imaging, utilizing A549 cells, that can visualize and quantify autophagic flux in real time in single live cells. This approach is relatively straightforward in comparison to other experimental procedures and should be applicable to any in vitro cell/tissue models. Key features • Allows real-time qualitative imaging of autophagic flux at single-cell level. • Primary cells and cell lines can also be utilized with this technique. • Use of confocal microscopy allows visualization of autophagy without disturbing cellular functions.
    Keywords:  A549 cells; Autophagic flux; Confocal microscopy; DAPRed; Live cell imaging
    DOI:  https://doi.org/10.21769/BioProtoc.4949
  39. Neural Regen Res. 2024 Oct 01. 19(10): 2202-2211
    Endoplasmic reticulum stress, autophagy, neuroinflammation, and sigma 1 receptors as contributors to depression and its treatment.
    Chika Fujii, Charles F Zorumski, Yukitoshi Izumi.
      The etiological factors contributing to depression and other neuropsychiatric disorders are largely undefined. Endoplasmic reticulum stress pathways and autophagy are well-defined mechanisms that play critical functions in recognizing and resolving cellular stress and are possible targets for the pathophysiology and treatment of psychiatric and neurologic illnesses. An increasing number of studies indicate the involvement of endoplasmic reticulum stress and autophagy in the control of neuroinflammation, a contributing factor to multiple neuropsychiatric illnesses. Initial inflammatory triggers induce endoplasmic reticulum stress, leading to neuroinflammatory responses. Subsequently, induction of autophagy by neurosteroids and other signaling pathways that converge on autophagy induction are thought to participate in resolving neuroinflammation. The aim of this review is to summarize our current understanding of the molecular mechanisms governing the induction of endoplasmic reticulum stress, autophagy, and neuroinflammation in the central nervous system. Studies focused on innate immune factors, including neurosteroids with anti-inflammatory roles will be reviewed. In the context of depression, animal models that led to our current understanding of molecular mechanisms underlying depression will be highlighted, including the roles of sigma 1 receptors and pharmacological agents that dampen endoplasmic reticulum stress and associated neuroinflammation.
    DOI:  https://doi.org/10.4103/1673-5374.391334
  40. Int J Mol Sci. 2024 Feb 22. pii: 2560. [Epub ahead of print]25(5):
    Cisplatin Nephrotoxicity Is Critically Mediated by the Availability of BECLIN1.
    Tillmann Bork, Camila Hernando-Erhard, Wei Liang, Zhejia Tian, Kosuke Yamahara, Tobias B Huber.
      Cisplatin nephrotoxicity is a critical limitation of solid cancer treatment. Until now, the complex interplay of various pathophysiological mechanisms leading to proximal tubular cell apoptosis after cisplatin exposure has not been fully understood. In our study, we assessed the role of the autophagy-related protein BECLIN1 (ATG6) in cisplatin-induced acute renal injury (AKI)-a candidate protein involved in autophagy and with putative impact on apoptosis by harboring a B-cell lymphoma 2 (BCL2) interaction site of unknown significance. By using mice with heterozygous deletion of Becn1, we demonstrate that reduced intracellular content of BECLIN1 does not impact renal function or autophagy within 12 months. However, these mice were significantly sensitized towards cisplatin-induced AKI, and by using Becn1+/-;Sglt2-Cre;Tomato/EGFP mice with subsequent primary cell analysis, we confirmed that nephrotoxicity depends on proximal tubular BECLIN1 content. Mechanistically, BECLIN1 did not impact autophagy or primarily the apoptotic pathway. In fact, a lack of BECLIN1 sensitized mice towards cisplatin-induced ER stress. Accordingly, the ER stress inhibitor tauroursodeoxycholic acid (TUDCA) blunted cisplatin-induced cell death in Becn1 heterozygosity. In conclusion, our data first highlight a novel role of BECLIN1 in protecting against cellular ER stress independent from autophagy. These novel findings open new therapeutic avenues to intervene in this important intracellular stress response pathway with a promising impact on future AKI management.
    Keywords:  AKI; BECLIN1; ER stress; apoptosis; autophagy; cisplatin
    DOI:  https://doi.org/10.3390/ijms25052560
  41. Molecules. 2024 Feb 21. pii: 948. [Epub ahead of print]29(5):
    Utilizing Extracellular Vesicles for Eliminating 'Unwanted Molecules': Harnessing Nature's Structures in Modern Therapeutic Strategies.
    Monika Kisielewska, Katarzyna Rakoczy, Izabela Skowron, Julia Górczyńska, Julia Kacer, Agata Bocheńska, Anna Choromańska.
      Extracellular vesicles (EVs) are small phospholipid bilayer-bond structures released by diverse cell types into the extracellular environment, maintaining homeostasis of the cell by balancing cellular stress. This article provides a comprehensive overview of extracellular vesicles, their heterogeneity, and diversified roles in cellular processes, emphasizing their importance in the elimination of unwanted molecules. They play a role in regulating oxidative stress, particularly by discarding oxidized toxic molecules. Furthermore, endoplasmic reticulum stress induces the release of EVs, contributing to distinct results, including autophagy or ER stress transmission to following cells. ER stress-induced autophagy is a part of unfolded protein response (UPR) and protects cells from ER stress-related apoptosis. Mitochondrial-derived vesicles (MDVs) also play a role in maintaining homeostasis, as they carry damaged mitochondrial components, thereby preventing inflammation. Moreover, EVs partake in regulating aging-related processes, and therefore they can potentially play a crucial role in anti-aging therapies, including the treatment of age-related diseases such as Alzheimer's disease or cardiovascular conditions. Overall, the purpose of this article is to provide a better understanding of EVs as significant mediators in both physiological and pathological processes, and to shed light on their potential for therapeutic interventions targeting EV-mediated pathways in various pathological conditions, with an emphasis on age-related diseases.
    Keywords:  age-related diseases; aging process; autophagy; endoplasmic reticulum stress; extracellular vesicles; mitochondrial-derived vesicles; oxidative stress
    DOI:  https://doi.org/10.3390/molecules29050948
  42. Nat Commun. 2024 Mar 12. 15(1): 2235
    Theileria parasites sequester host eIF5A to escape elimination by host-mediated autophagy.
    Marie Villares, Nelly Lourenço, Ivan Ktorza, Jérémy Berthelet, Aristeidis Panagiotou, Aurélie Richard, Angélique Amo, Yulianna Koziy, Souhila Medjkane, Sergio Valente, Rossella Fioravanti, Catherine Pioche-Durieu, Laurent Lignière, Guillaume Chevreux, Antonello Mai, Jonathan B Weitzman.
      Intracellular pathogens develop elaborate mechanisms to survive within the hostile environments of host cells. Theileria parasites infect bovine leukocytes and cause devastating diseases in cattle in developing countries. Theileria spp. have evolved sophisticated strategies to hijack host leukocytes, inducing proliferative and invasive phenotypes characteristic of cell transformation. Intracellular Theileria parasites secrete proteins into the host cell and recruit host proteins to induce oncogenic signaling for parasite survival. It is unknown how Theileria parasites evade host cell defense mechanisms, such as autophagy, to survive within host cells. Here, we show that Theileria annulata parasites sequester the host eIF5A protein to their surface to escape elimination by autophagic processes. We identified a small-molecule compound that reduces parasite load by inducing autophagic flux in host leukocytes, thereby uncoupling Theileria parasite survival from host cell survival. We took a chemical genetics approach to show that this compound induced host autophagy mechanisms and the formation of autophagic structures via AMPK activation and the release of the host protein eIF5A which is sequestered at the parasite surface. The sequestration of host eIF5A to the parasite surface offers a strategy to escape elimination by autophagic mechanisms. These results show how intracellular pathogens can avoid host defense mechanisms and identify a new anti-Theileria drug that induces autophagy to target parasite removal.
    DOI:  https://doi.org/10.1038/s41467-024-45022-7
  43. Cells. 2024 Mar 01. pii: 437. [Epub ahead of print]13(5):
    GLA Mutations Suppress Autophagy and Stimulate Lysosome Generation in Fabry Disease.
    Ping Li, Yuqian Xi, Yanping Zhang, Abdus Samad, Wenli Lan, Ya Wu, Jiayu Zhao, Guangxin Chen, Changxin Wu, Qiuhong Xiong.
      Fabry disease (FD) is an X-linked recessive inheritance lysosomal storage disorder caused by pathogenic mutations in the GLA gene leading to a deficiency of the enzyme alpha-galactosidase A (α-Gal A). Multiple organ systems are implicated in FD, most notably the kidney, heart, and central nervous system. In our previous study, we identified four GLA mutations from four independent Fabry disease families with kidney disease or neuropathic pain: c.119C>A (p.P40H), c.280T>C (C94R), c.680G>C (p.R227P) and c.801+1G>A (p.L268fsX3). To reveal the molecular mechanism underlying the predisposition to Fabry disease caused by GLA mutations, we analyzed the effects of these four GLA mutations on the protein structure of α-galactosidase A using bioinformatics methods. The results showed that these mutations have a significant impact on the internal dynamics and structures of GLA, and all these altered amino acids are close to the enzyme activity center and lead to significantly reduced enzyme activity. Furthermore, these mutations led to the accumulation of autophagosomes and impairment of autophagy in the cells, which may in turn negatively regulate autophagy by slightly increasing the phosphorylation of mTOR. Moreover, the overexpression of these GLA mutants promoted the expression of lysosome-associated membrane protein 2 (LAMP2), resulting in an increased number of lysosomes. Our study reveals the pathogenesis of these four GLA mutations in FD and provides a scientific foundation for accurate diagnosis and precise medical intervention for FD.
