bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2023–11–12
fifty papers selected by
Viktor Korolchuk, Newcastle University
  1. Growth or death? Control of cell destiny by mTOR and autophagy pathways.
  2. Autophagy captures the retromer-TBC1D5 complex to inhibit receptor recycling.
  3. A conserved requirement for RME-8/DNAJC13 in neuronal autophagic lysosome reformation.
  4. Synthetic autophagy receptor.
  5. CSNK2 suppresses autophagy by activating FLN-NHL-containing TRIM proteins.
  6. Targeted clearance of mitochondria by an autophagy-tethering compound (ATTEC) and its potential therapeutic effects.
  7. FUNDC1 collaborates with PINK1 in regulating mitochondrial Fission and compensating for PINK1 deficiency.
  8. V-ATPase recruitment to ER exit sites switches COPII-mediated transport to lysosomal degradation.
  9. Autophagy-mediated control of ribosome homeostasis in oncogene-induced senescence.
  10. Autophagy-mediated post-transcriptional surveillance of meiotic translation in Saccharomyces Cerevisiae.
  11. Metformin attenuates mechanistic target of rapamycin complex 1/hypoxia-inducible factor-1α-driven glycolysis reducing keratinocyte and T helper 17 cell proliferation in hyperproliferative inflammatory skin diseases.
  12. Duck Tembusu virus induces incomplete autophagy via the ERK/mTOR and AMPK/mTOR signalling pathways to promote viral replication in neuronal cells.
  13. CBAP regulates the function of Akt-associated TSC protein complexes to modulate mTORC1 signaling.
  14. ATG9B is a tissue-specific homotrimeric lipid scramblase that can compensate for ATG9A.
  15. Resolvin D1 Induces mTOR-independent and ATG5-dependent Autophagy in BV-2 Microglial Cells.
  16. Spatiotemporal roles of AMPK in PARP-1- and autophagy-dependent retinal pigment epithelial cell death caused by UVA.
  17. SREBF1/SREBP-1 concurrently regulates lipid synthesis and lipophagy to maintain lipid homeostasis and tumor growth.
  18. Glucagon-like peptide-1 receptor activation stimulates PKA-mediated phosphorylation of raptor and this contributes to the weight loss effect of liraglutide.
  19. Upregulated Chaperone-Mediated Autophagy May Perform a Key Role in Reduced Cancer Incidence in Huntington's Disease.
  20. Seneca Valley virus 3C protease cleaves OPTN (optineurin) to Impair selective autophagy and type I interferon signaling.
  21. c-MYC-dependent transcriptional inhibition of autophagy is implicated in cisplatin sensitivity in HPV-positive head and neck cancer.
  22. Selective Inhibition of mTORC1 Signaling Supports the Development and Maintenance of Pluripotency.
  23. Modulating mitochondrial calcium channels (TRPM2/MCU/NCX) as a therapeutic strategy for neurodegenerative disorders.
  24. Rapamycin exerts an antidepressant effect and enhances myelination in the prefrontal cortex of chronic restraint stress mice.
  25. Mitophagy Activation by Urolithin A to Target Muscle Aging.
  26. The Small GTPase Rab7 Regulates Antigen Processing in B Cells in a Possible Interplay with Autophagy Machinery.
  27. Hyperoxia can Induce Lung Injury by Upregulating AECII Autophagy and Apoptosis Via the mTOR Pathway.
  28. NDP52 SUMOylation contributes to low-dose X-rays-induced cardiac hypertrophy through PINK1/Parkin-mediated mitophagy via MUL1/SUMO2 signalling.
  29. p62 bodies: cytosolic zoning by phase separation.
  30. Epithelial cell NOD1/IRGM recruits STX17 to Neisseria gonorrhoeae-containing endosomes to initiate lysosomal degradation.
  31. The ortholog of human REEP1-4 is required for autophagosomal enclosure of ER-phagy/nucleophagy cargos in fission yeast.
  32. Connecting reticulophagy and neuronal NTRK2/TrkB signaling.
  33. Pulmonary tuberculosis biomarker miR-215-5p inhibits autophagosome-lysosome fusion in macrophages.
  34. ATGL promotes colorectal cancer growth by regulating autophagy process and SIRT1 expression.
  35. Autophagy protects against vocal fold injury-induced fibrosis.
  36. Mitochondrial Inherited Disorders and their Correlation with Neurodegenerative Diseases.
  37. Head and neck cancer stem cell maintenance relies on mTOR signaling, specifically involving the mechanistic target of rapamycin complexes 1 and 2 (mTORC1 and mTORC2).
