bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2024–01–07
57 papers selected by
Viktor Korolchuk, Newcastle University
  1. The ER membrane protein complex restricts mitophagy by controlling BNIP3 turnover.
  2. Lysosomal TBK1 Responds to Amino Acid Availability to Relieve Rab7-Dependent mTORC1 Inhibition.
  3. 4R MAPT/tau drives endolysosomal and autophagy dysfunction in frontotemporal dementia.
  4. HKDC1, a target of TFEB, is essential to maintain both mitochondrial and lysosomal homeostasis, preventing cellular senescence.
  5. Molecular Modulators and Receptors of Selective Autophagy: Disease Implication and Identification Strategies.
  6. Reduction of DHHC5-mediated beclin 1 S-palmitoylation underlies autophagy decline in aging.
  7. MCOLN/TRPML channels in the regulation of MTORC1 and autophagy.
  8. The nascent polypeptide-associated complex subunit Egd1 is required for efficient selective mitochondrial degradation in budding yeast.
  9. TMEM55B links autophagy flux, lysosomal repair, and TFE3 activation in response to oxidative stress.
  10. The STX17-SNAP47-VAMP7/VAMP8 complex is the default SNARE complex mediating autophagosome-lysosome fusion.
  11. Lipid droplets, autophagy, and ER stress as key (survival) pathways during ischemia-reperfusion of transplanted grafts.
  12. Lysosome identity crisis: Phosphoinositides and mTORC1 negotiate lysosomal behavior.
  13. Hypoxia induced Galectin-8 maintains stemness in glioma stem cells via autophagy regulation.
  14. HCMV miR-UL70-3p downregulates the rapamycin-induced autophagy by targeting the autophagy-related protein 9A (ATG9A).
  15. REEPing the harvest of reticulophagy and nucleophagy.
  16. A conserved ion channel function of STING mediates noncanonical autophagy and cell death.
  17. Autophagy protein ATG-16.2 and its WD40 domain mediate the beneficial effects of inhibiting early-acting autophagy genes in C. elegans neurons.
  18. FUNDC1-induced mitophagy protects spinal cord neurons against ischemic injury.
  19. Selective Autophagy Receptor NBR1 Retards Nucleus Pulposus Cell Senescence by Directing the Clearance of SRBD1.
  20. Dual-Labeled Single Fluorescent Probes for the Simultaneous Two-Color Visualization of Dual Organelles and for Monitoring Cell Autophagy.
  21. The MuSK-BMP pathway maintains myofiber size in slow muscle through regulation of Akt-mTOR signaling.
  22. Lipid peroxidation products' role in autophagy regulation.
  23. DIRAS3 induces autophagy and enhances sensitivity to anti-autophagic therapy in KRAS-driven pancreatic and ovarian carcinomas.
  24. Advances in the regulatory mechanisms of mTOR in necroptosis.
  25. Target lysis by cholesterol extraction is a rate limiting step in the resolution of phagolysosomes.
  26. Targeted Degradation of Signal Transduction and Activator of Transcription 3 by Chaperone-Mediated Autophagy Targeting Chimeric Nanoplatform.
  27. Evaluation of Beclin1 and mTOR genes and p62 protein expression in breast tumor tissues of Iranian patients.
  28. Selective induction of Rab9-dependent alternative mitophagy using a synthetic derivative of isoquinoline alleviates mitochondrial dysfunction and cognitive deficits in Alzheimer's disease models.
  29. Proximity labeling reveals dynamic changes in the SQSTM1 protein network.
  30. Eat at Right Time: Regulations of Plant ER-phagy Receptors in Responses to Environmental Stresses.
  31. PFOS exposure destroys the integrity of the blood-testis barrier (BTB) through PI3K/AKT/mTOR-mediated autophagy.
  32. A Fluorogenic-Based Assay to Measure Chaperone-Mediated Autophagic Activity in Cells and Tissues.
  33. MK8722 initiates early-stage autophagy while inhibiting late-stage autophagy via FASN-dependent reprogramming of lipid metabolism.
  34. An autophagy-independent role of ULK1/ULK2 in mechanotransduction and breast cancer cell migration.
  35. ABCG2 is an itaconate exporter that limits antibacterial innate immunity by alleviating TFEB-dependent lysosomal biogenesis.
  36. P75NTR regulates autophagy through the YAP-mTOR pathway to increase the proliferation of interfollicular epidermal cells and promote wound healing in diabetic mice.
  37. A nano-bioconjugate modified with anti-SIRPα antibodies and antisense oligonucleotides of mTOR for anti-atherosclerosis therapy.
  38. GRB2 is a BECN1 interacting protein that regulates autophagy.
  39. Porcine reproductive and respiratory syndrome virus triggers Golgi apparatus fragmentation-mediated autophagy to facilitate viral self-replication.
  40. Mitochondrial-derived vesicles in metabolism, disease, and aging.
  41. Fundamental roles of the Optineurin gene in the molecular pathology of Amyotrophic Lateral Sclerosis.
  42. Fission-independent compartmentalization of mitochondria during budding yeast cell division.
  43. Innate immune and proinflammatory signals activate the Hippo pathway via a Tak1-STRIPAK-Tao axis.
  44. The molecular mechanism of MiR-26a-5p regulates autophagy and activates NLRP3 inflammasome to mediate cardiomyocyte hypertrophy.
  45. Sex differences in response to obesity and caloric restriction on cognition and hippocampal measures of autophagic-lysosomal transcripts and signaling pathways.
  46. PINK1 restrains periodontitis-induced bone loss by preventing osteoclast mitophagy impairment.
  47. NCOA4 requires a [3Fe-4S] to sense and maintain the iron homeostasis.
  48. Activation of autophagy depends on Atg1/Ulk1-mediated phosphorylation and inhibition of the Hsp90 chaperone machinery.
  49. Motor neuron activity enhances the proteomic stress caused by autophagy defects in the target muscle.
  50. Sestrin2 ameliorates diabetic retinopathy by regulating autophagy and ferroptosis.
  51. Editorial: Autophagy and hypoxia-inducible factor in diabetes.
  52. Mitochondrial quality control in liver fibrosis: Epigenetic hallmarks and therapeutic strategies.
  53. Key roles of autophagosome/endosome maturation mediated by Syntaxin17 in methamphetamine-induced neuronal damage in mice.
  54. TLR-mediated aggresome-like induced structures comprise antimicrobial peptides and attenuate intracellular bacterial survival.
  55. Mammalian target of rapamycin inhibitors: A new-possible approach for in-utero medication therapy.
  56. Chronic hypoxia stabilizes 3βHSD1 via autophagy suppression.
  57. Autophagy induces hair follicle stem cell activation and hair follicle regeneration by regulating glycolysis.
  1. EMBO J. 2024 Jan;43(1): 32-60
    The ER membrane protein complex restricts mitophagy by controlling BNIP3 turnover.
    Jose M Delgado, Logan Wallace Shepard, Sarah W Lamson, Samantha L Liu, Christopher J Shoemaker.
      Lysosomal degradation of autophagy receptors is a common proxy for selective autophagy. However, we find that two established mitophagy receptors, BNIP3 and BNIP3L/NIX, are constitutively delivered to lysosomes in an autophagy-independent manner. This alternative lysosomal delivery of BNIP3 accounts for nearly all its lysosome-mediated degradation, even upon mitophagy induction. To identify how BNIP3, a tail-anchored protein in the outer mitochondrial membrane, is delivered to lysosomes, we performed a genome-wide CRISPR screen for factors influencing BNIP3 flux. This screen revealed both known modifiers of BNIP3 stability as well as a pronounced reliance on endolysosomal components, including the ER membrane protein complex (EMC). Importantly, the endolysosomal system and the ubiquitin-proteosome system regulated BNIP3 independently. Perturbation of either mechanism is sufficient to modulate BNIP3-associated mitophagy and affect underlying cellular physiology. More broadly, these findings extend recent models for tail-anchored protein quality control and install endosomal trafficking and lysosomal degradation in the canon of pathways that tightly regulate endogenous tail-anchored protein localization.
    Keywords:  BNIP3; EMC; Mitophagy; Secretory Pathway; TA Protein
    DOI:  https://doi.org/10.1038/s44318-023-00006-z
  2. bioRxiv. 2023 Dec 17. pii: 2023.12.16.571979. [Epub ahead of print]
    Lysosomal TBK1 Responds to Amino Acid Availability to Relieve Rab7-Dependent mTORC1 Inhibition.
    Gabriel Talaia, Amanda Bentley-DeSousa, Shawn M Ferguson.
      Lysosomes play a pivotal role in coordinating macromolecule degradation and regulating cell growth and metabolism. Despite substantial progress in identifying lysosomal signaling proteins, understanding the pathways that synchronize lysosome functions with changing cellular demands remains incomplete. This study uncovers a role for TANK-binding kinase 1 (TBK1), well known for its role in innate immunity and organelle quality control, in modulating lysosomal responsiveness to nutrients. Specifically, we identify a pool of TBK1 that is recruited to lysosomes in response to elevated amino acid levels. At lysosomes, this TBK1 phosphorylates Rab7 on serine 72. This is critical for alleviating Rab7-mediated inhibition of amino acid-dependent mTORC1 activation. Furthermore, a TBK1 mutant (E696K) associated with amyotrophic lateral sclerosis and frontotemporal dementia constitutively accumulates at lysosomes, resulting in elevated Rab7 phosphorylation and increased mTORC1 activation. This data establishes the lysosome as a site of amino acid regulated TBK1 signaling that is crucial for efficient mTORC1 activation. This lysosomal pool of TBK1 has broader implications for lysosome homeostasis, and its dysregulation could contribute to the pathogenesis of ALS-FTD.
    DOI:  https://doi.org/10.1101/2023.12.16.571979
  3. Autophagy. 2024 Jan 04.
    4R MAPT/tau drives endolysosomal and autophagy dysfunction in frontotemporal dementia.
    Christy Hung, Rickie Patani.
      Dysfunction of the neuronal endolysosome and macroautophagy/autophagy pathway is emerging as an important pathogenic mechanism in frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). The VCP (valosin-containing protein) gene is of significant relevance, directly implicated in both FTD and ALS. In our recent study, we used patient-derived stem cells to study the effects of VCP mutations on the endolysosome and autophagy system in human cortical excitatory neurons. We found that VCP mutations cause an abnormal accumulation of enlarged endosomes and lysosomes, accompanied by reduced autophagy flux. VCP mutations also lead to the spatial dissociation of intra-nuclear RNA-binding proteins, FUS and SFPQ, which correlates with alternative splicing of the MAPT pre-mRNA and increased MAPT/tau phosphorylation. Importantly, we found that an increase in the 4 R-MAPT/tau isoform is sufficient to drive toxic changes in healthy human cortical excitatory neurons, including MAPT/tau hyperphosphorylation, endolysosomal dysfunction, lysosomal membrane rupture, endoplasmic reticulum stress, and apoptosis. Together, our data suggest that endolysosomal and autophagy dysfunction could represent a convergent pathogenic "design principle" shared by both FTD and ALS.
    Keywords:  Autophagy; endosomes; lysosome; tau; tauopathy
    DOI:  https://doi.org/10.1080/15548627.2023.2300917
  4. Proc Natl Acad Sci U S A. 2024 Jan 09. 121(2): e2306454120
    HKDC1, a target of TFEB, is essential to maintain both mitochondrial and lysosomal homeostasis, preventing cellular senescence.
    Mengying Cui, Koji Yamano, Kenichi Yamamoto, Hitomi Yamamoto-Imoto, Satoshi Minami, Takeshi Yamamoto, Sho Matsui, Tatsuya Kaminishi, Takayuki Shima, Monami Ogura, Megumi Tsuchiya, Kohei Nishino, Brian T Layden, Hisakazu Kato, Hidesato Ogawa, Shinya Oki, Yukinori Okada, Yoshitaka Isaka, Hidetaka Kosako, Noriyuki Matsuda, Tamotsu Yoshimori, Shuhei Nakamura.
      Mitochondrial and lysosomal functions are intimately linked and are critical for cellular homeostasis, as evidenced by the fact that cellular senescence, aging, and multiple prominent diseases are associated with concomitant dysfunction of both organelles. However, it is not well understood how the two important organelles are regulated. Transcription factor EB (TFEB) is the master regulator of lysosomal function and is also implicated in regulating mitochondrial function; however, the mechanism underlying the maintenance of both organelles remains to be fully elucidated. Here, by comprehensive transcriptome analysis and subsequent chromatin immunoprecipitation-qPCR, we identified hexokinase domain containing 1 (HKDC1), which is known to function in the glycolysis pathway as a direct TFEB target. Moreover, HKDC1 was upregulated in both mitochondrial and lysosomal stress in a TFEB-dependent manner, and its function was critical for the maintenance of both organelles under stress conditions. Mechanistically, the TFEB-HKDC1 axis was essential for PINK1 (PTEN-induced kinase 1)/Parkin-dependent mitophagy via its initial step, PINK1 stabilization. In addition, the functions of HKDC1 and voltage-dependent anion channels, with which HKDC1 interacts, were essential for the clearance of damaged lysosomes and maintaining mitochondria-lysosome contact. Interestingly, HKDC1 regulated mitophagy and lysosomal repair independently of its prospective function in glycolysis. Furthermore, loss function of HKDC1 accelerated DNA damage-induced cellular senescence with the accumulation of hyperfused mitochondria and damaged lysosomes. Our results show that HKDC1, a factor downstream of TFEB, maintains both mitochondrial and lysosomal homeostasis, which is critical to prevent cellular senescence.