    Keywords:  GLA; LAMP2; autophagy; fabry disease; kidney; lysosome; mTOR
    DOI:  https://doi.org/10.3390/cells13050437
  44. Int J Mol Sci. 2024 Feb 23. pii: 2587. [Epub ahead of print]25(5):
    mTOR Signaling: Recent Progress.
    Antonios N Gargalionis, Kostas A Papavassiliou, Athanasios G Papavassiliou.
      In the intricate landscape of human biology, the mechanistic target of rapamycin (mTOR) emerges as a key regulator, orchestrating a vast array of processes in health and disease [...].
    DOI:  https://doi.org/10.3390/ijms25052587
  45. Cell Mol Neurobiol. 2024 Mar 10. 44(1): 28
    The Potential of Targeting Autophagy-Related Non-coding RNAs in the Treatment of Alzheimer's and Parkinson's Diseases.
    Abdolkarim Talebi Taheri, Zakieh Golshadi, Hamidreza Zare, Azam Alinaghipour, Zahra Faghihi, Ehsan Dadgostar, Zeinab Tamtaji, Michael Aschner, Hamed Mirzaei, Omid Reza Tamtaji, Fatemeh Nabavizadeh.
      Clearance of accumulated protein aggregates is one of the functions of autophagy. Recently, a clearer understanding of non-coding RNAs (ncRNAs) functions documented that ncRNAs have important roles in several biological processes associated with the development and progression of neurodegenerative disorders. Subtypes of ncRNA, including microRNA (miRNA), long noncoding RNA (lncRNA), and circular RNA (circRNA), are commonly dysregulated in neurodegenerative disorders such as Alzheimer and Parkinson diseases. Dysregulation of these non-coding RNAs has been associated with inhibition or stimulation of autophagy. Decreased miR-124 led to decreased/increased autophagy in experimental model of Alzheimer and Parkinson diseases. Increased BACE1-AS showed enhanced autophagy in Alzheimer disease by targeting miR-214-3p, Beclin-1, LC3-I/LC3-II, p62, and ATG5. A significant increase in NEAT1led to stimulated autophagy in experimental model of PD by targeting PINK1, LC3-I, LC3-II, p62 and miR-374c-5p. In addition, increased BDNF-AS and SNHG1 decreased autophagy in MPTP-induced PD by targeting miR-125b-5p and miR-221/222, respectively. The upregulation of circNF1-419 and circSAMD4A resulted in an increased autophagy by regulating Dynamin-1 and miR-29c 3p, respectively. A detailed discussion of miRNAs, circRNAs, and lncRNAs in relation to their autophagy-related signaling pathways is presented in this study.
    Keywords:  Autophagy; Long non-coding (lnc) RNA; Neurodegenerative disorders; Non-coding RNAs; microRNA
    DOI:  https://doi.org/10.1007/s10571-024-01461-w
  46. Clin Immunol. 2024 Mar 11. pii: S1521-6616(24)00060-3. [Epub ahead of print] 110169
    From homeostasis to defense: Exploring the role of selective autophagy in innate immunity and viral infections.
    Mengyao Huang, Wei Zhang, Yang Yang, Wenhua Shao, Jiali Wang, Weijun Cao, Zixiang Zhu, Fan Yang, Haixue Zheng.
      The process of autophagy, a conservative evolutionary mechanism, is responsible for the removal of surplus and undesirable cytoplasmic components, thereby ensuring cellular homeostasis. Autophagy exhibits a remarkable level of selectivity by employing a multitude of cargo receptors that possess the ability to bind both ubiquitinated cargoes and autophagosomes. In the context of viral infections, selective autophagy plays a crucial role in regulating the innate immune system. Notably, numerous viruses have developed strategies to counteract, evade, or exploit the antiviral effects of selective autophagy. This review encompasses the latest research progress of selective autophagy in regulating innate immunity and virus infectious.
    Keywords:  Autophagy; Cargo receptor; Innate immunity; Selective autophagy; Viral infection
    DOI:  https://doi.org/10.1016/j.clim.2024.110169
  47. Vasc Specialist Int. 2024 Mar 15. 40 9
    Role of PTEN-Induced Protein Kinase 1 as a Mitochondrial Dysfunction Regulator in Cardiovascular Disease Pathogenesis.
    Jun Gyo Gwon, Seung Min Lee.
      Cardiovascular disease (CVD) remains a global health challenge, primarily due to atherosclerosis, which leads to conditions such as coronary artery disease, cerebrovascular disease, and peripheral arterial disease. Mitochondrial dysfunction initiates endothelial dysfunction, a key contributor to CVD pathogenesis, as well as triggers the accumulation of reactive oxygen species (ROS), energy stress, and cell death in endothelial cells, which are crucial for atherosclerosis development. This review explores the role of PTEN-induced protein kinase 1 (PINK1) in mitochondrial quality control, focusing on its significance in cardiovascular health. PINK1 plays a pivotal role in mitophagy (selective removal of damaged mitochondria), contributing to the prevention of CVD progression. PINK1-mediated mitophagy also affects the maintenance of cardiomyocyte homeostasis in ischemic heart disease, thus mitigating mitochondrial dysfunction and oxidative stress, as well as regulates endothelial health in atherosclerosis through influencing ROS levels and inflammatory response. We also investigated the role of PINK1 in vascular smooth muscle cells, emphasizing on its role in apoptosis and atherosclerosis. Dysfunctional mitophagy in these cells accelerates cellular senescence and contributes to adverse effects including plaque rupture and inflammation. Mitophagy has also been explored as a potential therapeutic target for vascular calcification, a representative lesion in atherosclerosis, with a focus on lactate-induced mechanisms. Finally, we highlight the current research and clinical trials targeting mitophagy as a therapeutic avenue for CVD.
    Keywords:  Cardiovascular disease; Endothelial dysfunction; Mitophagy; PTEN-induced protein kinase 1; Vascular calcification
    DOI:  https://doi.org/10.5758/vsi.230116
  48. bioRxiv. 2024 Feb 28. pii: 2024.02.24.581168. [Epub ahead of print]
    The Ubiquitin Ligase RBX2/SAG Regulates Mitochondrial Ubiquitination and Mitophagy.
    Wenjuan Wang, Ermin Li, Jianqiu Zou, Qu Chen, Juan Ayala, Yuan Wen, Md Sadikul Islam, Neal L Weintraub, David J Fulton, Qiangrong Liang, Jiliang Zhou, Jinbao Liu, Jie Li, Yi Sun, Huabo Su.
      Clearance of damaged mitochondria via mitophagy is crucial for cellular homeostasis. While the role of ubiquitin (Ub) ligase PARKIN in mitophagy has been extensively studied, increasing evidence suggests the existence of PARKIN-independent mitophagy in highly metabolically active organs such as the heart. Here, we identify a crucial role for Cullin-RING Ub ligase 5 (CRL5) in basal mitochondrial turnover in cardiomyocytes. CRL5 is a multi-subunit Ub ligase comprised by the catalytic RING box protein RBX2 (also known as SAG), scaffold protein Cullin 5 (CUL5), and a substrate-recognizing receptor. Analysis of the mitochondrial outer membrane-interacting proteome uncovered a robust association of CRLs with mitochondria. Subcellular fractionation, immunostaining, and immunogold electron microscopy established that RBX2 and Cul5, two core components of CRL5, localizes to mitochondria. Depletion of RBX2 inhibited mitochondrial ubiquitination and turnover, impaired mitochondrial membrane potential and respiration, and increased cell death in cardiomyocytes. In vivo , deletion of the Rbx2 gene in adult mouse hearts suppressed mitophagic activity, provoked accumulation of damaged mitochondria in the myocardium, and disrupted myocardial metabolism, leading to rapid development of dilated cardiomyopathy and heart failure. Similarly, ablation of RBX2 in the developing heart resulted in dilated cardiomyopathy and heart failure. Notably, the action of RBX2 in mitochondria is not dependent on PARKIN, and PARKIN gene deletion had no impact on the onset and progression of cardiomyopathy in RBX2-deficient hearts. Furthermore, RBX2 controls the stability of PINK1 in mitochondria. Proteomics and biochemical analyses further revealed a global impact of RBX2 deficiency on the mitochondrial proteome and identified several mitochondrial proteins as its putative substrates. These findings identify RBX2-CRL5 as a mitochondrial Ub ligase that controls mitophagy under physiological conditions in a PARKIN-independent, PINK1-dependent manner, thereby regulating cardiac homeostasis.