  38. Spliceosome component Usp39 contributes to hepatic lipid homeostasis through the regulation of autophagy.
  39. Mitohormesis.
  40. ARL6IP1 gene delivery reduces neuroinflammation and neurodegenerative pathology in hereditary spastic paraplegia model.
  41. Aggregation of alpha-synuclein disrupts mitochondrial metabolism and induce mitophagy via cardiolipin externalization.
  42. ATM-CHK2-TRIM32 axis regulates ATG7 ubiquitination to initiate autophagy under oxidative stress.
  43. SNHG15 promotes gallbladder cancer progression by enhancing the autophagy of tumor cell under nutrition stress.
  44. Maackiain suppresses the development of cervical cancer via AMPK priming autophagy.
  45. Crucial role of autophagy in propofol-treated neurological diseases: a comprehensive review.
  46. Treatment of tuberous sclerosis complex manifestations in children with mTOR inhibitors.
  47. Liensinine alleviates LPS-induced acute lung injury by blocking autophagic flux via PI3K/AKT/mTOR signaling pathway.
  48. Integrative analysis reveals a conserved role for the amyloid precursor protein in proteostasis during aging.
  49. Cryo-electron tomography of NLRP3-activated ASC complexes reveals organelle co-localization.
  50. Dominant negative variants in KIF5B cause osteogenesis imperfecta via down regulation of mTOR signaling.
  1. Prog Biophys Mol Biol. 2023 Nov 07. pii: S0079-6107(23)00092-5. [Epub ahead of print]
    Growth or death? Control of cell destiny by mTOR and autophagy pathways.
    Mahmoud I Khalil, Mohamad M Ali, Jasmine Holail, Marwa Houssein.
      One of the central regulators of cell growth, proliferation, and metabolism is the mammalian target of rapamycin, mTOR, which exists in two structurally and functionally different complexes: mTORC1 and mTORC2; unlike m TORC2, mTORC1 is activated in response to the sufficiency of nutrients and is inhibited by rapamycin. mTOR complexes have critical roles not only in protein synthesis, gene transcription regulation, proliferation, tumor metabolism, but also in the regulation of the programmed cell death mechanisms such as autophagy and apoptosis. Autophagy is a conserved catabolic mechanism in which damaged molecules are recycled in response to nutrient starvation. Emerging evidence indicates that the mTOR signaling pathway is frequently activated in tumors. In addition, dysregulation of autophagy was associated with the development of a variety of human diseases, such as cancer and aging. Since mTOR can inhibit the induction of the autophagic process from the early stages of autophagosome formation to the late stage of lysosome degradation, the use of mTOR inhibitors to regulate autophagy could be considered a potential therapeutic option. The present review sheds light on the mTOR and autophagy signaling pathways and the mechanisms of regulation of mTOR-autophagy.
    Keywords:  AMPK; Apoptosis; Autophagy; Cancer; PI3K; mTOR
    DOI:  https://doi.org/10.1016/j.pbiomolbio.2023.10.002
  2. Autophagy. 2023 Nov 08.
    Autophagy captures the retromer-TBC1D5 complex to inhibit receptor recycling.
    Julian M Carosi, Leanne K Hein, Jarrod J Sandow, Linh V P Dang, Kathryn Hattersley, Donna Denton, Sharad Kumar, Timothy J Sargeant.
      Retromer prevents the destruction of numerous receptors by recycling them from endosomes to the trans-Golgi network or plasma membrane. This enables retromer to fine-tune the activity of many signaling pathways in parallel. However, the mechanism(s) by which retromer function adapts to environmental fluctuations such as nutrient withdrawal and how this affects the fate of its cargoes remains incompletely understood. Here, we reveal that macroautophagy/autophagy inhibition by MTORC1 controls the abundance of retromer+ endosomes under nutrient-replete conditions. Autophagy activation by chemical inhibition of MTOR or nutrient withdrawal does not affect retromer assembly or its interaction with the RAB7 GAP protein TBC1D5, but rather targets these endosomes for bulk destruction following their capture by phagophores. This process appears to be distinct from amphisome formation. TBC1D5 and its ability to bind to retromer, but not its C-terminal LC3-interacting region (LIR) or nutrient-regulated dephosphorylation, is critical for retromer to be captured by autophagosomes following MTOR inhibition. Consequently, endosomal recycling of its cargoes to the plasma membrane and trans-Golgi network is impaired, leading to their lysosomal turnover. These findings demonstrate a mechanistic link connecting nutrient abundance to receptor homeostasis.
