bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2024‒06‒09
forty-nine papers selected by
Viktor Korolchuk, Newcastle University
  1. Nanotherapeutics targeting autophagy regulation for improved cancer therapy.
  2. Comprehensive analysis of non-selective and selective autophagy in yeast atg mutants and characterization of autophagic activity in the absence of the Atg8 conjugation system.
  3. Flexible Atg1/ULK complex composition activates selective autophagy for phosphate starvation.
  4. A matter of timing.
  5. TORSEL, a 4EBP1-based mTORC1 live-cell sensor, reveals nutrient-sensing targeting by histone deacetylase inhibitors.
  6. Autophagy mediated targeting degradation, a promising strategy in drug development.
  7. The picky mTORC1 in metabolic enzyme degradation.
  8. The new kids on the block: RNA-binding proteins regulate autophagy in disease.
  9. Inhibition of autophagy prevents cardiac dysfunction at early stages of cardiomyopathy in Bag3-deficient hearts.
  10. Mitophagy in relation to chronic inflammation/ROS in aging.
  11. The role of Atg5 gene in tumorigenesis under autophagy deficiency conditions.
  12. Syntaxin 17 recruitment to mature autophagosomes is temporally regulated by PI4P accumulation.
  13. Atg45 is an autophagy receptor for glycogen, a non-preferred cargo of bulk autophagy in yeast.
  14. Autophagy suppression in DNA damaged cells occurs through a newly identified p53-proteasome-LC3 axis.
  15. A mild increase in nutrient signaling to mTORC1 in mice leads to parenchymal damage, myeloid inflammation and shortened lifespan.
  16. Lysosomal control of the cGAS-STING signaling.
  17. The structure and function of FUN14 domain-containing protein 1 and its contribution to cardioprotection by mediating mitophagy.
  18. Different ER-plasma membrane tethers play opposing roles in autophagy of the cortical ER.
  19. The DNA damage response and autophagy during cancer development: an antagonistic pleiotropy entanglement.
  20. Role of FMRP in AKT/mTOR pathway-mediated hippocampal autophagy in fragile X syndrome.
  21. STAT3 inhibition recovers regeneration of aged muscles by restoring autophagy in muscle stem cells.
  22. Functional role of autophagy in testicular and ovarian steroidogenesis.
  23. ZNPs reduce epidermal mechanical strain resistance by promoting desmosomal cadherin endocytosis via mTORC1-TFEB-BLOC1S3 axis.
  24. GPCR function in autophagy control: a systematic approach of chemical intervention.
  25. TFEB/LAMP2 contributes to PM0.2-induced autophagy-lysosome dysfunction and alpha-synuclein dysregulation in astrocytes.
  26. Extracellular vesicles promote autophagy in human microglia through lipid raft-dependent mechanisms.
  27. Styxl2 regulates de novo sarcomere assembly by binding to non-muscle myosin IIs and promoting their degradation.
  28. ATG16L1 induces the formation of phagophore-like membrane cups.
  29. ATP6V1A is required for synaptic rearrangements and plasticity in murine hippocampal neurons.
  30. ATG10S promotes IFNL1 expression and autophagic degradation of multiple viral proteins mediated by IFNL1.
  31. Mitophagy and cancer: role of BNIP3/BNIP3L as energetic drivers of stemness features, ATP production, proliferation, and cell migration.
  32. Dexmedetomidine enhances Mitophagy via PINK1 to alleviate hippocampal neuronal Pyroptosis and improve postoperative cognitive dysfunction in elderly rat.
  33. SIRT5-Mediated Desuccinylation of RAB7A Protects Against Cadmium-Induced Alzheimer's Disease-Like Pathology by Restoring Autophagic Flux.
  34. Chronic unpredictable stress induces autophagic death of adult hippocampal neural stem cells.
  35. Acidic Nanoparticles Restore Lysosomal Acidification and Rescue Metabolic Dysfunction in Pancreatic β-Cells under Lipotoxic Conditions.
  36. Mechanism of human PINK1 activation at the TOM complex in a reconstituted system.
  37. Epigenetic regulation of autophagy by non-coding RNAs and exosomal non-coding RNAs in colorectal cancer: A narrative review.
  38. The role of chaperone-mediated autophagy in drug resistance.
  39. Off-target autophagy inhibition by SHP2 allosteric inhibitors contributes to their anti-tumor activity in RAS-driven cancers.
  40. MFSD1 with its accessory subunit GLMP functions as a general dipeptide uniporter in lysosomes.
  41. Deciphering the molecular nexus of BTG2 in periodontitis and diabetic kidney disease.
  42. Morphine Induced Neuroprotection in Ischemic Stroke by Activating Autophagy Via mTOR-Independent Activation of the JNK1/2 Pathway.
  43. Burkholderia pseudomallei BipD modulates host mitophagy to evade killing.
  44. The WD Domain of Atg16l1 Crucial for LC3-Associated Phagocytosis Is Not Required for Preserving Skin Barrier Function in Mice.
  45. eIF4F complex dynamics are important for the activation of the integrated stress response.
  46. Decoding transcriptomic signatures of cysteine string protein alpha-mediated synapse maintenance.
  47. STING agonists as promising vaccine adjuvants to boost immunogenicity against SARS-related coronavirus derived infection: possible role of autophagy.
  48. ATG5-mediated keratinocyte ferroptosis promotes M1 polarization of macrophages to aggravate UVB-induced skin inflammation.
  49. Enhancing Rab7 Activity by Inhibiting TBC1D5 Expression Improves Mitophagy in Alzheimer's Disease Models.
  1. Acta Pharm Sin B. 2024 Jun;14(6): 2447-2474
    Nanotherapeutics targeting autophagy regulation for improved cancer therapy.
    Yunmeng Liu, Yaxin Wang, Jincheng Zhang, Qikai Peng, Xingdong Wang, Xiyue Xiao, Kai Shi.
      The clinical efficacy of current cancer therapies falls short, and there is a pressing demand to integrate new targets with conventional therapies. Autophagy, a highly conserved self-degradation process, has received considerable attention as an emerging therapeutic target for cancer. With the rapid development of nanomedicine, nanomaterials have been widely utilized in cancer therapy due to their unrivaled delivery performance. Hence, considering the potential benefits of integrating autophagy and nanotechnology in cancer therapy, we outline the latest advances in autophagy-based nanotherapeutics. Based on a brief background related to autophagy and nanotherapeutics and their impact on tumor progression, the feasibility of autophagy-based nanotherapeutics for cancer treatment is demonstrated. Further, emerging nanotherapeutics developed to modulate autophagy are reviewed from the perspective of cell signaling pathways, including modulation of the mammalian target of rapamycin (mTOR) pathway, autophagy-related (ATG) and its complex expression, reactive oxygen species (ROS) and mitophagy, interference with autophagosome-lysosome fusion, and inhibition of hypoxia-mediated autophagy. In addition, combination therapies in which nano-autophagy modulation is combined with chemotherapy, phototherapy, and immunotherapy are also described. Finally, the prospects and challenges of autophagy-based nanotherapeutics for efficient cancer treatment are envisioned.
    Keywords:  Autophagy regulation; Cancer therapy; Combination strategies; Delivery strategies; Dual effects; Nanomaterials; Nanotherapeutic; Signal transduction pathway
    DOI:  https://doi.org/10.1016/j.apsb.2024.03.019
  2. J Biochem. 2024 Jun 06. pii: mvae042. [Epub ahead of print]
    Comprehensive analysis of non-selective and selective autophagy in yeast atg mutants and characterization of autophagic activity in the absence of the Atg8 conjugation system.
    Tamara Ginevskaia, Aleksei Innokentev, Kentaro Furukawa, Tomoyuki Fukuda, Manabu Hayatsu, Shun-Ichi Yamashita, Keiichi Inoue, Shinsuke Shibata, Tomotake Kanki.
      Most autophagy-related genes, or ATG genes, have been identified in studies using budding yeast. Although the functions of the ATG genes are well understood, the contributions of individual genes to non-selective and various types of selective autophagy remain to be fully elucidated. In this study, we quantified the activity of non-selective autophagy, the cytoplasm-to-vacuole targeting (Cvt) pathway, mitophagy, endoplasmic reticulum (ER)-phagy, and pexophagy in all Saccharomyces cerevisiae atg mutants. Among the mutants of the core autophagy genes considered essential for autophagy, the atg13 mutant and mutants of the genes involved in the two ubiquitin-like conjugation systems retained residual autophagic functionality. In particular, mutants of the Atg8 ubiquitin-like conjugation system (the Atg8 system) exhibited substantial levels of non-selective autophagy, the Cvt pathway, and pexophagy, although mitophagy and ER-phagy were undetectable. Atg8-system mutants also displayed intravacuolar vesicles resembling autophagic bodies, albeit at significantly reduced size and frequency. Thus, our data suggest that membranous sequestration and vacuolar delivery of autophagic cargo can occur in the absence of the Atg8 system. Alongside these findings, the comprehensive analysis conducted here provides valuable datasets for future autophagy research.
    Keywords:  Atg8 conjugation system; Cvt pathway; autophagy; core autophagy genes; mitophagy
    DOI:  https://doi.org/10.1093/jb/mvae042
  3. Cell Mol Biol Lett. 2024 Jun 04. 29(1): 85
    Flexible Atg1/ULK complex composition activates selective autophagy for phosphate starvation.
    Yijia Fangma, Zhong Chen, Yanrong Zheng.
      The molecular basis for bulk autophagy activation due to a deficiency in essential nutrients such as carbohydrates, amino acids, and nitrogen is well understood. Given autophagy functions to reduce surplus to compensate for scarcity, it theoretically possesses the capability to selectively degrade specific substrates to meet distinct metabolic demands. However, direct evidence is still lacking that substantiates the idea that autophagy selectively targets specific substrates (known as selective autophagy) to address particular nutritional needs. Recently, Gross et al. found that during phosphate starvation (P-S), rather than nitrogen starvation (N-S), yeasts selectively eliminate peroxisomes by dynamically altering the composition of the Atg1/ULK kinase complex (AKC) to adapt to P-S. This study elucidates how the metabolite sensor Pho81 flexibly interacts with AKC and guides selective autophagic clearance of peroxisomes during P-S, providing novel insights into the metabolic contribution of autophagy to special nutritional needs.
    Keywords:  Atg1/ULK kinase complex; Pexophagy; Phosphate starvation; Selective autophagy
    DOI:  https://doi.org/10.1186/s11658-024-00597-3
  4. Elife. 2024 Jun 04. pii: e99181. [Epub ahead of print]13
    A matter of timing.
    Zhiqi Tian, Jiajie Diao.
      A change in the electric charge of autophagosome membranes controls the recruitment of SNARE proteins to ensure that membrane fusion occurs at the right time during autophagy.
    Keywords:  SNARE; autophagosome; autophagy; cell biology; human; membrane charge; mouse; phosphatidylinositol 4-phosphate; syntaxin 17
    DOI:  https://doi.org/10.7554/eLife.99181
  5. Cell Biosci. 2024 Jun 01. 14(1): 68
    TORSEL, a 4EBP1-based mTORC1 live-cell sensor, reveals nutrient-sensing targeting by histone deacetylase inhibitors.