    Keywords:  HKDC1; TFEB; cellular senescence; mitochondria–lysosome contact; mitophagy
    DOI:  https://doi.org/10.1073/pnas.2306454120
  5. Int J Biol Sci. 2024 ;20(2): 751-764
    Molecular Modulators and Receptors of Selective Autophagy: Disease Implication and Identification Strategies.
    Ming-Yue Wu, Zhe-Wei Li, Jia-Hong Lu.
      Autophagy is a highly conserved physiological process that maintains cellular homeostasis by recycling cellular contents. Selective autophagy is based on the specificity of cargo recognition and has been implicated in various human diseases, including neurodegenerative diseases and cancer. Selective autophagy receptors and modulators play key roles in this process. Identifying these receptors and modulators and their roles is critical for understanding the machinery and physiological function of selective autophagy and providing therapeutic value for diseases. Using modern researching tools and novel screening technologies, an increasing number of selective autophagy receptors and modulators have been identified. A variety of Strategies and approaches, including protein-protein interactions (PPIs)-based identification and genome-wide screening, have been used to identify selective autophagy receptors and modulators. Understanding the strengths and challenges of these approaches not only promotes the discovery of even more such receptors and modulators but also provides a useful reference for the identification of regulatory proteins or genes involved in other cellular mechanisms. In this review, we summarize the functions, disease association, and identification strategies of selective autophagy receptors and modulators.
    Keywords:  autophagy; genome-wide screening; protein-protein interaction; screening technology; selective autophagy
    DOI:  https://doi.org/10.7150/ijbs.83205
  6. Nat Struct Mol Biol. 2024 Jan 04.
    Reduction of DHHC5-mediated beclin 1 S-palmitoylation underlies autophagy decline in aging.
    Rui Guo, Jianping Liu, Xia Min, Wen Zeng, Bing Shan, Mengmeng Zhang, Zhuohao He, Yaoyang Zhang, Kaiwen He, Junying Yuan, Daichao Xu.
      Autophagy is a lysosome-dependent degradation pathway essential for cellular homeostasis, which decreases with age. However, it is unclear how aging induces autophagy decline. Here we show the role of protein S-palmitoylation in autophagy. We identify the palmitoyl acyltransferase DHHC5 as a regulator of autophagy by mediating the palmitoylation of beclin 1, which in turn promotes the formation of ATG14L-containing class III phosphatidylinositol-3-kinase complex I and its lipid kinase activity by promoting the hydrophobic interactions between beclin 1 and adapter proteins ATG14L and VPS15. In aging brains of human and nonhuman primate, the levels of DHHC5 exhibit a marked decrease in expression. We show that DHHC5 deficiency in neurons leads to reduced cellular protein homeostasis in two established murine models of Alzheimer's disease, which exaggerates neurodegeneration in an autophagy-dependent manner. These findings identify reduction of DHHC5-mediated beclin 1 S-palmitoylation as an underlying mechanism by which aging induces autophagy decline.
    DOI:  https://doi.org/10.1038/s41594-023-01163-9
  7. Autophagy. 2024 Jan 05. 1-2
    MCOLN/TRPML channels in the regulation of MTORC1 and autophagy.
    Peng Huang, Rose Yang Dong, Pingping Wang, Mengnan Xu, Xue Sun, Xian-Ping Dong.
      MCOLN1 and MCOLN3 are two Ca2+ release channels residing in the endolysosomal membrane. They are activated by phosphatidylinositol (PtdIns)-3-phosphate (PtdIns3P) and/or PtdIns(3,5)P2. Their activities are also regulated by lumenal pH, with low pH enhancing that of MCOLN1 and high pH increasing that of MCOLN3. Recent studies further suggest that upon starvation, both MCOLN1 and MCOLN3 are activated by a reduction in MTORC1 activity; their activation in turn regulates MTORC1 activity to facilitate macroautophagic/autophagic flux. On the one hand, MCOLN3 appears to be recruited to phagophores where it is activated by PtdIns3P and high pH to inhibit MTORC1 activity using a positive feedback mechanism, thereby increasing autophagy induction. On the other hand, MCOLN1 is activated by PtdIns(3,5)P2 and low pH in (auto)lysosomes to increase MTORC1 activity using a negative feedback mechanism, promoting autophagic lysosome reformation. The cell uses the two feedback mechanisms to ensure efficient autophagic flux to survive adverse conditions such as nutrient deprivation and bacterial infection.
    Keywords:  Autophagy; MCOLN1; MCOLN3; MTORC1; TRPML1; TRPML3
    DOI:  https://doi.org/10.1080/15548627.2023.2300922
  8. Sci Rep. 2024 Jan 04. 14(1): 546
    The nascent polypeptide-associated complex subunit Egd1 is required for efficient selective mitochondrial degradation in budding yeast.
    Yuan Tian, Koji Okamoto.
      Selective degradation of dysfunctional or excess mitochondria is a fundamental process crucial for cell homeostasis in almost all eukaryotes. This process relies on autophagy, an intracellular self-eating system conserved from yeast to humans and is thus called mitophagy. Detailed mechanisms of mitophagy remain to be fully understood. Here we show that mitochondrial degradation in budding yeast, which requires the pro-mitophagic protein Atg32, is strongly reduced in cells lacking Egd1, a beta subunit of the nascent polypeptide-associated complex acting in cytosolic ribosome attachment and protein targeting to mitochondria. By contrast, loss of the sole alpha subunit Egd2 or the beta subunit paralogue Btt1 led to only a partial or slight reduction in mitophagy. We also found that phosphorylation of Atg32, a crucial step for priming mitophagy, is decreased in the absence of Egd1. Forced Atg32 hyperphosphorylation almost completely restored mitophagy in egd1-null cells. Together, we propose that Egd1 acts in Atg32 phosphorylation to facilitate mitophagy.
    DOI:  https://doi.org/10.1038/s41598-023-50245-7
  9. Nat Commun. 2024 Jan 02. 15(1): 93
    TMEM55B links autophagy flux, lysosomal repair, and TFE3 activation in response to oxidative stress.
    Eutteum Jeong, Rose Willett, Alberto Rissone, Martina La Spina, Rosa Puertollano.
      Lysosomes have emerged as critical regulators of cellular homeostasis. Here we show that the lysosomal protein TMEM55B contributes to restore cellular homeostasis in response to oxidative stress by three different mechanisms: (1) TMEM55B mediates NEDD4-dependent PLEKHM1 ubiquitination, causing PLEKHM1 proteasomal degradation and halting autophagosome/lysosome fusion; (2) TMEM55B promotes recruitment of components of the ESCRT machinery to lysosomal membranes to stimulate lysosomal repair; and (3) TMEM55B sequesters the FLCN/FNIP complex to facilitate translocation of the transcription factor TFE3 to the nucleus, allowing expression of transcriptional programs that enable cellular adaptation to stress. Knockout of tmem55 genes in zebrafish embryos increases their susceptibility to oxidative stress, causing early death of tmem55-KO animals in response to arsenite toxicity. Altogether, our work identifies a role for TMEM55B as a molecular sensor that coordinates autophagosome degradation, lysosomal repair, and activation of stress responses.
    DOI:  https://doi.org/10.1038/s41467-023-44316-6
  10. Cell Res. 2024 Jan 05.
    The STX17-SNAP47-VAMP7/VAMP8 complex is the default SNARE complex mediating autophagosome-lysosome fusion.
    Fenglei Jian, Shen Wang, Rui Tian, Yufen Wang, Chuangpeng Li, Yan Li, Shixuan Wang, Chao Fang, Cong Ma, Yueguang Rong.
      Autophagosome-lysosome fusion mediated by SNARE complexes is an essential step in autophagy. Two SNAP29-containing SNARE complexes have been extensively studied in starvation-induced bulk autophagy, while the relevant SNARE complexes in other types of autophagy occurring under non-starvation conditions have been overlooked. Here, we found that autophagosome-lysosome fusion in selective autophagy under non-starvation conditions does not require SNAP29-containing SNARE complexes, but requires the STX17-SNAP47-VAMP7/VAMP8 SNARE complex. Further, the STX17-SNAP47-VAMP7/VAMP8 SNARE complex also functions in starvation-induced autophagy. SNAP47 is recruited to autophagosomes following concurrent detection of ATG8s and PI(4,5)P2 via its Pleckstrin homology domain. By contrast, SNAP29-containing SNAREs are excluded from selective autophagy due to inactivation by O-GlcNAcylation under non-starvation conditions. These findings depict a previously unknown, default SNARE complex responsible for autophagosome-lysosome fusion in both selective and bulk autophagy, which could guide research and therapeutic development in autophagy-related diseases.
    DOI:  https://doi.org/10.1038/s41422-023-00916-x
  11. Cell Biol Int. 2024 Jan 04.
    Lipid droplets, autophagy, and ER stress as key (survival) pathways during ischemia-reperfusion of transplanted grafts.
    Daria Kamińska, Michał Skrzycki.
      Ischemia-reperfusion injury is an event concerning any organ under a procedure of transplantation. The early result of ischemia is hypoxia, which causes malfunction of mitochondria and decrease in cellular ATP. This leads to disruption of cellular metabolism. Reperfusion also results in cell damage due to reoxygenation and increased production of reactive oxygen species, and later by induced inflammation. In damaged and hypoxic cells, the endoplasmic reticulum (ER) stress pathway is activated by increased amount of damaged or misfolded proteins, accumulation of free fatty acids and other lipids due to inability of their oxidation (lipotoxicity). ER stress is an adaptive response and a survival pathway, however, its prolonged activity eventually lead to induction of apoptosis. Sustaining cell functionality in stress conditions is a great challenge for transplant surgeons as it is crucial for maintaining a desired level of graft vitality. Pathways counteracting negative consequences of ischemia-reperfusion are autophagy and lipid droplets (LD) metabolism. Autophagy remove damaged organelles and molecules driving them to lysosomes, digested simpler compounds are energy source for the cell. Mitophagy and ER-phagy results in improvement of cell energetic balance and alleviation of ER stress. This is important in sustaining metabolic homeostasis and thus cell survival. LD metabolism is connected with autophagy as LD are degraded by lipophagy, a source of free fatty acids and glycerol-thus autophagy and LD can readily remove lipotoxic compounds in the cell. In conclusion, monitoring and pharmaceutic regulation of those pathways during transplantation procedure might result in increased/improved vitality of transplanted organ.
    Keywords:  ER stress; IRI; MAMs; autophagy; lipid droplets; transplantation
    DOI:  https://doi.org/10.1002/cbin.12114
  12. Mol Cell. 2024 Jan 04. pii: S1097-2765(23)01028-6. [Epub ahead of print]84(1): 17-19
    Lysosome identity crisis: Phosphoinositides and mTORC1 negotiate lysosomal behavior.
    Mélanie Mansat, Roberto J Botelho.
      Ebner et al.1 discovered a nutrient-dependent molecular feedback circuit that employs mTORC1, lipid kinases, and phosphatases to generate phosphatidylinositol-3-phosphate [PI(3)P] or phosphatidylinositol-4-phosphate [PI(4)P] in a mutually exclusive manner on lysosomes, which respectively convert lysosomes into organelles that support anabolism or catabolism.
    DOI:  https://doi.org/10.1016/j.molcel.2023.12.009
  13. Neuro Oncol. 2023 Dec 30. pii: noad264. [Epub ahead of print]
    Hypoxia induced Galectin-8 maintains stemness in glioma stem cells via autophagy regulation.
    Dan Liu, Hongtao Zhu, Lidong Cheng, Ran Li, Xiaoyu Ma, Jing Wang, Junwen Wang, Suojun Zhang, Yingjie Li, Kai Shu, Xingjiang Yu, Chuanzhou Li.
       BACKGROUND: Glioma stem cells (GSCs) are the root cause of relapse and treatment resistance in glioblastoma (GBM). In GSCs, hypoxia in the microenvironment is known to facilitate the maintenance of stem cells, and evolutionally conserved autophagy regulates cell homeostasis to control cell population. The precise involvement of autophagy regulation in hypoxic conditions in maintaining the stemness of GSCs remains unclear.
    METHODS: The association of autophagy regulation and hypoxia was first assessed by in silico analysis and validation in vitro. Glioma databases and clinical specimens were used to determine galectin-8 (Gal-8) expression in GSCs and human GBMs, and the regulation and function of Gal-8 in stemness maintenance were evaluated by genetic manipulation in vitro and in vivo. How autophagy was stimulated by Gal-8 under hypoxia was systematically investigated.
    RESULTS: Hypoxia enhances autophagy in GSCs to facilitate self-renewal, and Gal-8 in the galectin family is specifically involved and expressed in GSCs within the hypoxic niche. Gal-8 is highly expressed in GBM and predicts poor survival in patients. Suppression of Gal-8 prevents tumor growth and prolongs survival in mouse models of GBM. Gal-8 binds to the Ragulator-Rag complex at the lysosome membrane and inactivates mTORC1, leading to the nuclear translocation of downstream TFEB and initiation of autophagic lysosomal biogenesis. Consequently, the survival and proliferative activity of GSCs are maintained.
    CONCLUSIONS: Our findings reveal a novel Gal-8-mTOR-TFEB axis induced by hypoxia in the maintenance of GSC stemness via autophagy reinforcement, highlighting Gal-8 as a candidate for GSCs-targeted GBM therapy.