    Non-standard abbreviations and acronyms: RBX2, RING-Box Protein 2; SAG, Sensitive to Apoptosis Gene; Ub, Ubiquitin; pS65-Ub, phosphorylated Ub at serine 65; MAVS, mitochondrial antiviral-signaling protein; AAV, adeno-associated virus; AV, adenovirus; siRNA, Small interfering RNA; GFP, green fluorescent protein; CUL, cullin; RING, Really Interesting New Gene; CRLs, cullin-RING ligases; CSN, COP9 signalosome; APEX2, ascorbate peroxidase 2; mito, mitochondrial; cyto, cytosolic; MOM, mitochondrial outer membrane; CCCP, Carbonyl Cyanide Chlorophenylhydrazone; OMP25, Outer membrane protein 25; PK, proteinase K; HA, hemagglutinin; TMRM, Tetramethylrhodamine methyl ester perchlorate; αMHC,α-myosin heavy chain; CKO, cardiomyocyte-specific knockout; TAM, tamoxifen; TMT, tandem mass tag; KD, knockdown; CTL, control; MCM, MerCreMer; iCKO, inducible cardiomyocyte-specific knockout; BFA, bafilomycin A1; PCA, principle component analysis; MS, Mass spectrometry; DEPs, differentially expressed proteins; FC, fold change; FDR, False Discovery Rate; KEGG, Kyoto encyclopedia of genes and genomes; ER, endoplasmic reticulum; DKO, double knockout; CM, cardiomyocyte; cTnT, cardiac troponin T; NRVCs, neonatal rat ventricular cardiomyocytes; NRVMs, neonatal mouse ventricular cardiomyocytes; NMVFs, neonatal mouse ventricular fibroblasts; HF, heart failure; KO, knockout; MF, Molecular Functions; CC, Cellular Components; BP, Biological Process; TUNEL, Terminal deoxynucleotidyl transferase dUTP nick end labeling; SCF, Skp1-Cullin 1-F-box.
    DOI:  https://doi.org/10.1101/2024.02.24.581168
  49. J Diabetes Investig. 2024 Mar 12.
    Role of β-cell autophagy in β-cell physiology and the development of diabetes.
    Xaviera Riani Yasasilka, Myung-Shik Lee.
      Elucidating the molecular mechanism of autophagy was a landmark in understanding not only the physiology of cells and tissues, but also the pathogenesis of diverse diseases, including diabetes and metabolic disorders. Autophagy of pancreatic β-cells plays a pivotal role in the maintenance of the mass, structure and function of β-cells, whose dysregulation can lead to abnormal metabolic profiles or diabetes. Modulators of autophagy are being developed to improve metabolic profile and β-cell function through the removal of harmful materials and rejuvenation of organelles, such as mitochondria and endoplasmic reticulum. Among the known antidiabetic drugs, glucagon-like peptide-1 receptor agonists enhance the autophagic activity of β-cells, which might contribute to the profound effects of glucagon-like peptide-1 receptor agonists on systemic metabolism. In this review, the results from studies on the role of autophagy in β-cells and their implication in the development of diabetes are discussed. In addition to non-selective (macro)autophagy, the role and mechanisms of selective autophagy and other minor forms of autophagy that might occur in β-cells are discussed. As β-cell failure is the ultimate cause of diabetes and unresponsiveness to conventional therapy, modulation of β-cell autophagy might represent a future antidiabetic treatment approach, particularly in patients who are not well managed with current antidiabetic therapy.
    Keywords:  Autophagy; Lysosome; β-Cells
    DOI:  https://doi.org/10.1111/jdi.14184
  50. Nat Rev Clin Oncol. 2024 Mar 14.
    Targeting cuproplasia and cuproptosis in cancer.
    Daolin Tang, Guido Kroemer, Rui Kang.
      Copper, an essential trace element that exists in oxidized and reduced forms, has pivotal roles in a variety of biological processes, including redox chemistry, enzymatic reactions, mitochondrial respiration, iron metabolism, autophagy and immune modulation; maintaining copper homeostasis is crucial as both its deficiency and its excess are deleterious. Dysregulated copper metabolism has a dual role in tumorigenesis and cancer therapy. Specifically, cuproplasia describes copper-dependent cell growth and proliferation, including hyperplasia, metaplasia and neoplasia, whereas cuproptosis refers to a mitochondrial pathway of cell death triggered by excessive copper exposure and subsequent proteotoxic stress (although complex interactions between cuproptosis and other cell death mechanisms, such as ferroptosis, are likely and remain enigmatic). In this Review, we summarize advances in our understanding of copper metabolism, the molecular machineries underlying cuproplasia and cuproptosis, and their potential targeting for cancer therapy. These new findings advance the rapidly expanding field of translational cancer research focused on metal compounds.
    DOI:  https://doi.org/10.1038/s41571-024-00876-0
  51. Int J Mol Sci. 2024 Mar 02. pii: 2918. [Epub ahead of print]25(5):
    Autophagy and Symbiosis: Membranes, ER, and Speculations.
    Maria G Semenova, Alekandra N Petina, Elena E Fedorova.
      The interaction of plants and soil bacteria rhizobia leads to the formation of root nodule symbiosis. The intracellular form of rhizobia, the symbiosomes, are able to perform the nitrogen fixation by converting atmospheric dinitrogen into ammonia, which is available for plants. The symbiosis involves the resource sharing between two partners, but this exchange does not include equivalence, which can lead to resource scarcity and stress responses of one of the partners. In this review, we analyze the possible involvement of the autophagy pathway in the process of the maintenance of the nitrogen-fixing bacteria intracellular colony and the changes in the endomembrane system of the host cell. According to in silico expression analysis, ATG genes of all groups were expressed in the root nodule, and the expression was developmental zone dependent. The analysis of expression of genes involved in the response to carbon or nitrogen deficiency has shown a suboptimal access to sugars and nitrogen in the nodule tissue. The upregulation of several ER stress genes was also detected. Hence, the root nodule cells are under heavy bacterial infection, carbon deprivation, and insufficient nitrogen supply, making nodule cells prone to autophagy. We speculate that the membrane formation around the intracellular rhizobia may be quite similar to the phagophore formation, and the induction of autophagy and ER stress are essential to the success of this process.
    Keywords:  Medicago truncatula; autophagy; cell membranes; root nodule; symbiosis
    DOI:  https://doi.org/10.3390/ijms25052918
  52. J Pharm Anal. 2024 Feb;14(2): 211-224
    Pyrimethamine upregulates BNIP3 to interfere SNARE-mediated autophagosome-lysosomal fusion in hepatocellular carcinoma.
    Jingjing Wang, Qi Su, Kun Chen, Qing Wu, Jiayan Ren, Wenjuan Tang, Yu Hu, Zeren Zhu, Cheng Cheng, Kaihui Tu, Huaizhen He, Yanmin Zhang.
      Hepatocellular carcinoma (HCC) is one of the most common tumor types and remains a major clinical challenge. Increasing evidence has revealed that mitophagy inhibitors can enhance the effect of chemotherapy on HCC. However, few mitophagy inhibitors have been approved for clinical use in humans. Pyrimethamine (Pyr) is used to treat infections caused by protozoan parasites. Recent studies have reported that Pyr may be beneficial in the treatment of various tumors. However, its mechanism of action is still not clearly defined. Here, we found that blocking mitophagy sensitized cells to Pyr-induced apoptosis. Mechanistically, Pyr potently induced the accumulation of autophagosomes by inhibiting autophagosome-lysosome fusion in human HCC cells. In vitro and in vivo studies revealed that Pyr blocked autophagosome-lysosome fusion by upregulating BNIP3 to inhibit synaptosomal-associated protein 29 (SNAP29)-vesicle-associated membrane protein 8 (VAMP8) interaction. Moreover, Pyr acted synergistically with sorafenib (Sora) to induce apoptosis and inhibit HCC proliferation in vitro and in vivo. Pyr enhances the sensitivity of HCC cells to Sora, a common chemotherapeutic, by inhibiting mitophagy. Thus, these results provide new insights into the mechanism of action of Pyr and imply that Pyr could potentially be further developed as a novel mitophagy inhibitor. Notably, Pyr and Sora combination therapy could be a promising treatment for malignant HCC.
    Keywords:  Autophagosome-lysosome fusion; BNIP3; Hepatocellular carcinoma; Pyrimethamine; SNARE; Sorafenib
    DOI:  https://doi.org/10.1016/j.jpha.2023.05.014
  53. Cell Signal. 2024 Mar 10. pii: S0898-6568(24)00104-9. [Epub ahead of print] 111136
    microRNA-125b-1-3p mediates autophagy via the RRAGD/mTOR/ULK1 signaling pathway and mitigates atherosclerosis progression.
    Xin Chen, Yanhong Cao, Yining Guo, Jing Liu, Xiaohan Ye, Huan Li, Lu Zhang, Wenwei Feng, Shaoxiang Xian, Zhongqi Yang, Lingjun Wang, Ting Wang.