    Canrong Li, Yuguo Yi, Yingyi Ouyang, Fengzhi Chen, Chuxin Lu, Shujun Peng, Yifan Wang, Xinyu Chen, Xiao Yan, Haolun Xu, Shuiming Li, Lin Feng, Xiaoduo Xie.
      BACKGROUND: Mammalian or mechanistic target of rapamycin complex 1 (mTORC1) is an effective therapeutic target for diseases such as cancer, diabetes, aging, and neurodegeneration. However, an efficient tool for monitoring mTORC1 inhibition in living cells or tissues is lacking.RESULTS: We developed a genetically encoded mTORC1 sensor called TORSEL. This sensor changes its fluorescence pattern from diffuse to punctate when 4EBP1 dephosphorylation occurs and interacts with eIF4E. TORSEL can specifically sense the physiological, pharmacological, and genetic inhibition of mTORC1 signaling in living cells and tissues. Importantly, TORSEL is a valuable tool for imaging-based visual screening of mTORC1 inhibitors. Using TORSEL, we identified histone deacetylase inhibitors that selectively block nutrient-sensing signaling to inhibit mTORC1.
    CONCLUSIONS: TORSEL is a unique living cell sensor that efficiently detects the inhibition of mTORC1 activity, and histone deacetylase inhibitors such as panobinostat target mTORC1 signaling through amino acid sensing.
    Keywords:  Amino acid sensing; HDAC inhibitor; Live-cell sensor; Panobinostat; mTORC1
    DOI:  https://doi.org/10.1186/s13578-024-01250-4
  6. Bioorg Chem. 2024 May 20. pii: S0045-2068(24)00371-7. [Epub ahead of print]149 107466
    Autophagy mediated targeting degradation, a promising strategy in drug development.
    Jiantao Zhang, Xiangyi Pan, Wenshu Ji, Jinming Zhou.
      Targeted protein degradation (TPD) technologies have become promising therapeutic approaches through degrading disease-causing proteins via the protein degradation system. Autophagy is a fundamental biological process with a high relationship to protein degradation, which belongs to one of two main protein degradation pathways, the autophagy-lysosomal system. Recently, various autophagy-based TPD techniques ATTECs, AUTACs, and AUTOTACs, etc, have also been gradually developed, and they have achieved efficient degradation potency for the targeted protein, expanding the potential of degradation for large-size proteins or protein aggregates. Herein, we introduce the machinery of autophagy and its relation to protein degradation, and multiple methods for using autophagy to specifically degrade target proteins.
    Keywords:  ATTEC; AUTAC; AUTOTAC; Autophagy; Protein degradation
    DOI:  https://doi.org/10.1016/j.bioorg.2024.107466
  7. Mol Cell. 2024 Jun 06. pii: S1097-2765(24)00436-2. [Epub ahead of print]84(11): 2011-2013
    The picky mTORC1 in metabolic enzyme degradation.
    Yujin Chun, David A Fruman, Gina Lee.
      In this issue of Molecular Cell, Yi et al.1 demonstrate that reduced mTORC1 activity induces the CTLH E3 ligase-dependent degradation of HMGCS1, an enzyme in the mevalonate pathway, thus revealing a unique connection between mTORC1 signaling and the degradation of a specific metabolic enzyme via the ubiquitin-proteasome system.
    DOI:  https://doi.org/10.1016/j.molcel.2024.05.013
  8. FEBS J. 2024 Jun 02.
    The new kids on the block: RNA-binding proteins regulate autophagy in disease.
    Shai Dushnitzky, Hasan Ishtayeh, Avraham Ashkenazi.
      Mammalian autophagy is a highly regulated and conserved cellular homeostatic process. Its existence allows the degradation of self-components to mediate cell survival in different stress conditions. Autophagy is involved in the regulation of cellular metabolic needs, protecting the cell or tissue from starvation through the degradation and recycling of cytoplasmic materials and organelles to basic molecular building blocks. It also plays a critical role in eliminating damaged or harmful proteins, organelles, and intracellular pathogens. Thus, a deterioration of the process may result in pathological conditions, such as aging-associated disorders and cancer. Understanding the crucial role of autophagy in maintaining the normal physiological function of cells, tissue, or organs has led to copious and expansive research regarding the regulation of this process. So far, most of the research has revolved around transcriptional and post-translational regulation. Here, we discuss the regulation of autophagy-related (ATG) mRNA transcripts by RNA-binding proteins (RBPs). This analysis focuses on how RBPs modulate autophagy in disease. A deeper understanding of the involvement of RBPs in autophagy can facilitate further research and treatment of a variety of human diseases.
    Keywords:  aging; autophagy‐related genes; cancer; mammalian autophagy
    DOI:  https://doi.org/10.1111/febs.17195
  9. J Mol Cell Cardiol. 2024 Jun 03. pii: S0022-2828(24)00090-7. [Epub ahead of print]
    Inhibition of autophagy prevents cardiac dysfunction at early stages of cardiomyopathy in Bag3-deficient hearts.
    Giovanni Maroli, Anne Schänzer, Stefan Günther, Claudia Garcia-Gonzalez, Stefan Rupp, Hannah Schlierbach, Yanpu Chen, Johannes Graumann, Astrid Wietelmann, Johnny Kim, Thomas Braun.
      The HSP70 co-chaperone BAG3 targets unfolded proteins to degradation via chaperone assisted selective autophagy (CASA), thereby playing pivotal roles in the proteostasis of adult cardiomyocytes (CMs). However, the complex functions of BAG3 for regulating autophagy in cardiac disease are not completely understood. Here, we demonstrate that conditional inactivation of Bag3 in murine CMs leads to age-dependent dysregulation of autophagy, associated with progressive cardiomyopathy. Surprisingly, Bag3-deficient CMs show increased canonical and non-canonical autophagic flux in the juvenile period when first signs of cardiac dysfunction appear, but reduced autophagy during later stages of the disease. Juvenile Bag3-deficient CMs are characterized by decreased levels of soluble proteins involved in synchronous contraction of the heart, including the gap junction protein Connexin 43 (CX43). Reiterative administration of chloroquine (CQ), an inhibitor of canonical and non-canonical autophagy, but not inactivation of Atg5, restores normal concentrations of soluble cardiac proteins in juvenile Bag3-deficient CMs without an increase of detergent-insoluble proteins, leading to complete recovery of early-stage cardiac dysfunction in Bag3-deficient mice. We conclude that loss of Bag3 in CMs leads to age-dependent differences in autophagy and cardiac dysfunction. Increased non-canonical autophagic flux in the juvenile period removes soluble proteins involved in cardiac contraction, leading to early-stage cardiomyopathy, which is prevented by reiterative CQ treatment.
    Keywords:  Autophagy; Bag3; Cardiomyopathy; Chloroquine; Cx43; Heart failure; Hypertrophic cardiomyopathy; Pediatric
    DOI:  https://doi.org/10.1016/j.yjmcc.2024.06.001
  10. Mol Cell Biochem. 2024 Jun 04.
    Mitophagy in relation to chronic inflammation/ROS in aging.
    Liang Kong, Shuhao Li, Yu Fu, Qinyun Cai, Xinyun Du, Jingyan Liang, Tan Ma.
      Various assaults on mitochondria occur during the human aging process, contributing to mitochondrial dysfunction. This mitochondrial dysfunction is intricately connected with aging and diseases associated with it. In vivo, the accumulation of defective mitochondria can precipitate inflammatory and oxidative stress, thereby accelerating aging. Mitophagy, an essential selective autophagy process, plays a crucial role in managing mitochondrial quality control and homeostasis. It is a highly specialized mechanism that systematically removes damaged or impaired mitochondria from cells, ensuring their optimal functioning and survival. By engaging in mitophagy, cells are able to maintain a balanced and stable environment, free from the potentially harmful effects of dysfunctional mitochondria. An ever-growing body of research highlights the significance of mitophagy in both aging and age-related diseases. Nonetheless, the association between mitophagy and inflammation or oxidative stress induced by mitochondrial dysfunction remains ambiguous. We review the fundamental mechanisms of mitophagy in this paper, delve into its relationship with age-related stress, and propose suggestions for future research directions.
    Keywords:  Aging; Chronic inflammation; Mitophagy; ROS
    DOI:  https://doi.org/10.1007/s11010-024-05042-9
  11. Kaohsiung J Med Sci. 2024 Jun 03.
    The role of Atg5 gene in tumorigenesis under autophagy deficiency conditions.
    Hsiao-Sheng Liu, Yin-Ping Wang, Pei-Wen Lin, Man-Ling Chu, Sheng-Hui Lan, Shan-Ying Wu, Ying-Ray Lee, Hong-Yi Chang.
      Autophagy is a self-recycling machinery to maintain cellular homeostasis by degrading harmful materials in the cell. Autophagy-related gene 5 (Atg5) is required for autophagosome maturation. However, the role of Atg5 in tumorigenesis under autophagy deficient conditions remains unclear. This study focused on the autophagy-independent role of Atg5 and the underlying mechanism in tumorigenesis. We demonstrated that knockout of autophagy-related genes including Atg5, Atg7, Atg9, and p62 in mouse embryonic fibroblast (MEF) cells consistently decreased cell proliferation and motility, implying that autophagy is required to maintain diverse cellular functions. An Atg7 knockout MEF (Atg7-/- MEF) cell line representing deprivation of autophagy function was used to clarify the role of Atg5 transgene in tumorigenesis. We found that Atg5-overexpressed Atg7-/-MEF (clone A) showed increased cell proliferation, colony formation, and migration under autophagy deficient conditions. Accordingly, rescuing the autophagy deficiency of clone A by overexpression of Atg7 gene shifts the role of Atg5 from pro-tumor to anti-tumor status, indicating the dual role of Atg5 in tumorigenesis. Notably, the xenograft mouse model showed that clone A of Atg5-overexpressed Atg7-/- MEF cells induced temporal tumor formation, but could not prolong further tumor growth. Finally, biomechanical analysis disclosed increased Wnt5a secretion and p-JNK expression along with decreased β-catenin expression. In summary, Atg5 functions as a tumor suppressor to protect the cell under normal conditions. In contrast, Atg5 shifts to a pro-tumor status under autophagy deprivation conditions.
    Keywords:  autophagy; autophagy‐related gene 5 (Atg5); tumorigenesis
    DOI:  https://doi.org/10.1002/kjm2.12853
  12. Elife. 2024 Jun 04. pii: RP92189. [Epub ahead of print]12
    Syntaxin 17 recruitment to mature autophagosomes is temporally regulated by PI4P accumulation.
    Saori Shinoda, Yuji Sakai, Takahide Matsui, Masaaki Uematsu, Ikuko Koyama-Honda, Jun-Ichi Sakamaki, Hayashi Yamamoto, Noboru Mizushima.
