bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2024–05–19
sixty papers selected by
Viktor Korolchuk, Newcastle University
  1. Unexpected roles for AMPK in the suppression of autophagy and the reactivation of MTORC1 signaling during prolonged amino acid deprivation.
  2. Mitophagy in health and disease. Molecular mechanisms, regulatory pathways, and therapeutic implications.
  3. Autophagy initiation triggers p150Glued-AP-2β interaction on the lysosomes and facilitates their transport.
  4. CALCOCO2/NDP52 associates with RAB9 to initiate an antiviral response to hepatitis B virus infection through a lysosomal degradation pathway.
  5. Receptor-mediated cargo hitchhiking on bulk autophagy.
  6. Targeting selective autophagy and beyond: From underlying mechanisms to potential therapies.
  7. New insight in treating autoimmune diseases by targeting autophagy.
  8. Reduction of spermine synthase enhances autophagy to suppress Tau accumulation.
  9. Alterations of PINK1-PRKN signaling in mice during normal aging.
  10. Lack of compensatory mitophagy in skeletal muscles during sepsis.
  11. Mammalian pexophagy at a glance.
  12. A delicate decision between repair and degradation of damaged lysosomes.
  13. Methylmalonic acidemia triggers lysosomal-autophagy dysfunctions.
  14. Urolithin A improves Alzheimer's disease cognition and restores mitophagy and lysosomal functions.
  15. Autophagy in hematopoietic stem cell development of the embryo.
  16. Lipid turnover through lipophagy in the newly identified extremophilic green microalga Chlamydomonas urium.
  17. Autophagy preferentially degrades non-fibrillar polyQ aggregates.
  18. Picornavirus VP3 protein induces autophagy through the TP53-BAD-BAX axis to promote viral replication.
  19. Exploiting sweet relief for preeclampsia by targeting autophagy-lysosomal machinery and proteinopathy.
  20. The Drosophila Nesprin-1 homolog MSP300 is required for muscle autophagy and proteostasis.
  21. ATG14 and STX18: gatekeepers of lipid droplet degradation and the implications for disease modulation.
  22. PROPPINs and membrane fission in the endo-lysosomal system.
  23. Autophagy counters inflammation-driven glycolytic impairment in aging hematopoietic stem cells.
  24. Exploring the Link Between Autophagy-Lysosomal Dysfunction and Early Heterotopic Ossification in Tendons.
  25. Multiple inositol phosphate species enhance stability of active mTOR.
  26. The multifaceted role of extracellular vesicles (EVs) in colorectal cancer: metastasis, immune suppression, therapy resistance, and autophagy crosstalk.
  27. Autophagy activated by GR/miR-421-3p/mTOR pathway as a compensatory mechanism participates in chondrodysplasia induced by prenatal caffeine exposure in male fetal rats.
  28. Matrine induces autophagic cell death by triggering ROS/AMPK/mTOR axis and apoptosis in multiple myeloma.
  29. ncRNAs and Their Impact on Dopaminergic Neurons: Autophagy Pathways in Parkinson's Disease.
  30. The CTLH Ubiquitin Ligase Substrates ZMYND19 and MKLN1 Negatively Regulate mTORC1 at the Lysosomal Membrane.
  31. V-ATPase B2 promotes microglial phagocytosis of myelin debris by inactivating the MAPK signaling pathway.
  32. A potential early-atheroprotective target: Irgm1 mediates lymphangiogenesis through LEC autophagy by Tfeb translocation.
  33. Timing of TORC1 inhibition dictates Pol III involvement in Caenorhabditis elegans longevity.
  34. TRIM44 Promotes Rabies Virus Replication by Autophagy-Dependent Mechanism.
  35. Ti3C2 nanosheet-induced autophagy derails ovarian functions.
  36. TASL mediates keratinocyte differentiation by regulating intracellular calcium levels and lysosomal function.
  37. Stem cell models of TAFAZZIN deficiency reveal novel tissue-specific pathologies in Barth Syndrome.
  38. FOXC1 regulates endothelial CD98 (LAT1/4F2hc) expression in retinal angiogenesis and blood-retina barrier formation.
  39. Mitophagy in mammalian follicle development and health.
  40. Interplay of Proteostasis Capacity and Protein Aggregation: Implications for Cellular Function and Disease.
  41. Mitophagy Regulates the Circadian Rhythms by Degrading NR1D1 in Simulated Microgravity and Isolation Environments.
  42. Lysosomal dysfunction and overload of nucleosides in thymidine phosphorylase deficiency of MNGIE.
  43. UVB radiation exposure modulates mitophagy in embryonic cells of freshwater prawn Macrobrachium olfersii: Exploring a protective organelle quality control mechanism.
  44. Exploring the neuroprotective role of artesunate in mouse models of anti-NMDAR encephalitis: insights from molecular mechanisms and transmission electron microscopy.
  45. Inhibition of mTOR prevents glucotoxicity-mediated increase of SA-beta-gal, p16INK4a, and insulin hypersecretion, without restoring electrical features of mouse pancreatic islets.
  46. DDX58 variant triggers IFN-β-induced autophagy in trabecular meshwork and influences intraocular pressure.
  47. Bone mesenchymal stem cells improve cholestatic liver fibrosis by targeting ULK1 to regulate autophagy through PI3K/AKT/mTOR pathway.
  48. mTORC1 regulates cell survival under glucose starvation through 4EBP1/2-mediated translational reprogramming of fatty acid metabolism.
  49. Risk factors of using late-autophagy inhibitors: Aspects to consider when combined with anticancer therapies.
  50. mTORC1/S6K1 signaling promotes sustained oncogenic translation through modulating CRL3IBTK-mediated ubiquitination of eIF4A1 in cancer cells.
  51. The ion channel TRPM8 is a direct target of the immunosuppressant rapamycin in primary sensory neurons.
  52. L-serine restored lysosomal failure in cells derived from patients with BPAN reducing iron accumulation with eliminating lipofuscin.
  53. Autophagy favors survival of corpora lutea during the long-lasting pregnancy of the South American plains vizcacha, Lagostomus maximus (Rodentia, Caviomorpha).
  54. Down-regulation of O-GlcNAcylation alleviates insulin signaling pathway impairment following arsenic exposure via suppressing the AMPK/mTOR-autophagy pathway.
  55. FGFR2-triggered autophagy and activation of Nrf-2 reduce breast cancer cell response to anti-ER drugs.
  56. FUDNC1-dependent mitophagy ameliorate motor neuron death in an amyotrophic lateral sclerosis mouse model.
  57. p62/sequestosome-1 as a severity-reflecting plasma biomarker in Charcot-Marie-Tooth disease type 1A.
  58. Autophagy-related protein 5 (ATG5) interacts with bone marrow stromal cell antigen 2 (BST2) to stimulate HBV replication through antagonizing the antiviral activity of BST2.
  59. Melatonin ameliorates 10-hydroxycamptothecin-induced oxidative stress and apoptosis via autophagy-regulated p62/Keap1/Nrf2 pathway in mouse testicular cells.
  60. AMPK activation eliminates senescent cells in diabetic wound by inducing NCOA4 mediated ferritinophagy.
  1. Autophagy. 2024 May 14.
    Unexpected roles for AMPK in the suppression of autophagy and the reactivation of MTORC1 signaling during prolonged amino acid deprivation.
    Dubek Kazyken, Sydney G Dame, Claudia Wang, Maxwell Wadley, Diane C Fingar.
      AMPK promotes catabolic and suppresses anabolic cell metabolism to promote cell survival during energetic stress, in part by inhibiting MTORC1, an anabolic kinase requiring sufficient levels of amino acids. We found that cells lacking AMPK displayed increased apoptotic cell death during nutrient stress caused by prolonged amino acid deprivation. We presumed that impaired macroautophagy/autophagy explained this phenotype, as a prevailing view posits that AMPK initiates autophagy (often a pro-survival response) through phosphorylation of ULK1. Unexpectedly, however, autophagy remained unimpaired in cells lacking AMPK, as monitored by several autophagic readouts in several cell lines. More surprisingly, the absence of AMPK increased ULK1 signaling and MAP1LC3B/LC3B lipidation during amino acid deprivation while AMPK-mediated phosphorylation of ULK1 S555 (a site proposed to initiate autophagy) decreased upon amino acid withdrawal or pharmacological MTORC1 inhibition. In addition, activation of AMPK with compound 991, glucose deprivation, or AICAR blunted autophagy induced by amino acid withdrawal. These results demonstrate that AMPK activation and glucose deprivation suppress autophagy. As AMPK controlled autophagy in an unexpected direction, we examined how AMPK controls MTORC1 signaling. Paradoxically, we observed impaired reactivation of MTORC1 in cells lacking AMPK upon prolonged amino acid deprivation. Together these results oppose established views that AMPK promotes autophagy and inhibits MTORC1 universally. Moreover, they reveal unexpected roles for AMPK in the suppression of autophagy and the support of MTORC1 signaling in the context of prolonged amino acid deprivation. These findings prompt a reevaluation of how AMPK and its control of autophagy and MTORC1 affect health and disease.
    Keywords:  ATG16L1; EIF4EBP1/4EBP1; LC3B; MTOR; RPS6KB1/S6K1; ULK1
    DOI:  https://doi.org/10.1080/15548627.2024.2355074
  2. Apoptosis. 2024 May 17.
    Mitophagy in health and disease. Molecular mechanisms, regulatory pathways, and therapeutic implications.
    Mark S D'Arcy.
      Mitophagy, a specialised form of autophagy, selectively targeting damaged or dysfunctional mitochondria, and is crucial for maintaining cellular homeostasis and mitochondrial quality control. Dysregulation of mitophagy contributes to various pathological conditions, including cancer, neurodegenerative and cardiovascular diseases. This review presents a comprehensive analysis of the molecular mechanisms, regulatory pathways, and interplay with other cellular processes governing mitophagy, emphasizing its importance in physiological and pathological contexts. We explore the PINK1/Parkin-mediated and receptor-mediated mitophagy pathways, encompassing BNIP3/NIX, FUNDC1, and Bcl2-L-13. Additionally, we discuss post-translational modifications and cellular signalling pathways modulating mitophagy, as well as the connection between mitophagy and ageing, highlighting the decline in mitophagy efficiency and its impact on age-related pathologies. The review also investigates mitophagy's role in human diseases such as cancer, myocardial ischemia-reperfusion injury, Parkinson's, and Alzheimer's disease. We assess the potential of mitophagy-targeting therapeutic strategies, focusing on the development of dietary therapies, small molecules, drugs, and gene therapy approaches that modulate mitophagy levels and efficiency for treating these diseases and dysfunctions commonly observed in ageing individuals. In summary, this review offers an extensive overview of the molecular mechanisms and regulatory networks involved in mitophagy, its association with autophagy, and implications in human health and disease. By examining the potential of mitophagy-modulating therapies in disease and non-disease settings, we aim to inspire further research to develop innovative treatment strategies for various pathological conditions linked to mitochondrial dysfunction and to ageing.
    Keywords:  Ageing; Autophagy; Mitophagy
    DOI:  https://doi.org/10.1007/s10495-024-01977-y
  3. Cell Mol Life Sci. 2024 May 17. 81(1): 218
    Autophagy initiation triggers p150Glued-AP-2β interaction on the lysosomes and facilitates their transport.
    Aleksandra Tempes, Karolina Bogusz, Agnieszka Brzozowska, Jan Weslawski, Matylda Macias, Oliver Tkaczyk, Katarzyna Orzoł, Aleksandra Lew, Malgorzata Calka-Kresa, Tytus Bernas, Andrzej A Szczepankiewicz, Magdalena Mlostek, Shiwani Kumari, Ewa Liszewska, Katarzyna Machnicka, Magdalena Bakun, Tymon Rubel, Anna R Malik, Jacek Jaworski.
      The endocytic adaptor protein 2 (AP-2) complex binds dynactin as part of its noncanonical function, which is necessary for dynein-driven autophagosome transport along microtubules in neuronal axons. The absence of this AP-2-dependent transport causes neuronal morphology simplification and neurodegeneration. The mechanisms that lead to formation of the AP-2-dynactin complex have not been studied to date. However, the inhibition of mammalian/mechanistic target of rapamycin complex 1 (mTORC1) enhances the transport of newly formed autophagosomes by influencing the biogenesis and protein interactions of Rab-interacting lysosomal protein (RILP), another dynein cargo adaptor. We tested effects of mTORC1 inhibition on interactions between the AP-2 and dynactin complexes, with a focus on their two essential subunits, AP-2β and p150Glued. We found that the mTORC1 inhibitor rapamycin enhanced p150Glued-AP-2β complex formation in both neurons and non-neuronal cells. Additional analysis revealed that the p150Glued-AP-2β interaction was indirect and required integrity of the dynactin complex. In non-neuronal cells rapamycin-driven enhancement of the p150Glued-AP-2β interaction also required the presence of cytoplasmic linker protein 170 (CLIP-170), the activation of autophagy, and an undisturbed endolysosomal system. The rapamycin-dependent p150Glued-AP-2β interaction occurred on lysosomal-associated membrane protein 1 (Lamp-1)-positive organelles but without the need for autolysosome formation. Rapamycin treatment also increased the acidification and number of acidic organelles and increased speed of the long-distance retrograde movement of Lamp-1-positive organelles. Altogether, our results indicate that autophagy regulates the p150Glued-AP-2β interaction, possibly to coordinate sufficient motor-adaptor complex availability for effective lysosome transport.
    Keywords:  AP-2 adaptor complex; Autophagy; Dynactin; Lysosomes; mTORC1; p150Glued
    DOI:  https://doi.org/10.1007/s00018-024-05256-6
  4. Autophagy. 2024 May 16. 1-3
    CALCOCO2/NDP52 associates with RAB9 to initiate an antiviral response to hepatitis B virus infection through a lysosomal degradation pathway.
    Shuzhi Cui, Mathias Faure, Yu Wei.
      CALCOCO2/NDP52 recognizes LGALS8 (galectin 8)-coated invading bacteria and initiates anti-bacterial autophagy by recruiting RB1CC1/FIP200 and TBKBP1/SINTBAD-AZI2/NAP1. Whether CALCOCO2 exerts similar functions against viral infection is unknown. In our recent study we show that CALCOCO2 targets envelope proteins of hepatitis B virus (HBV) to the lysosome for degradation, resulting in inhibition of viral replication. In contrast to anti-bacterial autophagy, lysosomal degradation of HBV does not require either LGALS8 or ATG5, and CALCOCO2 mutants abolishing the formation of the RB1CC1-CALCOCO2-TBKBP1-AZI2 complex maintain their inhibitory function on the virus. CALCOCO2-mediated inhibition depends on RAB9, which is a key factor in the alternative autophagy pathway. CALCOCO2 forms a complex with RAB9 only in the presence of viral envelope proteins and links HBV to the RAB9-dependent lysosomal degradation pathway. These findings reveal a new mechanism by which CALCOCO2 triggers antiviral responses against HBV infection and suggest direct roles for autophagy receptors in other lysosomal degradation pathways than canonical autophagy.