      Atherosclerosis is characterised by lipid accumulation and formation of foam cells in arterial walls. Dysregulated autophagy is a crucial factor in atherosclerosis development. The significance of microRNA (miR)-125b-1-3p in cardiovascular disease is well-established; however, its precise role in regulating autophagy and impact on atherosclerosis in vascular smooth muscle cells (VSMCs) remain unclear. Here, we observed reduced autophagic activity and decreased miR-125b expression during atherosclerosis progression. miR-125b-1-3p overexpression significantly reduced atherosclerotic plaque development in mice; it also led to decreased lipid uptake and deposition in VSMCs, enhanced autophagy, and suppression of smooth muscle cell phenotypic changes in-vitro. An interaction between miR-125b-1-3p and the RRAGD/mTOR/ULK1 pathway was revealed, elucidating its role in promoting autophagy. Therefore, miR-125b-1-3p plays a pivotal role in enhancing autophagic processes, inhibiting foam cell formation in VSMCs and mitigating atherosclerosis progression, partly through RRAGD/mTOR/ULK1 signaling axis modulation. Thus, miR-125b-1-3p is a promising target for preventive and therapeutic strategies for atherosclerosis.
    Keywords:  Atherosclerosis; Autophagic activity; RRAGD/mTOR/ULK1 pathway; miR-125b-1-3p
    DOI:  https://doi.org/10.1016/j.cellsig.2024.111136
  54. Environ Pollut. 2024 Mar 08. pii: S0269-7491(24)00454-8. [Epub ahead of print] 123740
    TDCPP and TiO2 NPs aggregates synergistically induce SH-SY5Y cell neurotoxicity by excessive mitochondrial fission and mitophagy inhibition.
    Ling Wang, Binquan Wang, Xiaoyan Zhang, Ziyi Yang, Xing Zhang, Hongyang Gong, Yuanyuan Song, Ke Zhang, Mingkuan Sun.
      Tris (1,3-dichloro-2-propyl) phosphate (TDCPP), a halogen-containing phosphorus flame retardant, is widely used and has been shown to possess health risks to humans. The sustained release of artificial nanomaterials into the environment increases the toxicological risks of their coexisting pollutants. Nanomaterials may seriously change the environmental behavior and fate of pollutants. In this study, we investigated this combined toxicity and the potential mechanisms of toxicity of TDCPP and titanium dioxide nanoparticles (TiO2 NPs) aggregates on human neuroblastoma SH-SY5Y cells. TDCPP and TiO2 NPs aggregates were exposed in various concentration combinations, revealing that TDCPP (25 μg/mL) reduced cell viability, while synergistic exposure to TiO2 NPs aggregates exacerbated cytotoxicity. This combined exposure also disrupted mitochondrial function, leading to dysregulation in the expression of mitochondrial fission proteins (DRP1 and FIS1) and fusion proteins (OPA1 and MFN1). Consequently, excessive mitochondrial fission occurred, facilitating the translocation of cytochrome C from mitochondria to activate apoptotic signaling pathways. Furthermore, exposure of the combination of TDCPP and TiO2 NPs aggregates activated upstream mitochondrial autophagy but disrupted downstream Parkin recruitment to damaged mitochondria, preventing autophagosome-lysosome fusion and thereby disrupting mitochondrial autophagy. Altogether, our findings suggest that TDCPP and TiO2 NPs aggregates may stimulate apoptosis in neuronal SH-SY5Y cells by inducing mitochondrial hyperfission and inhibiting mitochondrial autophagy.
    Keywords:  Apoptosis; Autophagic flux; Mitochondrial dysfunction; Neurotoxic effects; TDCPP; TiO(2) NPs aggregates
    DOI:  https://doi.org/10.1016/j.envpol.2024.123740
  55. Sci Rep. 2024 03 13. 14(1): 6049
    Pathogenic mutations in UBQLN2 exhibit diverse aggregation propensity and neurotoxicity.
    Nathaniel Safren, Thuy P Dao, Harihar Milaganur Mohan, Camellia Huang, Bryce Trotter, Carlos A Castañeda, Henry Paulson, Sami Barmada, Lisa M Sharkey.
      The ubiquitin-adaptor protein UBQLN2 promotes degradation of several aggregate-prone proteins implicated in neurodegenerative diseases. Missense UBQLN2 mutations also cause X-linked amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Previously we demonstrated that the liquid-like properties of UBQLN2 molecular assemblies are altered by a specific pathogenic mutation, P506T, and that the propensity of UBQLN2 to aggregate correlated with neurotoxicity. Here, we systematically assess the effects of multiple, spatially distinct ALS/FTD-linked missense mutations on UBQLN2 aggregation propensity, neurotoxicity, phase separation, and autophagic flux. In contrast to what we observed for the P506T mutation, no other tested pathogenic mutant exhibited a clear correlation between aggregation propensity and neurotoxicity. These results emphasize the unique nature of pathogenic UBQLN2 mutations and argue against a generalizable link between aggregation propensity and neurodegeneration in UBQLN2-linked ALS/FTD.
    DOI:  https://doi.org/10.1038/s41598-024-55582-9
  56. J Virol. 2024 Mar 11. e0005124
    SQSTM1 downregulates avian metapneumovirus subgroup C replication via mediating selective autophagic degradation of viral M2-2 protein.
    Jinshuo Guo, Yongyan Shi, Genghong Jiang, Penghui Zeng, Zhi Wu, Dedong Wang, Yongqiu Cui, Xiaoyu Yang, Jianwei Zhou, Xufei Feng, Lei Hou, Jue Liu.
      Avian metapneumovirus subgroup C (aMPV/C), an important pathogen causing acute respiratory infection in chickens and turkeys, contributes to substantial economic losses in the poultry industry worldwide. aMPV/C has been reported to induce autophagy, which is beneficial to virus replication. Sequestosome 1 (SQSTM1/P62), a selective autophagic receptor, plays a crucial role in viral replication by clearing ubiquitinated proteins. However, the relationship between SQSTM1-mediated selective autophagy and aMPV/C replication is unclear. In this study, we found that the expression of SQSTM1 negatively regulates aMPV/C replication by reducing viral protein expression and viral titers. Further studies revealed that the interaction between SQSTM1 and aMPV/C M2-2 protein is mediated via the Phox and Bem1 (PB1) domain of the former, which recognizes a ubiquitinated lysine at position 67 of the M2-2 protein, and finally degrades M2-2 via SQSTM1-mediated selective autophagy. Collectively, our results reveal that SQSTM1 degrades M2-2 via a process of selective autophagy to suppress aMPV/C replication, thereby providing novel insights for the prevention and control of aMPV/C infection.IMPORTANCEThe selective autophagy plays an important role in virus replication. As an emerging pathogen of avian respiratory virus, clarification of the effect of SQSTM1, a selective autophagic receptor, on aMPV/C replication in host cells enables us to better understand the viral pathogenesis. Previous study showed that aMPV/C infection reduced the SQSTM1 expression accompanied by virus proliferation, but the specific regulatory mechanism between them was still unclear. In this study, we demonstrated for the first time that SQSTM1 recognizes the 67th amino acid of M2-2 protein by the interaction between them, followed by M2-2 degradation via the SQSTM1-mediated selective autophagy, and finally inhibits aMPV/C replication. This information supplies the mechanism by which SQSTM1 negatively regulates viral replication, and provides new insights for preventing and controlling aMPV/C infection.
    Keywords:  M2-2 protein; SQSTM1; aMPV/C; selective autophagy; viral replication
    DOI:  https://doi.org/10.1128/jvi.00051-24
  57. Environ Toxicol. 2024 Mar 13.
    Lysine specific demethylase 1 inhibits sodium arsenite activation of HSCs by regulating SESN2/AMPK/ULK1 signaling pathway activity.
    Yingwan Zhang, Tian Tian, Cai Liang, Junli Wang, Jiayuan Zhang, Shanshan Tian, Rujia Xie, Ting Yang, Bing Han.
      Lysine specific demethylase 1 (LSD1) is a histone demethylase that specifically catalyzes the demethylation of histone H3K4 (H3K4me1/2) and regulates gene expression. In addition, it can mediate the process of autophagy through its demethylase activity. Sestrin2 (SESN2) is a stress-induced protein and a positive regulator of autophagy. In NaAsO2 -induced mouse fibrotic livers and activated hepatic stellate cells (HSCs), LSD1 expression is decreased, SESN2 expression is increased, and autophagy levels are also increased. Overexpression of LSD1 and silencing of SESN2 decreased the level of autophagy and attenuated the activation of HSCs induced by NaAsO2 . LSD1 promoted SESN2 gene transcription by increasing H3K4me1/2 in the SESN2 promoter region. 3-methyladenine (3-MA) and chloroquine were used to inhibit autophagy of HSCs, and the degree of activation was also alleviated. Taken together, LSD1 positively regulates SESN2 by increasing H3K4me1/2 enrichment in the SESN2 promoter region, which in turn increases the level of autophagy and promotes the activation of HSCs. Our results may provide new evidence for the importance of LSD1 in the process of autophagy and activation of HSCs induced by arsenic poisoning. Increasing the expression and activity of LSD1 is expected to be an effective way to reverse the autophagy and activation of HSCs induced by arsenic poisoning.