      During macroautophagy, cytoplasmic constituents are engulfed by autophagosomes. Lysosomes fuse with closed autophagosomes but not with unclosed intermediate structures. This is achieved in part by the late recruitment of the autophagosomal SNARE syntaxin 17 (STX17) to mature autophagosomes. However, how STX17 recognizes autophagosome maturation is not known. Here, we show that this temporally regulated recruitment of STX17 depends on the positively charged C-terminal region of STX17. Consistent with this finding, mature autophagosomes are more negatively charged compared with unclosed intermediate structures. This electrostatic maturation of autophagosomes is likely driven by the accumulation of phosphatidylinositol 4-phosphate (PI4P) in the autophagosomal membrane. Accordingly, dephosphorylation of autophagosomal PI4P prevents the association of STX17 to autophagosomes. Furthermore, molecular dynamics simulations support PI4P-dependent membrane insertion of the transmembrane helices of STX17. Based on these findings, we propose a model in which STX17 recruitment to mature autophagosomes is temporally regulated by a PI4P-driven change in the surface charge of autophagosomes.
    Keywords:  SNARE; autophagosome; autophagy; cell biology; human; membrane charge; mouse; phosphatidylinositol 4-phosphate; syntaxin 17
    DOI:  https://doi.org/10.7554/eLife.92189
  13. iScience. 2024 Jun 21. 27(6): 109810
    Atg45 is an autophagy receptor for glycogen, a non-preferred cargo of bulk autophagy in yeast.
    Takahiro Isoda, Eigo Takeda, Sachiko Hosokawa, Shukun Hotta-Ren, Yoshinori Ohsumi.
      The mechanisms governing autophagy of proteins and organelles have been well studied, but how other cytoplasmic components such as RNA and polysaccharides are degraded remains largely unknown. In this study, we examine autophagy of glycogen, a storage form of glucose. We find that cells accumulate glycogen in the cytoplasm during nitrogen starvation and that this carbohydrate is rarely observed within autophagosomes and autophagic bodies. However, sequestration of glycogen by autophagy is observed following prolonged nitrogen starvation. We identify a yet-uncharacterized open reading frame, Yil024c (herein Atg45), as encoding a cytosolic receptor protein that mediates autophagy of glycogen (glycophagy). Furthermore, we show that, during sporulation, Atg45 is highly expressed and is associated with an increase in glycophagy. Our results suggest that cells regulate glycophagic activity by controlling the expression level of Atg45.
    Keywords:  Biomolecules; Cell biology; Glycobiology; Model organism
    DOI:  https://doi.org/10.1016/j.isci.2024.109810
  14. bioRxiv. 2024 May 23. pii: 2024.05.21.595139. [Epub ahead of print]
    Autophagy suppression in DNA damaged cells occurs through a newly identified p53-proteasome-LC3 axis.
    D'Feau J Lieu, Molly K Crowder, Jordan R Kryza, Batcha Tamilselvam, Paul J Kaminski, Ik-Jung Kim, Yingxing Li, Eunji Jeong, Michidmaa Enkhbaatar, Henry Chen, Sophia B Son, Hanlin Mok, Kenneth A Bradley, Heidi Phillips, Steven R Blanke.
      Macroautophagy is thought to have a critical role in shaping and refining cellular proteostasis in eukaryotic cells recovering from DNA damage. Here, we report a mechanism by which autophagy is suppressed in cells exposed to bacterial toxin-, chemical-, or radiation-mediated sources of genotoxicity. Autophagy suppression is directly linked to cellular responses to DNA damage, and specifically the stabilization of the tumor suppressor p53, which is both required and sufficient for regulating the ubiquitination and proteasome-dependent reduction in cellular pools of microtubule-associated protein 1 light chain 3 (LC3A/B), a key precursor of autophagosome biogenesis and maturation, in both epithelial cells and an ex vivo organoid model. Our data indicate that suppression of autophagy, through a newly identified p53-proteasome-LC3 axis, is a conserved cellular response to multiple sources of genotoxicity. Such a mechanism could potentially be important for realigning proteostasis in cells undergoing DNA damage repair.
    DOI:  https://doi.org/10.1101/2024.05.21.595139
  15. Nat Aging. 2024 Jun 07.
    A mild increase in nutrient signaling to mTORC1 in mice leads to parenchymal damage, myeloid inflammation and shortened lifespan.
    Ana Ortega-Molina, Cristina Lebrero-Fernández, Alba Sanz, Miguel Calvo-Rubio, Nerea Deleyto-Seldas, Lucía de Prado-Rivas, Ana Belén Plata-Gómez, Elena Fernández-Florido, Patricia González-García, Yurena Vivas-García, Elena Sánchez García, Osvaldo Graña-Castro, Nathan L Price, Alejandra Aroca-Crevillén, Eduardo Caleiras, Daniel Monleón, Consuelo Borrás, María Casanova-Acebes, Rafael de Cabo, Alejo Efeyan.
      The mechanistic target of rapamycin complex 1 controls cellular anabolism in response to growth factor signaling and to nutrient sufficiency signaled through the Rag GTPases. Inhibition of mTOR reproducibly extends longevity across eukaryotes. Here we report that mice that endogenously express active mutant variants of RagC exhibit multiple features of parenchymal damage that include senescence, expression of inflammatory molecules, increased myeloid inflammation with extensive features of inflammaging and a ~30% reduction in lifespan. Through bone marrow transplantation experiments, we show that myeloid cells are abnormally activated by signals emanating from dysfunctional RagC-mutant parenchyma, causing neutrophil extravasation that inflicts additional inflammatory damage. Therapeutic suppression of myeloid inflammation in aged RagC-mutant mice attenuates parenchymal damage and extends survival. Together, our findings link mildly increased nutrient signaling to limited lifespan in mammals, and support a two-component process of parenchymal damage and myeloid inflammation that together precipitate a time-dependent organ deterioration that limits longevity.
    DOI:  https://doi.org/10.1038/s43587-024-00635-x
  16. Trends Cell Biol. 2024 Jun 06. pii: S0962-8924(24)00111-9. [Epub ahead of print]
    Lysosomal control of the cGAS-STING signaling.
    Yinfeng Xu, Wei Wan.
      The cyclic GMP-AMP (cGAMP) synthase (cGAS)-stimulator of interferon genes (STING) pathway has a crucial role in combating pathogen infection. However, its aberrant activation is involved in several human disorders. Lysosomes are emerging as key negative regulators of cGAS-STING signaling. Here, we discuss the lysosomal control of cGAS-STING signaling and its implication in human disorders.
    Keywords:  STING; autophagy; cGAS; human disorders; innate immunity; lysosome
    DOI:  https://doi.org/10.1016/j.tcb.2024.05.004
  17. Front Pharmacol. 2024 ;15 1389953
    The structure and function of FUN14 domain-containing protein 1 and its contribution to cardioprotection by mediating mitophagy.
    Yuhu Lv, Zhengze Yu, Peiwen Zhang, Xiqian Zhang, Huarui Li, Ting Liang, Yanju Guo, Lin Cheng, Fenglin Peng.
      Cardiovascular disease (CVD) is a serious public health risk, and prevention and treatment efforts are urgently needed. Effective preventive and therapeutic programs for cardiovascular disease are still lacking, as the causes of CVD are varied and may be the result of a multifactorial combination. Mitophagy is a form of cell-selective autophagy, and there is increasing evidence that mitophagy is involved in cardioprotective processes. Recently, many studies have shown that FUN14 domain-containing protein 1 (FUNDC1) levels and phosphorylation status are highly associated with many diseases, including heart disease. Here, we review the structure and functions of FUNDC1 and the path-ways of its mediated mitophagy, and show that mitophagy can be effectively activated by dephosphorylation of Ser13 and Tyr18 sites, phosphorylation of Ser17 site and ubiquitination of Lys119 site in FUNDC1. By effectively activating or inhibiting excessive mitophagy, the quality of mitochondria can be effectively controlled. The main reason is that, on the one hand, improper clearance of mitochondria and accumulation of damaged mitochondria are avoided, and on the other hand, excessive mitophagy causing apoptosis is avoided, both serving to protect the heart. In addition, we explore the possible mechanisms by which FUNDC1-mediated mitophagy is involved in exercise preconditioning (EP) for cardioprotection. Finally, we also point out unresolved issues in FUNDC1 and its mediated mitophagy and give directions where further research may be needed.
    Keywords:  FUN14 domain-containing protein 1; cardioprotection; exercise preconditioning; mitochondria; mitophagy
    DOI:  https://doi.org/10.3389/fphar.2024.1389953
  18. Proc Natl Acad Sci U S A. 2024 Jun 11. 121(24): e2321991121
    Different ER-plasma membrane tethers play opposing roles in autophagy of the cortical ER.
    Dongmei Liu, Hua Yuan, Shuliang Chen, Susan Ferro-Novick, Peter Novick.
      The endoplasmic reticulum (ER) undergoes degradation by selective macroautophagy (ER-phagy) in response to starvation or the accumulation of misfolded proteins within its lumen. In yeast, actin assembly at sites of contact between the cortical ER (cER) and endocytic pits acts to displace elements of the ER from their association with the plasma membrane (PM) so they can interact with the autophagosome assembly machinery near the vacuole. A collection of proteins tether the cER to the PM. Of these, Scs2/22 and Ist2 are required for cER-phagy, most likely through their roles in lipid transport, while deletion of the tricalbins, TCB1/2/3, bypasses those requirements. An artificial ER-PM tether blocks cER-phagy in both the wild type (WT) and a strain lacking endogenous tethers, supporting the importance of cER displacement from the PM. Scs2 and Ist2 can be cross-linked to the selective cER-phagy receptor, Atg40. The COPII cargo adaptor subunit, Lst1, associates with Atg40 and is required for cER-phagy. This requirement is also bypassed by deletion of the ER-PM tethers, suggesting a role for Lst1 prior to the displacement of the cER from the PM during cER-phagy. Although pexophagy and mitophagy also require actin assembly, deletion of ER-PM tethers does not bypass those requirements. We propose that within the context of rapamycin-induced cER-phagy, Scs2/22, Ist2, and Lst1 promote the local displacement of an element of the cER from the cortex, while Tcb1/2/3 act in opposition, anchoring the cER to the plasma membrane.
    Keywords:  autophagy; endoplasmic reticulum; lipid transfer; membrane tether
    DOI:  https://doi.org/10.1073/pnas.2321991121
  19. Autophagy. 2024 Jun 02.
    The DNA damage response and autophagy during cancer development: an antagonistic pleiotropy entanglement.
    Vassilis G Gorgoulis, Konstantinos Evangelou, Daniel J Klionsky.
      The DNA damage response (DDR) pathway is a cardinal cellular stress response mechanism that during cancer development follows an antagonistic pleiotropy mode of action. Given that DDR activation is an energy demanding process, interplay with macroautophagy/autophagy, a stress response and energy providing mechanism, is likely to take place. While molecular connections between both mechanisms have been reported, an open question regards whether autophagy activation follows solely or is entangled with DDR in a similar antagonistic pleiotropy pattern during cancer development. Combing evidence on the spatiotemporal relationship of DDR and autophagy in the entire spectrum of carcinogenesis from our previous studies, we discuss these issues in the current addendum.
    Keywords:  Disease; genomic instability; macroautophagy; stress; tumor
    DOI:  https://doi.org/10.1080/15548627.2024.2362121
  20. Prog Neuropsychopharmacol Biol Psychiatry. 2024 May 30. pii: S0278-5846(24)00104-0. [Epub ahead of print] 111036
    Role of FMRP in AKT/mTOR pathway-mediated hippocampal autophagy in fragile X syndrome.