    Keywords:  Autophagy; Galectin-8; Glioma stem cells; Hypoxia; TFEB
    DOI:  https://doi.org/10.1093/neuonc/noad264
  14. Int Rev Immunol. 2024 Jan 02. 1-14
    HCMV miR-UL70-3p downregulates the rapamycin-induced autophagy by targeting the autophagy-related protein 9A (ATG9A).
    Raj Kumar Khalko, Abhishek Pandeya, Sangeeta Saxena, Sunil Babu Gosipatala.
      Human cytomegalovirus (HCMV) is a representative β-herpesvirus that establishes persistent infections in humans, and exhibits high seropositivity rates in adults. It has co-evolved with its human host and employs various strategies to evade antiviral mechanisms by utilizing a significant portion of its genome. HCMV-encoded proteins and miRNAs have been implicated in regulating these mechanisms, enabling viral survival within the human body. During viral infections, autophagy, a conserved catabolic process essential for cellular homeostasis, acts as an antiviral defense mechanism. Multiple studies have reported that HCMV can modulate autophagy through its proteins and miRNAs, thereby influencing its survival within the host. In this study, we showed the potential involvement of HCMV miRNAs in cellular autophagy. We employed various bioinformatic tools to predict putative HCMV miRNAs that target autophagy-related genes and their corresponding cellular autophagy genes. Our results show that the 3'UTR of autophagy-related genes, including ATG9A, ATG9B, ATG16L2, SQSTM1, and EIF2AK2, harbors potential binding sites for hcmv-miR-UL70-3p. Experimental manipulation involving ectopic expression of hcmv-miR-UL70-3p demonstrated a significant reduction in rapamycin-induced autophagy, with ATG9A as its functional target. These findings establish that hcmv-miR-UL70-3p acts as an autophagy inhibitor by suppressing the expression of ATG9A.
    Keywords:  Autophagy; autophagy-related protein 9A (ATG9A); hcmv-miR-UL70-3p; human cytomegalovirus (HCMV)
    DOI:  https://doi.org/10.1080/08830185.2023.2296488
  15. Autophagy. 2024 Jan 01.
    REEPing the harvest of reticulophagy and nucleophagy.
    Chen-Xi Zou, Li-Lin Du.
      Under stress conditions, the endoplasmic reticulum and nucleus undergo turnover through selective macroautophagy/autophagy processes termed reticulophagy and nucleophagy, respectively. Our recent study has identified the protein Hva22/Rop1/Yep1, a member of the REEP1-REEP4 subfamily of the REEP protein family, as an essential factor for both processes in the fission yeast Schizosaccharomyces pombe. In the absence of Hva22/Yep1, reticulophagy and nucleophagy cargos without surrounding autophagic membranes accumulate in the cytoplasm. Interestingly, human proteins in the REEP1-REEP4 subfamily can functionally substitute for Hva22/Yep1 to facilitate reticulophagy. Phylogenetic and synteny analyses further reveal that the budding yeast reticulophagy receptor Atg40 is also a REEP1-REEP4 subfamily member. Similar to human REEP1-REEP4 subfamily proteins, Atg40 can functionally replace Hva22/Yep1. Based on our findings, we propose that promoting reticulophagy is a conserved function of REEP1-REEP4 subfamily proteins.
    Keywords:  ER-phagy; REEP protein family; Schizosaccharomyces pombe; nucleophagy; reticulophagy
    DOI:  https://doi.org/10.1080/15548627.2023.2300915
  16. EMBO Rep. 2024 Jan 02.
    A conserved ion channel function of STING mediates noncanonical autophagy and cell death.
    Jinrui Xun, Zhichao Zhang, Bo Lv, Defen Lu, Haoxiang Yang, Guijun Shang, Jay Xiaojun Tan.
      The cGAS/STING pathway triggers inflammation upon diverse cellular stresses such as infection, cellular damage, aging, and diseases. STING also triggers noncanonical autophagy, involving LC3 lipidation on STING vesicles through the V-ATPase-ATG16L1 axis, as well as induces cell death. Although the proton pump V-ATPase senses organelle deacidification in other contexts, it is unclear how STING activates V-ATPase for noncanonical autophagy. Here we report a conserved channel function of STING in proton efflux and vesicle deacidification. STING activation induces an electron-sparse pore in its transmembrane domain, which mediates proton flux in vitro and the deacidification of post-Golgi STING vesicles in cells. A chemical ligand of STING, C53, which binds to and blocks its channel, strongly inhibits STING-mediated proton flux in vitro. C53 fully blocks STING trafficking from the ER to the Golgi, but adding C53 after STING arrives at the Golgi allows for selective inhibition of STING-dependent vesicle deacidification, LC3 lipidation, and cell death, without affecting trafficking. The discovery of STING as a channel opens new opportunities for selective targeting of canonical and noncanonical STING functions.
    Keywords:  Ion Channel; Membrane Trafficking; Noncanonical Autophagy; STING; Vesicle Deacidification
    DOI:  https://doi.org/10.1038/s44319-023-00045-x
  17. Nat Aging. 2024 Jan 04.
    Autophagy protein ATG-16.2 and its WD40 domain mediate the beneficial effects of inhibiting early-acting autophagy genes in C. elegans neurons.
    Yongzhi Yang, Meghan Lee Arnold, Caitlin M Lange, Ling-Hsuan Sun, Michael Broussalian, Saam Doroodian, Hiroshi Ebata, Elizabeth H Choy, Karie Poon, Tatiana M Moreno, Anupama Singh, Monica Driscoll, Caroline Kumsta, Malene Hansen.
      While autophagy genes are required for lifespan of long-lived animals, their tissue-specific roles in aging remain unclear. Here, we inhibited autophagy genes in Caenorhabditis elegans neurons, and found that knockdown of early-acting autophagy genes, except atg-16.2, increased lifespan, and decreased neuronal PolyQ aggregates, independently of autophagosomal degradation. Neurons can secrete protein aggregates via vesicles called exophers. Inhibiting neuronal early-acting autophagy genes, except atg-16.2, increased exopher formation and exopher events extended lifespan, suggesting exophers promote organismal fitness. Lifespan extension, reduction in PolyQ aggregates and increase in exophers were absent in atg-16.2 null mutants, and restored by full-length ATG-16.2 expression in neurons, but not by ATG-16.2 lacking its WD40 domain, which mediates noncanonical functions in mammalian systems. We discovered a neuronal role for C. elegans ATG-16.2 and its WD40 domain in lifespan, proteostasis and exopher biogenesis. Our findings suggest noncanonical functions for select autophagy genes in both exopher formation and in aging.
    DOI:  https://doi.org/10.1038/s43587-023-00548-1
  18. Cell Death Discov. 2024 Jan 05. 10(1): 4
    FUNDC1-induced mitophagy protects spinal cord neurons against ischemic injury.
    Dehui Chen, Linquan Zhou, Gang Chen, Taotao Lin, Jiemin Lin, Xin Zhao, Wenwen Li, Shengyu Guo, Rongcan Wu, Zhenyu Wang, Wenge Liu.
      Local ischemia and hypoxia are the most important pathological processes in the early phase of secondary spinal cord injury (SCI), in which mitochondria are the main target of ischemic injury. Mitochondrial autophagy, also known as mitophagy, acts as a selective autophagy that specifically identifies and degrades damaged mitochondria, thereby reducing mitochondria-dependent apoptosis. Accumulating evidence shows that the mitophagy receptor, FUN14 domain-containing 1 (FUNDC1), plays an important role in ischemic injury, but the role of FUNDC1 in SCI has not been reported. In this study, we aimed to investigate whether FUNDC1 can enhance mitophagy and inhibit neuronal apoptosis in the early stage of SCI. In a rat SCI model, we found that FUNDC1 overexpression enhanced neuronal autophagy and decreased neuronal apoptosis in the early stage of injury, thereby reducing spinal cord damage. In vitro studies showed that the neuroprotective effects of FUNDC1 were achieved by inhibiting mitochondria-dependent apoptosis and improving mitochondrial function. In addition, FUNDC1 enhanced mitophagy. The protective effects of FUNDC1 against apoptosis and mitochondrial dysfunction were reversed by 3-methyladenine (3-MA), an autophagy inhibitor. Taken together, our results confirm that FUNDC1 can protect against neuronal loss after SCI by inducing mitophagy, inhibiting mitochondria-dependent apoptosis, and improving mitochondrial function.
    DOI:  https://doi.org/10.1038/s41420-023-01780-9
  19. Int J Biol Sci. 2024 ;20(2): 701-717
    Selective Autophagy Receptor NBR1 Retards Nucleus Pulposus Cell Senescence by Directing the Clearance of SRBD1.
    Honghai Song, Yutao Zhu, Chuan Hu, Qianyu Liu, Yang Jin, Pan Tang, Jiechao Xia, Dingqi Xie, Sicheng Jiang, Geliang Yao, Zhili Liu, Zhijun Hu.
      Intervertebral disc degeneration (IDD) is a prevalent degenerative disorder that closely linked to aging. Numerous studies have indicated the crucial involvement of autophagy in the development of IDD. However, the non-selective nature of autophagy substrates poses great limitations on the application of autophagy-related medications. This study aims to enhance our comprehension of autophagy in the development of IDD and investigate a novel therapeutic approach from the perspective of selective autophagy receptor NBR1. Proteomics and immunoprecipitation and mass spectrometry analysis, combined with in vivo and in vitro experimental verification were performed. NBR1 is found to be reduced in IDD, and NBR1 retards cellular senescence and senescence-associated secretory phenotype (SASP) of nucleus pulposus cells (NPCs), primarily through its autophagy-dependent function. Mechanistically, NBR1 knockdown leads to the accumulation of S1 RNA-binding domain-containing protein 1 (SRBD1), which triggers cellular senescence via AKT1/p53 and RB/p16 pathways, and promotes SASP via NF-κβ pathway in NPCs. Our findings reveal the function and mechanism of selective autophagy receptor NBR1 in regulating NPCs senescence and degeneration. Targeting NBR1 to facilitate the clearance of detrimental substances holds the potential to provide novel insights for IDD treatment.
    Keywords:  NBR1; SRBD1; cellular senescence; intervertebral disc degeneration; selective autophagy
    DOI:  https://doi.org/10.7150/ijbs.90186
  20. Anal Chem. 2024 Jan 02.
    Dual-Labeled Single Fluorescent Probes for the Simultaneous Two-Color Visualization of Dual Organelles and for Monitoring Cell Autophagy.
    Liping Wang, Mengye He, Xingyue Liu, Bang-Ping Jiang, Hua Chen, Xing-Can Shen.
      Dual-labeled single fluorescent probes are powerful tools for studying autophagy on the molecular scale, yet their development has been hampered by design complexity and a lack of valid strategies. Herein, for the first time, we introduce a combinatorial regulation strategy to fabricate dual-labeled probes for studying autophagy by integrating the specific organelle-targeting group and the functional fluorescence switch into a pentacyclic pyrylium scaffold (latent dual-target scaffold). For proof of concept, we prepared a range of dual-labeled probes (TMOs) that display different emission colors in duple organelles. In these probes, TMO1 and TMO2 enabled the simultaneous two-color visualization of the lysosomes and mitochondria. The other probes (TMO3 and TMO4) discriminatively targeted lysosomes/nucleolus and lysosomes/lipid droplets (LDs) with dual-color emission characteristics, respectively. Intriguingly, by simply connecting the endoplasmic reticulum (ER) targeting group to the pentacyclic pyrylium scaffold, we created the first dual-labeled probe TMO5 for simultaneously labeling lysosomes/ER in distinctive fluorescent colors. Subsequently, using the dual-labeled probe TMO2, drug-induced mitophagy was successfully recorded by evaluating the alterations of multiple mitophagy-related parameters, and the mitophagy defects in a cellular model of Parkinson's disease (PD) were also revealed by simultaneous dual-color/dual-organelle imaging. Further, the probe TMO4 can track the movement of lysosomes and LDs in real time and monitor the dynamic process of lipophagy. Therefore, this work not only presents attractive dual-labeled probes to promote the study of organelle interactions during autophagy but also provides a promising combinatorial regulation strategy that may be generalized for designing other dual-labeled probes with multiple organelle combinations.
    DOI:  https://doi.org/10.1021/acs.analchem.3c04520
  21. Skelet Muscle. 2024 Jan 03. 14(1): 1
    The MuSK-BMP pathway maintains myofiber size in slow muscle through regulation of Akt-mTOR signaling.
    Diego Jaime, Lauren A Fish, Laura A Madigan, Chengjie Xi, Giorgia Piccoli, Madison D Ewing, Bert Blaauw, Justin R Fallon.
      Myofiber size regulation is critical in health, disease, and aging. MuSK (muscle-specific kinase) is a BMP (bone morphogenetic protein) co-receptor that promotes and shapes BMP signaling. MuSK is expressed at all neuromuscular junctions and is also present extrasynaptically in the mouse soleus, whose predominantly oxidative fiber composition is akin to that of human muscle. To investigate the role of the MuSK-BMP pathway in vivo, we generated mice lacking the BMP-binding MuSK Ig3 domain. These ∆Ig3-MuSK mice are viable and fertile with innervation levels comparable to wild type. In 3-month-old mice, myofibers are smaller in the slow soleus, but not in the fast tibialis anterior (TA). Transcriptomic analysis revealed soleus-selective decreases in RNA metabolism and protein synthesis pathways as well as dysregulation of IGF1-Akt-mTOR pathway components. Biochemical analysis showed that Akt-mTOR signaling is reduced in soleus but not TA. We propose that the MuSK-BMP pathway acts extrasynaptically to maintain myofiber size in slow muscle by promoting protein synthetic pathways including IGF1-Akt-mTOR signaling. These results reveal a novel mechanism for regulating myofiber size in slow muscle and introduce the MuSK-BMP pathway as a target for promoting muscle growth and combatting atrophy.