    Keywords:  LSD1; NaAsO2; SESN2; autophagy; hepatic fibrosis
    DOI:  https://doi.org/10.1002/tox.24184
  58. Clin Transl Sci. 2024 Mar;17(3): e13749
    Investigating the role of an immediate early gene FOS as a potential regulator of autophagic response to hypoglycemia in embryonic hypothalamic neurons.
    Rakhee K Ramakrishnan, Ankita Srivastava, Reeja Rajan, Salah Abusnana, Bashair M Mussa.
      Hypoglycemia-associated autonomic failure (HAAF) is a well-established complication of diabetes. Although HAAF has serious outcomes such as recurrent morbidity, coma, and death, the mechanisms of HAAF and its pathological components are largely unknown. Our previous studies have revealed that hypoglycemia is associated with the upregulation of an immediate early gene - FOS. In addition, it is documented that glucose deprivation activates neuronal autophagic activities. Therefore, the present study aimed to identify the role of FOS and one of the core components of the autophagy pathway, Beclin-1 (encoded by the BECN1 gene), in the regulation of autophagic mechanisms in embryonic hypothalamic neurons in response to hypoglycemic conditions. Embryonic Mouse Hypothalamic Cell Line N39 (mHypoE-N39 or N39) was cultured in reduced concentrations of glucose (2000, 900, 500, and 200 mg/L). Gene and protein expression, as well as immunofluorescence studies on autophagy were conducted under different reduced glucose concentrations in N39 hypothalamic neurons with and without FOS and BECN1 gene knockdowns (KD). The outcomes of the present study have demonstrated a significant increase in autophagosome formation and subsequent lysosomal degradation in the hypothalamic neurons in response to reduced glucose concentrations. This hypoglycemic response appears to be lowered to a similar extent in the FOS KD and BECN1 KD cells, albeit insignificantly from the negative control, is indicative of the involvement of FOS in the autophagic response of hypothalamic neurons to hypoglycemia. Moreover, the KD cells exhibited a change in morphology and reduced cell viability compared with the control cells. Our findings suggest that reduced FOS expression could potentially be associated with impaired autophagic activities that are dependent on BECN1, which could lead to decreased or blunted hypothalamic activation in response to hypoglycemia, and this, in turn, may contribute to the development of HAAF.
    DOI:  https://doi.org/10.1111/cts.13749
  59. J Mol Cell Cardiol. 2024 Mar 13. pii: S0022-2828(24)00034-8. [Epub ahead of print]189 83-89
    Myocardial glycophagy flux dysregulation and glycogen accumulation characterize diabetic cardiomyopathy.
    Kimberley M Mellor, Upasna Varma, Parisa Koutsifeli, Lorna J Daniels, Victoria L Benson, Marco Annandale, Xun Li, Yohanes Nursalim, Johannes V Janssens, Kate L Weeks, Kim L Powell, Terence J O'Brien, Rajesh Katare, Rebecca H Ritchie, James R Bell, Roberta A Gottlieb, Lea M D Delbridge.
      Diabetic heart disease morbidity and mortality is escalating. No specific therapeutics exist and mechanistic understanding of diabetic cardiomyopathy etiology is lacking. While lipid accumulation is a recognized cardiomyocyte phenotype of diabetes, less is known about glycolytic fuel handling and storage. Based on in vitro studies, we postulated the operation of an autophagy pathway in the myocardium specific for glycogen homeostasis - glycophagy. Here we visualize occurrence of cardiac glycophagy and show that the diabetic myocardium is characterized by marked glycogen elevation and altered cardiomyocyte glycogen localization. We establish that cardiac glycophagy flux is disturbed in diabetes. Glycophagy may represent a potential therapeutic target for alleviating the myocardial impacts of metabolic disruption in diabetic heart disease.
    Keywords:  Autophagy; Cardiac glycogen; Cardiac metabolism; Diabetic heart disease; Glycophagy
    DOI:  https://doi.org/10.1016/j.yjmcc.2024.02.009
  60. Genet Med. 2024 Mar 09. pii: S1098-3600(24)00053-4. [Epub ahead of print] 101120
    Biallelic USP14 variants cause a syndromic neurodevelopmental disorder.
    Frédéric Ebstein, Xenia Latypova, Ka Ying Sharon Hung, Miguel A Prado, Byung-Hoon Lee, Sophie Möller, Martin Wendlandt, Barbara A Zieba, Laëtitia Florenceau, Virginie Vignard, Léa Poirier, Bérénice Toutain, Isabella Moroni, Charlotte Dubucs, Nicolas Chassaing, Judit Horvath, Holger Prokisch, Sébastien Küry, Stéphane Bézieau, Joao A Paulo, Daniel Finley, Elke Krüger, Daniele Ghezzi, Bertrand Isidor.
       PURPOSE: Imbalances in protein homeostasis affect human brain development, with the ubiquitin-proteasome system (UPS) and autophagy playing crucial roles in neurodevelopmental disorders (NDD). This study explores the impact of biallelic USP14 variants on neurodevelopment, focusing on its role as a key hub connecting UPS and autophagy.
    METHODS: Here, we identified biallelic USP14 variants in four individuals from three unrelated families: one fetus, a newborn with a syndromic NDD, and two siblings affected by a progressive neurological disease. Specifically, the two siblings from the latter family carried two compound heterozygous variants c.8T>C p.(Leu3Pro) and c.988C>T p.(Arg330*), while the fetus had a homozygous frameshift c.899_902del p.(Lys300Serfs*24) variant and the newborn patient harbored a homozygous frameshift c.233_236del p.(Leu78Glnfs*11) variant. Functional studies were conducted using SDS-PAGE, Western blotting, and mass spectrometry analyses in both patient-derived and CRISPR-Cas-generated cells.
    RESULTS: Our investigations indicated that the USP14 variants correlated with reduced N-terminal methionine excision, along with profound alterations in proteasome, autophagy, and mitophagy activities.
    CONCLUSION: Biallelic USP14 variants in NDD patients perturbed protein degradation pathways, potentially contributing to disorder etiology. Altered UPS, autophagy, and mitophagy activities underscore the intricate interplay, elucidating their significance in maintaining proper protein homeostasis during brain development.
    Keywords:  N-terminal methionine excision; Neurodevelopmental disorders; USP14; loss-of-function variants; ubiquitin-proteasome system
    DOI:  https://doi.org/10.1016/j.gim.2024.101120
  61. J Vis Exp. 2024 Feb 23.
    Ferritinophagy: Assessing the Selective Degradation of Iron by Autophagy in Human Fibroblasts.
    Carmen J Pastor-Maldonado, Tassula Proikas-Cezanne.
      Mutations in the autophagy gene WDR45/WIPI4 are the cause of beta-propeller-associated neurodegeneration (BPAN), a subtype of human diseases known as neurodegeneration with brain iron accumulation (NBIA) due to the presence of iron deposits in the brains of patients. Intracellular iron levels are tightly regulated by a number of cellular mechanisms, including the critical mechanism of ferritinophagy. This paper describes how ferritinophagy can be assessed in primary, skin-derived human fibroblasts. In this protocol, we use iron-modulating conditions for inducing or inhibiting ferritinophagy at the cellular level, such as the administration of bafilomycin A1 to inhibit lysosome function and ferric ammonium citrate (FAC) or deferasiox (DFX) treatments to overload or deplete iron, respectively. Such treated fibroblasts are then subjected to high-throughput imaging and CellProfiler-based quantitative localization analysis of endogenous ferritin and autophagosomal/lysosomal markers, here LAMP2. Based on the level of autophagosomal/lysosomal ferritin, conclusions can be drawn regarding the level of ferritinophagy. This protocol can be used to assess ferritinophagy in BPAN patient-derived primary fibroblasts or other types of mammalian cells.
    DOI:  https://doi.org/10.3791/65110
  62. Toxicol Lett. 2024 Mar 07. pii: S0378-4274(24)00043-2. [Epub ahead of print]394 102-113
    Toosendanin induces hepatotoxicity by restraining autophagy and lysosomal function through inhibiting STAT3/CTSC axis.
    Li Luo, Jiajie Ni, Jiahui Zhang, Jinxian Lin, Sixin Chen, Feihai Shen, Zhiying Huang.
      Toosendanin (TSN) is the main active component in the traditional herb Melia toosendan Siebold & Zucc, which exhibits promising potential for development due to its diverse pharmacological properties. However, the hepatotoxicity associated with TSN needs further investigation. Previous research has implicated autophagy dysregulation in TSN-induced hepatotoxicity, yet the underlying mechanisms remain elusive. In this study, the mechanisms of signal transducer and activator of transcription 3 (STAT3) in TSN-induced autophagy inhibition and liver injury were explored using Stat3 knockout C57BL/6 mice and HepG2 cells. TSN decreased cell viability, increased lactate dehydrogenase (LDH) production in vitro, and elevated serum aspartate transaminase (AST) and alanine aminotransferase (ALT) levels as well as liver lesions in vivo, suggesting TSN had significant hepatotoxicity. TSN inhibited Janus kinase 2 (JAK2)/STAT3 pathway and the expression of cathepsin C (CTSC). Inhibition of STAT3 exacerbated TSN-induced autophagy inhibition and hepatic injury, whereas activation of STAT3 attenuated these effects of TSN. Mechanistically, STAT3 transcriptionally regulated the level of CTSC gene, which in turn affected autophagy and the process of liver injury. TSN-administered Stat3 knockout mice showed more severe hepatotoxicity, CTSC downregulation, and autophagy blockade than wildtype mice. In summary, TSN caused hepatotoxicity by inhibiting STAT3/CTSC axis-dependent autophagy and lysosomal function.