    Bohan Zhang, Jingbao Zhang, Huan Chen, Dan Qiao, Fangzhen Guo, Xiangting Hu, Chao Qin, Xiaowen Jin, Kaixi Zhang, Chang Wang, Huixian Cui, Sha Li.
      Fragile X syndrome (FXS) is caused by epigenetic silencing of the Fmr1 gene, leading to the deletion of the coding protein FMRP. FXS induces abnormal hippocampal autophagy and mTOR overactivation. However, it remains unclear whether FMRP regulates hippocampal autophagy through the AKT/mTOR pathway, which influences the neural behavior of FXS. Our study revealed that FMRP deficiency increased the protein levels of p-ULK-1 and p62 and decreased LC3II/LC3I(LC3-II/I) level in Fmr1 knockout (KO) mice. The mouse hippocampal neuronal cell line HT22 with knockdown of Fmr1 by lentivirus showed that the protein levels of p-ULK-1 and p62 were increased, whereas LC3II/LC3I was unchanged. Further observations revealed that FMRP deficiency obstructed autophagic flow in HT22 cells. Therefore, FMRP deficiency inhibited autophagy in the mouse hippocampus and HT22 cells. Moreover, FMRP deficiency increased reactive oxygen species (ROS) level, decreased the co-localization between the mitochondrial outer membrane proteins TOM20 and LC3 in HT22 cells, and caused a decrease in the mitochondrial autophagy protein PINK1 in HT22 cells and Fmr1 KO mice, indicating that FMRP deficiency caused mitochondrial autophagy disorder in HT22 cells and Fmr1 KO mice. To explore the mechanism by which FMRP deficiency inhibits autophagy, we examined the AKT/mTOR signaling pathway in the hippocampus of Fmr1 KO mice, found that FMRP deficiency caused overactivation of the AKT/mTOR pathway. Rapamycin-mediated mTOR inhibition activated and enhanced mitochondrial autophagy. Finally, we examined whether rapamycin affected the neurobehavior of Fmr1 KO mice. The Fmr1 KO mice exhibited stereotypical behavior, impaired social ability, and learning and memory impairment, while rapamycin treatment improved behavioral disorders in Fmr1 KO mice. Thus, our study revealed the molecular mechanism by which FMRP regulates autophagy function, clarifying the role of hippocampal neuron mitochondrial autophagy in the pathogenesis of FXS, and providing novel insights into potential therapeutic targets of FXS.
    Keywords:  AKT/mTOR pathway; Autophagy; FMRP; Fragile X syndrome; Neurobehavioral
    DOI:  https://doi.org/10.1016/j.pnpbp.2024.111036
  21. Life Sci Alliance. 2024 Aug;pii: e202302503. [Epub ahead of print]7(8):
    STAT3 inhibition recovers regeneration of aged muscles by restoring autophagy in muscle stem cells.
    Giorgia Catarinella, Andrea Bracaglia, Emilia Skafida, Paola Procopio, Veronica Ruggieri, Cristina Parisi, Marco De Bardi, Giovanna Borsellino, Luca Madaro, Pier Lorenzo Puri, Alessandra Sacco, Lucia Latella.
      Age-related reduction in muscle stem cell (MuSC) regenerative capacity is associated with cell-autonomous and non-cell-autonomous changes caused by alterations in systemic and skeletal muscle environments, ultimately leading to a decline in MuSC number and function. Previous studies demonstrated that STAT3 plays a key role in driving MuSC expansion and differentiation after injury-activated regeneration, by regulating autophagy in activated MuSCs. However, autophagy gradually declines in MuSCs during lifespan and contributes to the impairment of MuSC-mediated regeneration of aged muscles. Here, we show that STAT3 inhibition restores the autophagic process in aged MuSCs, thereby recovering MuSC ability to promote muscle regeneration in geriatric mice. We show that STAT3 inhibition could activate autophagy at the nuclear level, by promoting transcription of autophagy-related genes, and at the cytoplasmic level, by targeting STAT3/PKR phosphorylation of eIF2α. These results point to STAT3 inhibition as a potential intervention to reverse the age-related autophagic block that impairs MuSC ability to regenerate aged muscles. They also reveal that STAT3 regulates MuSC function by both transcription-dependent and transcription-independent regulation of autophagy.
    DOI:  https://doi.org/10.26508/lsa.202302503
  22. Front Cell Dev Biol. 2024 ;12 1384047
    Functional role of autophagy in testicular and ovarian steroidogenesis.
    Ali Afzal, Yue Zhang, Hanan Afzal, Umair Ali Khan Saddozai, Lei Zhang, Xin-Ying Ji, Muhammad Babar Khawar.
      Autophagy is an evolutionarily conserved cellular recycling process that maintains cellular homeostasis. Despite extensive research in endocrine contexts, the role of autophagy in ovarian and testicular steroidogenesis remains elusive. The significant role of autophagy in testosterone production suggests potential treatments for conditions like oligospermia and azoospermia. Further, influence of autophagy in folliculogenesis, ovulation, and luteal development emphasizes its importance for improved fertility and reproductive health. Thus, investigating autophagy in gonadal cells is clinically significant. Understanding these processes could transform treatments for endocrine disorders, enhancing reproductive health and longevity. Herein, we provide the functional role of autophagy in testicular and ovarian steroidogenesis to date, highlighting its modulation in testicular steroidogenesis and its impact on hormone synthesis, follicle development, and fertility therapies.
    Keywords:  autophagy; ovarian steroidogenesis; progesterone; testicular steroidogenesis; testosterone
    DOI:  https://doi.org/10.3389/fcell.2024.1384047
  23. J Nanobiotechnology. 2024 Jun 05. 22(1): 312
    ZNPs reduce epidermal mechanical strain resistance by promoting desmosomal cadherin endocytosis via mTORC1-TFEB-BLOC1S3 axis.
    Xuan Lai, Menglei Wang, Zhen Zhang, Suya Chen, Xiner Tan, Wenjing Liu, Huimin Liang, Li Li, Longquan Shao.
      Zinc oxide nanoparticles (ZNPs) are widely used in sunscreens and nanomedicines, and it was recently confirmed that ZNPs can penetrate stratum corneum into deep epidermis. Therefore, it is necessary to determine the impact of ZNPs on epidermis. In this study, ZNPs were applied to mouse skin at a relatively low concentration for one week. As a result, desmosomes in epidermal tissues were depolymerized, epidermal mechanical strain resistance was reduced, and the levels of desmosomal cadherins were decreased in cell membrane lysates and increased in cytoplasmic lysates. This finding suggested that ZNPs promote desmosomal cadherin endocytosis, which causes desmosome depolymerization. In further studies, ZNPs were proved to decrease mammalian target of rapamycin complex 1 (mTORC1) activity, activate transcription factor EB (TFEB), upregulate biogenesis of lysosome-related organelle complex 1 subunit 3 (BLOC1S3) and consequently promote desmosomal cadherin endocytosis. In addition, the key role of mTORC1 in ZNP-induced decrease in mechanical strain resistance was determined both in vitro and in vivo. It can be concluded that ZNPs reduce epidermal mechanical strain resistance by promoting desmosomal cadherin endocytosis via the mTORC1-TFEB-BLOC1S3 axis. This study helps elucidate the biological effects of ZNPs and suggests that ZNPs increase the risk of epidermal fragmentation.
    Keywords:  Desmosome; Epidermis; Fragmentation; Zinc oxide nanoparticles
    DOI:  https://doi.org/10.1186/s12951-024-02519-z
  24. J Mol Biol. 2024 Jun 05. pii: S0022-2836(24)00238-9. [Epub ahead of print] 168643
    GPCR function in autophagy control: a systematic approach of chemical intervention.
    Pablo Sanz-Martinez, Georg Tascher, Sara Cano, Paloma Poveda, Christian Münch, Evert J Homan, Alexandra Stolz.
      Autophagy facilitates the degradation of cellular content via the lysosome and is involved in cellular homeostasis and stress response pathways. As such, malfunction of autophagy is linked to a variety of diseases ranging from organ-specific illnesses like cardiomyopathy to systemic illnesses such as cancer or metabolic syndromes. Given the variety of autophagic functions within a cell and tissue, regulation of autophagy is complex and contains numerous positive and negative feedback loops. While our knowledge of mechanisms for cargo selectivity has significantly improved over the last decade, our understanding of signaling routes activating individual autophagy pathways remains rather sparse. In this resource study, we report on a well-characterized chemical library containing 77 GPCR-targeting ligands that was used to systematically analyze LC3B-based autophagy as well as ER-phagy flux upon compound treatment. Upon others, compounds TC-G 1004, BAY 60-6583, PSNCBAM-1, TC-G 1008, LPA2 Antagonist 1, ML154, JTC-801 and ML-290 targeting adenosine receptor A2a (ADORA2A), adenosine receptor A2b (ADORA2B), cannabinoid receptor 1 (CNR1), G-protein coupled receptor 39 (GPR39), lysophosphatidic acid receptor 2 (LPAR2), neuropeptide S receptor 1 (NPSR1), opioid related nociceptin receptor 1 (OPRL1), and relaxin receptor 1 (RXFP1), respectively, were hit compounds for general autophagy flux. From these compounds, only JTC-801 markly increased ER-phagy flux. In addition, the global impact of these selected hit compounds were analyzed by TMT-based mass spectrometry and demonstrated the differential impact of targeting GPCRs on autophagy-associated proteins. This chemical screening exercise indicates to a significant cross-talk between GPCR signaling and regulation of autophagy pathways.
    DOI:  https://doi.org/10.1016/j.jmb.2024.168643
  25. J Environ Sci (China). 2024 Nov;pii: S1001-0742(23)00443-6. [Epub ahead of print]145 117-127
    TFEB/LAMP2 contributes to PM0.2-induced autophagy-lysosome dysfunction and alpha-synuclein dysregulation in astrocytes.
    Ben Li, Ting Liu, Yongmei Shen, Jiangnan Qin, Xiaohan Chang, Meiqiong Wu, Jianquan Guo, Liangpo Liu, Cailing Wei, Yi Lyu, Fengjie Tian, Jinzhu Yin, Tong Wang, Wenping Zhang, Yulan Qiu.
      Atmospheric particulate matter (PM) exacerbates the risk factor for Alzheimer's and Parkinson's diseases (PD) by promoting the alpha-synuclein (α-syn) pathology in the brain. However, the molecular mechanisms of astrocytes involvement in α-syn pathology underlying the process remain unclear. This study investigated PM with particle size <200 nm (PM0.2) exposure-induced α-syn pathology in ICR mice and primary astrocytes, then assessed the effects of mammalian target of rapamycin inhibitor (PP242) in vitro studies. We observed the α-syn pathology in the brains of exposed mice. Meanwhile, PM0.2-exposed mice also exhibited the activation of glial cell and the inhibition of autophagy. In vitro study, PM0.2 (3, 10 and 30 µg/mL) induced inflammatory response and the disorders of α-syn degradation in primary astrocytes, and lysosomal-associated membrane protein 2 (LAMP2)-mediated autophagy underlies α-syn pathology. The abnormal function of autophagy-lysosome was specifically manifested as the expression of microtubule-associated protein light chain 3 (LC3II), cathepsin B (CTSB) and lysosomal abundance increased first and then decreased, which might both be a compensatory mechanism to toxic α-syn accumulation induced by PM0.2. Moreover, with the transcription factor EB (TFEB) subcellular localization and the increase in LC3II, LAMP2, CTSB, and cathepsin D proteins were identified, leading to the restoration of the degradation of α-syn after the intervention of PP242. Our results identified that PM0.2 exposure could promote the α-syn pathological dysregulation in astrocytes, providing mechanistic insights into how PM0.2 increases the risk of developing PD and highlighting TFEB/LAMP2 as a promising therapeutic target for antagonizing PM0.2 toxicity.