    Keywords:  Atrophy; BMP; Cachexia; IGF1; MuSK; Muscle fiber types; Slow muscle; mTOR
    DOI:  https://doi.org/10.1186/s13395-023-00329-9
  22. Free Radic Biol Med. 2024 Jan 03. pii: S0891-5849(24)00001-7. [Epub ahead of print]
    Lipid peroxidation products' role in autophagy regulation.
    Agnieszka Gęgotek, Elżbieta Skrzydlewska.
      Autophagy, which is responsible for removing damaged molecules, prevents their accumulation in cells, thus maintaining intracellular homeostasis. It is also responsible for removing the effects of oxidative stress, so its activation takes place during increased reactive oxygen species (ROS) generation and lipid peroxidation. Therefore, the aim of this review was to summarize all the available knowledge about the effect of protein modifications by lipid peroxidation products on autophagy activation and the impact of this interaction on the functioning of cells. This review shows that reactive aldehydes (including 4-hydroxynonenal and malondialdehyde), either directly or by the formation of adducts with autophagic proteins, can activate or prevent autophagy, depending on their concentration. This effect relates not only to the initial stages of autophagy, when 4-hydroxynonenal and malondialdehyde affect the levels of proteins involved in autophagy initiation and phagophore formation, but also to the final stage, degradation, when reactive aldehydes, by binding to the active center of cathepsins, inactivate their proteolytic functions. Moreover, this review also shows how little research exists on analyzing the impact of lipid peroxidation products and their protein adducts on autophagy. Such knowledge could be used in the therapy of diseases related to autophagy disorders.
    Keywords:  4-Hydroxynonenal; Autophagy; Lipid peroxidation products; Malondialdehyde; Protein modification
    DOI:  https://doi.org/10.1016/j.freeradbiomed.2024.01.001
  23. Autophagy. 2024 Jan 03. 1-17
    DIRAS3 induces autophagy and enhances sensitivity to anti-autophagic therapy in KRAS-driven pancreatic and ovarian carcinomas.
    Gamze Bildik, Joshua P Gray, Weiqun Mao, Hailing Yang, Rumeysa Ozyurt, Vivian R Orellana, Olivier De Wever, Mark S Carey, Robert C Bast, Zhen Lu.
      Pancreatic ductal adenocarcinoma (PDAC) and low-grade ovarian cancer (LGSOC) are characterized by the prevalence of KRAS oncogene mutations. DIRAS3 is the first endogenous non-RAS protein that heterodimerizes with RAS, disrupts RAS clustering, blocks RAS signaling, and inhibits cancer cell growth. Here, we found that DIRAS3-mediated KRAS inhibition induces ROS-mediated apoptosis in PDAC and LGSOC cells with KRAS mutations, but not in cells with wild-type KRAS, by downregulating NFE2L2/Nrf2 transcription, reducing antioxidants, and inducing oxidative stress. DIRAS3 also induces cytoprotective macroautophagy/autophagy that may protect mutant KRAS cancer cells from oxidative stress, by inhibiting mutant KRAS, activating the STK11/LKB1-PRKAA/AMPK pathway, increasing lysosomal CDKN1B/p27 localization, and inducing autophagic gene expression. Treatment with chloroquine or the novel dimeric chloroquine analog DC661 significantly enhances DIRAS3-mediated inhibition of mutant KRAS tumor cell growth in vitro and in vivo. Taken together, our study demonstrates that DIRAS3 plays a critical role in regulating mutant KRAS-driven oncogenesis in PDAC and LGSOC.Abbreviations: AFR: autophagic flux reporter; ATG: autophagy related; CQ: chloroquine; DCFDA: 2'-7'-dichlorodihydrofluorescein diacetate; DIRAS3: DIRAS family GTPase 3; DOX: doxycycline; KRAS: KRAS proto-oncogene, LGSOC: low-grade serous ovarian cancer; MiT/TFE: microphthalmia family of transcription factors; NAC: N-acetylcysteine; PDAC: pancreatic ductal adenocarcinoma; ROS: reactive oxygen species; TFEB: transcription factor EB.
    Keywords:  Autophagy; DIRAS3; KRAS; LGSOC; PDAC; chloroquine
    DOI:  https://doi.org/10.1080/15548627.2023.2299516
  24. Front Immunol. 2023 ;14 1297408
    Advances in the regulatory mechanisms of mTOR in necroptosis.
    Yawen Xie, Guoyu Zhao, Xianli Lei, Na Cui, Hao Wang.
      The mammalian target of rapamycin (mTOR), an evolutionarily highly conserved serine/threonine protein kinase, plays a prominent role in controlling gene expression, metabolism, and cell death. Programmed cell death (PCD) is indispensable for maintaining homeostasis by removing senescent, defective, or malignant cells. Necroptosis, a type of PCD, relies on the interplay between receptor-interacting serine-threonine kinases (RIPKs) and the membrane perforation by mixed lineage kinase domain-like protein (MLKL), which is distinguished from apoptosis. With the development of necroptosis-regulating mechanisms, the importance of mTOR in the complex network of intersecting signaling pathways that govern the process has become more evident. mTOR is directly responsible for the regulation of RIPKs. Autophagy is an indirect mechanism by which mTOR regulates the removal and interaction of RIPKs. Another necroptosis trigger is reactive oxygen species (ROS) produced by oxidative stress; mTOR regulates necroptosis by exploiting ROS. Considering the intricacy of the signal network, it is reasonable to assume that mTOR exerts a bifacial effect on necroptosis. However, additional research is necessary to elucidate the underlying mechanisms. In this review, we summarized the mechanisms underlying mTOR activation and necroptosis and highlighted the signaling pathway through which mTOR regulates necroptosis. The development of therapeutic targets for various diseases has been greatly advanced by the expanding knowledge of how mTOR regulates necroptosis.
    Keywords:  RIPK; ROS; autophagy; mTOR; necroptosis
    DOI:  https://doi.org/10.3389/fimmu.2023.1297408
  25. Eur J Cell Biol. 2023 Dec 27. pii: S0171-9335(23)00097-3. [Epub ahead of print]103(1): 151382
    Target lysis by cholesterol extraction is a rate limiting step in the resolution of phagolysosomes.
    Dante Barreda, Sergio Grinstein, Spencer A Freeman.
      The ongoing phagocytic activity of macrophages necessitates an extraordinary capacity to digest and resolve incoming material. While the initial steps leading to the formation of a terminal phagolysosome are well studied, much less is known about the later stages of this process, namely the degradation and resolution of the phagolysosomal contents. We report that the degradation of targets such as splenocytes and erythrocytes by phagolysosomes occurs in a stepwise fashion, requiring lysis of their plasmalemmal bilayer as an essential initial step. This is achieved by the direct extraction of cholesterol facilitated by Niemann-Pick protein type C2 (NPC2), which in turn hands off cholesterol to NPC1 for export from the phagolysosome. The removal of cholesterol ulimately destabilizes and permeabilizes the membrane of the phagocytic target, allowing access of hydrolases to its internal compartments. In contrast, we found that saposins, which activate the hydrolysis of sphingolipids, are required for lysosomal tubulation, yet are dispensable for the resolution of targets by macrophages. The extraction of cholesterol by NPC2 is therefore envisaged as rate-limiting in the clearance of membrane-bound targets such as apoptotic cells. Selective cholesterol removal appears to be a primary mechanism that enables professional phagocytes to distinguish the target membrane from the phagolysosomal membrane and may be conserved in the resolution of autolysosomes.
    Keywords:  Autophagy; Hydrolases; Lysosome; Niemann-Pick type C1 (NPC1); Niemann-Pick type C2 (NPC2); Phagocytosis; Saposin; V-ATPase
    DOI:  https://doi.org/10.1016/j.ejcb.2023.151382
  26. ACS Nano. 2023 Dec 29.
    Targeted Degradation of Signal Transduction and Activator of Transcription 3 by Chaperone-Mediated Autophagy Targeting Chimeric Nanoplatform.
    Haohao Song, Wenping Huang, Fuhao Jia, Zhihang Wang, Jie Zhang, Ruihao Qian, Gungjun Nie, Hai Wang.
      Chaperone-mediated autophagy (CMA) is a lysosomal-dependent proteolysis pathway for the degradation of cytosolic proteins. However, exploiting CMA-mediated proteolysis to degrade proteins of interest in cancer therapy has not been widely applied. In this study, we develop a CMA-targeting chimera (CMATAC) to efficiently and specifically degrade signal transduction and activator of transcription 3 (STAT3) in tumor cells. CMATAC consists of STAT3 and heat shock cognate 70 kDa protein (HSC70) targeting peptides connected by a linker. To efficiently deliver CMATACs into tumor cells, lipid nanoparticles (LNPs) are used to encapsulate CMATACs (nCMATACs) and decorated with an insulin-like growth factor 2 receptor (IGF2R) targeting peptide (InCMATACs) to achieve tumor targeting and precise delivery. The CMA pathway is activated in tumor cells by a fasting-mimicking diet (FMD). Furthermore, FMD treatment strongly enhances the cellular uptake and tumor accumulation of InCMATACs by upregulating the IGF2R expression. As a result, InCMATACs efficiently degrade STAT3 protein in both A549 and HCC827 tumor cells and inhibit tumor growths in vivo. This study demonstrates that InCMATACs can be used for selective proteolysis in cancer therapy.
    Keywords:  STAT3; chaperone-mediated autophagy; lipid nanoparticles; protein degradation; targeted delivery
    DOI:  https://doi.org/10.1021/acsnano.3c09536
  27. Mol Biol Res Commun. 2024 ;13(1): 11-19
    Evaluation of Beclin1 and mTOR genes and p62 protein expression in breast tumor tissues of Iranian patients.
    Maryam Adelipour, Mahshid Naghashpour, Mohammad Reza Roshanazadeh, Hadi Chenaneh, Asma Mohammadi, Pegah Pourangi, Seyed Rouhollah Miri, Atefeh Zahedi, Mahmood Haghighatnezhad, Sahar Golabi.
      Autophagy is a cellular process that plays a major role in the fate of tumor cells. Understanding the role of autophagy in cancer therapy is a major challenge, particularly for breast cancer as the sole top cause of mortality among women. In this study, we evaluated the gene expression of mTOR and Beclin1 and the levels of p62 protein, in breast tumors and compared them to a control condition. To explore the role of autophagy in breast cancer, we acquired tumor biopsies from 41 new cases of breast cancer patients. We extracted total RNA from each biopsy and used real-time PCR to quantify Beclin1 and mTOR-specific RNA expression. In addition, we evaluated the expression of the p62 protein in paraffin-embedded tumor tissue using the immunohistochemistry technique. The data revealed an upregulation of Beclin1 and a downregulation of mTOR in tumor tissues compared to the control condition. The correlation between p62 expression and Beclin1/mTOR showed a negative and positive correlation, respectively, confirming autophagy activation in the tumor tissues. However, there was no correlation between autophagy markers and tumor size, grade and stage. The findings revealed that autophagy activation was found in breast tumor tissues, suggesting that autophagy can be a target for breast cancer therapy.
    Keywords:  Autophagy; Beclin-1; Breast cancer; Tumor grade; mTOR
    DOI:  https://doi.org/10.22099/mbrc.2023.47597.1837
  28. Theranostics. 2024 ;14(1): 56-74
    Selective induction of Rab9-dependent alternative mitophagy using a synthetic derivative of isoquinoline alleviates mitochondrial dysfunction and cognitive deficits in Alzheimer's disease models.
    Jee-Hyun Um, Dong Jin Shin, Se Myeong Choi, Alen Benhur Pravin Nathan, Young Yeon Kim, Da Ye Lee, Dae Jin Jeong, Dong Hyun Kim, Kyung Hwa Kim, Young Hye Kim, Jihoon Nah, Jeong-Hee Jeong, Eunhee Yoo, Hwa Kyoung Shin, Hwan Tae Park, Jihoon Jo, Jong Hyun Cho, Jeanho Yun.
      Rationale: Promotion of mitophagy is considered a promising strategy for the treatment of neurodegenerative diseases including Alzheimer's disease (AD). The development of mitophagy-specific inducers with low toxicity and defined molecular mechanisms is essential for the clinical application of mitophagy-based therapy. The aim of this study was to investigate the potential of a novel small-molecule mitophagy inducer, ALT001, as a treatment for AD. Methods: ALT001 was developed through chemical optimization of an isoquinolium scaffold, which was identified from a chemical library screening using a mitophagy reporter system. In vitro and in vivo experiments were conducted to evaluate the potential of ALT001 as a mitophagy-targeting therapeutic agent and to investigate the molecular mechanisms underlying ALT001-induced mitophagy. The therapeutic effect of ALT001 was assessed in SH-SY5Y cells expressing mutant APP and mouse models of AD (5×FAD and PS2APP) by analyzing mitochondrial dysfunction and cognitive defects. Results: ALT001 specifically induces mitophagy both in vitro and in vivo but is nontoxic to mitochondria. Interestingly, we found that ALT001 induces mitophagy through the ULK1-Rab9-dependent alternative mitophagy pathway independent of canonical mitophagy pathway regulators such as ATG7 and PINK1. Importantly, ALT001 reverses mitochondrial dysfunction in SH-SY5Y cells expressing mutant APP in a mitophagy-dependent manner. ALT001 induces alternative mitophagy in mice and restores the decreased mitophagy level in a 5×FAD AD model mouse. In addition, ALT001 reverses mitochondrial dysfunction and cognitive defects in the PS2APP and 5×FAD AD mouse models. AAV-mediated silencing of Rab9 in the hippocampus further confirmed that ALT001 exerts its therapeutic effect through alternative mitophagy. Conclusion: Our results highlight the therapeutic potential of ALT001 for AD via alleviation of mitochondrial dysfunction and indicate the usefulness of the ULK1-Rab9 alternative mitophagy pathway as a therapeutic target.