    Keywords:  Autophagy; Cathepsin C; Hepatotoxicity; Lysosome; Signal transducer and activator of transcription 3; Toosendanin
    DOI:  https://doi.org/10.1016/j.toxlet.2024.03.002
  63. Cell Death Discov. 2024 Mar 11. 10(1): 127
    mTORC1 accelerates osteosarcoma progression via m6A-dependent stabilization of USP7 mRNA.
    Zhengming Yang, Wei Yu, Ankai Xu, Bing Liu, Libin Jin, Huimin Tao, Dimin Wang.
      Osteosarcoma (OS) is considered a sex steroid hormone-dependent bone tumor. The development and progression of OS are regulated by 17β-estradiol (E2). However, the detailed mechanisms of E2-modulated OS progression remained to be elucidated. Here, we found that E2-activated mammalian target of rapamycin (mTOR) signaling promoted N6-methyladenosine (m6A) modification through regulating WTAP. Inhibition of mTOR complex 1 (mTORC1) reversed E2-activated WTAP expression. Meanwhile, inhibition of mTORC1 suppressed OS cell proliferation and migration. Deficiency of TSC2 activated mTORC1 signaling and enhanced OS cell proliferation and migration, while abrogated by Rapamycin. Interestingly, mTOMC1 promoted mRNA stability of ubiquitin-specific protease 7 (USP7) through m6A modification. Loss of USP7 suppressed the proliferation, migration, and ASC specks, while promoted apoptosis of OS cells. USP7 interacted with NLRP3 and deubiquitinated NLRP3 through K48-ubiquitination. USP7 was upregulated and positive correlation with NLRP3 in OS patients with high level of E2. Loss of USP7 suppressed the progression of OS via inhibiting NLRP3 inflammasome signaling pathway. Our results demonstrated that E2-activtated mTORC1 promoted USP7 stability, which promoted OS cell proliferation and migration via upregulating NLRP3 expression and enhancing NLRP3 inflammasome signaling pathway. These results discover a novel mechanism of E2 regulating OS progression and provide a promising therapeutic target for OS progression.
    DOI:  https://doi.org/10.1038/s41420-024-01893-9
  64. Cancer Res Commun. 2024 Mar 11.
    Autophagy inhibition-induced cytosolic DNA sensing combined with differentiation therapy induces irreversible myeloid differentiation in leukemia cells.
    Tomohisa Baba, Utano Tomaru, Atsushi Hirao, Naofumi Mukaida, Yoshikazu Johmura.
      Accumulating evidence indicates that various oncogenic mutations interfere with normal myeloid differentiation of leukemogenic cells during the early process of acute myeloid leukemia (AML) development. Differentiation therapy is a therapeutic strategy capable of terminating leukemic expansion by reactivating the differentiation potential; however, the plasticity and instability of leukemia cells counteract the establishment of treatments aimed at irreversibly inducing and maintaining their differentiation states. Based on our previous observation that autophagy inhibitor treatment induces the accumulation of cytosolic DNA and activation of cytosolic DNA-sensor signaling selectively in leukemia cells, we herein examined the synergistic effect of cytosolic DNA-sensor signaling activation with conventional differentiation therapy on AML. The combined treatment succeeded in inducing irreversible differentiation in AML cell lines. Mechanistically, cytosolic DNA was sensed by absent in melanoma 2 (AIM2), a cytosolic DNA sensor. Activation of the AIM2 inflammasome resulted in the accumulation of p21 through the inhibition of its proteasomal degradation, thereby facilitating the myeloid differentiation. Importantly, the combined therapy dramatically reduced the total leukemia cell counts and proportion of blast cells in the spleens of AML mice. Collectively, these findings indicate that the autophagy inhibition-cytosolic DNA-sensor signaling axis can potentiate AML differentiation therapy.
    DOI:  https://doi.org/10.1158/2767-9764.CRC-23-0507
  65. Nat Commun. 2024 Mar 13. 15(1): 2264
    NME3 is a gatekeeper for DRP1-dependent mitophagy in hypoxia.
    Chih-Wei Chen, Chi Su, Chang-Yu Huang, Xuan-Rong Huang, Xiaojing Cuili, Tung Chao, Chun-Hsiang Fan, Cheng-Wei Ting, Yi-Wei Tsai, Kai-Chien Yang, Ti-Yen Yeh, Sung-Tsang Hsieh, Yi-Ju Chen, Yuxi Feng, Tony Hunter, Zee-Fen Chang.
      NME3 is a member of the nucleoside diphosphate kinase (NDPK) family localized on the mitochondrial outer membrane (MOM). Here, we report a role of NME3 in hypoxia-induced mitophagy dependent on its active site phosphohistidine but not the NDPK function. Mice carrying a knock-in mutation in the Nme3 gene disrupting NME3 active site histidine phosphorylation are vulnerable to ischemia/reperfusion-induced infarction and develop abnormalities in cerebellar function. Our mechanistic analysis reveals that hypoxia-induced phosphatidic acid (PA) on mitochondria is essential for mitophagy and the interaction of DRP1 with NME3. The PA binding function of MOM-localized NME3 is required for hypoxia-induced mitophagy. Further investigation demonstrates that the interaction with active NME3 prevents DRP1 susceptibility to MUL1-mediated ubiquitination, thereby allowing a sufficient amount of active DRP1 to mediate mitophagy. Furthermore, MUL1 overexpression suppresses hypoxia-induced mitophagy, which is reversed by co-expression of ubiquitin-resistant DRP1 mutant or histidine phosphorylatable NME3. Thus, the site-specific interaction with active NME3 provides DRP1 a microenvironment for stabilization to proceed the segregation process in mitophagy.
    DOI:  https://doi.org/10.1038/s41467-024-46385-7
  66. Curr Mol Pharmacol. 2024 Feb 27.
    Quercetin Enhances 5-fluorouracil Sensitivity by Regulating the Autophagic Flux and Inducing Drp-1 Mediated Mitochondrial Fragmentation in Colorectal Cancer Cells.
    Mei Li, Jiaoxiu Fan, Min Hu, Junyu Xu, Ziyue He, Jun Zeng.
       BACKGROUND: While chemotherapy treatment demonstrates its initial effectiveness in eliminating the majority of the tumor cell population, nevertheless, most patients relapse and eventually succumb to the disease upon its recurrence. One promising approach is to explore novel, effective chemotherapeutic adjuvants to enhance the sensitivity of cancer cells to conventional chemotherapeutic agents. In the present study, we explored the effect of quercetin on the sensitivity of colorectal cancer (CRC) cells to conventional chemotherapeutic agent 5-fluorouracil (5-FU) and the molecular mechanisms.
    METHODS: MTT assay, colony formation assay and Hoechst staining were performed to investigate the growth inhibition effect of quercetin alone or combined with 5-FU. The expression levels of apoptosis- and autophagy-related proteins were assessed by western blotting. Intracellular ROS was detected using DCFH-DA. The change in the mitochondrial membrane potential was measured by a JC-1 probe. The effect of quercetin on mitochondrial morphology was examined using a mitochondrial-specific fluorescence probe, Mito-Tracker red.
    RESULTS: The results demonstrated quercetin-induced apoptosis and autophagy, as well as imbalanced ROS, decreased mitochondrial membrane potential, and Drp-1-mediated mitochondrial fission in CRC cells. Autophagy blockage with autophagy inhibitor chloroquine (CQ) enhanced quercetininduced cytotoxicity, indicating that quercetin-induced cytoprotective autophagy. Meanwhile, quercetin enhanced the sensitivity of CRC cells to 5- FU via the induction of mitochondrial fragmentation, which could be further enhanced when the quercetin-induced protective autophagy was blocked by CQ.
    CONCLUSION: Our findings suggested that quercetin could induce protective autophagy and Drp-1-mediated mitochondrial fragmentation and enhance the sensitivity of CRC cells to conventional agent 5-FU, which not only suggests that quercetin may act as a chemotherapeutic adjuvant but also implies that the regulation of autophagic flux may be a potential therapeutic strategy for colorectal cancer.
    Keywords:  Autophagic flux; Autophagy; Chemotheraphy.; Colorectal cancer; Mitochondrial fragmentation; Quercetin
    DOI:  https://doi.org/10.2174/0118761429283717231222104730
  67. Cell Mol Life Sci. 2024 Mar 14. 81(1): 141
    Lamin B1 curtails early human papillomavirus infection by safeguarding nuclear compartmentalization and autophagic capacity.