    Keywords:  Astrocytes; Autophagy-lysosome; PM(0.2); α-Synuclein
    DOI:  https://doi.org/10.1016/j.jes.2023.09.036
  26. FEBS J. 2024 Jun 05.
    Extracellular vesicles promote autophagy in human microglia through lipid raft-dependent mechanisms.
    Diana Romenskaja, Ugnė Jonavičė, Augustas Pivoriūnas.
      Autophagy dysfunction has been closely related with pathogenesis of many neurodegenerative diseases and therefore represents a potential therapeutic target. Extracellular vesicles (EVs) may act as potent anti-inflammatory agents and also modulators of autophagy in target cells. However, the molecular mechanisms by which EVs modulate autophagy flux in human microglia remain largely unexplored. In the present study, we investigated the effects of EVs derived from human oral mucosa stem cells on the autophagy in human microglia. We demonstrate that EVs promoted autophagy and autophagic flux in human microglia and that this process was dependent on the integrity of lipid rafts. Lipopolysaccharide (LPS) also activated autophagy, but combined treatment with EVs and LPS suppressed autophagy response, indicating interference between these signaling pathways. Blockage of Toll-like receptor 4 (TLR4) with anti-TLR4 antibody suppressed EV-induced autophagy. Furthermore, inhibition of the EV-associated heat shock protein (HSP70) chaperone which is one of the endogenous ligands of the TLR4 also suppressed EV-induced lipid raft formation and autophagy. Pre-treatment of microglia with a selective inhibitor of αvβ3/αvβ5 integrins cilengitide inhibited EV-induced autophagy. Finally, blockage of purinergic P2X4 receptor (P2X4R) with selective inhibitor 5-BDBD also suppressed EV-induced autophagy. In conclusion, we demonstrate that EVs activate autophagy in human microglia through interaction with HSP70/TLR4, αVβ3/αVβ5, and P2X4R signaling pathways and that these effects depend on the integrity of lipid rafts. Our findings could be used to develop new therapeutic strategies targeting disease-associated microglia.
    Keywords:  autophagy; extracellular vesicles; immune receptors; lipopolysaccharide; microglia
    DOI:  https://doi.org/10.1111/febs.17192
  27. Elife. 2024 Jun 03. pii: RP87434. [Epub ahead of print]12
    Styxl2 regulates de novo sarcomere assembly by binding to non-muscle myosin IIs and promoting their degradation.
    Xianwei Chen, Yanfeng Li, Jin Xu, Yong Cui, Qian Wu, Haidi Yin, Yuying Li, Chuan Gao, Liwen Jiang, Huating Wang, Zilong Wen, Zhongping Yao, Zhenguo Wu.
      Styxl2, a poorly characterized pseudophosphatase, was identified as a transcriptional target of the Jak1-Stat1 pathway during myoblast differentiation in culture. Styxl2 is specifically expressed in vertebrate striated muscles. By gene knockdown in zebrafish or genetic knockout in mice, we found that Styxl2 plays an essential role in maintaining sarcomere integrity in developing muscles. To further reveal the functions of Styxl2 in adult muscles, we generated two inducible knockout mouse models: one with Styxl2 being deleted in mature myofibers to assess its role in sarcomere maintenance, and the other in adult muscle satellite cells (MuSCs) to assess its role in de novo sarcomere assembly. We find that Styxl2 is not required for sarcomere maintenance but functions in de novo sarcomere assembly during injury-induced muscle regeneration. Mechanistically, Styxl2 interacts with non-muscle myosin IIs, enhances their ubiquitination, and targets them for autophagy-dependent degradation. Without Styxl2, the degradation of non-muscle myosin IIs is delayed, which leads to defective sarcomere assembly and force generation. Thus, Styxl2 promotes de novo sarcomere assembly by interacting with non-muscle myosin IIs and facilitating their autophagic degradation.
    Keywords:  Styxl2; autophagy; developmental biology; mouse; non-muscle myosin II; pseudophosphatase; sarcomere assembly; zebrafish
    DOI:  https://doi.org/10.7554/eLife.87434
  28. Nat Struct Mol Biol. 2024 Jun 04.
    ATG16L1 induces the formation of phagophore-like membrane cups.
    Jagan Mohan, Satish B Moparthi, Christine Girard-Blanc, Daniele Campisi, Stéphane Blanchard, Charlotte Nugues, Sowmya Rama, Audrey Salles, Esthel Pénard, Stéphane Vassilopoulos, Thomas Wollert.
      The hallmark of non-selective autophagy is the formation of cup-shaped phagophores that capture bulk cytoplasm. The process is accompanied by the conjugation of LC3B to phagophores by an E3 ligase complex comprising ATG12-ATG5 and ATG16L1. Here we combined two complementary reconstitution approaches to reveal the function of LC3B and its ligase complex during phagophore expansion. We found that LC3B forms together with ATG12-ATG5-ATG16L1 a membrane coat that remodels flat membranes into cups that closely resemble phagophores. Mechanistically, we revealed that cup formation strictly depends on a close collaboration between LC3B and ATG16L1. Moreover, only LC3B, but no other member of the ATG8 protein family, promotes cup formation. ATG16L1 truncates that lacked the C-terminal membrane binding domain catalyzed LC3B lipidation but failed to assemble coats, did not promote cup formation and inhibited the biogenesis of non-selective autophagosomes. Our results thus demonstrate that ATG16L1 and LC3B induce and stabilize the characteristic cup-like shape of phagophores.
    DOI:  https://doi.org/10.1038/s41594-024-01300-y
  29. Acta Physiol (Oxf). 2024 Jun 05. e14186
    ATP6V1A is required for synaptic rearrangements and plasticity in murine hippocampal neurons.
    Alessandro Esposito, Sara Pepe, Maria Sabina Cerullo, Katia Cortese, Hanako Tsushima Semini, Silvia Giovedì, Renzo Guerrini, Fabio Benfenati, Antonio Falace, Anna Fassio.
      AIM: Understanding the physiological role of ATP6V1A, a component of the cytosolic V1 domain of the proton pump vacuolar ATPase, in regulating neuronal development and function.METHODS: Modeling loss of function of Atp6v1a in primary murine hippocampal neurons and studying neuronal morphology and function by immunoimaging, electrophysiological recordings and electron microscopy.
    RESULTS: Atp6v1a depletion affects neurite elongation, stabilization, and function of excitatory synapses and prevents synaptic rearrangement upon induction of plasticity. These phenotypes are due to an overall decreased expression of the V1 subunits, that leads to impairment of lysosomal pH-regulation and autophagy progression with accumulation of aberrant lysosomes at neuronal soma and of enlarged vacuoles at synaptic boutons.
    CONCLUSIONS: These data suggest a physiological role of ATP6V1A in the surveillance of synaptic integrity and plasticity and highlight the pathophysiological significance of ATP6V1A loss in the alteration of synaptic function that is associated with neurodevelopmental and neurodegenerative diseases. The data further support the pivotal involvement of lysosomal function and autophagy flux in maintaining proper synaptic connectivity and adaptive neuronal properties.
    Keywords:  ATP6V1A; LTP; autophagy; lysosome; neurodevelopment; synapse; v‐ATPase
    DOI:  https://doi.org/10.1111/apha.14186
  30. Autophagy. 2024 Jun 06.
    ATG10S promotes IFNL1 expression and autophagic degradation of multiple viral proteins mediated by IFNL1.
    Miao-Qing Zhang, Jian-Rui Li, Lu Yang, Zong-Gen Peng, Shuo Wu, Jing-Pu Zhang.
      ATG10S is a newly discovered subtype of the autophagy protein ATG10. It promotes complete macroautophagy/autophagy, degrades multiple viral proteins, and increases the expression of type III interferons. Here, we aimed to investigate the mechanism of ATG10S cooperation with IFNL1 to degrade viral proteins from different viruses. Using western blot, immunoprecipitation (IP), tandem sensor RFP-GFP-LC3B and in situ proximity ligation assays, we showed that exogenous recombinant ATG10S protein (rHsATG10S) could enter into cells through clathrin, and ATG10S combined with ATG7 with IFNL1 assistance to facilitate ATG12-ATG5 conjugation, thereby contributing to the autophagosome formation in multiple cell lines containing different virions or viral proteins. The results of DNA IP and luciferase assays also showed that ATG10S was able to directly bind to a core motif (CAAGGG) within a binding site of transcription factor ZNF460 on the IFNL1 promoter, by which IFNL1 transcription was activated. These results clarified that ATG10S promoted autophagosome formation with the assistance of IFNL1 to ensure autophagy flux and autophagic degradation of multiple viral proteins and that ATG10S could also act as a novel transcription factor to promote IFNL1 gene expression. Importantly, this study further explored the antiviral mechanism of ATG10S interaction with type III interferon and provided a theoretical basis for the development of ATG10S into a new broad-spectrum antiviral protein drug.
    Keywords:  ATG10S; IFNL1 expression; ZNF460; autophagic degradation; core motif; viral proteins
    DOI:  https://doi.org/10.1080/15548627.2024.2361580
  31. Aging (Albany NY). 2024 Jun 04. 16
    Mitophagy and cancer: role of BNIP3/BNIP3L as energetic drivers of stemness features, ATP production, proliferation, and cell migration.
    Marta Mauro-Lizcano, Federica Sotgia, Michael P Lisanti.
      Mitophagy is a selective form of autophagy which permits the removal of dysfunctional or excess mitochondria. This occurs as an adaptative response to physiological stressors, such as hypoxia, nutrient deprivation, or DNA damage. Mitophagy is promoted by specific mitochondrial outer membrane receptors, among which are BNIP3 and BNIP3L. The role of mitophagy in cancer is being widely studied, and more specifically in the maintenance of cancer stem cell (CSC) properties, such as self-renewal. Given that CSCs are responsible for treatment failure and metastatic capacity, targeting mitophagy could be an interesting approach for CSC elimination. Herein, we describe a new model system to enrich sub-populations of cancer cells with high basal levels of mitophagy, based on the functional transcriptional activity of BNIP3 and BNIP3L. Briefly, we employed a BNIP3(L)-promoter-eGFP-reporter system to isolate cancer cells with high BNIP3/BNIP3L transcriptional activity by flow cytometry (FACS). The model was validated by using complementary lysosomal and mitophagy-specific probes, as well as the mitochondrially-targeted red fluorescent protein (RFP), namely mt-Keima. High BNIP3/BNIP3L transcriptional activity was accompanied by increases in i) BNIP3/BNIP3L protein levels, ii) lysosomal mass, and iii) basal mitophagy activity. Furthermore, cancer cells with increased BNIP3/BNIP3L transcriptional activity exhibited CSC features, such as greater mammosphere-forming ability and high CD44 levels. To further explore the model, we also analysed other stemness characteristics in MCF7 and MDA-MB-231 breast cancer cell lines, directly demonstrating that BNIP3(L)-high cells were more metabolically active, proliferative, migratory, and drug-resistant, with elevated anti-oxidant capacity. Therefore, high levels of basal mitophagy appear to enhance CSC features.