    Keywords:  Alzheimer's disease; Rab9; alternative mitophagy; mitochondrial dysfunction; mitophagy inducer
    DOI:  https://doi.org/10.7150/thno.88718
  29. bioRxiv. 2023 Dec 13. pii: 2023.12.12.571324. [Epub ahead of print]
    Proximity labeling reveals dynamic changes in the SQSTM1 protein network.
    Alejandro N Rondón Ortiz, Lushuang Zhang, Peter E A Ash, Avik Basu, Sambhavi Puri, Sophie J F van der Spek, Luke Dorrian, Andrew Emili, Benjamin Wolozin.
      Sequestosome1 (SQSTM1) is an autophagy receptor that mediates degrada4on of intracellular cargo, including protein aggregates, through mul4ple protein interac4ons. These interac4ons form the SQSTM1 protein network that are mediated by SQSTM1 func4onal interac4on domains, which include LIR, PB1, UBA and KIR. Despite various abempts to unravel the complexity of the SQSTM1 protein network, our understanding of the rela4onship of various components in cellular physiology and disease states con4nues to evolve. To inves4gate the SQSTM1 protein interac4on network, we performed proximity profile labeling by fusing TurboID with the human protein SQSTM1 (TurboID::SQSTM1). This chimeric protein displayed well-established SQSTM1 features including: produc4on of SQSTM1 intracellular bodies, binding to known SQSTM1 interac4ng partners via defined func4onal SQSTM1 interac4ng domains and capture of novel SQSTM1 interactors. Strikingly, aggregated tau protein altered the protein interac4on network of SQSTM1 to include many stress-associated proteins. Overall, our work reveals the dynamic landscape of the SQSTM1 protein network and offers a resource to study SQSTM1 func4on in cellular physiology and disease state. ProteomeXchange Consor4um PRIDE Submission: Submission details: Project Name: Proximity labeling reveals dynamic changes in the SQSTM1 protein network. Project accession: PXD047725 Project DOI: Not applicable.
    DOI:  https://doi.org/10.1101/2023.12.12.571324
  30. Mol Plant. 2024 Jan 03. pii: S1674-2052(24)00002-9. [Epub ahead of print]
    Eat at Right Time: Regulations of Plant ER-phagy Receptors in Responses to Environmental Stresses.
    Yang Shao, Jiaqi Sun, Huanquan Zheng.
      The endoplasmic reticulum (ER) is the site where proteins and lipids are made. Recent research has spotlighted ER-phagy, a selective autophagy of the ER, as an important player in plant adaptation to environmental stresses. Central to ER-phagy are diverse ER-phagy receptors in both mammalian and plant cells that not only facilitate the selective degradation of the ER but also participate in the formation of the ER under normal conditions. How do cells modulate these two actions of ER-phagy receptors? Recent studies suggest that three post-translational modifications: ubiquitination, phosphorylation and UFMylation, may act as switches for these dual roles. Given the importance of ER-phagy in plant stress responses, understanding the factors that govern these dual functions is crucial. Here we seek to integrate recent research in ER-phagy receptors in mammalian and plant cells. We hypothesize that ubiquitination and phosphorylation operate collaboratively in plant cells to determine action of ER-phagy receptors in tubular ER-phagy, while UFMylation acts in rough/sheet ER-phagy. We also suggest the need for further investigations into the specificity of ER-phagy receptors and signal pathways that relay environmental stresses to the two post-translational modifications of ER-phagy receptors.
    Keywords:  AtSec62; C53; ER-phagy; ER-phagy receptors; LUNAPARK; Phosphorylation; RHD3; RTNs; UFMylation; ubiquitination
    DOI:  https://doi.org/10.1016/j.molp.2024.01.002
  31. Reprod Biol. 2023 Dec 30. pii: S1642-431X(23)00118-3. [Epub ahead of print]24(1): 100846
    PFOS exposure destroys the integrity of the blood-testis barrier (BTB) through PI3K/AKT/mTOR-mediated autophagy.
    Zifeng Chen, Zhengru Chen, Sheng Gao, Jie Shi, Xinyao Li, Fei Sun.
      Perfluorooctanesulfonate or perfluorooctane sulfonic acid (PFOS), a type of perfluorinated compound, is mainly found in consumer products. Exposure to PFOS could cause male reproductive toxicity by causing injury to the blood-testis barrier (BTB). However, the specific mechanisms through which PFOS affects male reproduction remain unclear. The mammalian target of rapamycin (mTOR) is a vital protein kinase that is believed to be a central regulator of autophagy. In this study, we established in vivo and in vitro models to explore the effects of PFOS on the BTB, autophagy, and the regulatory role of the mTOR signaling pathway. Adult mice were developmentally exposed to 0, 0.5, 5, and 10 mg/kg/day PFOS for five weeks. Thereafter, their testicular morphology, sperm counts, serum testosterone, expression of BTB-related proteins, and autophagy-related proteins were evaluated. Additionally, TM4 cells (a mouse Sertoli cell line) were used to delineate the molecular mechanisms that mediate the effects of PFOS on BTB. Our results demonstrated that exposure to PFOS induced BTB injury and autophagy, as evidenced by increased expression of autophagy-related proteins, accumulation of autophagosomes, observed through representative electron micrographs, and decreased activity of the PI3K/AKT/mTOR pathway. Moreover, treatment with chloroquine, an autophagy inhibitor, alleviated the effects of PFOS on the integrity of TM4 cells in the BTB and the PI3K/AKT/mTOR pathway. Overall, this study highlights that exposure to PFOS destroys the integrity of the BTB through PI3K/AKT/mTOR-mediated autophagy.
    Keywords:  Autophagy; Blood-testis barrier; PI3K/AKT/mTOR pathway; Perfluorooctanesulfonate; Spermatogenesis
    DOI:  https://doi.org/10.1016/j.repbio.2023.100846
  32. bioRxiv. 2023 Dec 15. pii: 2023.12.14.571785. [Epub ahead of print]
    A Fluorogenic-Based Assay to Measure Chaperone-Mediated Autophagic Activity in Cells and Tissues.
    Anila Jonnavithula, Megan Tandar, Mohammed Umar, Scott N Orton, MacKenzie C Woodrum, Sohom Mookherjee, Sihem Boudina, J David Symons, Rajeshwary Ghosh.
       Objective: Pathologies including cardiovascular diseases, cancer, and neurological disorders are caused by the accumulation of misfolded / damaged proteins. Intracellular protein degradation mechanisms play a critical role in the clearance of these disease-causing proteins. Chaperone mediated autophagy (CMA) is a protein degradation pathway that employs chaperones to bind proteins, bearing a unique KFERQ-like motif, for delivery to a CMA-specific Lysosome Associated Membrane Protein 2a (LAMP2a) receptor for lysosomal degradation. To date, steady-state CMA function has been assessed by measuring LAMP2A protein expression. However, this does not provide information regarding CMA degradation activity. To fill this dearth of tools / assays to measure CMA activity, we generated a CMA-specific fluorogenic substrate assay.
    Methods: A KFERQ-AMC [Lys-Phe-Asp-Arg-Gln-AMC(7-amino-4-methylcou-marin)] fluorogenic CMA substrate was synthesized from Solid-Phase Peptide Synthesis. KFERQ-AMC, when cleaved via lysosomal hydrolysis, causes AMC to release and fluoresce (Excitation:355 nm, Emission:460 nm). Using an inhibitor of lysosomal proteases, i.e., E64D [L-trans-Epoxy-succinyl-leucylamido(4-guanidino)butane)], responsible for cleaving CMA substrates, the actual CMA activity was determined. Essentially, CMA activity = (substrate) fluorescence - (substrate+E64D) fluorescence . To confirm specificity of the KFERQ sequence for CMA, negative control peptides were used.
    Results: Heart, liver, and kidney lysates containing intact lysosomes were obtained from 4-month-old adult male mice. First, lysates incubated with KFERQ-AMC displayed a time dependent (0-5 hour) increase in AMC fluorescence vs. lysates incubated with negative control peptides. These data validate the specificity of KFERQ for CMA. Of note, liver exhibited the highest CMA (6-fold; p<0.05) > kidney (2.4-fold) > heart (0.4-fold) at 5-hours. Second, E64D prevented KFERQ-AMC degradation, substantiating that KFERQ-AMC is degraded via lysosomes. Third, cleavage of KFERQ-AMC and resulting AMC fluorescence was inhibited in Human embryonic kidney (HEK) cells and H9c2 cardiac cells transfected with Lamp2a vs. control siRNA. Further, enhancing CMA using Lamp2a adenovirus upregulated KFERQ degradation. These data suggest that LAMP2A is required for KFERQ degradation. Conclusion. We have generated a novel assay for measuring CMA activity in cells and tissues in a variety of experimental contexts.
    Abstract Figure:
    DOI:  https://doi.org/10.1101/2023.12.14.571785
  33. Theranostics. 2024 ;14(1): 75-95
    MK8722 initiates early-stage autophagy while inhibiting late-stage autophagy via FASN-dependent reprogramming of lipid metabolism.
    Luhui Wang, Haiyan Zhu, Zhehao Shi, Bo Chen, Huirong Huang, Ganglian Lin, Jiacheng Li, Haitao Yu, Shihao Xu, Gang Chen, Rongying Ou, Chunxiu Dai.
      Background and objective: Epithelial ovarian cancer (EOC) is associated with latent onset and poor prognosis, with drug resistance being a main concern in improving the prognosis of these patients. The resistance of cancer cells to most chemotherapeutic agents can be related to autophagy mechanisms. This study aimed to assess the therapeutic effect of MK8722, a small-molecule compound that activates AMP-activated protein kinase (AMPK), on EOC cells and to propose a novel strategy for the treatment of EOC. Purpose: To explore the therapeutic effects of MK8722 on EOC cells, and to elucidate the underlying mechanism. Methods and results: It was found that MK8722 effectively inhibited the malignant biological behaviors of EOC cells. In vitro experiments showed that MK8722 targeted and decreased the lipid metabolic pathway-related fatty acid synthase (FASN) expression levels, causing the accumulation of lipid droplets. In addition, transmission electron microscopy revealed the presence of autophagosome-affected mitochondria. Western blotting confirmed that MK8722 plays a role in activating autophagy upstream (PI3K/AKT/mTOR) and inhibiting autophagy downstream via FASN-dependent reprogramming of lipid metabolism. Plasmid transient transfection demonstrated that MK8722 suppressed late-stage autophagy by blocking autophagosome-lysosome fusion. Immunofluorescence and gene silencing revealed that this effect was achieved by inhibiting the interaction of FASN with the SNARE complexes STX17-SNP29-VAMP8. Furthermore, the antitumor effect of MK8722 was verified using a subcutaneous xenograft mouse model. Conclusion: The findings suggest that using MK8722 may be a new strategy for treating EOC, as it has the potential to be a new autophagy/mitophagy inhibitor. Its target of action, FASN, is a molecular crosstalk between lipid metabolism and autophagy, and exploration of the underlying mechanism of FASN may provide a new research direction.
    Keywords:  FASN; MK8722; STX17-SNAP29-VAMP8; epithelial ovarian cancer; mitochondrial fission
    DOI:  https://doi.org/10.7150/thno.83051
  34. Autophagy. 2024 Jan 01. 1-2
    An autophagy-independent role of ULK1/ULK2 in mechanotransduction and breast cancer cell migration.
    Peigang Liang, Bo Wang.
      The progression of breast cancer is often accompanied by changes in extracellular matrix stiffness and cell adhesion ability, which are closely related to cellular mechanotransduction. However, the underlying regulatory mechanisms remain mysterious. Our study reveals that the macroautophagy/autophagy-inducing kinases, ULK1 and ULK2, inhibit the assembly of focal adhesions and F-actin by phosphorylating the adhesion protein PXN, to prevent breast cancer cell migration in an autophagy-independent fashion. Interestingly, ULK1/ULK2-mediated serine phosphorylation of PXN counteracts PXN phosphorylation at the adjacent tyrosine residues by PTK2 and SRC, to gatekeep cellular mechanotransduction. Our research establishes a new function of ULK1/ULK2 in governing cellular mechanotransduction that might be harnessed for treating breast cancer.
    Keywords:  Breast cancer; PXN; ULK1/2; cell migration; focal adhesions; mechanotransduction
    DOI:  https://doi.org/10.1080/15548627.2023.2300916
  35. Cell Metab. 2024 Jan 02. pii: S1550-4131(23)00465-5. [Epub ahead of print]
    ABCG2 is an itaconate exporter that limits antibacterial innate immunity by alleviating TFEB-dependent lysosomal biogenesis.
    Chao Chen, Zhenxing Zhang, Caiyun Liu, Pengkai Sun, Ping Liu, Xinjian Li.