    Keywords:  Autophagy; MTOR; MTORC1; TBC1D5; VPS35; retromer
    DOI:  https://doi.org/10.1080/15548627.2023.2281126
  3. Autophagy. 2023 Nov 09. 1-17
    A conserved requirement for RME-8/DNAJC13 in neuronal autophagic lysosome reformation.
    Sierra B Swords, Nuo Jia, Anne Norris, Jil Modi, Qian Cai, Barth D Grant.
      Autophagosomes fuse with lysosomes, forming autolysosomes that degrade engulfed cargo. To maintain lysosomal capacity, autophagic lysosome reformation (ALR) must regenerate lysosomes from autolysosomes using a membrane tubule-based process. Maintaining lysosomal capacity is required to maintain cellular health, especially in neurons where lysosomal dysfunction has been repeatedly implicated in neurodegenerative disease. The DNA-J domain HSC70 co-chaperone RME-8/DNAJC13 has been linked to endosomal coat protein regulation and to neurological disease. We report new analysis of the requirements for the RME-8/DNAJC13 protein in neurons, focusing on intact C. elegans mechanosensory neurons, and primary mouse cortical neurons in culture. Loss of RME-8/DNAJC13 in both systems results in accumulation of grossly elongated autolysosomal tubules. Further C. elegans analysis revealed a similar autolysosome tubule accumulation defect in mutants known to be required for ALR in mammals, including mutants lacking bec-1/BECN1/Beclin1 and vps-15/PIK3R4/p150 that regulate the class III phosphatidylinositol 3-kinase (PtdIns3K) VPS-34, and dyn-1/dynamin that severs ALR tubules. Clathrin is also an important ALR regulator implicated in autolysosome tubule formation and release. In C. elegans we found that loss of RME-8 causes severe depletion of clathrin from neuronal autolysosomes, a phenotype shared with bec-1 and vps-15 mutants. We conclude that RME-8/DNAJC13 plays a previously unrecognized role in ALR, likely affecting autolysosome tubule severing. Additionally, in both systems, loss of RME-8/DNAJC13 reduced macroautophagic/autophagic flux, suggesting feedback regulation from ALR to autophagy. Our results connecting RME-8/DNAJC13 to ALR and autophagy provide a potential mechanism by which RME-8/DNAJC13 could influence neuronal health and the progression of neurodegenerative disease.Abbreviation: ALR, autophagic lysosome reformation; ATG-13/EPG-1, AuTophaGy (yeast Atg homolog)-13; ATG-18, AuTophaGy (yeast Atg homolog)-18; AV, autophagic vacuole; CLIC-1, Clathrin Light Chain-1; EPG-3, Ectopic P Granules-3; EPG-6, Ectopic P Granules-6; LGG-1, LC3, GABARAP and GATE-16 family-1; MAP1LC3/LC3, microtubule-associated protein 1 light chain 3; PD, Parkinson disease; PtdIns3P, phosphatidylinositol-3-phosphate; PtdIns(4,5)P2, phosphatidylinositol-4,5-bisphosphate; RME-8, Receptor Mediated Endocytosis-8; SNX-1, Sorting NeXin-1; VPS-34, related to yeast Vacuolar Protein Sorting factor-34.
    Keywords:  Autophagy; clathrin; endocytosis; lysosomes; neurodegeneration; trafficking
    DOI:  https://doi.org/10.1080/15548627.2023.2269028
  4. Autophagy. 2023 Nov 07.
    Synthetic autophagy receptor.
    Ziwen Jiang, Yu-Hsuan Kuo, Michelle R Arkin.