    Keywords:  BNIP3; BNIP3L(NIX); cancer stem cells (CSCs); flow cytometry (FACS); mitophagy
    DOI:  https://doi.org/10.18632/aging.205939
  32. Exp Neurol. 2024 May 30. pii: S0014-4886(24)00168-7. [Epub ahead of print] 114842
    Dexmedetomidine enhances Mitophagy via PINK1 to alleviate hippocampal neuronal Pyroptosis and improve postoperative cognitive dysfunction in elderly rat.
    Yayu Chen, Gen Wei, Lieliang Zhang, Xiaojin Feng, Enjun Lei.
      Postoperative cognitive dysfunction (POCD) is a common complication in elderly surgical patients, significantly affecting their quality of life. Dexmedetomidine (Dex), an anesthetic, has shown promise in alleviating POCD, but its underlying mechanism remains unclear. This study aims to explore how Dex improves POCD in aged rats by targeting the PINK1-mediated mitochondrial autophagy pathway, reducing caspase-1/11-GSDMD-induced hippocampal neuronal pyroptosis. Transcriptome sequencing identified 300 differentially expressed genes enriched in the mitochondrial autophagy pathway in Dex-treated POCD rat hippocampal tissue, with Pink1 as a key candidate. In a POCD rat model, Dex treatment upregulated hippocampal PINK1 expression. In vitro experiments using H19-7 rat hippocampal neurons revealed that Dex enhanced mitochondrial autophagy and suppressed neuronal pyroptosis by upregulating PINK1. Further mechanistic validation demonstrated that Dex activated PINK1-mediated mitochondrial autophagy, inhibiting caspase-1/11-GSDMD-induced neuronal pyroptosis. In vivo experiments confirmed Dex's ability to reduce caspase-1/11-GSDMD-dependent hippocampal neuronal pyroptosis and improve postoperative cognitive function in aged rats. Dexmedetomidine improves postoperative cognitive dysfunction in elderly rats by enhancing mitochondrial autophagy via PINK1 upregulation, mitigating caspase-1/11-GSDMD-induced neuronal pyroptosis.
    Keywords:  Caspase-1/11-GSDMD; Dexmedetomidine; Mitochondrial autophagy; PINK1; Postoperative cognitive dysfunction
    DOI:  https://doi.org/10.1016/j.expneurol.2024.114842
  33. Adv Sci (Weinh). 2024 Jun 05. e2402030
    SIRT5-Mediated Desuccinylation of RAB7A Protects Against Cadmium-Induced Alzheimer's Disease-Like Pathology by Restoring Autophagic Flux.
    Ping Deng, Tengfei Fan, Peng Gao, Yongchun Peng, Min Li, Jingdian Li, Mingke Qin, Rongrong Hao, Liting Wang, Min Li, Lei Zhang, Chunhai Chen, Mindi He, Yonghui Lu, Qinlong Ma, Yan Luo, Li Tian, Jia Xie, Mengyan Chen, Shangcheng Xu, Zhou Zhou, Zhengping Yu, Huifeng Pi.
      Cadmium (Cd) is a neurotoxic contaminant that induces cognitive decline similar to that observed in Alzheimer's disease (AD). Autophagic flux dysfunction is attributed to the pathogenesis of AD, and this study aimed to investigate the effect of autophagy on environmental Cd-induced AD progression and the underlying mechanism. Here, Cd exposure inhibited autophagosome-lysosome fusion and impaired lysosomal function, leading to defects in autophagic clearance and then to APP accumulation and nerve cell death. Proteomic analysis coupled with Ingenuity Pathway Analysis (IPA) identified SIRT5 as an essential molecular target in Cd-impaired autophagic flux. Mechanistically, Cd exposure hampered the expression of SIRT5, thus increasing the succinylation of RAB7A at lysine 31 and inhibiting RAB7A activity, which contributed to autophagic flux blockade. Importantly, SIRT5 overexpression led to the restoration of autophagic flux blockade, the alleviation of Aβ deposition and memory deficits, and the desuccinylation of RAB7A in Cd-exposed FAD4T mice. Additionally, SIRT5 levels decrease mainly in neurons but not in other cell clusters in the brains of AD patients according to single-nucleus RNA sequencing data from the public dataset GSE188545. This study reveals that SIRT5-catalysed RAB7A desuccinylation is an essential adaptive mechanism for the amelioration of Cd-induced autophagic flux blockade and AD-like pathogenesis.
    Keywords:  alzheimer's disease; autophagy; cadmium; rab7a; sirt5
    DOI:  https://doi.org/10.1002/advs.202402030
  34. Mol Brain. 2024 Jun 03. 17(1): 31
    Chronic unpredictable stress induces autophagic death of adult hippocampal neural stem cells.
    Seongwon Choe, Hyeonjeong Jeong, Jieun Choi, Seong-Woon Yu.
      Chronic psychological stress is a critical factor for neurological complications like anxiety disorders, dementia, and depression. Our previous results show that chronic restraint stress causes cognitive deficits and mood dysregulation by inducing autophagic death of adult hippocampal neural stem cells (NSCs). However, it is unknown whether other models of psychological stress also induce autophagic death of adult hippocampal NSCs. Here, we show that chronic unpredictable stress (CUS) for 10 days impaired memory function and increased anxiety in mice. Immunohistochemical staining with SOX2 and KI67 revealed a significant reduction in the number of NSCs in the hippocampus following exposure to CUS. However, these deficits were prevented by NSC-specific, inducible conditional deletion of Atg7. These findings suggest that autophagic death of adult hippocampal NSCs is a critical pathogenic mechanism underlying stress-induced brain disorders.
    DOI:  https://doi.org/10.1186/s13041-024-01105-6
  35. ACS Nano. 2024 Jun 03.
    Acidic Nanoparticles Restore Lysosomal Acidification and Rescue Metabolic Dysfunction in Pancreatic β-Cells under Lipotoxic Conditions.
    Chih Hung Lo, Lance M O'Connor, Gavin Wen Zhao Loi, Eka Norfaishanty Saipuljumri, Jonathan Indajang, Kaitlynn M Lopes, Orian S Shirihai, Mark W Grinstaff, Jialiu Zeng.
      Type 2 diabetes (T2D), a prevalent metabolic disorder lacking effective treatments, is associated with lysosomal acidification dysfunction, as well as autophagic and mitochondrial impairments. Here, we report a series of biodegradable poly(butylene tetrafluorosuccinate-co-succinate) polyesters, comprising a 1,4-butanediol linker and varying ratios of tetrafluorosuccinic acid (TFSA) and succinic acid as components, to engineer lysosome-acidifying nanoparticles (NPs). The synthesized NPs are spherical with diameters of ≈100 nm and have low polydispersity and good stability. Notably, TFSA NPs, which are composed entirely of TFSA, exhibit the strongest degradation capability and superior acidifying properties. We further reveal significant downregulation of lysosomal vacuolar (H+)-ATPase subunits, which are responsible for maintaining lysosomal acidification, in human T2D pancreatic islets, INS-1 β-cells under chronic lipotoxic conditions, and pancreatic tissues of high-fat-diet (HFD) mice. Treatment with TFSA NPs restores lysosomal acidification, autophagic function, and mitochondrial activity, thereby improving the pancreatic function in INS-1 cells and HFD mice with lipid overload. Importantly, the administration of TFSA NPs to HFD mice reduces insulin resistance and improves glucose clearance. These findings highlight the therapeutic potential of lysosome-acidifying TFSA NPs for T2D.
    Keywords:  Type 2 diabetes (T2D); V-ATPase; acidic nanoparticles; autophagic degradation; insulin secretion; lysosomal acidification; mitochondrial function
    DOI:  https://doi.org/10.1021/acsnano.3c09206
  36. Sci Adv. 2024 Jun 07. 10(23): eadn7191
    Mechanism of human PINK1 activation at the TOM complex in a reconstituted system.
    Olawale G Raimi, Hina Ojha, Kenneth Ehses, Verena Dederer, Sven M Lange, Cristian Polo Rivera, Tom D Deegan, Yinchen Chen, Melanie Wightman, Rachel Toth, Karim P M Labib, Sebastian Mathea, Neil Ranson, Rubén Fernández-Busnadiego, Miratul M K Muqit.
      Loss-of-function mutations in PTEN-induced kinase 1 (PINK1) are a frequent cause of early-onset Parkinson's disease (PD). Stabilization of PINK1 at the translocase of outer membrane (TOM) complex of damaged mitochondria is critical for its activation. The mechanism of how PINK1 is activated in the TOM complex is unclear. Here, we report that co-expression of human PINK1 and all seven TOM subunits in Saccharomyces cerevisiae is sufficient for PINK1 activation. We use this reconstitution system to systematically assess the role of each TOM subunit toward PINK1 activation. We unambiguously demonstrate that the TOM20 and TOM70 receptor subunits are required for optimal PINK1 activation and map their sites of interaction with PINK1 using AlphaFold structural modeling and mutagenesis. We also demonstrate an essential role of the pore-containing subunit TOM40 and its structurally associated subunits TOM7 and TOM22 for PINK1 activation. These findings will aid in the development of small-molecule activators of PINK1 as a therapeutic strategy for PD.
    DOI:  https://doi.org/10.1126/sciadv.adn7191
  37. Int J Biol Macromol. 2024 May 30. pii: S0141-8130(24)03537-2. [Epub ahead of print] 132732
    Epigenetic regulation of autophagy by non-coding RNAs and exosomal non-coding RNAs in colorectal cancer: A narrative review.
    Minghua Liu, Hongfang Jiang, Mohammad Reza Momeni.
      One of the major diseases affecting people globally is colorectal cancer (CRC), which is primarily caused by a lack of effective medical treatment and a limited understanding of its underlying mechanisms. Cellular autophagy functions to break down and eliminate superfluous proteins and substances, thereby facilitating the continual replacement of cellular elements and generating vital energy for cell processes. Non-coding RNAs and exosomal ncRNAs have a crucial impact on regulating gene expression and essential cellular functions such as autophagy, metastasis, and treatment resistance. The latest research has indicated that specific ncRNAs and exosomal ncRNA to influence the process of autophagy in CRC cells, which could have significant consequences for the advancement and treatment of this disease. It has been determined that a variety of ncRNAs have a vital function in regulating the genes essential for the formation and maturation of autophagosomes. Furthermore, it has been confirmed that ncRNAs have a considerable influence on the signaling pathways associated with autophagy, such as those involving AMPK, AKT, and mTOR. Additionally, numerous ncRNAs have the potential to affect specific genes involved in autophagy. This study delves into the control mechanisms of ncRNAs and exosomal ncRNAs and examines how they simultaneously influence autophagy in CRC.