      Itaconate is a metabolite that synthesized from cis-aconitate in mitochondria and transported into the cytosol to exert multiple regulatory effects in macrophages. However, the mechanism by which itaconate exits from macrophages remains unknown. Using a genetic screen, we reveal that itaconate is exported from cytosol to extracellular space by ATP-binding cassette transporter G2 (ABCG2) in an ATPase-dependent manner in human and mouse macrophages. Elevation of transcription factor TFEB-dependent lysosomal biogenesis and antibacterial innate immunity are observed in inflammatory macrophages with deficiency of ABCG2-mediated itaconate export. Furthermore, deficiency of ABCG2-mediated itaconate export in macrophages promotes antibacterial innate immune defense in a mouse model of S. typhimurium infection. Thus, our findings identify ABCG2-mediated itaconate export as a key regulatory mechanism that limits TFEB-dependent lysosomal biogenesis and antibacterial innate immunity in inflammatory macrophages, implying the potential therapeutic utility of blocking itaconate export in treating human bacterial infections.
    Keywords:  ABCG2; TFEB; exporter; innate immunity; itaconate; lysosomal biogenesis; macrophages
    DOI:  https://doi.org/10.1016/j.cmet.2023.12.015
  36. Biochim Biophys Acta Mol Basis Dis. 2024 Jan 02. pii: S0925-4439(23)00378-2. [Epub ahead of print] 167012
    P75NTR regulates autophagy through the YAP-mTOR pathway to increase the proliferation of interfollicular epidermal cells and promote wound healing in diabetic mice.
    Zhenjie Wu, Chunyan Liu, Siyuan Yin, Jiaxu Ma, Rui Sun, Guoqi Cao, Yongpan Lu, Jian Liu, Linqi Su, Ru Song, Yibing Wang.
      Wound healing is delayed in diabetic patients. Increased autophagy and dysfunction of interfollicular epidermal (IFE) cells are closely associated with delayed healing of diabetic wounds. Autophagy plays an important role in all stages of wound healing, but its role in diabetic wound healing and the underlying molecular mechanisms are not clear. Here, we found that diabetic mice had delayed wound healing and increased autophagy in wounds compared with normal mice and that chloroquine, an inhibitor of autophagy, decreased the level of autophagy, improved the function of IFE cells, and accelerated wound healing in diabetic mice. Treatment of IFE cells with advanced glycosylation end products (AGEs) resulted in increased microtubule-associated protein chain (LC3) expression and decreased prostacyclin-62 (P62) expression, indicating increased autophagy in AGE-treated IFE cells. Moreover, P75NTR reduced autophagy in IFE cells in the presence of AGEs and significantly increased the proliferation of IFE cells. In addition, P75NTR participated in regulating autophagy in IFE cells and in wounds in diabetic mice through the YAP-mTOR signalling pathway, which increased the functional activity of the cells and the healing rate of wounds in diabetic mice. Thus, our study suggests that P75NTR protects IFE cells against AGEs by affecting autophagy and accelerating wound healing in diabetic mice, providing a basis for understanding the role of autophagy in diabetic wound healing.
    Keywords:  Autophagy; Diabetic wound; Interfollicular epidermal (IFE) cells; P75NTR
    DOI:  https://doi.org/10.1016/j.bbadis.2023.167012
  37. Acta Biomater. 2023 Dec 30. pii: S1742-7061(23)00743-2. [Epub ahead of print]
    A nano-bioconjugate modified with anti-SIRPα antibodies and antisense oligonucleotides of mTOR for anti-atherosclerosis therapy.
    Yi Liu, Qian Huang, Mengyun He, Tingting Chen, Xia Chu.
      Atherosclerosis is the main cause of a series of fatal cardiovascular diseases, characterized by pathological accumulation of apoptotic cells and lipids. Pro-phagocytic antibody-based or pro-autophagy gene-based therapies are currently being explored to stimulate the phagocytic clearance of apoptotic cells and lipid metabolism; however, monotherapies are only moderately effective or require high doses with unacceptable side effects. Herein, we engineered a specific nano-bioconjugate loaded with antisense oligonucleotides (ASOs) of mammalian target of rapamycin (mTOR) and modified with anti-signal-regulated protein-α antibody (aSIRPα) for macrophage-mediated atherosclerosis therapy. The specific nano-bioconjugate utilized acid-responsive calcium phosphate (CaP) as a carrier to load mTOR ASOs, coated with lipid on the surface of CaP nanoparticles (ASOs@CaP), and subsequently modified with aSIRPα. The resulting nano-bioconjugates could accumulate within atherosclerotic plaques, target to macrophages and reactivate lesional phagocytosis through blocking the CD47-SIRPα signaling axis. In addition, efficient delivery of mTOR ASOs inhibited mTOR expression, which significantly restored impaired autophagy. The combined action of mTOR ASOs and aSIRPα reduced apoptotic cells and lipids accumulation. This nanotherapy significantly reduced plaque burden and inhibited progression of atherosclerotic lesions. These results show the potential of specific nano-bioconjugates for the prevention of atherosclerotic cardiovascular disease. STATEMENT OF SIGNIFICANCE: Atherosclerosis is the main cause of a series of fatal cardiovascular diseases. Pro-phagocytic antibody-based or pro-autophagy gene-based therapies are currently being explored to stimulate the phagocytic clearance of apoptotic cells and lipid metabolism; however, monotherapies are only moderately effective or require high doses with unacceptable side effects. Herein, we engineered a specific nano-bioconjugate loaded with antisense oligonucleotides (ASOs) of mammalian target of rapamycin (mTOR) and modified with anti-signal-regulated protein-α antibody (aSIRPα) for macrophage-mediated atherosclerosis therapy. Our study demonstrated that the combined action of mTOR ASOs and aSIRPα reduced apoptotic cells and lipids accumulation. This nanotherapy significantly reduced plaque burden and inhibited progression of atherosclerotic lesions. These results show the potential of specific nano-bioconjugates for the prevention of atherosclerotic cardiovascular disease.
    Keywords:  Antisense oligonucleotides; Atherosclerosis; Calcium phosphate; Mammalian target of rapamycin; Signal-regulated protein-α
    DOI:  https://doi.org/10.1016/j.actbio.2023.12.031
  38. Cell Death Dis. 2024 Jan 05. 15(1): 14
    GRB2 is a BECN1 interacting protein that regulates autophagy.
    Jetsy Montero-Vergara, Kira Plachetta, Lisa Kinch, Stephan Bernhardt, Kriti Kashyap, Beth Levine, Lipi Thukral, Martina Vetter, Christoph Thomssen, Stefan Wiemann, Samuel Peña-Llopis, Verena Jendrossek, Silvia Vega-Rubin-de-Celis.
      GRB2 is an adaptor protein of HER2 (and several other tyrosine kinases), which we identified as a novel BECN1 (Beclin 1) interacting partner. GRB2 co-immunoprecipitated with BECN1 in several breast cancer cell lines and regulates autophagy through a mechanism involving the modulation of the class III PI3Kinase VPS34 activity. In ovo studies in a CAM (Chicken Chorioallantoic Membrane) model indicated that GRB2 knockdown, as well as overexpression of GRB2 loss-of-function mutants (Y52A and S86A-R88A) compromised tumor growth. These differences in tumor growth correlated with differential autophagy activity, indicating that autophagy effects might be related to the effects on tumorigenesis. Our data highlight a novel function of GRB2 as a BECN1 binding protein and a regulator of autophagy.
    DOI:  https://doi.org/10.1038/s41419-023-06387-7
  39. J Virol. 2024 Jan 05. e0184223
    Porcine reproductive and respiratory syndrome virus triggers Golgi apparatus fragmentation-mediated autophagy to facilitate viral self-replication.
    Shuang-Shuang Zhao, Qisheng Qian, Xin-Xin Chen, Qingxia Lu, Guangxu Xing, Songlin Qiao, Rui Li, Gaiping Zhang.
       IMPORTANCE: Porcine reproductive and respiratory syndrome virus (PRRSV) infection results in a serious swine disease affecting pig farming worldwide. Despite that numerous studies have shown that PRRSV triggers autophagy for its self-replication, how PRRSV induces autophagy is incompletely understood. Here, we identify that PRRSV Nsp2 degrades GRASP65 to induce GA fragmentation, which dissociates RAB2 from GM130 and activates RAB2-ULK1-mediated autophagy to enhance viral replication. This work expands our understanding of PRRSV-induced autophagy and PRRSV replication, which is beneficial for anti-viral drug development.
    Keywords:  GA fragmentation; GRASP65; Nsp2; PRRSV; RAB2; ULK1; autophagy
    DOI:  https://doi.org/10.1128/jvi.01842-23
  40. Cell Metab. 2024 Jan 02. pii: S1550-4131(23)00446-1. [Epub ahead of print]36(1): 21-35
    Mitochondrial-derived vesicles in metabolism, disease, and aging.
    Tim König, Heidi M McBride.
      Mitochondria are central hubs of cellular metabolism and are tightly connected to signaling pathways. The dynamic plasticity of mitochondria to fuse, divide, and contact other organelles to flux metabolites is central to their function. To ensure bona fide functionality and signaling interconnectivity, diverse molecular mechanisms evolved. An ancient and long-overlooked mechanism is the generation of mitochondrial-derived vesicles (MDVs) that shuttle selected mitochondrial cargoes to target organelles. Just recently, we gained significant insight into the mechanisms and functions of MDV transport, ranging from their role in mitochondrial quality control to immune signaling, thus demonstrating unexpected and diverse physiological aspects of MDV transport. This review highlights the origin of MDVs, their biogenesis, and their cargo selection, with a specific focus on the contribution of MDV transport to signaling across cell and organ barriers. Additionally, the implications of MDVs in peroxisome biogenesis, neurodegeneration, metabolism, aging, and cancer are discussed.
    DOI:  https://doi.org/10.1016/j.cmet.2023.11.014
  41. Front Neurosci. 2023 ;17 1319706
    Fundamental roles of the Optineurin gene in the molecular pathology of Amyotrophic Lateral Sclerosis.
    Shumin Zhao, Ranran Chen, Ying Gao, Yanchao Lu, Xue Bai, Jingjing Zhang.
      Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the progressive loss of motor neurons (MNs) in the brain and spinal cord. It is caused by multiple factors, including mutations in any one of several specific genes. Optineurin (OPTN) mutation is an essential cause of some familial and sporadic ALS. Besides, as a multifunctional protein, OPTN is highly expressed and conserved in the central nervous system. OPTN exerts its functions by interacting with various proteins, often acting as an adaptor to provide a link between two or more core proteins related to autophagy and inflammation, etc. OPTN mutation mainly results in its function deficiency, which alters these interactions, leading to functional impairment in many processes. Meanwhile, OPTN immunopositive inclusions are also confirmed in the cases of ALS due to C9ORF72, FUS, TARDBP, and SOD1 mutations. Therefore, OPTN gene may play fundamental roles in the molecular pathology of ALS in addition to OPTN mutation. In this review, we summarize the recent advances in the ALS pathology of OPTN defect, such as mitophagy disorder, neuroinflammation, neuronal axonal degeneration, vesicular transport dysfunction, etc., which will provide a reference for research on the pathogenesis and treatment of ALS.
    Keywords:  amyotrophic lateral sclerosis; mitophagy; neuroinflammation; optineurin; protein aggregation
    DOI:  https://doi.org/10.3389/fnins.2023.1319706
  42. J Cell Biol. 2024 Mar 04. pii: e202211048. [Epub ahead of print]223(3):
    Fission-independent compartmentalization of mitochondria during budding yeast cell division.
    Saori R Yoshii, Yves Barral.
      Lateral diffusion barriers compartmentalize membranes to generate polarity or asymmetrically partition membrane-associated macromolecules. Budding yeasts assemble such barriers in the endoplasmic reticulum (ER) and the outer nuclear envelope at the bud neck to retain aging factors in the mother cell and generate naïve and rejuvenated daughter cells. However, little is known about whether other organelles are similarly compartmentalized. Here, we show that the membranes of mitochondria are laterally compartmentalized at the bud neck and near the cell poles. The barriers in the inner mitochondrial membrane are constitutive, whereas those in the outer membrane form in response to stresses. The strength of mitochondrial diffusion barriers is regulated positively by spatial cues from the septin axis and negatively by retrograde (RTG) signaling. These data indicate that mitochondria are compartmentalized in a fission-independent manner. We propose that these diffusion barriers promote mitochondrial polarity and contribute to mitochondrial quality control.
    DOI:  https://doi.org/10.1083/jcb.202211048
  43. Nat Commun. 2024 Jan 02. 15(1): 145
    Innate immune and proinflammatory signals activate the Hippo pathway via a Tak1-STRIPAK-Tao axis.
    Yinan Yang, Huijing Zhou, Xiawei Huang, Chengfang Wu, Kewei Zheng, Jingrong Deng, Yonggang Zheng, Jiahui Wang, Xiaofeng Chi, Xianjue Ma, Huimin Pan, Rui Shen, Duojia Pan, Bo Liu.
      The Hippo pathway controls developmental, homeostatic and regenerative tissue growth, and is frequently dysregulated in various diseases. Although this pathway can be activated by innate immune/inflammatory stimuli, the underlying mechanism is not fully understood. Here, we identify a conserved signaling cascade that leads to Hippo pathway activation by innate immune/inflammatory signals. We show that Tak1, a key kinase in innate immune/inflammatory signaling, activates the Hippo pathway by inducing the lysosomal degradation of Cka, an essential subunit of the STRIPAK PP2A complex that suppresses Hippo signaling. Suppression of STRIPAK results in the activation of Hippo pathway through Tao-Hpo signaling. We further show that Tak1-mediated Hippo signaling is involved in processes ranging from cell death to phagocytosis and innate immune memory. Our findings thus reveal a molecular connection between innate immune/inflammatory signaling and the evolutionally conserved Hippo pathway, thus contributing to our understanding of infectious, inflammatory and malignant diseases.