    Keywords:  CALCOCO2/NDP52; RAB9; hepatitis B virus; lysosomal degradation; viral envelop proteins
    DOI:  https://doi.org/10.1080/15548627.2024.2353499
  5. EMBO J. 2024 May 16.
    Receptor-mediated cargo hitchhiking on bulk autophagy.
    Eigo Takeda, Takahiro Isoda, Sachiko Hosokawa, Yu Oikawa, Shukun Hotta-Ren, Alexander I May, Yoshinori Ohsumi.
      While the molecular mechanism of autophagy is well studied, the cargoes delivered by autophagy remain incompletely characterized. To examine the selectivity of autophagy cargo, we conducted proteomics on isolated yeast autophagic bodies, which are intermediate structures in the autophagy process. We identify a protein, Hab1, that is highly preferentially delivered to vacuoles. The N-terminal 42 amino acid region of Hab1 contains an amphipathic helix and an Atg8-family interacting motif, both of which are necessary and sufficient for the preferential delivery of Hab1 by autophagy. We find that fusion of this region with a cytosolic protein results in preferential delivery of this protein to the vacuole. Furthermore, attachment of this region to an organelle allows for autophagic delivery in a manner independent of canonical autophagy receptor or scaffold proteins. We propose a novel mode of selective autophagy in which a receptor, in this case Hab1, binds directly to forming isolation membranes during bulk autophagy.
    Keywords:   Saccharomyces cerevisiae ; Atg8; Autophagy; Hab1; Selective Autophagy
    DOI:  https://doi.org/10.1038/s44318-024-00091-8
  6. J Adv Res. 2024 May 13. pii: S2090-1232(24)00199-1. [Epub ahead of print]
    Targeting selective autophagy and beyond: From underlying mechanisms to potential therapies.
    Wei Ma, Yingying Lu, Xin Jin, Na Lin, Lan Zhang, Yaowen Song.
       BACKGROUND: Autophagy is an evolutionarily conserved turnover process for intracellular substances in eukaryotes, relying on lysosomal (in animals) or vacuolar (in yeast and plants) mechanisms. In the past two decades, emerging evidence suggests that, under specific conditions, autophagy can target particular macromolecules or organelles for degradation, a process termed selective autophagy. Recently, accumulating studies have demonstrated that the abnormality of selective autophagy is closely associated with the occurrence and progression of many human diseases, including neurodegenerative diseases, cancers, metabolic diseases, and cardiovascular diseases.
    AIM OF REVIEW: This review aims at systematically and comprehensively introducing selective autophagy and its role in various diseases, while unravelling the molecular mechanisms of selective autophagy. By providing a theoretical basis for the development of related small-molecule drugs as well as treating related human diseases, this review seeks to contribute to the understanding of selective autophagy and its therapeutic potential.
    KEY SCIENTIFIC CONCEPTS OF REVIEW: In this review, we systematically introduce and dissect the major categories of selective autophagy that have been discovered. We also focus on recent advances in understanding the molecular mechanisms underlying both classical and non-classical selective autophagy. Moreover, the current situation of small-molecule drugs targeting different types of selective autophagy is further summarized, providing valuable insights into the discovery of more candidate small-molecule drugs targeting selective autophagy in the future. On the other hand, we also reveal clinically relevant implementations that are potentially related to selective autophagy, such as predictive approaches and treatments tailored to individual patients.
    Keywords:  Autophagy; Clinically relevant implementation; Human disease; Molecular mechanism; Selective autophagy; Small-molecule drug
    DOI:  https://doi.org/10.1016/j.jare.2024.05.009
  7. Autoimmunity. 2024 Dec;57(1): 2351872
    New insight in treating autoimmune diseases by targeting autophagy.
    Jiao Lyu, Hongqian Zhang, Chaoyang Wang, Mingyu Pan.
      Autophagy is a highly conserved biological process in eukaryotes, which degrades cellular misfolded proteins, damaged organelles and invasive pathogens in the lysosome-dependent manner. Autoimmune diseases caused by genetic elements, environments and aberrant immune responses severely impact patients' living quality and even threaten life. Recently, numerous studies have reported autophagy can regulate immune responses, and play an important role in autoimmune diseases. In this review, we summarised the features of autophagy and autophagy-related genes, enumerated some autophagy-related genes involved in autoimmune diseases, and further overviewed how to treat autoimmune diseases through targeting autophagy. Finally, we outlooked the prospect of relieving and curing autoimmune diseases by targeting autophagy pathway.
    Keywords:  ATGs; Autoimmune diseases; autophagy; treatments strategies
    DOI:  https://doi.org/10.1080/08916934.2024.2351872
  8. Cell Death Dis. 2024 May 13. 15(5): 333
    Reduction of spermine synthase enhances autophagy to suppress Tau accumulation.
    Xianzun Tao, Jiaqi Liu, Zoraida Diaz-Perez, Jackson R Foley, Ashley Nwafor, Tracy Murray Stewart, Robert A Casero, R Grace Zhai.
      Precise polyamine metabolism regulation is vital for cells and organisms. Mutations in spermine synthase (SMS) cause Snyder-Robinson intellectual disability syndrome (SRS), characterized by significant spermidine accumulation and autophagy blockage in the nervous system. Emerging evidence connects polyamine metabolism with other autophagy-related diseases, such as Tauopathy, however, the functional intersection between polyamine metabolism and autophagy in the context of these diseases remains unclear. Here, we altered SMS expression level to investigate the regulation of autophagy by modulated polyamine metabolism in Tauopathy in Drosophila and human cellular models. Interestingly, while complete loss of Drosophila spermine synthase (dSms) impairs lysosomal function and blocks autophagic flux recapitulating SRS disease phenotype, partial loss of dSms enhanced autophagic flux, reduced Tau protein accumulation, and led to extended lifespan and improved climbing performance in Tauopathy flies. Measurement of polyamine levels detected a mild elevation of spermidine in flies with partial loss of dSms. Similarly, in human neuronal or glial cells, partial loss of SMS by siRNA-mediated knockdown upregulated autophagic flux and reduced Tau protein accumulation. Importantly, proteomics analysis of postmortem brain tissue from Alzheimer's disease (AD) patients showed a significant albeit modest elevation of SMS level. Taken together, our study uncovers a functional correlation between polyamine metabolism and autophagy in AD: SMS reduction upregulates autophagy, suppresses Tau accumulation, and ameliorates neurodegeneration and cell death. These findings provide a new potential therapeutic target for AD.
    DOI:  https://doi.org/10.1038/s41419-024-06720-8
  9. bioRxiv. 2024 May 01. pii: 2024.04.29.591753. [Epub ahead of print]
    Alterations of PINK1-PRKN signaling in mice during normal aging.
    Zahra Baninameh, Jens O Watzlawik, Xu Hou, Tyrique Richardson, Nicholas W Kurchaba, Tingxiang Yan, Damian N Di Florio, DeLisa Fairweather, Lu Kang, Justin H Nguyen, Takahisa Kanekiyo, Dennis W Dickson, Sachiko Noda, Shigeto Sato, Nobutaka Hattori, Matthew S Goldberg, Ian G Ganley, Kelly L Stauch, Fabienne C Fiesel, Wolfdieter Springer.
      The ubiquitin kinase-ligase pair PINK1-PRKN identifies and selectively marks damaged mitochondria for elimination via the autophagy-lysosome system (mitophagy). While this cytoprotective pathway has been extensively studied in vitro upon acute and complete depolarization of mitochondria, the significance of PINK1-PRKN mitophagy in vivo is less well established. Here we used a novel approach to study PINK1-PRKN signaling in different energetically demanding tissues of mice during normal aging. We demonstrate a generally increased expression of both genes and enhanced enzymatic activity with aging across tissue types. Collectively our data suggest a distinct regulation of PINK1-PRKN signaling under basal conditions with the most pronounced activation and flux of the pathway in mouse heart compared to brain or skeletal muscle. Our biochemical analyses complement existing mitophagy reporter readouts and provide an important baseline assessment in vivo, setting the stage for further investigations of the PINK1-PRKN pathway during stress and in relevant disease conditions.
    DOI:  https://doi.org/10.1101/2024.04.29.591753
  10. J Physiol. 2024 May 15.
    Lack of compensatory mitophagy in skeletal muscles during sepsis.
    Sami Sedraoui, Jean-Philippe Leduc-Gaudet, Dominique Mayaki, Alaa Moamer, Laurent Huck, Gilles Gouspillou, Basil J Petrof, Sabah Hussain.
      Skeletal muscle dysfunction is a major problem in critically ill patients suffering from sepsis. This condition is associated with mitochondrial dysfunction and increased autophagy in skeletal muscles. Autophagy is a proteolytic mechanism involved in eliminating dysfunctional cellular components, including mitochondria. The latter process, referred to as mitophagy, is essential for maintaining mitochondrial quality and skeletal muscle health. Recently, a fluorescent reporter system called mito-QC (i.e. mitochondrial quality control) was developed to specifically quantify mitophagy levels. In the present study, we used mito-QC transgenic mice and confocal microscopy to morphologically monitor mitophagy levels during sepsis. To induce sepsis, Mito-QC mice received Escherichia coli lipopolysaccharide (10 mg kg-1 i.p.) or phosphate-buffered saline and skeletal muscles (hindlimb and diaphragm) were excised 48 h later. In control groups, there was a negative correlation between the basal mitophagy level and overall muscle mitochondrial content. Sepsis increased general autophagy in both limb muscles and diaphragm but had no effect on mitophagy levels. Sepsis was associated with a downregulation of certain mitophagy receptors (Fundc1, Bcl2L13, Fkbp8 and Phbb2). The present study suggests that general autophagy and mitophagy can be dissociated from one another, and that the characteristic accumulation of damaged mitochondria in skeletal muscles under the condition of sepsis may reflect a failure of adequate compensatory mitophagy. KEY POINTS: There was a negative correlation between the basal level of skeletal muscle mitophagy and the mitochondrial content of individual muscles. Mitophagy levels in limb muscles and the diaphragm were unaffected by lipopolysaccharide (LPS)-induced sepsis. With the exception of BNIP3 in sepsis, LPS administration induced either no change or a downregulation of mitophagy receptors in skeletal muscles.
    Keywords:  autophagy; mitochondria; mitophagy; mito‐QC; sepsis; skeletal muscles
    DOI:  https://doi.org/10.1113/JP286216
  11. J Cell Sci. 2024 May 01. pii: jcs259775. [Epub ahead of print]137(9):
    Mammalian pexophagy at a glance.
    Justyna Bajdzienko, Anja Bremm.
      Peroxisomes are highly plastic organelles that are involved in several metabolic processes, including fatty acid oxidation, ether lipid synthesis and redox homeostasis. Their abundance and activity are dynamically regulated in response to nutrient availability and cellular stress. Damaged or superfluous peroxisomes are removed mainly by pexophagy, the selective autophagy of peroxisomes induced by ubiquitylation of peroxisomal membrane proteins or ubiquitin-independent processes. Dysregulated pexophagy impairs peroxisome homeostasis and has been linked to the development of various human diseases. Despite many recent insights into mammalian pexophagy, our understanding of this process is still limited compared to our understanding of pexophagy in yeast. In this Cell Science at a Glance article and the accompanying poster, we summarize current knowledge on the control of mammalian pexophagy and highlight which aspects require further attention. We also discuss the role of ubiquitylation in pexophagy and describe the ubiquitin machinery involved in regulating signals for the recruitment of phagophores to peroxisomes.
    Keywords:  Peroxisome; Pexophagy; Selective autophagy; Ubiquitylation
    DOI:  https://doi.org/10.1242/jcs.259775
  12. Autophagy. 2024 May 14. 1-2
    A delicate decision between repair and degradation of damaged lysosomes.
    Yuchen Lei, Daniel J Klionsky.
      The destination of a damaged lysosome is either being repaired if the damage is small or degraded through a lysosome-specific macroautophagy/autophagy pathway named lysophagy when the damage is too extensive to repair. Even though previous studies report lumenal glycan exposure during lysosome damage as a signal to trigger lysophagy, it is possibly beneficial for cells to initiate lysophagy earlier than membrane rupture. In a recently published article, Gahlot et al. determined that SPART/SPG20 senses lipid-packing defects and recruits and activates the ubiquitin ligase ITCH, which labels damaged lysosomes with ubiquitin chains to initiate lysophagy.
    Keywords:  ESCRT; lipid-packing defect; lysophagy; lysosome damage; ubiquitination
    DOI:  https://doi.org/10.1080/15548627.2024.2350738
  13. Cell Biosci. 2024 May 17. 14(1): 63
    Methylmalonic acidemia triggers lysosomal-autophagy dysfunctions.
    Michele Costanzo, Armando Cevenini, Laxmikanth Kollipara, Marianna Caterino, Sabrina Bianco, Francesca Pirozzi, Gianluca Scerra, Massimo D'Agostino, Luigi Michele Pavone, Albert Sickmann, Margherita Ruoppolo.
       BACKGROUND: Methylmalonic acidemia (MMA) is a rare inborn error of propionate metabolism caused by deficiency of the mitochondrial methylmalonyl-CoA mutase (MUT) enzyme. As matter of fact, MMA patients manifest impairment of the primary metabolic network with profound damages that involve several cell components, many of which have not been discovered yet. We employed cellular models and patients-derived fibroblasts to refine and uncover new pathologic mechanisms connected with MUT deficiency through the combination of multi-proteomics and bioinformatics approaches.
    RESULTS: Our data show that MUT deficiency is connected with profound proteome dysregulations, revealing molecular actors involved in lysosome and autophagy functioning. To elucidate the effects of defective MUT on lysosomal and autophagy regulation, we analyzed the morphology and functionality of MMA-lysosomes that showed deep alterations, thus corroborating omics data. Lysosomes of MMA cells present as enlarged vacuoles with low degradative capabilities. Notwithstanding, treatment with an anti-propionigenic drug is capable of totally rescuing lysosomal morphology and functional activity in MUT-deficient cells. These results indicate a strict connection between MUT deficiency and lysosomal-autophagy dysfunction, providing promising therapeutic perspectives for MMA.
    CONCLUSIONS: Defective homeostatic mechanisms in the regulation of autophagy and lysosome functions have been demonstrated in MUT-deficient cells. Our data prove that MMA triggers such dysfunctions impacting on autophagosome-lysosome fusion and lysosomal activity.
    Keywords:  Autophagy; Lysosomes; MMA therapy; Metabolic disease; Methylmalonic acidemia; Multi-omics; Multi-proteomics
    DOI:  https://doi.org/10.1186/s13578-024-01245-1
  14. Alzheimers Dement. 2024 May 16.
    Urolithin A improves Alzheimer's disease cognition and restores mitophagy and lysosomal functions.
    Yujun Hou, Xixia Chu, Jae-Hyeon Park, Qing Zhu, Mansoor Hussain, Zhiquan Li, Helena Borland Madsen, Beimeng Yang, Yong Wei, Yue Wang, Evandro F Fang, Deborah L Croteau, Vilhelm A Bohr.
       BACKGROUND: Compromised autophagy, including impaired mitophagy and lysosomal function, plays pivotal roles in Alzheimer's disease (AD). Urolithin A (UA) is a gut microbial metabolite of ellagic acid that stimulates mitophagy. The effects of UA's long-term treatment of AD and mechanisms of action are unknown.