    Keywords:  Autophagy; Biomarker; Colorectal cancer; Exosome; Non-coding RNAs; Therapy
    DOI:  https://doi.org/10.1016/j.ijbiomac.2024.132732
  38. Genet Mol Biol. 2024 ;pii: S1415-47572024000200105. [Epub ahead of print]47(Suppl 1): e20230317
    The role of chaperone-mediated autophagy in drug resistance.
    Ana Beatriz da Silva Teixeira, Maria Carolina Clares Ramalho, Izadora de Souza, Izabela Amélia Marques de Andrade, Isabeli Yumi Araújo Osawa, Camila Banca Guedes, Beatriz Silva de Oliveira, Cláudio Henrique Dahne de Souza Filho, Tainá Lins da Silva, Natália Cestari Moreno, Marcela Teatin Latancia, Clarissa Ribeiro Reily Rocha.
      In the search for alternatives to overcome the challenge imposed by drug resistance development in cancer treatment, the modulation of autophagy has emerged as a promising alternative that has achieved good results in clinical trials. Nevertheless, most of these studies have overlooked a novel and selective type of autophagy: chaperone-mediated autophagy (CMA). Following its discovery, research into CMA's contribution to tumor progression has accelerated rapidly. Therefore, we now understand that stress conditions are the primary signal responsible for modulating CMA in cancer cells. In turn, the degradation of proteins by CMA can offer important advantages for tumorigenesis, since tumor suppressor proteins are CMA targets. Such mutual interaction between the tumor microenvironment and CMA also plays a crucial part in establishing therapy resistance, making this discussion the focus of the present review. Thus, we highlight how suppression of LAMP2A can enhance the sensitivity of cancer cells to several drugs, just as downregulation of CMA activity can lead to resistance in certain cases. Given this panorama, it is important to identify selective modulators of CMA to enhance the therapeutic response.
    DOI:  https://doi.org/10.1590/1678-4685-GMB-2023-0317
  39. J Clin Invest. 2024 Jun 06. pii: e177142. [Epub ahead of print]
    Off-target autophagy inhibition by SHP2 allosteric inhibitors contributes to their anti-tumor activity in RAS-driven cancers.
    Yiming Miao, Yunpeng Bai, Jinmin Miao, Allison A Murray, Jianping Lin, Jiajun Dong, Zihan Qu, Ruo-Yu Zhang, Quyen D Nguyen, Shaomeng Wang, Jingmei Yu, Frederick Nguele Meke, Zhong-Yin Zhang.
      Aberrant activation of RAS-MAPK signaling is common in cancer, and efforts to inhibit pathway components have yielded drugs with promising clinical activities. Unfortunately, treatment-provoked adaptive resistance mechanisms inevitably develop, limiting their therapeutic potential. As a central node essential for receptor tyrosine kinase mediated RAS activation, SHP2 has emerged as an attractive cancer target. Consequently, many SHP2 allosteric inhibitors are now in clinical testing. Here we discovered a previously unrecognized off-target effect associated with SHP2 allosteric inhibitors. We found that these inhibitors accumulate in the lysosome and block autophagic flux in a SHP2-independent manner. We showed that off-target autophagy inhibition by SHP2 allosteric inhibitors contributes to their anti-tumor activity. We also demonstrated that SHP2 allosteric inhibitors harboring this off-target activity not only suppress oncogenic RAS signaling but also overcome drug resistance such as MAPK rebound and protective autophagy in response to RAS-MAPK pathway blockage. Finally, we exemplified a therapeutic framework that harnesses both the on- and off-target activities of SHP2 allosteric inhibitors for improved treatment of mutant RAS driven and drug resistant malignancies such as pancreatic and colorectal cancers. Brief Summary: SHP2 allosteric inhibitors elicit off-target autophagy blockade that can be exploited for improved treatment of RAS-driven and drug-resistant cancers.
    Keywords:  Cancer; Drug therapy; Oncology; Phosphoprotein phosphatases; Therapeutics
    DOI:  https://doi.org/10.1172/JCI177142
  40. Nat Cell Biol. 2024 Jun 05.
    MFSD1 with its accessory subunit GLMP functions as a general dipeptide uniporter in lysosomes.
    Katharina Esther Julia Jungnickel, Océane Guelle, Miharu Iguchi, Wentao Dong, Vadim Kotov, Florian Gabriel, Cécile Debacker, Julien Dairou, Isabelle McCort-Tranchepain, Nouf N Laqtom, Sze Ham Chan, Akika Ejima, Kenji Sato, David Massa López, Paul Saftig, Ahmad Reza Mehdipour, Monther Abu-Remaileh, Bruno Gasnier, Christian Löw, Markus Damme.
      The lysosomal degradation of macromolecules produces diverse small metabolites exported by specific transporters for reuse in biosynthetic pathways. Here we deorphanized the major facilitator superfamily domain containing 1 (MFSD1) protein, which forms a tight complex with the glycosylated lysosomal membrane protein (GLMP) in the lysosomal membrane. Untargeted metabolomics analysis of MFSD1-deficient mouse lysosomes revealed an increase in cationic dipeptides. Purified MFSD1 selectively bound diverse dipeptides, while electrophysiological, isotope tracer and fluorescence-based studies in Xenopus oocytes and proteoliposomes showed that MFSD1-GLMP acts as a uniporter for cationic, neutral and anionic dipeptides. Cryoelectron microscopy structure of the dipeptide-bound MFSD1-GLMP complex in outward-open conformation characterized the heterodimer interface and, in combination with molecular dynamics simulations, provided a structural basis for its selectivity towards diverse dipeptides. Together, our data identify MFSD1 as a general lysosomal dipeptide uniporter, providing an alternative route to recycle lysosomal proteolysis products when lysosomal amino acid exporters are overloaded.
    DOI:  https://doi.org/10.1038/s41556-024-01436-5
  41. BMC Med Genomics. 2024 Jun 03. 17(1): 152
    Deciphering the molecular nexus of BTG2 in periodontitis and diabetic kidney disease.
    Binhui Pan, Yangyang Teng, Renban Wang, Dan Chen, Hui Chen.
      OBJECTIVE: To investigate the role of BTG2 in periodontitis and diabetic kidney disease (DKD) and its potential underlying mechanism.METHODS: Gene expression data for periodontitis and DKD were acquired from the Gene Expression Omnibus (GEO) database. Differential expression analysis identified co-expressed genes between these conditions. The Nephroseq V5 online nephropathy database validated the role of these genes in DKD. Pearson correlation analysis identified genes associated with our target gene. We employed Gene Set Enrichment Analysis (GSEA) and Protein-Protein Interaction (PPI) networks to elucidate potential mechanisms. Expression levels of BTG2 mRNA were examined using quantitative polymerase Chain Reaction (qPCR) and immunofluorescence assays. Western blotting quantified proteins involved in epithelial-to-mesenchymal transition (EMT), apoptosis, mTORC1 signaling, and autophagy. Additionally, wound healing and flow cytometric apoptosis assays evaluated podocyte migration and apoptosis, respectively.
    RESULTS: Analysis of GEO database data revealed BTG2 as a commonly differentially expressed gene in both DKD and periodontitis. BTG2 expression was reduced in DKD compared to normal conditions and correlated with proteinuria. GSEA indicated enrichment of BTG2 in the EMT and mTORC1 signaling pathways. The PPI network highlighted BTG2's relevance to S100A9, S100A12, and FPR1. Immunofluorescence assays demonstrated significantly lower BTG2 expression in podocytes under high glucose (HG) conditions. Reduced BTG2 expression in HG-treated podocytes led to increased levels of EMT markers (α-SMA, vimentin) and the apoptotic protein Bim, alongside a decrease in nephrin. Lower BTG2 levels were associated with increased podocyte mobility and apoptosis, as well as elevated RPS6KB1 and mTOR levels, but reduced autophagy marker LC3.
    CONCLUSION: Our findings suggest that BTG2 is a crucial intermediary gene linking DKD and periodontitis. Modulating autophagy via inhibition of the mTORC1 signaling pathway, and consequently suppressing EMT, may be pivotal in the interplay between periodontitis and DKD.
    Keywords:  Autophagy; Bioinformatics analysis; Diabetic kidney disease; EMT; Periodontitis
    DOI:  https://doi.org/10.1186/s12920-024-01915-6
  42. Neurochem Res. 2024 Jun 05.
    Morphine Induced Neuroprotection in Ischemic Stroke by Activating Autophagy Via mTOR-Independent Activation of the JNK1/2 Pathway.
    Wenying Chi, Yaru Huang, Peilong Li, Xia Wang, Junfa Li, Fanjun Meng.
      Morphine (Mor) has exhibited efficacy in safeguarding neurons against ischemic injuries by simulating ischemic/hypoxic preconditioning (I/HPC). Concurrently, autophagy plays a pivotal role in neuronal survival during IPC against ischemic stroke. However, the involvement of autophagy in Mor-induced neuroprotection and the potential mechanisms remain elusive. Our experiments further confirmed the effect of Mor in cellular and animal models of ischemic stroke and explored its potential mechanism. The findings revealed that Mor enhanced cell viability in a dose-dependent manner by augmenting autophagy levels and autophagic flux in neurons subjected to oxygen-glucose deprivation/reoxygenation (OGD/R). Pretreatment of Mor improved neurological outcome and reduced infarct size in mice with middle cerebral artery occlusion/reperfusion (MCAO/R) at 1, 7 and 14 days. Moreover, the use of autophagy inhibitors nullified the protective effects of Mor, leading to reactive oxygen species (ROS) accumulation, increased loss of mitochondrial membrane potential (MMP) and neuronal apoptosis in OGD/R neurons. Results further demonstrated that Mor-induced autophagy activation was regulated by mTOR-independent activation of the c-Jun NH2- terminal kinase (JNK)1/2 Pathway, both in vitro and in vivo. Overall, these findings suggested Mor-induced neuroprotection by activating autophagy, which were regulated by JNK1/2 pathway in ischemic stroke.
    Keywords:  Autophagy; Ischemic Stroke; Morphine (Mor); Neuroprotection; c-Jun NH2- terminal Kinase (JNK)1/2
    DOI:  https://doi.org/10.1007/s11064-024-04181-1
  43. Nat Commun. 2024 Jun 04. 15(1): 4740
    Burkholderia pseudomallei BipD modulates host mitophagy to evade killing.
    Dongqi Nan, Chenglong Rao, Zhiheng Tang, Wenbo Yang, Pan Wu, Jiangao Chen, Yupei Xia, Jingmin Yan, Wenzheng Liu, Ziyuan Zhang, Zhiqiang Hu, Hai Chen, Yaling Liao, Xuhu Mao, Xiaoyun Liu, Quanming Zou, Qian Li.