    DOI:  https://doi.org/10.1038/s41467-023-44542-y
  44. BMC Cardiovasc Disord. 2024 Jan 03. 24(1): 18
    The molecular mechanism of MiR-26a-5p regulates autophagy and activates NLRP3 inflammasome to mediate cardiomyocyte hypertrophy.
    Li-Qun Tang, Wei Wang, Qi-Feng Tang, Ling-Ling Wang.
       OBJECTIVE: Many studies have found that miR-26a-5p plays an essential role in the progression of pathological cardiac hypertrophy, however, there is still no evidence on whether miR-26a-5p is related to the activation of autophagy and NLRP3 inflammasome. And the mechanism of miR-26a-5p and NLRP3 inflammasome aggravating pathological cardiac hypertrophy remain unclear.
    METHODS: Cardiomyocytes were treated with 200µM PE to induce cardiac hypertrophy and intervened with 10mM NLRP3 inhibitor INF39. In addition, we also used the MiR-26a-5p mimic and inhibitor to transfect PE-induced cardiac hypertrophy. RT-qPCR and western blotting were used to detect the expressions of miR-26a-5p, NLRP3, ASC and Caspase-1 in each group, and we used α-SMA immunofluorescence to detect the change of cardiomyocyte area. The expression levels of autophagy proteins LC3, beclin-1 and p62 were detected by western blotting. Finally, we induced the SD rat cardiac hypertrophy model through aortic constriction (TAC) surgery. In the experimental group, rats were intervened with MiR-26a-5p mimic, MiR-26a-5p inhibitor, autophagy inhibitor 3-MA, and autophagy activator Rapamycin.
    RESULTS: In cell experiments, we observed that the expression of miR-26a-5p was associated with cardiomyocyte hypertrophy and increased surface area. Furthermore, miR-26a-5p facilitated autophagy and activated the NLRP3 inflammasome pathway, which caused changes in the expression of genes and proteins including LC3, beclin-1, p62, ACS, NLRP3, and Caspase-1. We discovered similar outcomes in the TAC rat model, where miR-26a-5p expression corresponded with cardiomyocyte enlargement and fibrosis in the cardiac interstitial and perivascular regions. In conclusion, miR-26a-5p has the potential to regulate autophagy and activate the NLRP3 inflammasome, contributing to the development of cardiomyocyte hypertrophy.
    CONCLUSION: Our study found a relationship between the expression of miR-26a-5p and cardiomyocyte hypertrophy. The mechanism behind this relationship appears to involve the activation of the NLRP3 inflammasome pathway, which is caused by miR-26a-5p promoting autophagy. Targeting the expression of miR-26a-5p, as well as inhibiting the activation of autophagy and the NLRP3 inflammasome pathway, could offer additional treatments for pathological cardiac hypertrophy.
    Keywords:  Apoptosis; Autophagy; Cardiac hypertrophy; Cardiomyocytes; miR-26a-5p
    DOI:  https://doi.org/10.1186/s12872-023-03695-w
  45. BMC Neurosci. 2024 Jan 02. 25(1): 1
    Sex differences in response to obesity and caloric restriction on cognition and hippocampal measures of autophagic-lysosomal transcripts and signaling pathways.
    Sadie B Baer, Adrianah D Dorn, Danielle M Osborne.
       BACKGROUND: Obesity rates in the U.S. continue to increase, with nearly 50% of the population being either obese or morbidly obese. Obesity, along with female sex, are leading risk factors for sporadic Alzheimer's Disease (AD) necessitating the need to better understand how these variables impact cellular function independent of age or genetic mutations. Animal and clinical studies both indicate that autophagy-lysosomal pathway (ALP) dysfunction is among the earliest known cellular systems to become perturbed in AD, preceding cognitive decline, yet little is known about how obesity and sex affects these cellular functions in the hippocampus, a brain region uniquely susceptible to the negative effects of obesity. We hypothesized that obesity would negatively affect key markers of ALP in the hippocampus, effects would vary based on sex, and that caloric restriction would counteract obesity effects.
    METHODS: Female and male mice were placed on an obesogenic diet for 10 months, at which point half were switched to caloric restriction for three months, followed by cognitive testing in the Morris watermaze. Hippocampus was analyzed by western blot and qPCR.
    RESULTS: Cognitive function in female mice responded differently to caloric restriction based on whether they were on a normal or obesogenic diet; male cognition was only mildly affected by caloric restriction and not obesity. Significant male-specific changes occurred in cellular markers of autophagy, including obesity increasing pAkt, Slc38a9, and Atg12, while caloric restriction reduced pRPS6 and increased Atg7. In contrast females experienced changes due to diet/caloric restriction predominately in lysosomal markers including increased TFE3, FLCN, FNIP2, and pAMPK.
    CONCLUSIONS: Results support that hippocampal ALP is a target of obesity and that sex shapes molecular responses, while providing insight into how dietary manipulations affect learning and memory based on sex.
    Keywords:  Autophagy; Caloric restriction; Lysosomal degradation; Obesity; Sex-differences; TFE3; Watermaze
    DOI:  https://doi.org/10.1186/s12868-023-00840-1
  46. Redox Biol. 2023 Dec 30. pii: S2213-2317(23)00424-X. [Epub ahead of print]69 103023
    PINK1 restrains periodontitis-induced bone loss by preventing osteoclast mitophagy impairment.
    Ji Sun Jang, Seo Jin Hong, Shenzheng Mo, Min Kyung Kim, Yong-Gun Kim, Youngkyun Lee, Hong-Hee Kim.
      The oral colonization of periodontal pathogens onto gingival tissues establishes hypoxic microenvironment, often disrupting periodontal homeostasis in conjunction with oxidative stress. The association between reactive oxygen species (ROS) and osteolytic periodontitis have been suggested by recent studies. PTEN-induced kinase 1 (PINK1), a mitochondrial serine/threonine kinase, is an essential protein for mitochondrial quality control as it protects cells from oxidative stress by promoting degradation of damaged mitochondria through mitophagy. However, the pathophysiological roles of PINK1 in osteoclast-mediated bone loss have not been explored. Here we aimed to determine whether PINK1 plays a role in the regulation of osteoclastogenesis and alveolar bone resorption associated with periodontitis. C57BL/6 wild type (WT) and Pink1 knockout (KO) mice were subjected to ligature-induced periodontitis (LIP), and alveolar bones were evaluated by μCT-analysis and tartrate-resistant acid phosphatase (TRAP) staining. The μCT-analysis showed that bone volume fraction and travecular thickness were lower in Pink1 KO compared to WT mice. The number of TRAP-positive osteoclasts was markedly increased in the periodontal tissues of Pink1 KO mice with LIP. The genetic silencing or deletion of Pink1 promoted excessive osteoclast differentiation and bone resorption in vitro, as respectively indicated by TRAP staining and resorption pits on dentin slices. PINK1 deficiency led to mitochondrial instabilities as indicated by confocal microscopy of mitochondrial ROS, mitochondrial oxygen consumption rate (OCR) analysis, and transmission electron microscopy (TEM). Consequently, a significant increase in Ca2+-nuclear factor of activated T cells 1 (NFATc1) signaling was also found. On the other hand, restoration of mitophagy and autophagy by spermidine (SPD) treatment and the resolution of oxidative stress by N-acetyl-l-cysteine (NAC) treatment protected PINK1 deficiency-induced excessive generation of osteoclasts. Taken together, our findings demonstrate that PINK1 is essential for maintaining mitochondrial homeostasis during osteoclast differentiation. Therefore, targeting PINK1 may provide a novel therapeutic strategy for severe periodontitis with fulminant osteolysis.
    Keywords:  Mitophagy; Osteoclast; PINK1; Periodontitis; ROS
    DOI:  https://doi.org/10.1016/j.redox.2023.103023
  47. J Biol Chem. 2023 Dec 28. pii: S0021-9258(23)02641-8. [Epub ahead of print] 105612
    NCOA4 requires a [3Fe-4S] to sense and maintain the iron homeostasis.
    Hongting Zhao, Yao Lu, Jinghua Zhang, Zichen Sun, Chen Cheng, Yutong Liu, Lin Wu, Meng Zhang, Weijiang He, Shuangying Hao, Kuanyu Li.
      NCOA4 is a selective cargo receptor for ferritinophagy, the autophagic turnover of ferritin (FTH), a process critical for regulating intracellular iron bioavailability. However, how ferritinophagy flux is controlled through NCOA4 in iron-dependent processes needs to be better understood. Here, we show that the C-terminal FTH-binding domain of NCOA4 harbors a [3Fe-4S] binding site with a stoichiometry of approximately one labile [3Fe-4S] cluster per NCOA4 monomer. By analyzing the interaction between NCOA4 and HERC2 ubiquitin ligase or NCOA4 and FTH, we demonstrate that NCOA4 regulates ferritinophagy by sensing the intracellular iron-sulfur-cluster levels. Under iron repletion conditions, HERC2 recognizes and recruits holo-NCOA4 as a substrate for polyubiquitination and degradation, favoring ferritin iron storage. Under iron depletion conditions, NCOA4 exists in the form of apo-protein and binds ferritin to promote the occurrence of ferritinophagy and release iron. Thus, we identify an iron-sulfur cluster [3Fe-4S] as a critical cofactor in determining the fate of NCOA4 in favoring iron storage in ferritin or iron release via ferritinophagy and provide a dual mechanism for selective interaction between HERC2 and [3Fe-4S]-NCOA4 for proteasomal degradation or between ferritin and apo-NCOA4 for ferritinophagy in the control of iron homeostasis.
    Keywords:  Iron-sulfur protein; NCOA4; autophagy; ferritin; iron metabolism; protein degradation
    DOI:  https://doi.org/10.1016/j.jbc.2023.105612
  48. Cell Rep. 2024 Jan 04. pii: S2211-1247(23)01683-2. [Epub ahead of print]43(1): 113672
    Activation of autophagy depends on Atg1/Ulk1-mediated phosphorylation and inhibition of the Hsp90 chaperone machinery.
    Sarah J Backe, Rebecca A Sager, Jennifer A Heritz, Laura A Wengert, Katherine A Meluni, Xavier Aran-Guiu, Barry Panaretou, Mark R Woodford, Chrisostomos Prodromou, Dimitra Bourboulia, Mehdi Mollapour.
      
    DOI:  https://doi.org/10.1016/j.celrep.2023.113672
  49. PLoS One. 2024 ;19(1): e0291477
    Motor neuron activity enhances the proteomic stress caused by autophagy defects in the target muscle.
    Saurabh Srivastav, Kevin van der Graaf, Prisha C Jonnalagadda, Maanvi Thawani, James A McNew, Michael Stern.
      Several lines of evidence demonstrate that increased neuronal excitability can enhance proteomic stress. For example, epilepsy can enhance the proteomic stress caused by the expression of certain aggregation-prone proteins implicated in neurodegeneration. However, unanswered questions remain concerning the mechanisms by which increased neuronal excitability accomplishes this enhancement. Here we test whether increasing neuronal excitability at a particular identified glutamatergic synapse, the Drosophila larval neuromuscular junction, can enhance the proteomic stress caused by mutations in the ER fusion/GTPase gene atlastin (atl). It was previously shown that larval muscle from the atl2 null mutant is defective in autophagy and accumulates protein aggregates containing ubiquitin (poly-UB aggregates). To determine if increased neuronal excitability might enhance the increased proteomic stress caused by atl2, we activated the TrpA1-encoded excitability channel within neurons. We found that TrpA1 activation had no effect on poly-UB aggregate accumulation in wildtype muscle, but significantly increased poly-UB aggregate number in atl2 muscle. Previous work has shown that atl loss from either neuron or muscle increases muscle poly-UB aggregate number. We found that neuronal TrpA1 activation enhanced poly-UB aggregate number when atl was removed from muscle, but not from neuron. Neuronal TrpA1 activation enhanced other phenotypes conferred by muscle atl loss, such as decreased pupal size and decreased viability. Taken together, these results indicate that the proteomic stress caused by muscle atl loss is enhanced by increasing neuronal excitability.
    DOI:  https://doi.org/10.1371/journal.pone.0291477
  50. J Mol Histol. 2024 Jan 02.
    Sestrin2 ameliorates diabetic retinopathy by regulating autophagy and ferroptosis.
    Xiaoting Xi, Qianbo Chen, Jia Ma, Xuewei Wang, Junyan Zhang, Yan Li.
      Diabetic retinopathy (DR) is a serious microvascular complication of diabetes. The aim of this study was to explore the effect of Sestrin2 on DR through the regulation of autophagy and ferroptosis levels and its mechanism. In vitro and in vivo DR models were established by high glucose (HG) and streptozotocin (STZ) induction of ARPE-19 human retinal pigment epithelial cells and C57BL/6 mice, respectively. In this study, we demonstrated that after HG treatment, the activity of ARPE-19 cells was decreased, the apoptosis rate was increased, endoplasmic reticulum (ER) stress was activated, autophagy levels were decreased, and ferroptosis levels were increased. Overexpression of Sestrin2 enhanced cell viability, reduced apoptosis and ferroptosis, and enhanced autophagy. However, the effect of overexpression of Sestrin2 was attenuated after the addition of the STAT3 phosphorylation activator Colivelin TFA (C-TFA), the mTOR pathway activator MHY1485 or the autophagy inhibitor 3-methyladenine (3-MA). In addition, the effect of Sestrin2 knockdown on cells was opposite to the effect of overexpression of Sestrin2, while the effect of Sestrin2 knockdown was attenuated after treatment with the ER stress inhibitor 4-phenylbutyric acid (4-PBA). Animal experiments also confirmed the results of cell experiments and attenuated the effects of overexpression of Sestrin2 after injection of the ferroptosis activators erastin or 3-MA. Our study revealed that Sestrin2 inhibits ferroptosis by inhibiting STAT3 phosphorylation and ER stress and promoting autophagy levels, thereby alleviating DR.