    METHODS: We addressed these questions in three mouse models of AD with behavioral, electrophysiological, biochemical, and bioinformatic approaches.
    RESULTS: Long-term UA treatment significantly improved learning, memory, and olfactory function in different AD transgenic mice. UA also reduced amyloid beta (Aβ) and tau pathologies and enhanced long-term potentiation. UA induced mitophagy via increasing lysosomal functions. UA improved cellular lysosomal function and normalized lysosomal cathepsins, primarily cathepsin Z, to restore lysosomal function in AD, indicating the critical role of cathepsins in UA-induced therapeutic effects on AD.
    CONCLUSIONS: Our study highlights the importance of lysosomal dysfunction in AD etiology and points to the high translational potential of UA.
    HIGHLIGHTS: Long-term urolithin A (UA) treatment improved learning, memory, and olfactory function in Alzheimer's disease (AD) mice. UA restored lysosomal functions in part by regulating cathepsin Z (Ctsz) protein. UA modulates immune responses and AD-specific pathophysiological pathways.
    Keywords:  Alzheimer's disease; DNA repair; autophagy; cathepsin Z; lysosome; mitophagy; neuroinflammation; urolithin A
    DOI:  https://doi.org/10.1002/alz.13847
  15. Autophagy. 2024 May 14.
    Autophagy in hematopoietic stem cell development of the embryo.
    Yumin Liu, Sifan Luo, Yuehang Chen, Zhuan Li.
      Hematopoietic stem cells (HSC) emerge from hemogenic endothelial cells (HEC) in the aorta-gonad-mesonephros (AGM) region of embryos, which go through the pre-HSC process. Various intrinsic and extrinsic factors are involved in this process. We recently discovered that the existence of distinct macroautophagic/autophagic statuses in hematopoietic precursors is related to the hematopoietic potential of pre-HSCs and the depletion of the Atg5 (autophagy related 5) gene specifically in endothelial cells impaired in the transition of endothelial to pre-HSCs, by hampering the autophagic process, likely via the NCL (nucleolin) pathway.
    Keywords:  Atg5; NCL; autophagy; hematopoietic development; hematopoietic precursors; hematopoietic stem cells
    DOI:  https://doi.org/10.1080/15548627.2024.2355072
  16. New Phytol. 2024 May 10.
    Lipid turnover through lipophagy in the newly identified extremophilic green microalga Chlamydomonas urium.
    María Esther Pérez-Pérez, Manuel J Mallén-Ponce, Yosu Odriozola-Gil, Alejandro Rubio, Joaquín J Salas, Enrique Martínez-Force, Antonio J Pérez-Pulido, José L Crespo.
      Autophagy is a central degradative pathway highly conserved among eukaryotes, including microalgae, which remains unexplored in extremophilic organisms. In this study, we described and characterized autophagy in the newly identified extremophilic green microalga Chlamydomonas urium, which was isolated from an acidic environment. The nuclear genome of C. urium was sequenced, assembled and annotated in order to identify autophagy-related genes. Transmission electron microscopy, immunoblotting, metabolomic and photosynthetic analyses were performed to investigate autophagy in this extremophilic microalga. The analysis of the C. urium genome revealed the conservation of core autophagy-related genes. We investigated the role of autophagy in C. urium by blocking autophagic flux with the vacuolar ATPase inhibitor concanamycin A. Our results indicated that inhibition of autophagic flux in this microalga resulted in a pronounced accumulation of triacylglycerols and lipid droplets (LDs). Metabolomic and photosynthetic analyses indicated that C. urium cells with impaired vacuolar function maintained an active metabolism. Such effects were not observed in the neutrophilic microalga Chlamydomonas reinhardtii. Inhibition of autophagic flux in C. urium uncovered an active recycling of LDs through lipophagy, a selective autophagy pathway for lipid turnover. This study provided the metabolic basis by which extremophilic algae are able to catabolize lipids in the vacuole.
    Keywords:  Chlamydomonas; autophagy; extremophile; lipid; lipophagy; metabolism; microalga
    DOI:  https://doi.org/10.1111/nph.19811
  17. Mol Cell. 2024 May 16. pii: S1097-2765(24)00383-6. [Epub ahead of print]84(10): 1980-1994.e8
    Autophagy preferentially degrades non-fibrillar polyQ aggregates.
    Dorothy Y Zhao, Felix J B Bäuerlein, Itika Saha, F Ulrich Hartl, Wolfgang Baumeister, Florian Wilfling.
      Aggregation of proteins containing expanded polyglutamine (polyQ) repeats is the cytopathologic hallmark of a group of dominantly inherited neurodegenerative diseases, including Huntington's disease (HD). Huntingtin (Htt), the disease protein of HD, forms amyloid-like fibrils by liquid-to-solid phase transition. Macroautophagy has been proposed to clear polyQ aggregates, but the efficiency of aggrephagy is limited. Here, we used cryo-electron tomography to visualize the interactions of autophagosomes with polyQ aggregates in cultured cells in situ. We found that an amorphous aggregate phase exists next to the radially organized polyQ fibrils. Autophagosomes preferentially engulfed this amorphous material, mediated by interactions between the autophagy receptor p62/SQSTM1 and the non-fibrillar aggregate surface. In contrast, amyloid fibrils excluded p62 and evaded clearance, resulting in trapping of autophagic structures. These results suggest that the limited efficiency of autophagy in clearing polyQ aggregates is due to the inability of autophagosomes to interact productively with the non-deformable, fibrillar disease aggregates.
    Keywords:  aggrephagy; amyloid fibril; autophagy; cryo-electron microscopy; cryo-electron tomography; neurodegeneration; p62/SQSTM1/sequestosome 1; phase separation; polyglutamine/polyQ expansion; protein aggregation
    DOI:  https://doi.org/10.1016/j.molcel.2024.04.018
  18. Autophagy. 2024 May 16. 1-20
    Picornavirus VP3 protein induces autophagy through the TP53-BAD-BAX axis to promote viral replication.
    Ruoqing Mao, Zixiang Zhu, Fan Yang, Dehui Sun, Xiaoli Zhou, Weijun Cao, Xiaodong Qin, Wen Dang, Huanan Liu, Hong Tian, Keshan Zhang, Qingfeng Wu, Xiangtao Liu, Haixue Zheng.
      Macroautophagy/autophagy and apoptosis are pivotal interconnected host cell responses to viral infection, including picornaviruses. Here, the VP3 proteins of picornaviruses were determined to trigger autophagy, with the autophagic flux being triggered by the TP53-BAD-BAX axis. Using foot-and-mouth disease virus (FMDV) as a model system, we unraveled a novel mechanism of how picornavirus hijacks autophagy to bolster viral replication and enhance pathogenesis. FMDV infection induced both autophagy and apoptosis in vivo and in vitro. FMDV VP3 protein facilitated the phosphorylation and translocation of TP53 from the nucleus into the mitochondria, resulting in BAD-mediated apoptosis and BECN1-mediated autophagy. The amino acid Gly129 in VP3 is essential for its interaction with TP53, and crucial for induction of autophagy and apoptosis. VP3-induced autophagy and apoptosis are both essential for FMDV replication, while, autophagy plays a more important role in VP3-mediated pathogenesis. Mutation of Gly129 to Ala129 in VP3 abrogated the autophagic regulatory function of VP3, which significantly decreased the viral replication and pathogenesis of FMDV. This suggested that VP3-induced autophagy benefits viral replication and pathogenesis. Importantly, this Gly is conserved and showed a common function in various picornaviruses. This study provides insight for developing broad-spectrum antivirals and genetic engineering attenuated vaccines against picornaviruses.Abbreviations: 3-MA, 3-methyladenine; ATG, autophagy related; BAD, BCL2 associated agonist of cell death; BAK1, BCL2 antagonist/killer 1; BAX, BCL2 associated X, apoptosis regulator; BBC3/PUMA, BCL2 binding component 3; BCL2, BCL2 apoptosis regulator; BID, BH3 interacting domain death agonist; BIP-V5, BAX inhibitor peptide V5; CFLAR/FLIP, CASP8 and FADD like apoptosis regulator; CPE, cytopathic effects; CQ, chloroquine; CV, coxsackievirus; DAPK, death associated protein kinase; DRAM, DNA damage regulated autophagy modulator; EV71, enterovirus 71; FMDV, foot-and-mouth disease virus; HAV, hepatitis A virus; KD, knockdown; MAP1LC3/LC3, microtubule associated protein 1 light chain 3; MOI, multiplicity of infection; MTOR, mechanistic target of rapamycin kinase; PML, promyelocytic leukemia; PV, poliovirus; SVA, Seneca Valley virus; TCID50, 50% tissue culture infectious doses; TOR, target of rapamycin. TP53/p53, tumor protein p53; WCL, whole-cell lysate.
    Keywords:  Autophagy; TP53-BAD-BAX axis; VP3; picornavirus; replication
    DOI:  https://doi.org/10.1080/15548627.2024.2350270
  19. Exp Mol Med. 2024 May 17.
    Exploiting sweet relief for preeclampsia by targeting autophagy-lysosomal machinery and proteinopathy.
    Zheping Huang, Shibin Cheng, Sukanta Jash, Jamie Fierce, Anthony Agudelo, Takanobu Higashiyama, Nazeeh Hanna, Akitoshi Nakashima, Shigeru Saito, James Padbury, Jessica Schuster, Surendra Sharma.
      The etiology of preeclampsia (PE), a severe complication of pregnancy with several clinical manifestations and a high incidence of maternal and fetal morbidity and mortality, remains unclear. This issue is a major hurdle for effective treatment strategies. We recently demonstrated that PE exhibits an Alzheimer-like etiology of impaired autophagy and proteinopathy in the placenta. Targeting of these pathological pathways may be a novel therapeutic strategy for PE. Stimulation of autophagy with the natural disaccharide trehalose and its lacto analog lactotrehalose in hypoxia-exposed primary human trophoblasts restored autophagy, inhibited the accumulation of toxic protein aggregates, and restored the ultrastructural features of autophagosomes and autolysosomes. Importantly, trehalose and lactotrehalose inhibited the onset of PE-like features in a humanized mouse model by normalizing autophagy and inhibiting protein aggregation in the placenta. These disaccharides restored the autophagy-lysosomal biogenesis machinery by increasing nuclear translocation of the master transcriptional regulator TFEB. RNA-seq analysis of the placentas of mice with PE indicated the normalization of the PE-associated transcriptome profile in response to trehalose and lactotrehalose. In summary, our results provide a novel molecular rationale for impaired autophagy and proteinopathy in patients with PE and identify treatment with trehalose and its lacto analog as promising therapeutic options for this severe pregnancy complication.
    DOI:  https://doi.org/10.1038/s12276-024-01234-x
  20. J Cell Sci. 2024 May 17. pii: jcs.262096. [Epub ahead of print]
    The Drosophila Nesprin-1 homolog MSP300 is required for muscle autophagy and proteostasis.
    Kevin van der Graaf, Saurabh Srivastav, Rajkishor Nishad, Michael Stern, James A McNew.
      Nesprin proteins, which are components of the LINC complex, are located within the nuclear envelope and play prominent roles in nuclear architecture. For example, LINC complex proteins interact with both chromatin and the cytoskeleton. Here we report that the Drosophila Nesprin MSP300 has an additional function in autophagy within larval body wall muscles. RNAi-mediated MSP300 knockdown in larval body wall muscles resulted in defects in the contractile apparatus, muscle degeneration, and defective autophagy. In particular, MSP300 knockdown caused accumulation of cytoplasmic aggregates that contained poly-ubiquitinated cargo, as well as the autophagy receptor ref(2)P/p62/SQSTM and Atg8a. Furthermore, MSP300 knockdown larvae expressing an mCh-GFP-tagged Atg8a transgene exhibited aberrant persistence of the GFP signal within these aggregates, indicating failure of autophagosome maturation. These autophagy deficits were similar to those exhibited by loss of the ER fusion protein Atlastin (Atl), raising the possibility that Atl and MSP300 might function in the same pathway. In support of this possibility, we found that a GFP-tagged MSP300 protein trap exhibit extensive localization to the ER. Alteration of ER-directed MSP300 might abrogate important cytoskeletal contacts necessary for autophagosome completion.
    Keywords:  Aggregate; Autophagy; Endoplasmic reticulum; Poly Ubiquitin
    DOI:  https://doi.org/10.1242/jcs.262096
  21. Autophagy. 2024 May 12. 1-3
    ATG14 and STX18: gatekeepers of lipid droplet degradation and the implications for disease modulation.
    Nathan Shatz, Yashveer Chohan, Daniel J Klionsky.
      Lipophagy, a form of autophagy specific to the degradation of lipid droplets (LDs), plays an important role in the maintenance of cellular homeostasis and metabolic processes. A recent study has identified ATG14 (autophagy related 14) as a molecule that targets LDs and marks them for degradation via lipophagy; a process that is inhibited by the binding of STX18 (syntaxin 18) to ATG14 in mammalian cells. The exact mechanism of regulation of lipophagy, and subsequently of cellular LD levels, is still under investigation; however, dysregulation of this process has been linked to a number of disease phenotypes. An imbalance of lipid levels can result in a wide variety of conditions depending on the cell/tissue type in which they occur. In cells of the retinal pigment epithelium, lipid accumulation can result in dry age-related macular degeneration, in hepatocytes it can result in nonalcoholic fatty liver diseases and in neural cells it can result in the pathogenesis of neurodegenerative conditions such as Alzheimer and Parkinson diseases. Based upon its wide range of implications in diseases, modulation of lipophagy is currently being further investigated for its potential as a treatment for a variety of conditions ranging from viral infection to developmental illnesses.
    Keywords:  ATG14; STX18; lipid droplets; lipid metabolism-associated diseases; lipophagy
    DOI:  https://doi.org/10.1080/15548627.2024.2350739
  22. Biochem Soc Trans. 2024 May 15. pii: BST20230897. [Epub ahead of print]
    PROPPINs and membrane fission in the endo-lysosomal system.
    Navin Gopaldass, Andreas Mayer.
      PROPPINs constitute a conserved protein family with multiple members being expressed in many eukaryotes. PROPPINs have mainly been investigated for their role in autophagy, where they co-operate with several core factors for autophagosome formation. Recently, novel functions of these proteins on endo-lysosomal compartments have emerged. PROPPINs support the division of these organelles and the formation of tubulo-vesicular cargo carriers that mediate protein exit from them, such as those generated by the Retromer coat. In both cases, PROPPINs provide membrane fission activity. Integrating information from yeast and human cells this review summarizes the most important molecular features that allow these proteins to facilitate membrane fission and thus provide a critical element to endo-lysosomal protein traffic.
    Keywords:  Retromer; WIPI proteins; autophagy; endosomes; lysosomes; protein sorting
    DOI:  https://doi.org/10.1042/BST20230897
  23. Cell Stem Cell. 2024 May 13. pii: S1934-5909(24)00174-7. [Epub ahead of print]
    Autophagy counters inflammation-driven glycolytic impairment in aging hematopoietic stem cells.