      Macroautophagy/autophagy receptors target their substrates to phagophores for subsequent sequestration within autophagosomes. During phagophore membrane expansion in mammalian cells, autophagy receptors simultaneously interact with the ubiquitinated substrates and the LC3/GABARAP proteins on the expanding membrane. In this punctum, we summarize and discuss our recent research progress on synthetic autophagy receptors (AceTACs). The series of AceTACs were designed by engineering the essential interacting domains and motifs of SQSTM1/p62 (sequestosome 1), a major mammalian autophagy receptor. Particularly, we replaced the ubiquitin-associated domain of SQSTM1 with a target-specific antibody, redirecting the bifunctional interactions of wild-type SQSTM1 and directing the degradation target into the autophagy process. We successfully demonstrated the targeted degradation of aggregation-prone proteins using the AceTAC degraders. Moreover, we presented a model system with a guideline to induce targeted degradation of organelles through the autophagy machinery.
    Keywords:  Antibody-fusion protein; autophagy receptor; targeted organelle degradation; targeted protein degradation
    DOI:  https://doi.org/10.1080/15548627.2023.2278954
  5. Autophagy. 2023 Nov 08.
    CSNK2 suppresses autophagy by activating FLN-NHL-containing TRIM proteins.
    Helene Hoenigsperger, Lennart Koepke, Dhiraj Acharya, Victoria Hunszinger, Dennis Freisem, Alexander Grenzner, Sebastian Wiese, Frank Kirchhoff, Michaela U Gack, Konstantin M J Sparrer.
      Macroautophagy/autophagy is a tightly regulated cellular process integral to homeostasis and innate immunity. As such, dysregulation of autophagy is associated with cancer, neurodegenerative disorders, and infectious diseases. While numerous factors that promote autophagy have been characterized, the key mechanisms that prevent excessive autophagy are less well understood. Here, we identify CSNK2/CK2 (casein kinase 2) as a negative regulator of autophagy. Pharmacological inhibition of CSNK2 activity or siRNA-mediated depletion of CSNK2 increased basal autophagic flux in cell lines and primary human lung cells. Vice versa, ectopic expression of CSNK2 reduced autophagic flux. Mechanistically, CSNK2 interacted with the FLN (filamin)-NHL domain-containing tripartite motif (TRIM) family members TRIM2, TRIM3 and TRIM71. Our data show that recruitment of CSNK2 to the C-terminal NHL domain of TRIM3 lead to its robust phosphorylation at serine 661 by CSNK2. A phosphorylation-defective mutant of TRIM3 was unable to reduce autophagosome numbers indicating that phosphorylation by CSNK2 is required for TRIM-mediated autophagy inhibition. All three TRIMs facilitated inactivation of the ULK1-BECN1 autophagy initiation complex by facilitating ULK1 serine 757 phosphorylation. Inhibition of CSNK2 promoted autophagy upon influenza A virus (IAV) and measles virus (MeV) infection. In line with this, targeting of CSNK2 or depletion of TRIM2, TRIM3 or TRIM71 enhanced autophagy-dependent restriction of IAV, MeV and human immunodeficiency virus 1 (HIV-1). Thus, our results identify the CSNK2-TRIM2, -TRIM3, -TRIM71 axis as a key regulatory pathway that limits autophagy. Targeting this axis may allow for therapeutic induction of autophagy against viral infections and in diseases associated with dysregulated autophagy.
    Keywords:  Autophagy; casein kinase; tripartite motif proteins; virus
    DOI:  https://doi.org/10.1080/15548627.2023.2281128
  6. Sci Bull (Beijing). 2023 Oct 26. pii: S2095-9273(23)00721-1. [Epub ahead of print]
    Targeted clearance of mitochondria by an autophagy-tethering compound (ATTEC) and its potential therapeutic effects.
    Shuixia Tan, Da Wang, Yuhua Fu, Huiwen Zheng, Yan Liu, Boxun Lu.
      Increased mitochondrial damage plays a critical role in many neurodegeneration-related diseases such as Parkinson's disease (PD) and Down syndrome (DS). Thus, enhancement of mitochondrial degradation by small molecule compounds may provide promising new strategies to tackle these diseases. Here, we explored the strategy to induce clearance of mitochondria by targeting them to the autophagy machinery by autophagy-tethering compounds (ATTECs). We provided the proof-of-concept evidence demonstrating that the bifunctional compound (mT1) binding to both the outer mitochondrial membrane protein TSPO and the autophagosome protein LC3B simultaneously may enhance the engulfment of damaged mitochondria by autophagosomes and subsequent autophagic degradation of them. In addition, preliminary experiments suggest that mT1 attenuated disease-relevant phenotypes in both a PD cellular model and a DS organoid model. Taken together, we demonstrate the possibility of degrading mitochondria by bifunctional ATTECs, which confirms the capability of degrading organelles by ATTECs and provides potential new strategies in the intervention of mitochondria-related disorders.