      Mitophagy is critical for mitochondrial quality control and function to clear damaged mitochondria. Here, we found that Burkholderia pseudomallei maneuvered host mitophagy for its intracellular survival through the type III secretion system needle tip protein BipD. We identified BipD, interacting with BTB-containing proteins KLHL9 and KLHL13 by binding to the Back and Kelch domains, recruited NEDD8 family RING E3 ligase CUL3 in response to B. pseudomallei infection. Although evidently not involved in regulation of infectious diseases, KLHL9/KLHL13/CUL3 E3 ligase complex was essential for BipD-dependent ubiquitination of mitochondria in mouse macrophages. Mechanistically, we discovered the inner mitochondrial membrane IMMT via host ubiquitome profiling as a substrate of KLHL9/KLHL13/CUL3 complex. Notably, K63-linked ubiquitination of IMMT K211 was required for initiating host mitophagy, thereby reducing mitochondrial ROS production. Here, we show a unique mechanism used by bacterial pathogens that hijacks host mitophagy for their survival.
    DOI:  https://doi.org/10.1038/s41467-024-48824-x
  44. JID Innov. 2024 Jul;4(4): 100283
    The WD Domain of Atg16l1 Crucial for LC3-Associated Phagocytosis Is Not Required for Preserving Skin Barrier Function in Mice.
    Shannon Conway, Matthew Jefferson, Derek T Warren, Thomas Wileman, Christopher J Morris.
      The skin is a multifunctional organ, forming a barrier between the external and internal environment, thereby functioning as a safeguard against extrinsic factors. Autophagy has been implicated in epidermal differentiation and in preserving skin homeostasis. LC3-associated phagocytosis (LAP) uses some but not all components of autophagy. The Atg16l1 (Δ WD) mouse model lacks the WD40 domain required for LAP and has been widely used to study the effects of LAP deficiency and autophagy on tissue homeostasis and response to infection. In this study, the Δ WD model was used to study the relationship between LAP and skin homeostasis by determining whether LAP-deficient mice display a cutaneous phenotype. Skin histology of wild-type and Δ WD mice aged 1 year revealed minor morphological differences in the tail skin dermal layer. RT-qPCR and western blot analysis showed no differences in key keratin expression between genotypes. Skin barrier formation, assessed by dye permeation assays, demonstrated full and proper formation of the skin barrier at embryonic day 18.5 in both genotypes. Biomechanical analysis of the skin showed decreased skin elasticity in aged Δ WD but not wild-type mice. In summary, the LAP-deficient Δ WD mice displayed subtle alterations in dermal histology and age-related biomechanical changes.
    Keywords:  Autophagy; Barrier function; Epidermal structure
    DOI:  https://doi.org/10.1016/j.xjidi.2024.100283
  45. Mol Cell. 2024 Jun 06. pii: S1097-2765(24)00331-9. [Epub ahead of print]84(11): 2135-2151.e7
    eIF4F complex dynamics are important for the activation of the integrated stress response.
    Kyusik Q Kim, Ankanahalli N Nanjaraj Urs, Victor Lasehinde, Alison C Greenlaw, Benjamin H Hudson, Hani S Zaher.
      In response to stress, eukaryotes activate the integrated stress response (ISR) via phosphorylation of eIF2α to promote the translation of pro-survival effector genes, such as GCN4 in yeast. Complementing the ISR is the target of rapamycin (TOR) pathway, which regulates eIF4E function. Here, we probe translational control in the absence of eIF4E in Saccharomyces cerevisiae. Intriguingly, we find that loss of eIF4E leads to de-repression of GCN4 translation. In addition, we find that de-repression of GCN4 translation is accompanied by neither eIF2α phosphorylation nor reduction in initiator ternary complex (TC). Our data suggest that when eIF4E levels are depleted, GCN4 translation is de-repressed via a unique mechanism that may involve faster scanning by the small ribosome subunit due to increased local concentration of eIF4A. Overall, our findings suggest that relative levels of eIF4F components are key to ribosome dynamics and may play important roles in translational control of gene expression.
    Keywords:  Gcn4; TOR; eIF4A; eIF4E; eIF4F complex; initiation; integrated stress response; ribosome; translation
    DOI:  https://doi.org/10.1016/j.molcel.2024.04.016
  46. Proc Natl Acad Sci U S A. 2024 Jun 11. 121(24): e2320064121
    Decoding transcriptomic signatures of cysteine string protein alpha-mediated synapse maintenance.
    Na Wang, Biqing Zhu, Mary Alice Allnutt, Rosalie M Grijalva, Hongyu Zhao, Sreeganga S Chandra.
      Synapse maintenance is essential for generating functional circuitry, and decrement in this process is a hallmark of neurodegenerative disease. Yet, little is known about synapse maintenance in vivo. Cysteine string protein α (CSPα), encoded by the Dnajc5 gene, is a synaptic vesicle chaperone that is necessary for synapse maintenance and linked to neurodegeneration. To investigate the transcriptional changes associated with synapse maintenance, we performed single-nucleus transcriptomics on the cortex of young CSPα knockout (KO) mice and littermate controls. Through differential expression and gene ontology analysis, we observed that both neurons and glial cells exhibit unique signatures in the CSPα KO brain. Significantly, all neuronal classes in CSPα KO brains show strong signatures of repression in synaptic pathways, while up-regulating autophagy-related genes. Through visualization of synapses and autophagosomes by electron microscopy, we confirmed these alterations especially in inhibitory synapses. Glial responses varied by cell type, with microglia exhibiting activation. By imputing cell-cell interactions, we found that neuron-glia interactions were specifically increased in CSPα KO mice. This was mediated by synaptogenic adhesion molecules, with the classical Neurexin1-Neuroligin 1 pair being the most prominent, suggesting that communication of glial cells with neurons is strengthened in CSPα KO mice to preserve synapse maintenance. Together, this study provides a rich dataset of transcriptional changes in the CSPα KO cortex and reveals insights into synapse maintenance and neurodegeneration.
    Keywords:  Neurexin1–Neuroligin 1; autophagosome; chaperone; synapse loss
    DOI:  https://doi.org/10.1073/pnas.2320064121
  47. Cell Commun Signal. 2024 Jun 03. 22(1): 305
    STING agonists as promising vaccine adjuvants to boost immunogenicity against SARS-related coronavirus derived infection: possible role of autophagy.
    Aysa Rezabakhsh, M Reza Sadaie, Alireza Ala, Yousef Roosta, Solomon Habtemariam, Adeleh Sahebnasagh, Mohammad Rafi Khezri.
      As a major component of innate immunity and a positive regulator of interferons, the Stimulator of interferon gene (STING) has an immunotherapy potential to govern a variety of infectious diseases. Despite the recent advances regarding vaccines against COVID-19, nontoxic novel adjuvants with the potential to enhance vaccine efficacy are urgently desired. In this connection, it has been well-documented that STING agonists are applied to combat COVID-19. This approach is of major significance for boosting immune responses most likely through an autophagy-dependent manner in susceptible individuals against infection induced by severe acute respiratory syndrome Coronavirus (SARS‑CoV‑2). Given that STING agonists exert substantial immunomodulatory impacts under a wide array of pathologic conditions, these agents could be considered novel adjuvants for enhancing immunogenicity against the SARS-related coronavirus. Here, we intend to discuss the recent advances in STING agonists' recruitment to boost innate immune responses upon vaccination against SARS-related coronavirus infections. In light of the primordial role of autophagy modulation, the potential of being an antiviral vaccine adjuvant was also explored.
    Keywords:  Autophagy; COVID-19; Immunogenicity; SARS-CoV-2; Stimulator of interferon gene; Vaccine adjuvant
    DOI:  https://doi.org/10.1186/s12964-024-01680-0
  48. J Photochem Photobiol B. 2024 May 29. pii: S1011-1344(24)00108-8. [Epub ahead of print]257 112948
    ATG5-mediated keratinocyte ferroptosis promotes M1 polarization of macrophages to aggravate UVB-induced skin inflammation.
    Ta Xiao, Jinfeng Liang, Min Li, Yiming Guo, Sihan Chen, Yangying Ke, Xiang Gao, Heng Gu, Xu Chen.
      Autophagy participates in the regulation of ferroptosis. Among numerous autophagy-related genes (ATGs), ATG5 plays a pivotal role in ferroptosis. However, how ATG5-mediated ferroptosis functions in UVB-induced skin inflammation is still unclear. In this study, we unveil that the core ferroptosis inhibitor GPX4 is significantly decreased in human skin tissue exposed to sunlight. We report that ATG5 deletion in mouse keratinocytes strongly protects against UVB-induced keratinocyte ferroptosis and skin inflammation. Mechanistically, ATG5 promotes the autophagy-dependent degradation of GPX4 in UVB-exposed keratinocytes, which leads to UVB-induced keratinocyte ferroptosis. Furthermore, we find that IFN-γ secreted by ferroptotic keratinocytes facilitates the M1 polarization of macrophages, which results in the exacerbation of UVB-induced skin inflammation. Together, our data indicate that ATG5 exacerbates UVB-induced keratinocyte ferroptosis in the epidermis, which subsequently gives rise to the secretion of IFN-γ and M1 polarization. Our study provides novel evidence that targeting ATG5 may serve as a potential therapeutic strategy for the amelioration of UVB-caused skin damage.
    Keywords:  Autophagy; Ferroptosis; GPX4; Keratinocytes; Macrophages; Ultraviolet
    DOI:  https://doi.org/10.1016/j.jphotobiol.2024.112948
  49. J Alzheimers Dis. 2024 Jun 01.
    Enhancing Rab7 Activity by Inhibiting TBC1D5 Expression Improves Mitophagy in Alzheimer's Disease Models.
    Xiao Liang, Yangyang Wang, Siyu Li, Jianing Fan, Fanlin Zhou, Xiaoju Li, Shijie Li, Yu Li.
      Background: Mitochondrial dysfunction exists in Alzheimer's disease (AD) brain, and damaged mitochondria need to be removed by mitophagy. Small GTPase Rab7 regulates the fusion of mitochondria and lysosome, while TBC1D5 inhibits Rab7 activation. However, it is not clear whether the regulation of Rab7 activity by TBC1D5 can improve mitophagy and inhibit AD progression.Objective: To investigate the role of TBC1D5 in mitophagy and its regulatory mechanism for Rab7, and whether activation of mitophagy can inhibit the progression of AD.
    Methods: Mitophagy was determined by western blot and immunofluorescence. The morphology and quantity of mitochondria were tracked by TEM. pCMV-Mito-AT1.03 was employed to detect the cellular ATP. Amyloid-β secreted by AD cells was detected by ELISA. Co-immunoprecipitation was used to investigate the binding partner of the target protein. Golgi-cox staining was applied to observe neuronal morphology of mice. The Morris water maze test and Y-maze were performed to assess spatial learning and memory, and the open field test was measured to evaluate motor function and anxiety-like phenotype of experimental animals.
    Results: Mitochondrial morphology was impaired in AD models, and TBC1D5 was highly expressed. Knocking down TBC1D5 increased the expression of active Rab7, promoted the fusion of lysosome and autophagosome, thus improving mitophagy, and improved the morphology of hippocampal neurons and the impaired behavior in AD mice.
    Conclusions: Knocking down TBC1D5 increased Rab7 activity and promoted the fusion of autophagosome and lysosome. Our study provided insights into the mechanisms that bring new possibilities for AD therapy targeting mitophagy.
    Keywords:  Alzheimer’s disease; Rab7; TBC1D5; mitophagy
    DOI:  https://doi.org/10.3233/JAD-231300
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