    Freya Molenberghs, Marlies Verschuuren, Lauran Vandeweyer, Sarah Peeters, Johannes J Bogers, Claudina Perez Novo, Wim Vanden Berghe, Hans De Reu, Nathalie Cools, Mario Schelhaas, Winnok H De Vos.
      Human papillomavirus (HPV) infection is a primary cause of cervical and head-and-neck cancers. The HPV genome enters the nucleus during mitosis when the nuclear envelope disassembles. Given that lamins maintain nuclear integrity during interphase, we asked to what extent their loss would affect early HPV infection. To address this question, we infected human cervical cancer cells and keratinocytes lacking the major lamins with a HPV16 pseudovirus (HP-PsV) encoding an EGFP reporter. We found that a sustained reduction or complete loss of lamin B1 significantly increased HP-PsV infection rate. A corresponding greater nuclear HP-PsV load in LMNB1 knockout cells was directly related to their prolonged mitotic window and extensive nuclear rupture propensity. Despite the increased HP-PsV presence, EGFP transcript levels remained virtually unchanged, indicating an additional defect in protein turnover. Further investigation revealed that LMNB1 knockout led to a substantial decrease in autophagic capacity, possibly linked to the persistent activation of cGAS by cytoplasmic chromatin exposure. Thus, the attrition of lamin B1 increases nuclear perviousness and attenuates autophagic capacity, creating an environment conducive to unrestrained accumulation of HPV capsids. Our identification of lower lamin B1 levels and nuclear BAF foci in the basal epithelial layer of several human cervix samples suggests that this pathway may contribute to an increased individual susceptibility to HPV infection.
    Keywords:  Autophagy; Human papilloma pseudovirus; Infection kinetics; Lamin B1; Mitotic window; Nuclear lamina; Nuclear rupture
    DOI:  https://doi.org/10.1007/s00018-024-05194-3
  68. Allergol Immunopathol (Madr). 2024 ;52(2): 3-9
    RNF135 promotes cell proliferation and autophagy in lung adenocarcinoma by promoting the phosphorylation of ULK1.
    Lichun Zhuang, Guanhui Shi, Yuejun Sun.
       OBJECTIVE: To detect the expression of RING finger protein 135 (RNF135) in lung adenocarcinoma tissues and explore its role in the progression of lung adenocarcinoma.
    METHODS: Bioinformation analysis, quantitative polymerase chain reaction, and immunoblotting technique discovered the expression of RNF135 in lung adenocarcinoma tissues. Cell counting kit-8 and colony formation, immunostaining, and immunoblot assays examined the effects of RNF135 on cell growth and autophagy. Co-immunoprecipitation (Co-IP), immunostaining, and immuoblotting were conducted to confirm the mechanism.
    RESULTS: RNF135 was highly expressed in lung adenocarcinoma. In addition, RNF135 promoted lung adenocarcinoma cell growth. Further, data confirmed that RNF135 promoted autophagy in lung adenocarcinoma cells. Mechanically, RNF135 directly interacted with Unc-51-like autophagy activating kinase 1 (ULK1) to promote its phosphorylation level.
    CONCLUSION: RNF135 promoted cell growth and autophagy in lung adenocarcinoma by promoting the phosphorylation of ULK1.
    Keywords:  Autophagy; Lung Adenocarcinoma; Phosphorylation; Rnf135; Ulk1
    DOI:  https://doi.org/10.15586/aei.v52i2.1048
  69. ACS Chem Neurosci. 2024 Mar 14.
    Influence of Cigarette Aerosol in Alpha-Synuclein Oligomerization and Cell Viability in SH-SY5Y: Implications for Parkinson's Disease.
    Yu-Xin Shen, Pe-Shuen Lee, Ming-Chu Teng, Jhih-Hong Huang, Chia C Wang, Hsiu-Fang Fan.
      Although cigarette aerosol exposure is associated with various adverse health issues, its impact on Parkinson's disease (PD) remains elusive. Here, we investigated the effect of cigarette aerosol extract (CAE) on SH-SY5Y cells for the first time, both with and without α-synuclein (α-Syn) overexpression. We found that α-Syn aggravates CAE-induced cell death, oxidative stress, and mitochondrial dysfunction. Fluorescence cross-correlation spectroscopy (FCCS) revealed a dual distribution of α-Syn within the cells, with homogeneous regions indicative of monomeric α-Syn and punctated regions, suggesting the formation of oligomers. Moreover, we observed colocalization of α-Syn oligomers with lysosomes along with a reduction in autophagy activity. These findings suggest that α-Syn overexpression exacerbates CAE-induced intracellular cytotoxicity, mitochondrial dysfunction, and autophagy dysregulation, leading to elevated cell mortality. Our findings provide new insights into the pathogenic mechanisms linking exposure to cigarette aerosols with neurodegenerative diseases.
    Keywords:  Parkinson’s disease; autophagy activity; cigarette aerosol; fluorescence correlation spectroscopy; particulate matter; α-synuclein oligomerization
    DOI:  https://doi.org/10.1021/acschemneuro.3c00771
  70. Transl Cancer Res. 2024 Feb 29. 13(2): 661-675
    HES1 induces ITPR1-mediated autophagy to exert anti-metastatic effects in pituitary adenomas.
    Chunjian Qiu, Yao Yao, Suqin Hu, Yixin Xu.
       Background: Pituitary adenomas (PAs) are prevalent intracranial tumors necessitating a comprehensive exploration of their molecular intricacies. This study delved into the molecular interactions among HES1 (hairy and enhancer of split 1), ITPR1 (inositol 1,4,5-trisphosphate receptor, type 1), and autophagy to elucidate their contributions to PA progression.
    Methods: Our in-depth bioinformatics analysis identified ITPR1 as a central hub gene in the PA-associated dataset. It exhibited reduced expression in PA and held significant clinical diagnostic relevance. Motivated by this discovery, we investigated the consequences of ITPR1 overexpression, as well as the use of autophagy inhibitors 3-Methyladenine (3-MA) and Baf A1, while considering the transcriptional influence of HES1.
    Results: In vitro experiments utilizing PA cell lines revealed that ITPR1 overexpression significantly hindered tumorigenic activities. In contrast, both 3-MA and Baf A1 exacerbated these tumorigenic properties, confirmed by a decreased LC3 II/LC3 I ratio, indicative of autophagy inhibition. Intriguingly, the concurrent introduction of ITPR1 and these inhibitors mitigated these intensified effects, implying a tumor-suppressive role for ITPR1. Further investigations pinpoint HES1 as a potential upstream regulator of ITPR1 transcription. Silencing HES1 lead to reduced ITPR1 promoter activity, weakening the impact of ITPR1 overexpression on autophagy. This neutralized the ITPR1-mediated suppressions on PA cell activities, including proliferation, invasion, and migration.
    Conclusions: In summary, our research uncovered a complex regulatory interplay among HES1, ITPR1, and autophagy in the context of PA progression. These findings opened up promising avenues for novel therapeutic interventions targeting this intricate network to enhance PA treatment.
    Keywords:  Pituitary adenomas (PAs); autophagy; hairy and enhancer of split 1 (HES1); inositol 1,4,5-trisphosphate receptor, type 1 (ITPR1); tumor metastasis
    DOI:  https://doi.org/10.21037/tcr-23-1320
  71. Cell Mol Life Sci. 2024 Mar 13. 81(1): 134
    The Janus-faced functions of Apolipoproteins L in membrane dynamics.
    Etienne Pays.
      The functions of human Apolipoproteins L (APOLs) are poorly understood, but involve diverse activities like lysis of bloodstream trypanosomes and intracellular bacteria, modulation of viral infection and induction of apoptosis, autophagy, and chronic kidney disease. Based on recent work, I propose that the basic function of APOLs is the control of membrane dynamics, at least in the Golgi and mitochondrion. Together with neuronal calcium sensor-1 (NCS1) and calneuron-1 (CALN1), APOL3 controls the activity of phosphatidylinositol-4-kinase-IIIB (PI4KB), involved in both Golgi and mitochondrion membrane fission. Whereas secreted APOL1 induces African trypanosome lysis through membrane permeabilization of the parasite mitochondrion, intracellular APOL1 conditions non-muscular myosin-2A (NM2A)-mediated transfer of PI4KB and APOL3 from the Golgi to the mitochondrion under conditions interfering with PI4KB-APOL3 interaction, such as APOL1 C-terminal variant expression or virus-induced inflammatory signalling. APOL3 controls mitophagy through complementary interactions with the membrane fission factor PI4KB and the membrane fusion factor vesicle-associated membrane protein-8 (VAMP8). In mice, the basic APOL1 and APOL3 activities could be exerted by mAPOL9 and mAPOL8, respectively. Perspectives regarding the mechanism and treatment of APOL1-related kidney disease are discussed, as well as speculations on additional APOLs functions, such as APOL6 involvement in adipocyte membrane dynamics through interaction with myosin-10 (MYH10).
    Keywords:  APOL1 risk variants; Adipocyte adipogenesis; Apoptosis; Autophagy; Kidney disease; Membrane fission; Membrane fusion; Mitophagy; Secretion; Sleeping sickness
    DOI:  https://doi.org/10.1007/s00018-024-05180-9
  72. Cancer Lett. 2024 Mar 09. pii: S0304-3835(24)00195-2. [Epub ahead of print] 216802
    Targeting PARP14 with lomitapide suppresses drug resistance through the activation of DRP1-induced mitophagy in multiple myeloma.