    Paul V Dellorusso, Melissa A Proven, Fernando J Calero-Nieto, Xiaonan Wang, Carl A Mitchell, Felix Hartmann, Meelad Amouzgar, Patricia Favaro, Andrew DeVilbiss, James W Swann, Theodore T Ho, Zhiyu Zhao, Sean C Bendall, Sean Morrison, Berthold Göttgens, Emmanuelle Passegué.
      Autophagy is central to the benefits of longevity signaling programs and to hematopoietic stem cell (HSC) response to nutrient stress. With age, a subset of HSCs increases autophagy flux and preserves regenerative capacity, but the signals triggering autophagy and maintaining the functionality of autophagy-activated old HSCs (oHSCs) remain unknown. Here, we demonstrate that autophagy is an adaptive cytoprotective response to chronic inflammation in the aging murine bone marrow (BM) niche. We find that inflammation impairs glucose uptake and suppresses glycolysis in oHSCs through Socs3-mediated inhibition of AKT/FoxO-dependent signaling, with inflammation-mediated autophagy engagement preserving functional quiescence by enabling metabolic adaptation to glycolytic impairment. Moreover, we show that transient autophagy induction via a short-term fasting/refeeding paradigm normalizes glycolytic flux and significantly boosts oHSC regenerative potential. Our results identify inflammation-driven glucose hypometabolism as a key driver of HSC dysfunction with age and establish autophagy as a targetable node to reset oHSC regenerative capacity.
    Keywords:  aging; autophagy; hematopoietic stem cells; inflammation; metabolism; regeneration
    DOI:  https://doi.org/10.1016/j.stem.2024.04.020
  24. Adv Sci (Weinh). 2024 May 13. e2400790
    Exploring the Link Between Autophagy-Lysosomal Dysfunction and Early Heterotopic Ossification in Tendons.
    Chang-He Gao, Qian-Qian Wan, Jan-Fei Yan, Yi-Na Zhu, Lei Tian, Jian-Hua Wei, Bin Feng, Li-Na Niu, Kai Jiao.
      Heterotopic ossification (HO), the pathological formation of bone within soft tissues such as tendon and muscle, is a notable complication resulting from severe injury. While soft tissue injury is necessary for HO development, the specific molecular pathology responsible for trauma-induced HO remains a mystery. The previous study detected abnormal autophagy function in the early stages of tendon HO. Nevertheless, it remains to be determined whether autophagy governs the process of HO generation. Here, trauma-induced tendon HO model is used to investigate the relationship between autophagy and tendon calcification. In the early stages of tenotomy, it is observed that autophagic flux is significantly impaired and that blocking autophagic flux promoted the development of more rampant calcification. Moreover, Gt(ROSA)26sor transgenic mouse model experiments disclosed lysosomal acid dysfunction as chief reason behind impaired autophagic flux. Stimulating V-ATPase activity reinstated both lysosomal acid functioning and autophagic flux, thereby reversing tendon HO. This present study demonstrates that autophagy-lysosomal dysfunction triggers HO in the stages of tendon injury, with potential therapeutic targeting implications for HO.
    Keywords:  autophagy; heterotopic ossification; lysosome; pathological calcification; tendon injury
    DOI:  https://doi.org/10.1002/advs.202400790
  25. bioRxiv. 2024 May 02. pii: 2024.05.01.592113. [Epub ahead of print]
    Multiple inositol phosphate species enhance stability of active mTOR.
    Lucia E Rameh, John D York, Raymond D Blind.
      Mechanistic Target of Rapamycin (mTOR) binds the small metabolite inositol hexakisphosphate (IP 6 ) as shown in structures of mTOR, however it remains unclear if IP 6 , or any other inositol phosphate species, can activate mTOR kinase activity. Here, we show that multiple, exogenously added inositol phosphate species (IP 6 , IP 5 , IP 4 and IP 3 ) can all enhance the ability of mTOR and mTORC1 to auto-phosphorylate and incorporate radiolabeled phosphate into peptide substrates in in vitro kinase reactions. Although IP 6 did not affect the apparent K M of mTORC1 for ATP, monitoring kinase activity over longer reaction times showed increased product formation, suggesting inositol phosphates stabilize an active form of mTORC1 in vitro . The effects of IP 6 on mTOR were reversible, suggesting IP 6 bound to mTOR can be exchanged dynamically with the free solvent. Interestingly, we also observed that IP 6 could alter mTOR solubility and electrophoretic mobility in SDS-PAGE in the presence of manganese, suggesting divalent cations may play a role in inositol phosphate regulation of mTOR. Together, these data suggest for the first time that multiple inositol phosphate species (IP 4 , IP 5 and IP 6 ) can dynamically regulate mTOR and mTORC1 by promoting a stable, active state of the kinase. Our data suggest that studies of the dynamics of inositol phosphate regulation of mTOR are well justified.
    DOI:  https://doi.org/10.1101/2024.05.01.592113
  26. J Transl Med. 2024 May 13. 22(1): 452
    The multifaceted role of extracellular vesicles (EVs) in colorectal cancer: metastasis, immune suppression, therapy resistance, and autophagy crosstalk.
    Soheil Rahmati, Aysan Moeinafshar, Nima Rezaei.
      Extracellular vesicles (EVs) are lipid bilayer structures released by all cells and widely distributed in all biological fluids. EVs are implicated in diverse physiopathological processes by orchestrating cell-cell communication. Colorectal cancer (CRC) is one of the most common cancers worldwide, with metastasis being the leading cause of mortality in CRC patients. EVs contribute significantly to the advancement and spread of CRC by transferring their cargo, which includes lipids, proteins, RNAs, and DNAs, to neighboring or distant cells. Besides, they can serve as non-invasive diagnostic and prognostic biomarkers for early detection of CRC or be harnessed as effective carriers for delivering therapeutic agents. Autophagy is an essential cellular process that serves to remove damaged proteins and organelles by lysosomal degradation to maintain cellular homeostasis. Autophagy and EV release are coordinately activated in tumor cells and share common factors and regulatory mechanisms. Although the significance of autophagy and EVs in cancer is well established, the exact mechanism of their interplay in tumor development is obscure. This review focuses on examining the specific functions of EVs in various aspects of CRC, including progression, metastasis, immune regulation, and therapy resistance. Further, we overview emerging discoveries relevant to autophagy and EVs crosstalk in CRC.
    Keywords:  Autophagy; Biomarkers; Colorectal cancer; Exosomes; Extracellular vesicles; Immune suppression; Metastasis; Therapy resistance; miRNAs
    DOI:  https://doi.org/10.1186/s12967-024-05267-8
  27. Toxicol Lett. 2024 May 15. pii: S0378-4274(24)00094-8. [Epub ahead of print]
    Autophagy activated by GR/miR-421-3p/mTOR pathway as a compensatory mechanism participates in chondrodysplasia induced by prenatal caffeine exposure in male fetal rats.
    Hui Han, Huasong Shi, Lingxiao Jiang, Dingmei Zhang, Hui Wang, Jing Li, Liaobin Chen.
      Autophagy has been implicated in the developmental toxicity of multiple organs in offspring caused by adverse environmental conditions during pregnancy. We have previously found that prenatal caffeine exposure (PCE) can cause fetal overexposure to maternal glucocorticoids, leading to chondrodysplasia. However, whether autophagy is involved and what role it plays has not been reported. In this study, a PCE rat model was established by gavage of caffeine (120mg/kg.d) on gestational day 9-20. The results showed that reduced cartilage matrix synthesis in male fetal rats in the PCE group was accompanied by increased autophagy compared to the control group. Furthermore, the expression of mTOR, miR-421-3p, and glucocorticoid receptor (GR) in male fetal rat cartilage of PCE group was increased. At the cellular level, we confirmed that corticosterone inhibited matrix synthesis in fetal chondrocytes while increasing autophagic flux. However, administration of autophagy enhancer (rapamycin) or inhibitor (bafilomycin A1 or 3-methyladenine) partially increased or further decreased aggrecan expression respectively. At the same time, we found that corticosterone could increase the expression of miR-421-3p through GR and target to inhibit the expression of mTOR, thereby enhancing autophagy. In conclusion, PCE can cause chondrodysplasia and autophagy enhancement in male fetal rats. Intrauterine high corticosterone activates GR/miR-421-3p signaling and down-regulates mTOR signaling in fetal chondrocytes, resulting in enhanced autophagy, which can partially compensate for corticosterone-induced fetal chondrodysplasia. This study confirmed the compensatory protective effect of autophagy on the developmental toxicity of fetal cartilage induced by PCE and its epigenetic mechanism, providing novel insights for exploring the early intervention and therapeutic target of fetal-originated osteoarthritis.
    Keywords:  autophagy; chondrodysplasia; miR-421-3p; prenatal caffeine exposure
    DOI:  https://doi.org/10.1016/j.toxlet.2024.05.010
  28. Biomed Pharmacother. 2024 May 16. pii: S0753-3322(24)00622-X. [Epub ahead of print]175 116738
    Matrine induces autophagic cell death by triggering ROS/AMPK/mTOR axis and apoptosis in multiple myeloma.
    Xue Li, Jifan Zhou, Yixin Ling, Yicheng Tan, Jialing Zhang, Xiaofang Wang, Fanfan Li, Songfu Jiang, Shenghui Zhang, Kang Yu, Yixiang Han.
      Despite significant advancements in multiple myeloma (MM) treatment in recent years, most patients will eventually develop resistance or experience relapse. Matrine, a primary active compound of traditional Chinese medicinal herb Sophora flavescens Ait, has been found to have anti-tumor properties in various types of malignant tumors. Whether autophagy plays a crucial role in the anti-MM effect of matrine remain unknown. Herein, we found that matrine could trigger apoptosis and cell cycle arrest, and meanwhile induce autophagy in MM cells in vitro. We further ascertained the role of autophagy by using ATG5 siRNA or the autophagy inhibitor spautin-1, which partially reversed matrine's inhibitory effect on MM cells. Conversely, the combination of matrine with the autophagy inducer rapamycin enhanced their anti-tumor activity. These findings suggest that autophagy induced by matrine can lead to cell death in MM cells. Further mechanism investigation revealed that matrine treatment increased the levels of reactive oxygen species (ROS) and AMPKα1 phosphorylation and decreased the phosphorylation of mTOR in MM cells. Additionally, co-treatment with AMPKα1 siRNA or the ROS scavenger N-acetyl-1-cysteine weakened the increase in autophagy that was induced by matrine. Finally, we demonstrated a synergistic inhibitory effect of matrine and rapamycin against MM in a xenograft mouse model. Collectively, our findings provided novel insights into the anti-MM efficacy of matrine and suggest that matrine induces autophagy by triggering ROS/AMPK/mTOR axis in MM cells, and combinatorial treatment of matrine and rapamycin may be a promising therapeutic strategy against MM.
    Keywords:  Apoptosis; Autophagy; Matrine; Multiple myeloma; Reactive oxygen species
    DOI:  https://doi.org/10.1016/j.biopha.2024.116738
  29. Ageing Res Rev. 2024 May 09. pii: S1568-1637(24)00145-4. [Epub ahead of print] 102327
    ncRNAs and Their Impact on Dopaminergic Neurons: Autophagy Pathways in Parkinson's Disease.
    Riya Thapa, Ehssan Moglad, Muhammad Afzal, Gaurav Gupta, Asif Ahmad Bhat, Waleed Hassan Almalki, Imran Kazmi, Sami I Alzarea, Kumud Pant, Haider Ali, Keshav Raj Paudel, Harish Dureja, Thakur Gurjeet Singh, Sachin Kumar Singh, Kamal Dua.
      Parkinson's Disease (PD) is a complex neurological illness that causes severe motor and non-motor symptoms due to a gradual loss of dopaminergic neurons in the substantia nigra. The aetiology of PD is influenced by a variety of genetic, environmental, and cellular variables. One important aspect of this pathophysiology is autophagy, a crucial cellular homeostasis process that breaks down and recycles cytoplasmic components. Recent advances in genomic technologies have unravelled a significant impact of ncRNAs on the regulation of autophagy pathways, thereby implicating their roles in PD onset and progression. They are members of a family of RNAs that include miRNAs, circRNA and lncRNAs that have been shown to play novel pleiotropic functions in the pathogenesis of PD by modulating the expression of genes linked to autophagic activities and dopaminergic neuron survival. This review aims to integrate the current genetic paradigms with the therapeutic prospect of autophagy-associated ncRNAs in PD. By synthesizing the findings of recent genetic studies, we underscore the importance of ncRNAs in the regulation of autophagy, how they are dysregulated in PD, and how they represent novel dimensions for therapeutic intervention. The therapeutic promise of targeting ncRNAs in PD is discussed, including the barriers that need to be overcome and future directions that must be embraced to funnel these ncRNA molecules for the treatment and management of PD.
    Keywords:  Autophagy; Genetic Regulation; Parkinson's Disease; lncRNAs; miRNAs; ncRNAs
    DOI:  https://doi.org/10.1016/j.arr.2024.102327
  30. Res Sq. 2024 Apr 24. pii: rs.3.rs-4259395. [Epub ahead of print]
    The CTLH Ubiquitin Ligase Substrates ZMYND19 and MKLN1 Negatively Regulate mTORC1 at the Lysosomal Membrane.
    Yin Wang, Rui Guo, Brenda Iturbide Piedras, Hsin-Yao Tang, John M Asara, Italo Tempera, Paul M Lieberman, Benjamin E Gewurz.
      Most Epstein-Barr virus-associated gastric carcinoma (EBVaGC) harbor non-silent mutations that activate phosphoinositide 3 kinase (PI3K) to drive downstream metabolic signaling. To gain insights into PI3K/mTOR pathway dysregulation in this context, we performed a human genome-wide CRISPR/Cas9 screen for hits that synergistically blocked EBVaGC proliferation together with the PI3K antagonist alpelisib. Multiple subunits of carboxy terminal to LisH (CTLH) E3 ligase, including the catalytic MAEA subunit, were among top screen hits. CTLH negatively regulates gluconeogenesis in yeast, but not in higher organisms. Instead, we identified that the CTLH substrates MKLN1 and ZMYND19, which highly accumulated upon MAEA knockout, associated with one another and with lysosomes to inhibit mTORC1. ZMYND19/MKLN1 bound Raptor and RagA/C, but rather than perturbing mTORC1 lysosomal recruitment, instead blocked a late stage of its activation, independently of the tuberous sclerosis complex. Thus, CTLH enables cells to rapidly tune mTORC1 activity at the lysosomal membrane via the ubiquitin/proteasome pathway.
    DOI:  https://doi.org/10.21203/rs.3.rs-4259395/v1
  31. Neuropeptides. 2024 May 08. pii: S0143-4179(24)00035-0. [Epub ahead of print]106 102436
    V-ATPase B2 promotes microglial phagocytosis of myelin debris by inactivating the MAPK signaling pathway.
    Yao Li, Yuhan Dai, Lan Chu.