    Keywords:  Autophagy-tethering compounds; Chimera compound; Lysosome; Neurodegenerative diseases; TSPO; Targeted mitochondrial degradation
    DOI:  https://doi.org/10.1016/j.scib.2023.10.021
  7. Biochem Biophys Res Commun. 2023 Nov 01. pii: S0006-291X(23)01304-9. [Epub ahead of print]687 149210
    FUNDC1 collaborates with PINK1 in regulating mitochondrial Fission and compensating for PINK1 deficiency.
    Jing Xu, Zhouyang Deng, Shuai Shang, Caifang Wang, Hailong Han.
      Parkinson's disease is presently thought to have its molecular roots in the alteration of PINK1-mediated mitophagy and mitochondrial dynamics. Finding new suppressors of the pathway is essential for developing cutting-edge treatment approaches. Our study shows that FUNDC1 suppressed PINK1 mutant phenotypes in Drosophila. The restoration of PINK1-deficient phenotypes through FUNDC1 is not reliant on its LC3-binding motif Y (18)L (21) or autophagy-related pathway. Moreover, the absence of Drp1 affects the phenotypic restoration of PINK1 mediated by FUNDC1 in flies. In summary, our findings have unveiled a fresh mechanism through which FUNDC1 compensates for the loss of PINK1, operating independently of autophagy but exerting its influence via interaction with Drp1.
    Keywords:  Autophagy receptor; Drp1; Mitochondrial dynamics; PD; Ubiquitin-independent mitophagy
    DOI:  https://doi.org/10.1016/j.bbrc.2023.149210
  8. Dev Cell. 2023 Oct 29. pii: S1534-5807(23)00526-9. [Epub ahead of print]
    V-ATPase recruitment to ER exit sites switches COPII-mediated transport to lysosomal degradation.
    Yiwei Sun, Xi'e Wang, Xiaotong Yang, Lei Wang, Jingjin Ding, Chih-Chen Wang, Hong Zhang, Xi Wang.
      Endoplasmic reticulum (ER)-phagy is crucial to regulate the function and homeostasis of the ER via lysosomal degradation, but how it is initiated is unclear. Here we discover that Z-AAT, a disease-causing mutant of α1-antitrypsin, induces noncanonical ER-phagy at ER exit sites (ERESs). Accumulation of misfolded Z-AAT at the ERESs impairs coat protein complex II (COPII)-mediated ER-to-Golgi transport and retains V0 subunits that further assemble V-ATPase at the arrested ERESs. V-ATPase subsequently recruits ATG16L1 onto ERESs to mediate in situ lipidation of LC3C. FAM134B-II is then recruited by LC3C via its LIR motif and elicits ER-phagy leading to efficient lysosomal degradation of Z-AAT. Activation of this ER-phagy mediated by the V-ATPase-ATG16L1-LC3C axis (EVAC) is also triggered by blocking ER export. Our findings identify a pathway which switches COPII-mediated transport to lysosomal degradation for ER quality control.
    Keywords:  ATG16L1; COPII; ER exit sites; ER-phagy; LC3C; Sec24C; V-ATPase; autophagy; protein quality control; α1 antitrypsin
    DOI:  https://doi.org/10.1016/j.devcel.2023.10.007
  9. Cell Rep. 2023 Nov 05. pii: S2211-1247(23)01393-1. [Epub ahead of print]42(11): 113381
    Autophagy-mediated control of ribosome homeostasis in oncogene-induced senescence.
    Aida Rodríguez López, Maria H Jørgensen, Jesper F Havelund, Frederic S Arendrup, Srinivasa Prasad Kolapalli, Thorbjørn M Nielsen, Eva Pais, Carsten Jörn Beese, Ahmad Abdul-Al, Anna Constance Vind, Jiri Bartek, Simon Bekker-Jensen, Marta Montes, Panagiotis Galanos, Nils Faergeman, Lotta Happonen, Lisa B Frankel.