    Honghao Zhang, Hao Wang, Yuxing Hu, Yang Gao, Jianyu Chen, Yabo Meng, Yingqi Qiu, Rong Hu, Peiyun Liao, Meifang Li, Yanjie He, Zhao Liang, Xiaoling Xie, Yuhua Li.
      Multiple myeloma (MM) is a hematological malignancy that remains incurable, primarily due to the high likelihood of relapse or development of resistance to current treatments. To explore and discover new medications capable of overcoming drug resistance in MM, we conducted cell viability inhibition screens of 1504 FDA-approved drugs. Lomitapide, a cholesterol-lowering agent, was found to exhibit effective inhibition on bortezomib-resistant MM cells in vitro and in vivo. Our data also indicated that lomitapide decreases the permeability of the mitochondrial outer membrane and induces mitochondrial dysfunction in MM cells. Next, lomitapide treatment upregulated DRP1 and PINK1 expression levels, coupled with the mitochondrial translocation of Parkin, leading to MM cell mitophagy. Excessive mitophagy caused mitochondrial damage and dysfunction induced by lomitapide. Meanwhile, PARP14 was identified as a direct target of lomitapide by SPR-HPLC-MS, and we showed that DRP1-induced mitophagy was crucial in the anti-MM activity mediated by PARP14. Furthermore, PARP14 is overexpressed in MM patients, implying that it is a novel therapeutic target in MM. Collectively, our results demonstrate that DRP1-mediated mitophagy induced by PARP14 may be the cause for mitochondrial dysfunction and damage in response to lomitapide treatment.
    Keywords:  Drug resistance; Lomitapide; Mitophagy; Multiple myeloma; PARP14
    DOI:  https://doi.org/10.1016/j.canlet.2024.216802
  73. FASEB J. 2024 Mar 15. 38(5): e23515
    CircFOXO3 mediates hypoxia-induced autophagy of endometrial stromal cells in endometriosis.
    Ling Zhang, Hengwei Liu, Wenqian Xiong, Haitang He, Tian Fu, Xuefeng Long, Xiaoou Li, Jiaxin Liang, Hui Ding, Ying Xu, Yi Liu, Xin Dai.
      Endometriosis is a benign gynecological disease that shares some common features of malignancy. Autophagy plays vital roles in endometriosis and influences endometrial cell metastasis, and hypoxia was identified as the initiator of this pathological process through hypoxia inducible factor 1 alpha (HIF-1α). A newly discovered circular RNA FOXO3 (circFOXO3) is critical in cell autophagy, migration, and invasion of various diseases and is reported to be related to hypoxia, although its role in endometriosis remains to be elucidated up to now. In this study, a lower circFOXO3 expression in ectopic endometrium was investigated. Furthermore, we verified that circFOXO3 could regulate autophagy by downregulating the level of p53 protein to mediate the migration and invasion of human endometrial stromal cells (T HESCs). Additionally, the effects of HIF-1α on circFOXO3 and autophagy were examined in T HESCs. Notably, overexpression of HIF-1α could induce autophagy and inhibit circFOXO3 expression, whereas overexpressing of circFOXO3 under hypoxia significantly inhibited hypoxia-induced autophagy. Mechanistically, the direct combination between HIF-1α and HIF-1α-binding site on adenosine deaminase 1 acting on RNA (ADAR1) promoter increased the level of ADAR1 protein, which bind directly with circFOXO3 pre-mRNA to block the cyclization of circFOXO3. All these results support that hypoxia-mediated ADAR1 elevation inhibited the expression of circFOXO3, and then autophagy was induced upon loss of circFOXO3 via inhibition of p53 degradation, participating in the development of endometriosis.
    Keywords:  ADAR1; autophagy; circFOXO3; circRNA; endometriosis; hypoxia inducible factor 1 alpha (HIF-1α)
    DOI:  https://doi.org/10.1096/fj.202301654RR
  74. Acta Ophthalmol. 2024 Mar;102 Suppl 282 3-53
    Mitochondrial damage and clearance in retinal pigment epithelial cells.
    Iswariyaraja Sridevi Gurubaran.
      Age-related macular degeneration (AMD) is a devastating eye disease that causes permanent vision loss in the central part of the retina, known as the macula. Patients with such severe visual loss face a reduced quality of life and are at a 1.5 times greater risk of death compared to the general population. Currently, there is no cure for or effective treatment for dry AMD. There are several mechanisms thought to underlie the disease, for example, ageing-associated chronic oxidative stress, mitochondrial damage, harmful protein aggregation and inflammation. As a way of gaining a better understanding of the molecular mechanisms behind AMD and thus developing new therapies, we have created a peroxisome proliferator-activated receptor gamma coactivator 1-alpha and nuclear factor erythroid 2-related factor 2 (PGC1α/NFE2L2) double-knockout (dKO) mouse model that mimics many of the clinical features of dry AMD, including elevated levels of oxidative stress markers, damaged mitochondria, accumulating lysosomal lipofuscin and extracellular drusen-like structures in retinal pigment epithelial cells (RPE). In addition, a human RPE cell-based model was established to examine the impact of non-functional intracellular clearance systems on inflammasome activation. In this study, we found that there was a disturbance in the autolysosomal machinery responsible for clearing mitochondria in the RPE cells of one-year-old PGC1α/NFE2L2-deficient mice. The confocal immunohistochemical analysis revealed an increase in autophagosome marker microtubule-associated proteins 1A/1B light chain 3B (LC3B) as well as multiple mitophagy markers such as PTE-induced putative kinase 1 (PINK1) and E3 ubiquitin ligase (PARKIN), along with signs of damaged mitochondria. However, no increase in autolysosome formation was detected, nor was there a colocalization of the lysosomal marker LAMP2 or the mitochondrial marker, ATP synthase β. There was an upregulation of late autolysosomal fusion Ras-related protein (Rab7) in the perinuclear space of RPE cells, together with autofluorescent aggregates. Additionally, we observed an increase in the numbers of Toll-like receptors 3 and 9, while those of NOD-like receptor 3 were decreased in PGC1α/NFE2L2 dKO retinal specimens compared to wild-type animals. There was a trend towards increased complement component C5a and increased involvement of the serine protease enzyme, thrombin, in enhancing the terminal pathway producing C5a, independent of C3. The levels of primary acute phase C-reactive protein and receptor for advanced glycation end products were also increased in the PGC1α/NFE2L2 dKO retina. Furthermore, selective proteasome inhibition with epoxomicin promoted both nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and mitochondrial-mediated oxidative stress, leading to the release of mitochondrial DNA to the cytosol, resulting in potassium efflux-dependent activation of the absent in melanoma 2 (AIM2) inflammasome and the subsequent secretion of interleukin-1β in ARPE-19 cells. In conclusion, the data suggest that there is at least a relative decrease in mitophagy, increases in the amounts of C5 and thrombin and decreased C3 levels in this dry AMD-like model. Moreover, selective proteasome inhibition evoked mitochondrial damage and AIM2 inflammasome activation in ARPE-19 cells.
    Keywords:  ageing; inflammasomes; inflammation; macular degeneration; mitochondria; mitophagy; oxidative stress; protein aggregation; retinal pigment epithelium
    DOI:  https://doi.org/10.1111/aos.16661
  75. Diabetes. 2024 Mar 11. pii: db230688. [Epub ahead of print]
    Inhibition of HSP20 ameliorates steatotic liver disease by stimulating ERK2-dependent autophagy.
    Yanli Miao, Yi Zhong, Yutian Li, Haojie Qin, Ling Yang, Guojun Cao, Yong Tang, Ting Yu, Di Fan, Yang Lu, Jiangtong Peng, Kai Huang.
      Heat shock protein 20 (HSP20) emerges as a novel regulator of autophagy in the heart. Nonetheless, the detailed function of HSP20 in liver and its effect on autophagy remain unknown. Here, we observed that HSP20 expression is increased in liver tissues from mice and patients with metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as nonalcoholic fatty liver disease (NAFLD). Liver-specific downregulation of HSP20 mitigates hepatic steatosis and insulin resistance in obese mice, while upregulating HSP20 promotes lipid deposition and hepatocyte cell death. Mechanistically, Liquid chromatography tandem mass spectrometry (LC-MS/MS) revealed that HSP20 interacts with phosphorylated extracellular regulated protein kinases 2 (ERK2) and prevents its dephosphorylation by dual specificity phosphatase 6 (DUSP6), leading to ERK2-mediated repression of autophagy, resulting in aggravated saturated fatty acid (SFA)-triggered hepatocyte death. Importantly, such adverse effects could be ameliorated by ERK inhibitor. Our data reveals a framework of how HSP20 increases susceptibility of SFA-induced liver injury through enhancing ERK2 phosphorylation, which represents a plausible therapeutic intervention to combat MASLD.
    DOI:  https://doi.org/10.2337/db23-0688
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