      Microglial phagocytosis of myelin debris is a crucial process for promoting myelin regeneration in conditions such as multiple sclerosis (MS). Vacuolar-ATPase B2 (V-ATPase B2) has been implicated in various cellular processes, but its role in microglial phagocytosis and its potential impact on MS-related responses remain unclear. In this study, we employed BV-2 murine microglial cells to investigate the influence of V-ATPase B2 on the phagocytosis of myelin debris by microglia. The results revealed that V-ATPase B2 expression increased in response to myelin debris exposure. Overexpression of V-ATPase B2 significantly enhanced BV-2 phagocytosis of myelin debris. Additionally, V-ATPase B2 overexpression shifted microglial polarization towards an anti-inflammatory M2 phenotype, coupled with decreased lysosomal pH and enhanced lysosome degradation capacity. Moreover, endoplasmic reticulum (ER) stress inhibitor, 4-PBA, reversed the effects of V-ATPase B2 silencing on ER stress, M2 polarization, and lysosomal degradation of BV-2 cells. The MAPK pathway was inhibited upon V-ATPase B2 overexpression, contributing to heightened myelin debris clearance by BV-2 cells. Notably, MAPK pathway inhibition partially attenuated the inhibitory effects of V-ATPase B2 knockdown on myelin debris clearance. In conclusion, our findings reveal a pivotal role for V-ATPase B2 in promoting microglial phagocytosis of myelin debris by regulating microglial polarization and lysosomal function via the MAPK signaling pathway, suggesting that targeting V-ATPase B2 may hold therapeutic potential for enhancing myelin debris clearance and modulating microglial responses in MS and related neuroinflammatory disorders.
    Keywords:  MAPK; Microglia; Myelin debris; Phagocytosis; V-ATPase B2
    DOI:  https://doi.org/10.1016/j.npep.2024.102436
  32. Biochim Biophys Acta Mol Basis Dis. 2024 May 15. pii: S0925-4439(24)00227-8. [Epub ahead of print] 167238
    A potential early-atheroprotective target: Irgm1 mediates lymphangiogenesis through LEC autophagy by Tfeb translocation.
    Hengxuan Cai, Guanpeng Ma, Zhenming Zhang, Guojie Liu, Rongzhe Lu, Yige Liu, Jiaxin Wang, Shanjie Wang, Song Sun, E Mingyan, Zhaoying Li, Shaohong Fang, Bo Yu.
      Lymphatic dysfunction is a pivotal pathological mechanism underlying the development of early atherosclerotic plaques. Potential targets of lymphatic function must be identified to realize the early prevention and treatment of atherosclerosis (AS). The immunity-related GTPase Irgm1 is involved in orchestrating cellular autophagy and apoptosis. However, the effect of Irgm1 on early AS progression, particularly through alterations in lymphatic function, remains unclear. In this study, we confirmed the protective effect of lymphangiogenesis on early-AS in vivo. Subsequently, an in vivo model of early AS mice with Irgm1 knockdown shows that Irgm1 reduces early atherosclerotic plaque burden by promoting lymphangiogenesis. Given that lymphatic endothelial cell (LEC) autophagy significantly contributes to lymphangiogenesis, Irgm1 may enhance lymphatic circulation by promoting LEC autophagy. Moreover, Irgm1 orchestrates autophagy in LECs by inhibiting mTOR and facilitating nuclear translocation of Tfeb. Collectively, these processes lead to lymphangiogenesis. Thus, this study establishes a link between Irgm1 and early AS, thus revealing a novel mechanism by which Irgm1 exerts an early protective influence on AS within the context of lymphatic circulation. The insights gained from this study have the potential to revolutionize the approach and management of AS onset.
    Keywords:  Autophagy; Early atherosclerosis; Irgm1; Lymphangiogenesis; Lymphatic function
    DOI:  https://doi.org/10.1016/j.bbadis.2024.167238
  33. Life Sci Alliance. 2024 Jul;pii: e202402735. [Epub ahead of print]7(7):
    Timing of TORC1 inhibition dictates Pol III involvement in Caenorhabditis elegans longevity.
    Yasir Malik, Isabel Goncalves Silva, Rene Rivera Diazgranados, Colin Selman, Nazif Alic, Jennifer Ma Tullet.
      Organismal growth and lifespan are inextricably linked. Target of Rapamycin (TOR) signalling regulates protein production for growth and development, but if reduced, extends lifespan across species. Reduction in the enzyme RNA polymerase III, which transcribes tRNAs and 5S rRNA, also extends longevity. Here, we identify a temporal genetic relationship between TOR and Pol III in Caenorhabditis elegans, showing that they collaborate to regulate progeny production and lifespan. Interestingly, the lifespan interaction between Pol III and TOR is only revealed when TOR signaling is reduced, specifically in adulthood, demonstrating the importance of timing to control TOR regulated developmental versus adult programs. In addition, we show that Pol III acts in C. elegans muscle to promote both longevity and healthspan and that reducing Pol III even in late adulthood is sufficient to extend lifespan. This demonstrates the importance of Pol III for lifespan and age-related health in adult C. elegans.
    DOI:  https://doi.org/10.26508/lsa.202402735
  34. Int J Mol Sci. 2024 Apr 23. pii: 4616. [Epub ahead of print]25(9):
    TRIM44 Promotes Rabies Virus Replication by Autophagy-Dependent Mechanism.
    Hongling He, Ting Cai, Qiaozhu Chen, Zilian Chen, Boyue Zhang, Changyi Chen, Yueze Wang, Yan Liu, Yueming Wang, Yongwen Luo, Shile Huang, Jun Luo, Xiaofeng Guo.
      Tripartite motif (TRIM) proteins are a multifunctional E3 ubiquitin ligase family that participates in various cellular processes. Recent studies have shown that TRIM proteins play important roles in regulating host-virus interactions through specific pathways, but their involvement in response to rabies virus (RABV) infection remains poorly understood. Here, we identified that several TRIM proteins are upregulated in mouse neuroblastoma cells (NA) after infection with the rabies virus using RNA-seq sequencing. Among them, TRIM44 was found to regulate RABV replication. This is supported by the observations that downregulation of TRIM44 inhibits RABV replication, while overexpression of TRIM44 promotes RABV replication. Mechanistically, TRIM44-induced RABV replication is brought about by activating autophagy, as inhibition of autophagy with 3-MA attenuates TRIM44-induced RABV replication. Additionally, we found that inhibition of autophagy with rapamycin reverses the TRIM44-knockdown-induced decrease in LC3B expression and autophagosome formation as well as RABV replication. The results suggest that TRIM44 promotes RABV replication by an autophagy-dependent mechanism. Our work identifies TRIM44 as a key host factor for RABV replication, and targeting TRIM44 expression may represent an effective therapeutic strategy.
    Keywords:  E3 ubiquitin ligase; TRIM44; autophagy; rabies virus; replication
    DOI:  https://doi.org/10.3390/ijms25094616
  35. J Nanobiotechnology. 2024 May 12. 22(1): 242
    Ti3C2 nanosheet-induced autophagy derails ovarian functions.
    Limei Yang, Zhiting He, Le Hu, Hongyu Tang, Yanqing Geng, Qiaoyan Tan, Yue Zhang, Yixian Wen, Wei Wu, Huayan Gu, Xueqing Liu.
       BACKGROUND: Two-dimensional ultrathin Ti3C2 (MXene) nanosheets have gained significant attention in various biomedical applications. Although previous studies have described the accumulation and associated damage of Ti3C2 nanosheets in the testes and placenta. However, it is currently unclear whether Ti3C2 nanosheets can be translocated to the ovaries and cause ovarian damage, thereby impairing ovarian functions.
    RESULTS: We established a mouse model with different doses (1.25, 2.5, and 5 mg/kg bw/d) of Ti3C2 nanosheets injected intravenously for three days. We demonstrated that Ti3C2 nanosheets can enter the ovaries and were internalized by granulosa cells, leading to a decrease in the number of primary, secondary and antral follicles. Furthermore, the decrease in follicles is closely associated with higher levels of FSH and LH, as well as increased level of E2 and P4, and decreased level of T in mouse ovary. In further studies, we found that exposure toTi3C2 nanosheets increased the levels of Beclin1, ATG5, and the ratio of LC3II/Ι, leading to autophagy activation. Additionally, the level of P62 increased, resulting in autophagic flux blockade. Ti3C2 nanosheets can activate autophagy through the PI3K/AKT/mTOR signaling pathway, with oxidative stress playing an important role in this process. Therefore, we chose the ovarian granulosa cell line (KGN cells) for in vitro validation of the impact of autophagy on the hormone secretion capability. The inhibition of autophagy initiation by 3-Methyladenine (3-MA) promoted smooth autophagic flow, thereby partially reduced the secretion of estradiol and progesterone by KGN cells; Whereas blocking autophagic flux by Rapamycin (RAPA) further exacerbated the secretion of estradiol and progesterone in cells.
    CONCLUSION: Ti3C2 nanosheet-induced increased secretion of hormones in the ovary is mediated through the activation of autophagy and impairment of autophagic flux, which disrupts normal follicular development. These results imply that autophagy dysfunction may be one of the underlying mechanisms of Ti3C2-induced damage to ovarian granulosa cells. Our findings further reveal the mechanism of female reproductive toxicity induced by Ti3C2 nanosheets.
    Keywords:  Autophagy; Follicle; Hormone; PI3K/AKT/mTOR; Ti3C2 nanosheets
    DOI:  https://doi.org/10.1186/s12951-024-02495-4
  36. Sci Rep. 2024 05 14. 14(1): 10978
    TASL mediates keratinocyte differentiation by regulating intracellular calcium levels and lysosomal function.
    Ji Yeong Park, Hyeng-Soo Kim, Hyejin Hyung, Soyeon Jang, Jiwon Ko, Jin Hong Lee, Si-Yong Kim, Song Park, Junkoo Yi, Sijun Park, Su-Geun Lim, Seonggon Kim, Sanggyu Lee, Myoung Ok Kim, Soyoung Jang, Zae Young Ryoo.
      Maintaining epidermal homeostasis relies on a tightly organized process of proliferation and differentiation of keratinocytes. While past studies have primarily focused on calcium regulation in keratinocyte differentiation, recent research has shed light on the crucial role of lysosome dysfunction in this process. TLR adaptor interacting with SLC15A4 on the lysosome (TASL) plays a role in regulating pH within the endo-lysosome. However, the specific role of TASL in keratinocyte differentiation and its potential impact on proliferation remains elusive. In our study, we discovered that TASL deficiency hinders the proliferation and migration of keratinocytes by inducing G1/S cell cycle arrest. Also, TASL deficiency disrupts proper differentiation process in TASL knockout human keratinocyte cell line (HaCaT) by affecting lysosomal function. Additionally, our research into calcium-induced differentiation showed that TASL deficiency affects calcium modulation, which is essential for keratinocyte regulation. These findings unveil a novel role of TASL in the proliferation and differentiation of keratinocytes, providing new insights into the intricate regulatory mechanisms of keratinocyte biology.
    DOI:  https://doi.org/10.1038/s41598-024-61674-3
  37. bioRxiv. 2024 Apr 29. pii: 2024.04.28.591534. [Epub ahead of print]
    Stem cell models of TAFAZZIN deficiency reveal novel tissue-specific pathologies in Barth Syndrome.
    Olivia Sniezek Carney, Kodi William Harris, Yvonne Wohlfarter, Kyuna Lee, Grant Butschek, Arianna Anzmann, Steven M Claypool, Anne Hamacher-Brady, Markus Keller, Hilary J Vernon.
      Barth syndrome (BTHS) is a rare mitochondrial disease caused by pathogenic variants in the gene TAFAZZIN, which leads to abnormal cardiolipin (CL) metabolism on the inner mitochondrial membrane. Although TAFAZZIN is ubiquitously expressed, BTHS involves a complex combination of tissue specific phenotypes including cardiomyopathy, neutropenia, skeletal myopathy, and growth delays, with a relatively minimal neurological burden. To understand both the developmental and functional effects of TAZ-deficiency in different tissues, we generated isogenic TAZ knockout (TAZ- KO) and WT cardiomyocytes (CMs) and neural progenitor cells (NPCs) from CRISPR-edited induced pluripotent stem cells (iPSCs). In TAZ-KO CMs we discovered evidence of dysregulated mitophagy including dysmorphic mitochondria and mitochondrial cristae, differential expression of key autophagy-associated genes, and an inability of TAZ-deficient CMs to properly initiate stress-induced mitophagy. In TAZ-deficient NPCs we identified novel phenotypes including a reduction in CIV abundance and CIV activity in the CIII2&CIV2 intermediate complex. Interestingly, while CL acyl chain manipulation was unable to alter mitophagy defects in TAZ-KO CMs, we found that linoleic acid or oleic acid supplementation was able to partially restore CIV abundance in TAZ-deficient NPCs. Taken together, our results have implications for understanding the tissue-specific pathology of BTHS and potential for tissue-specific therapeutic targeting. Moreover, our results highlight an emerging role for mitophagy in the cardiac pathophysiology of BTHS and reveal a potential neuron-specific bioenergetic phenotype.
    DOI:  https://doi.org/10.1101/2024.04.28.591534
  38. Nat Commun. 2024 May 16. 15(1): 4097
    FOXC1 regulates endothelial CD98 (LAT1/4F2hc) expression in retinal angiogenesis and blood-retina barrier formation.
    Teena Bhakuni, Pieter R Norden, Naoto Ujiie, Can Tan, Sun Kyong Lee, Thomas Tedeschi, Yi-Wen Hsieh, Ying Wang, Ting Liu, Amani A Fawzi, Tsutomu Kume.
      Angiogenesis, the growth of new blood vessels from pre-existing vasculature, is essential for the development of new organ systems, but transcriptional control of angiogenesis remains incompletely understood. Here we show that FOXC1 is essential for retinal angiogenesis. Endothelial cell (EC)-specific loss of Foxc1 impairs retinal vascular growth and expression of Slc3a2 and Slc7a5, which encode the heterodimeric CD98 (LAT1/4F2hc) amino acid transporter and regulate the intracellular transport of essential amino acids and activation of the mammalian target of rapamycin (mTOR). EC-Foxc1 deficiency diminishes mTOR activity, while administration of the mTOR agonist MHY-1485 rescues perturbed retinal angiogenesis. EC-Foxc1 expression is required for retinal revascularization and resolution of neovascular tufts in a model of oxygen-induced retinopathy. Foxc1 is also indispensable for pericytes, a critical component of the blood-retina barrier during retinal angiogenesis. Our findings establish FOXC1 as a crucial regulator of retinal vessels and identify therapeutic targets for treating retinal vascular disease.
    DOI:  https://doi.org/10.1038/s41467-024-48134-2
  39. Reprod Biol. 2024 May 10. pii: S1642-431X(24)00035-4. [Epub ahead of print]24(2): 100889
    Mitophagy in mammalian follicle development and health.
    Zhengrong Zhou, Zhipeng Wu, Liufang Zhang, Yue Dai, Genbao Shao, Caifang Ren, Pan Huang.
      Mitophagy, the cellular process that removes damaged mitochondria, plays a crucial role in maintaining normal cell functions. It is deeply involved in the entire process of follicle development and is associated with various ovarian diseases. This review aims to provide a comprehensive overview of mitophagy regulation, emphasizing its role at different stages of follicular development. Additionally, the study illuminates the relationship between mitophagy and ovarian diseases, including ovary aging (OA), primary ovarian insufficiency (POI), and polycystic ovary syndrome (PCOS). A detailed understanding of mitophagy could reveal valuable insights and novel strategies for managing female ovarian reproductive health.