    Keywords:  Autophagy; Diabetic retinopathy; Ferroptosis; Sestrin2
    DOI:  https://doi.org/10.1007/s10735-023-10180-3
  51. Front Endocrinol (Lausanne). 2023 ;14 1349432
    Editorial: Autophagy and hypoxia-inducible factor in diabetes.
    Jing Guo, Xuefei Tian, Huafeng Liu, Wei Jing Liu.
      
    Keywords:  HMGB1; autophagy; diabetes mellitus; diabetic kidney disease; natural products
    DOI:  https://doi.org/10.3389/fendo.2023.1349432
  52. Cell Signal. 2024 Jan 03. pii: S0898-6568(24)00003-2. [Epub ahead of print] 111035
    Mitochondrial quality control in liver fibrosis: Epigenetic hallmarks and therapeutic strategies.
    Lin Jia, Yang Yang, Feng Sun, Hui Tao, Chao Lu, Jing-Jing Yang.
       BACKGROUND AND AIM: Mitochondrial quality control (MQC) plays a significant role in the progression of liver fibrosis, with key processes such as mitochondrial fission, fusion, mitophagy and biogenesis maintaining mitochondrial homeostasis. To understand the molecular mechanisms underlying epigenetic regulation of mitochondrial quality control in liver fibrosis, with the aim of uncovering novel therapeutic targets for treating, mitigating, and potentially reversing liver fibrosis, in light of the most recent advances in this field.
    METHODS: We searched PubMed, Web of Science, and Scopus for published manuscripts using terms "mitochondrial quality control" "mitochondrial fission" "mitochondrial fusion" "mitochondrial biogenesis" "mitophagy" "liver fibrosis" "epigenetic regulation" "DNA methylation" "RNA methylation" "histone modification" and "non-coding RNA". Manuscripts were collated, studied and carried forward for discussion where appropriate.
    RESULTS: Mitochondrial fission, fusion, biogenesis, and mitophagy regulate the homeostasis of mitochondria, and the imbalance of mitochondrial homeostasis can induce liver fibrosis. Epigenetic regulation, including DNA methylation, RNA methylation, histone modifications, and non-coding RNAs, plays a significant role in regulating the processes of mitochondrial homeostasis.
    CONCLUSION: Mitochondrial quality control and epigenetic mechanisms are intricately linked to the pathogenesis of liver fibrosis. Understanding these molecular interactions provides insight into potential therapeutic strategies. Further research is necessary to translate these findings into clinical applications, with a focus on developing epigenetic drugs to ameliorate liver fibrosis by modulating MQC and epigenetic pathways.
    Keywords:  Epigenetics; Liver fibrosis; Mitochondrial quality control; Molecular mechanisms
    DOI:  https://doi.org/10.1016/j.cellsig.2024.111035
  53. Mol Med. 2024 Jan 03. 30(1): 4
    Key roles of autophagosome/endosome maturation mediated by Syntaxin17 in methamphetamine-induced neuronal damage in mice.
    Xi Wang, Miaoyang Hu, Jingrong Chen, Xinyu Lou, Hongchao Zhang, Muhan Li, Jie Cheng, Tengfei Ma, Jianping Xiong, Rong Gao, Xufeng Chen, Jun Wang.
       BACKGROUND: Autophagic defects are involved in Methamphetamine (Meth)-induced neurotoxicity. Syntaxin 17 (Stx17), a member of the SNARE protein family, participating in several stages of autophagy, including autophagosome-late endosome/lysosome fusion. However, the role of Stx17 and potential mechanisms in autophagic defects induced by Meth remain poorly understood.
    METHODS: To address the mechanism of Meth-induced cognitive impairment, the adenovirus (AV) and adeno-associated virus (AAV) were injected into the hippocampus for stereotaxis to overexpress Stx17 in vivo to examine the cognitive ability via morris water maze and novel object recognition. In molecular level, the synaptic injury and autophagic defects were evaluated. To address the Meth induced neuronal damage, the epidermal growth factor receptor (EGFR) degradation assay was performed to evaluate the degradability of the "cargos" mediated by Meth, and mechanistically, the maturation of the vesicles, including autophagosomes and endosomes, were validated by the Co-IP and the GTP-agarose affinity isolation assays.
    RESULTS: Overexpression of Stx17 in the hippocampus markedly rescued the Meth-induced cognitive impairment and synaptic loss. For endosomes, Meth exposure upregulated Rab5 expression and its guanine-nucleotide exchange factor (GEF) (immature endosome), with a commensurate decreased active form of Rab7 (Rab7-GTP) and impeded the binding of Rab7 to CCZ1 (mature endosome); for autophagosomes, Meth treatment elicited a dramatic reduction in the overlap between Stx17 and autophagosomes but increased the colocalization of ATG5 and autophagosomes (immature autophagosomes). After Stx17 overexpression, the Rab7-GTP levels in purified late endosomes were substantially increased in parallel with the elevated mature autophagosomes, facilitating cargo (Aβ42, p-tau, and EGFR) degradation in the vesicles, which finally ameliorated Meth-induced synaptic loss and memory deficits in mice.
    CONCLUSION: Stx17 decrease mediated by Meth contributes to vesicle fusion defects which may ascribe to the immature autophagosomes and endosomes, leading to autophagic dysfunction and finalizes neuronal damage and cognitive impairments. Therefore, targeting Stx17 may be a novel therapeutic strategy for Meth-induced neuronal injury.
    Keywords:  Autophagosome; Autophagy; Endosome; Methamphetamine; Syntaxin 17
    DOI:  https://doi.org/10.1186/s10020-023-00765-9
  54. Mol Biol Cell. 2024 Jan 03. mbcE23090347
    TLR-mediated aggresome-like induced structures comprise antimicrobial peptides and attenuate intracellular bacterial survival.
    Anushree Bhatnagar, Umesh Chopra, Sebastian Raja, Krishanu Dey Das, S Mahalingam, Dipshikha Chakravortty, Srinivasa Murty Srinivasula.
      Immune cells employ diverse mechanisms for host defense. Macrophages, in response to TLR activation, assemble aggresome-like induced structures (ALIS). Our group has shown TLR4-signaling transcriptionally upregulates p62/sequestome1, which assembles ALIS. We have demonstrated that TLR4-mediated autophagy is, in fact, selective-autophagy of ALIS. We hypothesize that TLR-mediated autophagy and ALIS contribute to host-defense. Here we show that ALIS are assembled in macrophages upon exposure to different bacteria. These structures are associated with pathogen-containing phagosomes. Importantly, we present evidence of increased bacterial burden, where ALIS assembly is prevented with p62-specific siRNA. We have employed 3D-super-resolution structured illumination microscopy (3D-SR-SIM) and mass-spectrometric (MS) analyses to gain insight into the assembly of ALIS. Ultra-structural analyses of known constituents of ALIS (p62, ubiquitin, LC3) reveal that ALIS are organized structures with distinct patterns of alignment. Furthermore, MS-analyses of ALIS identified, among others, several proteins of known antimicrobial properties. We have validated MS data by testing the association of some of these molecules (Bst2, IFITM2, IFITM3) with ALIS and the phagocytosed-bacteria. We surmise that AMPs enrichment in ALIS leads to their delivery to bacteria-containing phagosomes and restricts the bacteria. Our findings in this paper support hitherto unknown functions of ALIS in host-defense. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text].
    DOI:  https://doi.org/10.1091/mbc.E23-09-0347
  55. Prenat Diagn. 2024 Jan 04.
    Mammalian target of rapamycin inhibitors: A new-possible approach for in-utero medication therapy.
    Shohra Qaderi, Ali Javinani, Yair J Blumenfeld, Eyal Krispin, Ramesha Papanna, Frank A Chervenak, Alireza A Shamshirsaz.
      The mammalian/mechanistic target of rapamycin (mTOR) is a protein kinase that plays a crucial role in regulating cellular growth, metabolism, and survival. Although there is no absolute contraindication for the use of mTOR inhibitors during pregnancy, the specific fetal effects remain unknown. Available data from the past 2 decades have examined the use of mTOR inhibitors during pregnancy in patients with solid organ transplantation, showing no clear link to fetal complications or structural abnormalities. Recently, a handful of case reports and series have described transplacental therapy of mTOR inhibitors to control symptomatic and complicated pathologies in the fetus. The effect of these agents includes a significant reduction in lesion size in the fetus and a reduced need for mechanical ventilation in neonates. In this context, we delve into the potential of mTOR inhibitors as in-utero therapy for fetal abnormalities, with a primary focus on lymphatic malformation (LM) and cardiac rhabdomyoma (CR). While preliminary reports underscore the efficacy of mTOR inhibitors for the treatment of fetal CR and fetal brain lesions associated with tuberous sclerosis complex, chylothorax, and LMs, additional investigation and clinical trials are essential to comprehensively assess the safety and efficacy of these medications.
    DOI:  https://doi.org/10.1002/pd.6492
  56. Cell Rep. 2023 Dec 13. pii: S2211-1247(23)01587-5. [Epub ahead of print] 113575
    Chronic hypoxia stabilizes 3βHSD1 via autophagy suppression.
    Liang Qin, Michael Berk, Yoon-Mi Chung, Di Cui, Ziqi Zhu, Abhishek A Chakraborty, Nima Sharifi.
      Progression of prostate cancer depends on androgen receptor, which is usually activated by androgens. Therefore, a mainstay treatment is androgen deprivation therapy. Unfortunately, despite initial treatment response, resistance nearly always develops, and disease progresses to castration-resistant prostate cancer (CRPC), which remains driven by non-gonadal androgens synthesized in prostate cancer tissues. 3β-Hydroxysteroid dehydrogenase/Δ5-->4 isomerase 1 (3βHSD1) catalyzes the rate-limiting step in androgen synthesis. However, how 3βHSD1, especially the "adrenal-permissive" 3βHSD1(367T) that permits tumor synthesis of androgen from dehydroepiandrosterone (DHEA), is regulated at the protein level is not well understood. Here, we investigate how hypoxia regulates 3βHSD1(367T) protein levels. Our results show that, in vitro, hypoxia stabilizes 3βHSD1 protein by suppressing autophagy. Autophagy inhibition promotes 3βHSD1-dependent tumor progression. Hypoxia represses transcription of autophagy-related (ATG) genes by decreasing histone acetylation. Inhibiting deacetylase (HDAC) restores ATG gene transcription under hypoxia. Therefore, HDAC inhibition may be a therapeutic target for hypoxic tumor cells.
    Keywords:  3βHSD1; CP: Cancer; CP: Molecular biology; androgen synthesis; autophagy; enzyme; germline; hypoxia; metabolism; prostate cancer; protein; steroid
    DOI:  https://doi.org/10.1016/j.celrep.2023.113575
  57. Cell Biosci. 2024 Jan 05. 14(1): 6
    Autophagy induces hair follicle stem cell activation and hair follicle regeneration by regulating glycolysis.
    Pingping Sun, Zhan Wang, Sixiao Li, Jiajing Yin, Yuyang Gan, Shizhao Liu, Zhen Lin, Hailin Wang, Zhexiang Fan, Qian Qu, Zhiqi Hu, Kaitao Li, Yong Miao.
       BACKGROUND: Hair follicle stem cells (HFSCs) typically remain quiescent and are activated only during the transition from telogen to anagen to ensure that the hair follicle enters a new cycle. The metabolic behavior of stem cells in tissues is regulated by macroautophagy/autophagy, and changes in HFSC metabolism directly affect their activation and maintenance. However, the role of autophagy in the regulation of HFSC metabolism and function remains unclear.
    METHODS: Back skin samples were obtained from mice at different hair follicle cycle stages, and immunofluorescence staining was used to monitor autophagy in HFSCs. Mouse and human hair follicles were treated with rapamycin (Rapa, an autophagy activator) or 3-methyladenine (3-MA, an autophagy inhibitor). The effects of autophagy on the hair follicle cycle and HFSC were investigated by imaging, cell proliferation staining, and HFSC-specific marker staining. The influence and mechanism of autophagy on HFSC metabolism were explored using RNA sequencing, real-time polymerase chain reaction, immunohistochemical staining, and detection of lactate and glucose concentrations. Finally, the influence of autophagy-induced glycolysis on HFSC and the hair follicle cycle was verified by stem cell characteristics and in vivo functional experiments.
    RESULTS: Autophagy in HFSC was highest during the transition from telogen to anagen. Inhibiting autophagy with 3-MA led to early entry into catagen and prolonged telogen, whereas Rapa promoted autophagy and hair growth. Autophagy activated HFSC by increasing the expression and activity of HFSC lactate dehydrogenase (Ldha), thereby transforming HFSC metabolism into glycolysis. Inhibition of Ldha expression counteracted the effects of autophagy.
    CONCLUSIONS: Autophagy activated HFSC by promoting the transition from HFSC metabolism to glycolysis, ultimately initiating the hair follicle cycle and promoting hair growth.
    Keywords:  Autophagy; Glycolysis; Hair follicle regeneration; Hair follicle stem cells
    DOI:  https://doi.org/10.1186/s13578-023-01177-2
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