      Oncogene-induced senescence (OIS) is a persistent anti-proliferative response that acts as a barrier against malignant transformation. During OIS, cells undergo dynamic remodeling, which involves alterations in protein and organelle homeostasis through autophagy. Here, we show that ribosomes are selectively targeted for degradation by autophagy during OIS. By characterizing senescence-dependent alterations in the ribosomal interactome, we find that the deubiquitinase USP10 dissociates from the ribosome during the transition to OIS. This release of USP10 leads to an enhanced ribosome ubiquitination, particularly of small subunit proteins, including lysine 275 on RPS2. Both reinforcement of the USP10-ribosome interaction and mutation of RPS2 K275 abrogate ribosomal delivery to lysosomes without affecting bulk autophagy. We show that the selective recruitment of ubiquitinated ribosomes to autophagosomes is mediated by the p62 receptor. While ribophagy is not required for the establishment of senescence per se, it contributes to senescence-related metabolome alterations and facilitates the senescence-associated secretory phenotype.
    Keywords:  CP: Cell biology; CP: Molecular biology; USP10; autophagy; oncogene-induced senescence; ribosomes; selective autophagy; ubiquitin
    DOI:  https://doi.org/10.1016/j.celrep.2023.113381
  10. Autophagy. 2023 Nov 05. 1-3
    Autophagy-mediated post-transcriptional surveillance of meiotic translation in Saccharomyces Cerevisiae.
    Rudian Zhang, Wenzhi Feng, Suhong Qian, Fei Wang.
      In Saccharomyces cerevisiae, macroautophagy/autophagy plays a pivotal role and is indispensable for multiple meiotic processes. In this study, we demonstrate that Rim4, a meiosis-specific RNA-binding protein (RBP) that holds back the translation of a specific subset of meiotic transcripts until its programmed degradation by autophagy during meiotic divisions, forms a heterotrimeric complex in vivo with the yeast YWHA/14-3-3 proteins Bmh1 and Bmh2, which effectively expels mRNAs from Rim4's binding grip. We pinpoint four distinct Bmh1 and Bhm2 binding sites (BBSs) in the Rim4 structure, with two of them nestled within the RNA recognition motifs (RRMs). The phosphorylation states at these BBSs controlled by counteracting PKA and Cdc14 phosphatase activities determine whether Rim4 interacts with Bmh1, Bmh2 or the mRNAs, thereby regulating Rim4's subcellular distribution, function, and stability for autophagy. Remarkably, we found that Rim4 is an Atg11-dependent selective autophagy substrate and activates Atg1 during meiotic divisions, only after its sequential dissociation from mRNAs and Bmh1 or Bmh2 assisted by PKA and cytosolic Cdc14, respectively. These findings reveal an intricate mechanism that underpins the autophagy-mediated surveillance of Rim4-mRNA interactions, orchestrated by meiotic PKA and Cdc14 activities, to ensure stage-specific translation of key meiotic transcripts.
    Keywords:  14-3-3 proteins; Cdc14; PKA; Rim4; Selective autophagy; meiotic translational control
    DOI:  https://doi.org/10.1080/15548627.2023.2276632
  11. Br J Dermatol. 2023 Nov 02. pii: ljad362. [Epub ahead of print]
    Metformin attenuates mechanistic target of rapamycin complex 1/hypoxia-inducible factor-1α-driven glycolysis reducing keratinocyte and T helper 17 cell proliferation in hyperproliferative inflammatory skin diseases.
    Bodo C Melnik.
      
    DOI:  https://doi.org/10.1093/bjd/ljad362
  12. Vet Res. 2023 Nov 07. 54(1): 103
    Duck Tembusu virus induces incomplete autophagy via the ERK/mTOR and AMPK/mTOR signalling pathways to promote viral replication in neuronal cells.
    Qing Wang, Yaqian Jiang, Guangbin Bao, Weiping Yao, Qing Yang, Shuyue Chen, Guijun Wang.
      Duck Tembusu virus (DTMUV) is a neurotropic virus in the genus Flavivirus that causes massive economic losses to the poultry industry in China and neighbouring countries. Autophagy is pivotal in cellular responses to pathogens and in viral pathogenesis. However, little is known about the roles of autophagy in DTMUV replication and viral pathogenesis, especially in neuropathogenesis. In this study, mouse neuroblastoma cells (Neuro-2a) were used to establish a cell model of DTMUV infection. Our experiments indicated that DTMUV infection induced incomplete autophagy in Neuro-2a cells. Then, we used different autophagy regulators to alter the autophagy induced by DTMUV and found that incomplete autophagy promoted DTMUV replication. Furthermore, we showed that DTMUV infection activated the ERK and AMPK pathways, resulting in decreased phosphorylation of the autophagy repressor mTOR, subsequently leading to autophagic induction. In addition, we utilized ICR mice in an animal model of DTMUV infection to evaluate the autophagic responses in brain tissues and investigate the effects of autophagy on viral replication and tissue lesions. Our results confirmed that DTMUV induced incomplete autophagy in mouse brain tissues and that autophagy inducer treatment promoted DTMUV replication and aggravated DTMUV-induced lesions, whereas autophagy inhibitor treatment had the opposite effects. In summary, DTMUV infection induced incomplete autophagy through the ERK/mTOR and AMPK/mTOR signalling pathways to promote viral replication in mouse neuronal cells, and DTMUV-induced incomplete autophagy contributed to the neuropathogenesis of DTMUV.