    Keywords:  Follicle development; Mitophagy; Ovary aging; Polycystic ovary syndrome; Primary ovarian insufficiency
    DOI:  https://doi.org/10.1016/j.repbio.2024.100889
  40. J Mol Biol. 2024 May 15. pii: S0022-2836(24)00210-9. [Epub ahead of print] 168615
    Interplay of Proteostasis Capacity and Protein Aggregation: Implications for Cellular Function and Disease.
    Mark S Hipp, F Ulrich Hartl.
      Eukaryotic cells are equipped with an intricate proteostasis network (PN), comprising nearly 3000 components dedicated to preserving proteome integrity and sustaining protein homeostasis. This protective system is particularly important under conditions of external and intrinsic cell stress, where inherently dynamic proteins may unfold and lose functionality. A decline in proteostasis capacity is associated with the aging process, resulting in a reduced folding efficiency of newly synthesized proteins and a deficit in the cellular capacity to degrade misfolded proteins. A critical consequence of PN insufficiency is the accumulation of cytotoxic protein aggregates that underlie various age-related neurodegenerative conditions and other pathologies. By interfering with specific proteostasis components, toxic aggregates place an excessive burden on the PN's ability to maintain proteome integrity. This initiates a feed-forward loop, wherein the generation of misfolded and aggregated proteins ultimately leads to proteostasis collapse and cellular demise.
    Keywords:  neurodegenerative disease; protein aggregation; protein folding; proteostasis
    DOI:  https://doi.org/10.1016/j.jmb.2024.168615
  41. Int J Mol Sci. 2024 Apr 29. pii: 4853. [Epub ahead of print]25(9):
    Mitophagy Regulates the Circadian Rhythms by Degrading NR1D1 in Simulated Microgravity and Isolation Environments.
    Sihai Zhou, Xiaopeng Li, Fengji Liang, Guohua Ji, Ke Lv, Yanhong Yuan, Yujie Zhao, Na Yan, Chuanjie Zhang, Shiou Cai, Shuhui Zhang, Xu Liu, Bo Song, Lina Qu.
      Long-term spaceflight is known to induce disruptions in circadian rhythms, which are driven by a central pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus, but the underlying molecular mechanisms remain unclear. Here, we developed a rat model that simulated microgravity and isolation environments through tail suspension and isolation (TSI). We found that the TSI environment imposed circadian disruptions to the core body temperature, heart rate, and locomotor-activity rhythms of rats, especially in the amplitude of these rhythms. In TSI model rats' SCNs, the core circadian gene NR1D1 showed higher protein but not mRNA levels along with decreased BMAL1 levels, which indicated that NR1D1 could be regulated through post-translational regulation. The autophagosome marker LC3 could directly bind to NR1D1 via the LC3-interacting region (LIR) motifs and induce the degradation of NR1D1 in a mitophagy-dependent manner. Defects in mitophagy led to the reversal of NR1D1 degradation, thereby suppressing the expression of BMAL1. Mitophagy deficiency and subsequent mitochondrial dysfunction were observed in the SCN of TSI models. Urolithin A (UA), a mitophagy activator, demonstrated an ability to enhance the amplitude of core body temperature, heart rate, and locomotor-activity rhythms by prompting mitophagy induction to degrade NR1D1. Cumulatively, our results demonstrate that mitophagy exerts circadian control by regulating NR1D1 degradation, revealing mitophagy as a potential target for long-term spaceflight as well as diseases with SCN circadian disruption.
    Keywords:  NR1D1; circadian rhythms; mitophagy; suprachiasmatic nucleus; tail-suspension-and-isolation model; urolithin A
    DOI:  https://doi.org/10.3390/ijms25094853
  42. J Transl Med. 2024 May 13. 22(1): 449
    Lysosomal dysfunction and overload of nucleosides in thymidine phosphorylase deficiency of MNGIE.
    Jixiang Du, Fuchen Liu, Xihan Liu, Dandan Zhao, Dongdong Wang, Hongsheng Sun, Chuanzhu Yan, Yuying Zhao.
      Inherited deficiency of thymidine phosphorylase (TP), encoded by TYMP, leads to a rare disease with multiple mitochondrial DNA (mtDNA) abnormalities, mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). However, the impact of TP deficiency on lysosomes remains unclear, which are important for mitochondrial quality control and nucleic acid metabolism. Muscle biopsy tissue and skin fibroblasts from MNGIE patients, patients with m.3243 A > G mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and healthy controls (HC) were collected to perform mitochondrial and lysosomal functional analyses. In addition to mtDNA abnormalities, compared to controls distinctively reduced expression of LAMP1 and increased mitochondrial content were detected in the muscle tissue of MNGIE patients. Skin fibroblasts from MNGIE patients showed decreased expression of LAMP2, lowered lysosomal acidity, reduced enzyme activity and impaired protein degradation ability. TYMP knockout or TP inhibition in cells can also induce the similar lysosomal dysfunction. Using lysosome immunoprecipitation (Lyso- IP), increased mitochondrial proteins, decreased vesicular proteins and V-ATPase enzymes, and accumulation of various nucleosides were detected in lysosomes with TP deficiency. Treatment of cells with high concentrations of dThd and dUrd also triggers lysosomal dysfunction and disruption of mitochondrial homeostasis. Therefore, the results provided evidence that TP deficiency leads to nucleoside accumulation in lysosomes and lysosomal dysfunction, revealing the widespread disruption of organelles underlying MNGIE.
    Keywords:  Lysosomal dysfunction; MNGIE; Nucleotide metabolism; TYMP; Thymidine phosphorylase
    DOI:  https://doi.org/10.1186/s12967-024-05275-8
  43. Comp Biochem Physiol A Mol Integr Physiol. 2024 May 10. pii: S1095-6433(24)00091-6. [Epub ahead of print]295 111664
    UVB radiation exposure modulates mitophagy in embryonic cells of freshwater prawn Macrobrachium olfersii: Exploring a protective organelle quality control mechanism.
    Giuliam K Strücker, Michael L Jaramillo, Thaline de Quadros, Evelise M Nazari.
      Aquatic environments are subject to ultraviolet B (UVB) radiation incidence, and its effects on organisms are dose-dependent. Besides DNA, mitochondria are an important target of this radiation that causes structural damage and impairs its functional dynamics. Here, we hypothesize that mitophagy acts as an organelle quality control mechanism to mitigate UVB impacts in embryonic cells. Then, freshwater prawn Macrobrachium olfersii embryos was used as a model to investigate the effects of UVB on genes (Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3) and proteins (TOM20, PINK1, p62 and LC3B) involved in mitophagy modulation. The choice of genes and proteins was based on the identification of mitochondrial membrane (Tomm20, Opa1 and TOM20), mediation of mitophagy (Pink1, Prkn and PINK1), and recognition of mitochondria by the autophagosome membrane (Sqstm1, Map1lc3, p62 and LC3B). First, the phylogeny of all genes presented bootstrap values >80 and conserved domains among crustacean species. Gene expression was inherently modulated during development, with transcripts (Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3) overexpressed in the initial and final stages of development. Moreover, UVB radiation induced upregulation of Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3 genes at 6 h after exposure. Interestingly, after 12 h, the protein content of PINK1, p62, and LC3B increased, while TOM20 was not responsive. Despite UVB radiation's harmful effects on embryonic cells, the chronology of gene expression and protein content indicates rapid activation of mitophagy, serving as an organelle quality control mechanism, given the analyzed cells' integrity.
    Keywords:  Aquatic embryo; Autophagy; Development; Mitochondria; Ultraviolet radiation
    DOI:  https://doi.org/10.1016/j.cbpa.2024.111664
  44. Cell Commun Signal. 2024 May 14. 22(1): 269
    Exploring the neuroprotective role of artesunate in mouse models of anti-NMDAR encephalitis: insights from molecular mechanisms and transmission electron microscopy.
    Jingsi Liu, Yingyi Huang, Tinglin Qian, Jinyu Chen, Yuewen Ding, Zhaohui Lai, Xinghua Zhong, Mingjun Lai, Huili Zhang, Yuanyuan Wang, Honghao Wang, Yu Peng.
       BACKGROUND: The pathway involving PTEN-induced putative kinase 1 (PINK1) and PARKIN plays a crucial role in mitophagy, a process activated by artesunate (ART). We propose that patients with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis exhibit insufficient mitophagy, and ART enhances mitophagy via the PINK1/PARKIN pathway, thereby providing neuroprotection.
    METHODS: Adult female mice aged 8-10 weeks were selected to create a passive transfer model of anti-NMDAR encephalitis. We conducted behavioral tests on these mice within a set timeframe. Techniques such as immunohistochemistry, immunofluorescence, and western blotting were employed to assess markers including PINK1, PARKIN, LC3B, p62, caspase3, and cleaved caspase3. The TUNEL assay was utilized to detect neuronal apoptosis, while transmission electron microscopy (TEM) was used to examine mitochondrial autophagosomes. Primary hippocampal neurons were cultured, treated, and then analyzed through immunofluorescence for mtDNA, mtROS, TMRM.
    RESULTS: In comparison to the control group, mitophagy levels in the experimental group were not significantly altered, yet there was a notable increase in apoptotic neurons. Furthermore, markers indicative of mitochondrial leakage and damage were found to be elevated in the experimental group compared to the control group, but these markers showed improvement following ART treatment. ART was effective in activating the PINK1/PARKIN pathway, enhancing mitophagy, and diminishing neuronal apoptosis. Behavioral assessments revealed that ART ameliorated symptoms in mice with anti-NMDAR encephalitis in the passive transfer model (PTM). The knockdown of PINK1 led to a reduction in mitophagy levels, and subsequent ART intervention did not alleviate symptoms in the anti-NMDAR encephalitis PTM mice, indicating that ART's therapeutic efficacy is mediated through the activation of the PINK1/PARKIN pathway.
    CONCLUSIONS: At the onset of anti-NMDAR encephalitis, mitochondrial damage is observed; however, this damage is mitigated by the activation of mitophagy via the PINK1/PARKIN pathway. This regulatory feedback mechanism facilitates the removal of damaged mitochondria, prevents neuronal apoptosis, and consequently safeguards neural tissue. ART activates the PINK1/PARKIN pathway to enhance mitophagy, thereby exerting neuroprotective effects and may achieve therapeutic goals in treating anti-NMDAR encephalitis.
    Keywords:  Artesunate; Mitophagy; PINK1/PARKIN pathway; anti-NMDAR encephalitis
    DOI:  https://doi.org/10.1186/s12964-024-01652-4
  45. Biogerontology. 2024 May 15.
    Inhibition of mTOR prevents glucotoxicity-mediated increase of SA-beta-gal, p16INK4a, and insulin hypersecretion, without restoring electrical features of mouse pancreatic islets.
    Tereso J Guzmán, Nina Klöpper, Carmen M Gurrola-Díaz, Martina Düfer.
      An over-activation of the mechanistic target of rapamycin (mTOR) pathway promotes senescence and age-related diseases like type 2 diabetes. Besides, the regenerative potential of pancreatic islets deteriorates with aging. Nevertheless, the role of mTOR on senescence promoted by metabolic stress in islet cells as well as its relevance for electrophysiological aspects is not yet known. Here, we investigated whether parameters suggested to be indicative for senescence are induced in vitro in mouse islet cells by glucotoxicity and if mTOR inhibition plays a protective role against this. Islet cells exhibit a significant increase (~ 76%) in senescence-associated beta-galactosidase (SA-beta-gal) activity after exposure to glucotoxicity for 72 h. Glucotoxicity does not markedly influence p16INK4a protein within 72 h, but p16INK4a levels increase significantly after a 7-days incubation period. mTOR inhibition with a low rapamycin concentration (1 nM) entirely prevents the glucotoxicity-mediated increase of SA-beta-gal and p16INK4a. At the functional level, reactive oxygen species, calcium homeostasis, and electrical activity are disturbed by glucotoxicity, and rapamycin fails to prevent this. In contrast, rapamycin significantly attenuates the insulin hypersecretion promoted by glucotoxicity by modifying the mRNA levels of Vamp2 and Snap25 genes, related to insulin exocytosis. Our data indicate an influence of glucotoxicity on pancreatic islet-cell senescence and a reduction of the senescence markers by mTOR inhibition, which is relevant to preserve the regenerative potential of the islets. Decreasing the influence of mTOR on islet cells exposed to glucotoxicity attenuates insulin hypersecretion, but is not sufficient to prevent electrophysiological disturbances, indicating the involvement of mTOR-independent mechanisms.
    Keywords:  Glucose-stimulated insulin secretion; Hyperglycemia; MIN6 cells; Microelectrode arrays; Oxidative stress; Pancreatic beta-cells; Senescence; Sirolimus
    DOI:  https://doi.org/10.1007/s10522-024-10107-9
  46. FASEB J. 2024 May 31. 38(10): e23651
    DDX58 variant triggers IFN-β-induced autophagy in trabecular meshwork and influences intraocular pressure.
    Xinting Huang, Xiaoyu Zhou, Feng Zhang, Xiaobo Wang, Xuanchu Duan, Ke Liu.
      Singleton-Merten syndrome (SMS) is a rare immunogenetic disorder affecting multiple systems, characterized by dental dysplasia, aortic calcification, glaucoma, skeletal abnormalities, and psoriasis. Glaucoma, a key feature of both classical and atypical SMS, remains poorly understood in terms of its molecular mechanism caused by DDX58 mutation. This study presented a novel DDX58 variant (c.1649A>C [p.Asp550Ala]) in a family with childhood glaucoma. Functional analysis showed that DDX58 variant caused an increase in IFN-stimulated gene expression and high IFN-β-based type-I IFN. As the trabecular meshwork (TM) is responsible for controlling intraocular pressure (IOP), we examine the effect of IFN-β on TM cells. Our study is the first to demonstrate that IFN-β significantly reduced TM cell viability and function by activating autophagy. In addition, anterior chamber injection of IFN-β remarkably increased IOP level in mice, which can be attenuated by treatments with autophagy inhibitor chloroquine. To uncover the specific mechanism underlying IFN-β-induced autophagy in TM cells, we performed microarray analysis in IFN-β-treated and DDX58 p.Asp550Ala TM cells. It showed that RSAD2 is necessary for IFN-β-induced autophagy. Knockdown of RSAD2 by siRNA significantly decreased autophagy flux induced by IFN-β. Our findings suggest that DDX58 mutation leads to the overproduction of IFN-β, which elevates IOP by modulating autophagy through RSAD2 in TM cells.
    Keywords:  DDX58; IFN‐β; RSAD2; Singleton–Merten syndrome; autophagy; open‐angle glaucoma; trabecular meshwork
    DOI:  https://doi.org/10.1096/fj.202302265RR
  47. Stem Cells Transl Med. 2024 May 13. pii: szae028. [Epub ahead of print]
    Bone mesenchymal stem cells improve cholestatic liver fibrosis by targeting ULK1 to regulate autophagy through PI3K/AKT/mTOR pathway.
    Tingjuan Huang, Chunhong Zhang, Ziyi Shang, Qizhi Shuai, Lina Nie, Junjie Ren, Shulin Hou, Jun Xie.
      Cholestatic liver disease (CLD) is a severe disease, which can progress to liver cirrhosis, even liver cancer. Hepatic stellate cells (HSCs) activation plays a crucial role in CLD development. Bone mesenchymal stem cells (BMSCs) treatment was demonstrated to be beneficial in liver diseases. However, the therapeutic effect and mechanism of BMSCs on CLD are poorly known. In the present study, we investigated the therapeutic effects and underlying mechanisms of BMSCs transplantation in mouse models of bile duct ligation-induced cholestatic liver fibrosis (CLF). The results revealed that BMSCs significantly improved liver function and reduced the formation of fibrosis after portal vein transplantation. Mechanistically, after coculturing BMSCs and HSCs, we identified that BMSCs alleviated starvation-induced HSCs activation. Further, BMSCs inhibited HSCs activation by decreasing autophagy, and PI3K/AKT/mTOR pathway was involved in the regulation. More importantly, ULK1 is identified as the main autophagy-related gene regulated by BMSCs in HSCs autophagy. Overexpression of ULK1 reversed the suppression of HSCs autophagy by BMSCs. Collectively, our results provide a theoretical basis for BMSCs targeting ULK1 to attenuate HSCs autophagy and activation and suggest that BMSCs or ULK1 may be an alternative therapeutic approach/target for the treatment of CLF.
    Keywords:  BMSCs; PI3K/AKT/mTOR; ULK1; autophagy; cholestatic liver fibrosis; hepatic stellate cells
    DOI:  https://doi.org/10.1093/stcltm/szae028
  48. Nat Commun. 2024 May 14. 15(1): 4083
    mTORC1 regulates cell survival under glucose starvation through 4EBP1/2-mediated translational reprogramming of fatty acid metabolism.
    Tal Levy, Kai Voeltzke, Laura Hruby, Khawla Alasad, Zuelal Bas, Marteinn Snaebjörnsson, Ran Marciano, Katerina Scharov, Mélanie Planque, Kim Vriens, Stefan Christen, Cornelius M Funk, Christina Hassiepen, Alisa Kahler, Beate Heider, Daniel Picard, Jonathan K M Lim, Anja Stefanski, Katja Bendrin, Andres Vargas-Toscano, Ulf D Kahlert, Kai Stühler, Marc Remke, Moshe Elkabets, Thomas G P Grünewald, Andreas S Reichert, Sarah-Maria Fendt, Almut Schulze, Guido Reifenberger, Barak Rotblat, Gabriel Leprivier.
      Energetic stress compels cells to evolve adaptive mechanisms to adjust their metabolism. Inhibition of mTOR kinase complex 1 (mTORC1) is essential for cell survival during glucose starvation. How mTORC1 controls cell viability during glucose starvation is not well understood. Here we show that the mTORC1 effectors eukaryotic initiation factor 4E binding proteins 1/2 (4EBP1/2) confer protection to mammalian cells and budding yeast under glucose starvation. Mechanistically, 4EBP1/2 promote NADPH homeostasis by preventing NADPH-consuming fatty acid synthesis via translational repression of Acetyl-CoA Carboxylase 1 (ACC1), thereby mitigating oxidative stress. This has important relevance for cancer, as oncogene-transformed cells and glioma cells exploit the 4EBP1/2 regulation of ACC1 expression and redox balance to combat energetic stress, thereby supporting transformation and tumorigenicity in vitro and in vivo. Clinically, high EIF4EBP1 expression is associated with poor outcomes in several cancer types. Our data reveal that the mTORC1-4EBP1/2 axis provokes a metabolic switch essential for survival during glucose starvation which is exploited by transformed and tumor cells.
    DOI:  https://doi.org/10.1038/s41467-024-48386-y
  49. Biochem Pharmacol. 2024 May 11. pii: S0006-2952(24)00260-0. [Epub ahead of print]225 116277
    Risk factors of using late-autophagy inhibitors: Aspects to consider when combined with anticancer therapies.
    Maciej Skrzeszewski, Monika Maciejewska, Dagmara Kobza, Aleksandra Gawrylak, Claudine Kieda, Halina Waś.
      Cancer resistance to therapy is still an unsolved scientific and clinical problem. In 2022, the hallmarks of cancer have been expanded to include four new features, including cellular senescence. Therapy-induced senescence (TIS) is a stressor-based response to conventional treatment methods, e.g. chemo- and radiotherapy, but also to non-conventional targeted therapies. Since TIS reinforces resistance in cancers, new strategies for sensitizing cancer cells to therapy are being adopted. These include macroautophagy as a potential target for inhibition due to its potential cytoprotective role in many cancers. The mechanism of late-stage autophagy inhibitors is based on blockage of autophagolysosome formation or an increase in lysosomal pH, resulting in disrupted cargo degradation. Such inhibitors are relevant candidates for increasing anticancer therapy effectiveness. In particular, 4-aminoquoline derivatives: chloroquine/hydroxychloroquine (CQ/HCQ) have been tested in multiple clinical trials in combination with senescence-inducing anti-cancer drugs. In this review, we summarize the properties of selected late-autophagy inhibitors and their role in the regulation of autophagy and senescent cell phenotype in vitro and in vivo models of cancer as well as treatment response in clinical trials on oncological patients. Additionally, we point out that, although these compounds increase the effectiveness of treatment in some cases, their practical usage might be hindered due to systemic toxicity, hypoxic environment, dose- ant time-dependent inhibitory effects, as well as a possible contribution to escaping from TIS.
    Keywords:  Anti-cancer therapy; Autophagy; Cancer; Hypoxia; Senescence; Side effects
    DOI:  https://doi.org/10.1016/j.bcp.2024.116277
  50. Elife. 2024 May 13. pii: RP92236. [Epub ahead of print]12
    mTORC1/S6K1 signaling promotes sustained oncogenic translation through modulating CRL3IBTK-mediated ubiquitination of eIF4A1 in cancer cells.
    Dongyue Jiao, Huiru Sun, Xiaying Zhao, Yingji Chen, Zeheng Lv, Qing Shi, Yao Li, Chenji Wang, Kun Gao.
      Enhanced protein synthesis is a crucial molecular mechanism that allows cancer cells to survive, proliferate, metastasize, and develop resistance to anti-cancer treatments, and often arises as a consequence of increased signaling flux channeled to mRNA-bearing eukaryotic initiation factor 4F (eIF4F). However, the post-translational regulation of eIF4A1, an ATP-dependent RNA helicase and subunit of the eIF4F complex, is still poorly understood. Here, we demonstrate that IBTK, a substrate-binding adaptor of the Cullin 3-RING ubiquitin ligase (CRL3) complex, interacts with eIF4A1. The non-degradative ubiquitination of eIF4A1 catalyzed by the CRL3IBTK complex promotes cap-dependent translational initiation, nascent protein synthesis, oncogene expression, and cervical tumor cell growth both in vivo and in vitro. Moreover, we show that mTORC1 and S6K1, two key regulators of protein synthesis, directly phosphorylate IBTK to augment eIF4A1 ubiquitination and sustained oncogenic translation. This link between the CRL3IBTK complex and the mTORC1/S6K1 signaling pathway, which is frequently dysregulated in cancer, represents a promising target for anti-cancer therapies.
    Keywords:  cancer biology; cell biology; human; mTORC1/S6K1 signaling; phosphorylation; translation; tumorigenesis; ubiquitination
    DOI:  https://doi.org/10.7554/eLife.92236
  51. Br J Pharmacol. 2024 May 13.
    The ion channel TRPM8 is a direct target of the immunosuppressant rapamycin in primary sensory neurons.
    José Miguel Arcas, Khalid Oudaha, Alejandro González, Jorge Fernández-Trillo, Francisco Andrés Peralta, Júlia Castro-Marsal, Seyma Poyraz, Francisco Taberner, Salvador Sala, Elvira de la Peña, Ana Gomis, Félix Viana.
       BACKGROUND AND PURPOSE: The mechanistic target of rapamycin (mTOR) signalling pathway is a key regulator of cell growth and metabolism. Its deregulation is implicated in several diseases. The macrolide rapamycin, a specific inhibitor of mTOR, has immunosuppressive, anti-inflammatory and antiproliferative properties. Recently, we identified tacrolimus, another macrolide immunosuppressant, as a novel activator of TRPM8 ion channels, involved in cold temperature sensing, thermoregulation, tearing and cold pain. We hypothesized that rapamycin may also have agonist activity on TRPM8 channels.
    EXPERIMENTAL APPROACH: Using calcium imaging and electrophysiology in transfected HEK293 cells and wildtype or Trpm8 KO mouse DRG neurons, we characterized rapamycin's effects on TRPM8 channels. We also examined the effects of rapamycin on tearing in mice.
    KEY RESULTS: Micromolar concentrations of rapamycin activated rat and mouse TRPM8 channels directly and potentiated cold-evoked responses, effects also observed in human TRPM8 channels. In cultured mouse DRG neurons, rapamycin increased intracellular calcium levels almost exclusively in cold-sensitive neurons. Responses were markedly decreased in Trpm8 KO mice or by TRPM8 channel antagonists. Cutaneous cold thermoreceptor endings were also activated by rapamycin. Topical application of rapamycin to the eye surface evokes tearing in mice by a TRPM8-dependent mechanism.
    CONCLUSION AND IMPLICATIONS: These results identify TRPM8 cationic channels in sensory neurons as novel molecular targets of the immunosuppressant rapamycin. These findings may help explain some of its therapeutic effects after topical application to the skin and the eye surface. Moreover, rapamycin could be used as an experimental tool in the clinic to explore cold thermoreceptors.
    Keywords:  ageing; cold; dry eye disease; mTOR; pain; thermoregulation
    DOI:  https://doi.org/10.1111/bph.16402
  52. Free Radic Biol Med. 2024 May 11. pii: S0891-5849(24)00452-0. [Epub ahead of print]
    L-serine restored lysosomal failure in cells derived from patients with BPAN reducing iron accumulation with eliminating lipofuscin.
    Hye Eun Lee, Minkyo Jung, Kiju Choi, Jae Hyuck Jang, Su-Kyeong Hwang, Sehyun Chae, Jae-Hyeok Lee, Ji Young Mun.
      Defective mitochondria and autophagy, as well as accumulation of lipid and iron in WDR45 mutant fibroblasts, is related to beta-propeller protein-associated neurodegeneration (BPAN). In this study, we found that enlarged lysosomes in cells derived from patients with BPAN had low enzyme activity, and most of the enlarged lysosomes had an accumulation of iron and oxidized lipid. Cryo-electron tomography revealed elongated lipid accumulation, and spectrometry-based elemental analysis showed that lysosomal iron and oxygen accumulation superimposed with lipid aggregates. Lysosomal lipid aggregates superimposed with autofluorescence as free radical generator, lipofuscin. To eliminate free radical stress by iron accumulation in cells derived from patients with BPAN, we investigated the effects of the iron chelator, 2,2'-bipyridine (bipyridyl, BIP). To study whether the defects in patient-derived cells can be rescued by an iron chelator BIP, we tested whether the level of iron and reactive oxygen species (ROS) in the cells and genes related to oxidative stress were rescued BIP treatment. Although BIP treatment decreased some iron accumulation in the cytoplasm and mitochondria, the accumulation of iron in the lysosomes and levels of cellular ROS were unaffected. In addition, the change of specific RNA levels related to free radical stress in patient fibroblasts was not rescued by BIP. To alleviate free radical stress, we investigated whether L-serine can regulate abnormal structures in cells derived from patients with BPAN through the regulation of free radical stress. L-serine treatment alleviated increase of enlarged lysosomes and iron accumulation and rescued impaired lysosomal activity by reducing oxidized lipid accumulation in the lysosomes of the cells. Lamellated lipids in the lysosomes of the cells were identified as lipofuscin through correlative light and electron microscopy, and L-serine treatment reduced the increase of lipofuscin. These data suggest that L-serine reduces oxidative stress-mediated lysosomal lipid oxidation and iron accumulation by rescuing lysosomal activity.
    Keywords:  BPAN; iron; lipid; lysosome; oxidative stress
    DOI:  https://doi.org/10.1016/j.freeradbiomed.2024.05.017
  53. Sci Rep. 2024 05 16. 14(1): 11220
    Autophagy favors survival of corpora lutea during the long-lasting pregnancy of the South American plains vizcacha, Lagostomus maximus (Rodentia, Caviomorpha).
    Daira A Caram, Pablo I F Inserra, Alfredo D Vitullo, Noelia P Leopardo.
      The corpus luteum (CL) is a transient endocrine gland that plays a crucial role in establishing and maintaining pregnancy. Although autophagy and apoptosis have been suggested as cooperative mechanisms, their interaction within the CL of pregnant mammals has not been thoroughly investigated. To understand the collaborative function of autophagy and apoptosis in the CL, we analyzed both mechanisms during pregnancy in the South American plains vizcacha, Lagostomus maximus. This rodent undergoes a decline in progesterone levels during mid-gestation, a reactivation of the hypothalamus-hypophysis-gonadal axis, and the incorporation of new functional secondary CL. Our analysis of autophagy markers BECLIN 1 (BECN1), SEQUESTOSOME1 (SQSTM1), Microtubule-associated protein light chain 3 (LC3B), and lysosomal-associated membrane protein 1 (LAMP1) and anti- and pro-apoptotic markers BCL2 and ACTIVE CASPASE 3 (A-C3) revealed interactive behaviors between both processes. Healthy primary and secondary CL exhibited positive expression of BECN1, SQSTM1, LC3B, and LAMP1, while regressed CL displayed enhanced expression of these autophagy markers along with nuclear A-C3. Transmission electron microscopy revealed a significant formation of autophagic vesicles in regressed CL during full-term pregnancy, whereas healthy CL exhibited a low number of autophagy vesicles. The co-localization between LC3B and SQSTM1 and LC3B with LAMP1 was observed in both healthy and regressed CL during pregnancy, while co-localization of BECN1 and BCL2 was only detected in healthy CL. LC3B and ACTIVE CASPASE 3 co-localization were detected in a subset of luteal cells within the regressing CL. We propose that autophagy could act as a survival mechanism in the CL, allowing the pregnancy to progress until full-term, while also serving as a mechanism to eliminate remnants of regressed CL, thereby providing the necessary space for subsequent follicular maturation.
    DOI:  https://doi.org/10.1038/s41598-024-61478-5
  54. Toxicol Lett. 2024 May 09. pii: S0378-4274(24)00089-4. [Epub ahead of print]397 67-78
    Down-regulation of O-GlcNAcylation alleviates insulin signaling pathway impairment following arsenic exposure via suppressing the AMPK/mTOR-autophagy pathway.
    Wenxin Zhang, Shuxian Zeng, Jieliang Huang, Xianbing Tian, Jiegen Wu, Lianxian Guo, Yi Liang.
      Impairment of the insulin signaling pathway is a key contributor to insulin resistance under arsenic exposure. Specifically, O-GlcNAcylation, an important post-translational modification, plays a crucial role in insulin resistance. Nevertheless, the concrete effect and mechanism of O-GlcNAcylation in arsenic-induced impairment of the insulin signaling pathway remain elusive. Herein, C57BL/6 mice were continuously fed arsenic-containing food, with a total arsenic concentration of 30 mg/kg. We observed that the IRS/Akt/GSK-3β insulin signaling pathway was impaired, and autophagy was activated in mouse livers and HepG2 cells exposed to arsenic. Additionally, O-GlcNAcylation expression in mouse livers and HepG2 cells was elevated, and the key O-GlcNAcylation homeostasis enzyme, O-GlcNAc transferase (OGT), was upregulated. In vitro, non-targeted metabolomic analysis showed that metabolic disorder was induced, and inhibition of O-GlcNAcylation restored the metabolic profile of HepG2 cells exposed to arsenic. In addition, we found that the compromised insulin signaling pathway was dependent on AMPK activation. Inhibition of AMPK mitigated autophagy activation and impairment of insulin signaling pathway under arsenic exposure. Furthermore, down-regulation of O-GlcNAcylation inhibited AMPK activation, thereby suppressing autophagy activation, and improving the impaired insulin signaling pathway. Collectively, our findings indicate that arsenic can impair the insulin signaling pathway by regulating O-GlcNAcylation homeostasis. Importantly, O-GlcNAcylation inhibition alleviated the impaired insulin signaling pathway by suppressing the AMPK/mTOR-autophagy pathway. This indicates that regulating O-GlcNAcylation may be a potential intervention for the impaired insulin signaling pathway induced by arsenic.
    Keywords:  AMPK; Arsenic; Insulin signaling pathway; O-GlcNAcylation
    DOI:  https://doi.org/10.1016/j.toxlet.2024.05.003
  55. Cell Mol Biol Lett. 2024 May 14. 29(1): 71
    FGFR2-triggered autophagy and activation of Nrf-2 reduce breast cancer cell response to anti-ER drugs.
    Monika Gorska-Arcisz, Marta Popeda, Marcin Braun, Dominika Piasecka, Joanna I Nowak, Kamila Kitowska, Grzegorz Stasilojc, Marcin Okroj, Hanna M Romanska, Rafal Sadej.
       BACKGROUND: Genetic abnormalities in the FGFR signalling occur in 40% of breast cancer (BCa) patients resistant to anti-ER therapy, which emphasizes the potential of FGFR-targeting strategies. Recent findings indicate that not only mutated FGFR is a driver of tumour progression but co-mutational landscapes and other markers should be also investigated. Autophagy has been recognized as one of the major mechanisms underlying the role of tumour microenvironment in promotion of cancer cell survival, and resistance to anti-ER drugs. The selective autophagy receptor p62/SQSTM1 promotes Nrf-2 activation by Keap1/Nrf-2 complex dissociation. Herein, we have analysed whether the negative effect of FGFR2 on BCa cell response to anti-ER treatment involves the autophagy process and/or p62/Keap1/Nrf-2 axis.
    METHODS: The activity of autophagy in ER-positive MCF7 and T47D BCa cell lines was determined by analysis of expression level of autophagy markers (p62 and LC3B) and monitoring of autophagosomes' maturation. Western blot, qPCR and proximity ligation assay were used to determine the Keap1/Nrf-2 interaction and Nrf-2 activation. Analysis of 3D cell growth in Matrigel® was used to assess BCa cell response to applied treatments. In silico gene expression analysis was performed to determine FGFR2/Nrf-2 prognostic value.
    RESULTS: We have found that FGFR2 signalling induced autophagy in AMPKα/ULK1-dependent manner. FGFR2 activity promoted dissociation of Keap1/Nrf-2 complex and activation of Nrf-2. Both, FGFR2-dependent autophagy and activation of Nrf-2 were found to counteract the effect of anti-ER drugs on BCa cell growth. Moreover, in silico analysis showed that high expression of NFE2L2 (gene encoding Nrf-2) combined with high FGFR2 expression was associated with poor relapse-free survival (RFS) of ER+ BCa patients.
    CONCLUSIONS: This study revealed the unknown role of FGFR2 signalling in activation of autophagy and regulation of the p62/Keap1/Nrf-2 interdependence, which has a negative impact on the response of ER+ BCa cells to anti-ER therapies. The data from in silico analyses suggest that expression of Nrf-2 could act as a marker indicating potential benefits of implementation of anti-FGFR therapy in patients with ER+ BCa, in particular, when used in combination with anti-ER drugs.
    Keywords:  Autophagy; FGFR2; Keap1; Luminal breast cancer; Nrf-2; p62
    DOI:  https://doi.org/10.1186/s11658-024-00586-6
  56. Neurobiol Dis. 2024 May 15. pii: S0969-9961(24)00133-5. [Epub ahead of print] 106534
    FUDNC1-dependent mitophagy ameliorate motor neuron death in an amyotrophic lateral sclerosis mouse model.
    Xia Guo, Zhuo Zhang, Juan Gu, PingYang Ke, Jing Liu, Yuan Meng, Wei Zheng, WenJun Que, Rui Fan, Jing Luo, Fei Xiao.
      Amyotrophic lateral sclerosis (ALS) is one of the most common neurodegenerative diseases, yet effective treatment is lacking. Moreover, the underlying pathomechanisms of ALS remain unclear, with impaired mitophagy function being increasingly recognized as a contributing factor. FUN14 domain-containing protein 1 (FUNDC1) is an autophagy receptor localized to the outer mitochondrial membrane and a mitochondrial membrane protein that mediates mitophagy and therefore considered as important factor in neurodegenerative diseases. However, its specific role in ALS is not yet clear. Therefore, this study aimed to investigate the regulatory role of FUNDC1 in ALS and determine its regulatory mechanisms. ALS transgenic mice were obtained and maintained under standard conditions. Cell lines were generated by stable transfection with hSOD1G93A or control vectors. Mice received intrathecal injections of AAV9 vectors expressing FUNDC1 or EGFP. Motor function was assessed through behavioral tests, and histological and immunostaining analyses were performed. Colocalization analysis was conducted in transfected cells, and protein expression was evaluated via western blotting. For the first time, we observed that FUNDC1 was significantly downregulated in the spinal cord tissues of SOD1G93A mice. FUNDC1 overexpression considerably improved locomotor activity and prolonged survival time in SOD1G93A mice. Mechanistically, reduced expression of FUNDC1 resulted in decreased mitophagy, as indicated by decreased recruitment through LC3 in SOD1G93A mice and cellular models. Consequently, this led to increased mitochondrial accumulation and cell apoptosis, exacerbating the ALS phenotype. Furthermore, we identified transcription factor FOXD3 as an essential upstream factor of FUNDC1, resulting in reduced transcription of FUNDC1 in ALS lesions. This study suggests a novel strategy of targeting FUNDC1-mediated mitophagy for developing therapeutic interventions to mitigate disease progression and improve outcomes for ALS patients.
    Keywords:  Amyotrophic lateral sclerosis; Apoptosis; FUNDC1; Mitochondrial; Mitophagy; Neurons
    DOI:  https://doi.org/10.1016/j.nbd.2024.106534
  57. Sci Rep. 2024 05 14. 14(1): 10972
    p62/sequestosome-1 as a severity-reflecting plasma biomarker in Charcot-Marie-Tooth disease type 1A.
    Byeol-A Yoon, Young Hee Kim, Soo Hyun Nam, Hye-Jin Lee, Seong-Il Oh, Namhee Kim, Kyeong-Hee Kim, Young Rae Jo, Jong Kuk Kim, Byung-Ok Choi, Hwan Tae Park.
      Autophagy is a self-degradation system for recycling to maintain homeostasis. p62/sequestosome-1 (p62) is an autophagy receptor that accumulates in neuroglia in neurodegenerative diseases. The objective of this study was to determine the elevation of plasma p62 protein levels in patients with Charcot-Marie-Tooth disease 1A (CMT1A) for its clinical usefulness to assess disease severity. We collected blood samples from 69 CMT1A patients and 59 healthy controls. Plasma concentrations of p62 were analyzed by ELISA, and we compared them with Charcot-Marie-Tooth neuropathy score version 2 (CMTNSv2). A mouse CMT1A model (C22) was employed to determine the source and mechanism of plasma p62 elevation. Plasma p62 was detected in healthy controls with median value of 1978 pg/ml, and the levels were significantly higher in CMT1A (2465 pg/ml, p < 0.001). The elevated plasma p62 levels were correlated with CMTNSv2 (r = 0.621, p < 0.0001), motor nerve conduction velocity (r =  - 0.490, p < 0.0001) and disease duration (r = 0.364, p < 0.01). In C22 model, increased p62 expression was observed not only in pathologic Schwann cells but also in plasma. Our findings indicate that plasma p62 measurement could be a valuable tool for evaluating CMT1A severity and Schwann cell pathology.
    DOI:  https://doi.org/10.1038/s41598-024-61794-w
  58. J Med Virol. 2024 May;96(5): e29659
    Autophagy-related protein 5 (ATG5) interacts with bone marrow stromal cell antigen 2 (BST2) to stimulate HBV replication through antagonizing the antiviral activity of BST2.
    Qingyuan Li, Wenxian Wen, Yijin Wang, Tao Gong, Xinwei Wang, Qi Tan, Bin Fan, He Xie, Yujia Li, Shilin Li, Chunhui Yang, Zhonghui Zhou, Xiaoqiong Duan, Wenyu Lin, Limin Chen.
      Hepatitis B virus (HBV) infection is a major global health burden with 820 000 deaths per year. In our previous study, we found that the knockdown of autophagy-related protein 5 (ATG5) significantly upregulated the interferon-stimulated genes (ISGs) expression to exert the anti-HCV effect. However, the regulation of ATG5 on HBV replication and its underlying mechanism remains unclear. In this study, we screened the altered expression of type I interferon (IFN-I) pathway genes using RT² Profiler™ PCR array following ATG5 knock-down and we found the bone marrow stromal cell antigen 2 (BST2) expression was significantly increased. We then verified the upregulation of BST2 by ATG5 knockdown using RT-qPCR and found that the knockdown of ATG5 activated the Janus kinase/signal transducer and activator of transcription (JAK-STAT) signaling pathway. ATG5 knockdown or BST2 overexpression decreased Hepatitis B core Antigen (HBcAg) protein, HBV DNA levels in cells and supernatants of HepAD38 and HBV-infected NTCP-HepG2. Knockdown of BST2 abrogated the anti-HBV effect of ATG5 knockdown. Furthermore, we found that ATG5 interacted with BST2, and further formed a ternary complex together with HBV-X (HBx). In conclusion, our finding indicates that ATG5 promotes HBV replication through decreasing BST2 expression and interacting with it directly to antagonize its antiviral function.
    Keywords:  autophagy; autophagy‐related protein 5 (ATG5); bone marrow stromal cell antigen 2 (BST2); hepatitis B virus (HBV); interact; interferon (IFN) signaling pathway
    DOI:  https://doi.org/10.1002/jmv.29659
  59. J Pineal Res. 2024 May;76(4): e12959
    Melatonin ameliorates 10-hydroxycamptothecin-induced oxidative stress and apoptosis via autophagy-regulated p62/Keap1/Nrf2 pathway in mouse testicular cells.
    Jinmei Cheng, Junjie Xu, Yimin Gu, Yueming Wang, Jianyu Wang, Fei Sun.
      10-Hydroxycamptothecin (HCPT) is a widely used clinical anticancer drug but has a significant side effect profile. Melatonin has a beneficial impact on the chemotherapy of different cancer cells and reproductive processes, but the effect and underlying molecular mechanism of melatonin's involvement in the HCPT-induced side effects in cells, especially in the testicular cells, are poorly understood. In this study, we found that melatonin therapy significantly restored HCPT-induced testicular cell damage and did not affect the antitumor effect of HCPT. Further analysis found that melatonin therapy suppressed HCPT-induced DNA damage associated with ataxia-telangiectasia mutated- and Rad3-related and CHK1 phosphorylation levels in the testis. Changes in apoptosis-associated protein levels (Bax, Bcl-2, p53, and Cleaved caspase-3) and in reactive oxygen species-associated proteins (Nrf2 and Keap1) and index (malondialdehyde and glutathione) suggested that melatonin treatment relieved HCPT-induced cell apoptosis and oxidative damage, respectively. Mechanistically, melatonin-activated autophagy proteins (ATG7, Beclin1, and LC3bII/I) may induce p62-dependent autophagy to degrade Keap1, eliciting Nrf2 from Keap1-Nrf2 interaction to promote antioxidant enzyme expression such as HO-1, which would salvage HCPT-induced ROS production and mitochondrial dysfunction. Collectively, this study reveals that melatonin therapy may protect testicular cells from HCPT-induced damage via the activation of autophagy, which alleviates oxidative stress, mitochondrial dysfunction, and cell apoptosis.
    Keywords:  HCPT; apoptosis; autophagy; melatonin; oxidative damage
    DOI:  https://doi.org/10.1111/jpi.12959
  60. Mol Med. 2024 May 17. 30(1): 63
    AMPK activation eliminates senescent cells in diabetic wound by inducing NCOA4 mediated ferritinophagy.
    Mengqian Liu, Xuerong Wei, Zijun Zheng, Erlian Xie, Qiuyi Yu, Yanbin Gao, Jun Ma, Lei Yang.
       BACKGROUND: Diabetic wounds are one of the long-term complications of diabetes, with a disordered microenvironment, diabetic wounds can easily develop into chronic non-healing wounds, which can impose a significant burden on healthcare. In diabetic condition, senescent cells accumulate in the wound area and suppress the wound healing process. AMPK, as a molecule related to metabolism, has a close relationship with aging and diabetes. The purpose of this study was to investigate the effects of AMPK activation on wound healing and explore the underlying mechanisms.
    METHODS: AMPK activator A769662 was topically applied in wound models of diabetic mice. Alterations in the wound site were observed and analyzed by immunohistochemistry. The markers related to autophagy and ferritinophagy were analyzed by western blotting and immunofluorescence staining. The role of AMPK activation and ferritinophagy were also analyzed by western blotting.
    RESULTS: Our results show that AMPK activation improved diabetic wound healing and reduced the accumulation of senescent cells. Intriguingly, we found that AMPK activation-induced ferroptosis is autophagy-dependent. We detected that the level of ferritin had deceased and NCOA4 was markedly increased after AMPK activation treatment. We further investigated that NCOA4-mediated ferritinophagy was involved in ferroptosis triggered by AMPK activation. Most importantly, AMPK activation can reverse the ferroptosis-insensitive of senescent fibroblast cells in diabetic mice wound area and promote wound healing.
    CONCLUSIONS: These results suggest that activating AMPK can promote diabetic wound healing by reversing the ferroptosis-insensitive of senescent fibroblast cells. AMPK may serve as a regulatory factor in senescent cells in the diabetic wound area, therefore AMPK activation can become a promising therapeutic method for diabetic non-healing wounds.
    Keywords:  AMPK; Autophagy; Cellular senescence; Diabetic wound; Ferroptosis
    DOI:  https://doi.org/10.1186/s10020-024-00825-8
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