    Keywords:  Duck Tembusu virus; incomplete autophagy; neuropathogenesis; signalling pathways; viral replication
    DOI:  https://doi.org/10.1186/s13567-023-01235-0
  13. J Biol Chem. 2023 Nov 08. pii: S0021-9258(23)02483-3. [Epub ahead of print] 105455
    CBAP regulates the function of Akt-associated TSC protein complexes to modulate mTORC1 signaling.
    Wei-Ting Liao, Yun-Jung Chiang, Hsin-Fang Yang-Yen, Li-Chung Hsu, Zee-Fen Chang, Jeffrey Jy Yen.
      The Akt-Rheb-mTORC1 pathway plays a crucial role in regulating cell growth, but the mechanisms underlying the activation of Rheb-mTORC1 by Akt remain unclear. In our previous study, we found that CBAP was highly expressed in human T-ALL cells and primary tumors, and its deficiency led to reduced phosphorylation of TSC2/S6K1 signaling proteins, as well as impaired cell proliferation and leukemogenicity. We also demonstrated that CBAP was required for Akt-mediated TSC2 phosphorylation in vitro. In response to insulin, CBAP was also necessary for phosphorylation of TSC2/S6K1 and the dissociation of TSC2 from the lysosomal membrane. Here we report that CBAP interacts with AKT and TSC2, and knockout of CBAP or serum starvation leads to an increase in TSC1 in the Akt/TSC2 immunoprecipitation complexes. Lysosomal-anchored CBAP was found to override serum starvation and promote S6K1 and 4EBP1 phosphorylation and c-Myc expression in a TSC2-dependent manner. Additionally, recombinant CBAP inhibited the GAP activity of TSC2 complexes in vitro, leading to increased Rheb-GTP loading, likely due to the competition between TSC1 and CBAP for binding to the HBD domain of TSC2. Overexpression of the N26 region of CBAP, which is crucial for binding to TSC2, resulted in a decrease in mTORC1 signaling and an increase in TSC1 association with the TSC2/AKT complex, ultimately leading to increased GAP activity toward Rheb and impaired cell proliferation. Thus, we propose that CBAP can modulate the stability of TSC1-TSC2 as well as promote translocation of TSC1/TSC2 complexes away from lysosomes to regulate Rheb-mTORC1 signaling.
    Keywords:  Akt; Rheb; cell growth; mTORC1 activation; small GTPase; tumor cell biology
    DOI:  https://doi.org/10.1016/j.jbc.2023.105455
  14. Autophagy. 2023 Nov 08.
    ATG9B is a tissue-specific homotrimeric lipid scramblase that can compensate for ATG9A.
    George N Chiduza, Acely Garza-Garcia, Eugenia Almacellas, Stefano De Tito, Valerie E Pye, Alexander R van Vliet, Peter Cherepanov, Sharon A Tooze.
      Macroautophagy/autophagy is a fundamental aspect of eukaryotic biology, and the autophagy-related protein ATG9A is part of the core machinery facilitating this process. In addition to ATG9A vertebrates encode ATG9B, a poorly characterized paralog expressed in a subset of tissues. Herein, we characterize the structure of human ATG9B revealing the conserved homotrimeric quaternary structure and explore the conformational dynamics of the protein. Consistent with the experimental structure and computational chemistry, we establish that ATG9B is a functional lipid scramblase. We show that ATG9B can compensate for the absence of ATG9A in starvation-induced autophagy displaying similar subcellular trafficking and steady-state localization. Finally, we demonstrate that ATG9B can form a heteromeric complex with ATG2A. By establishing the molecular structure and function of ATG9B, our results inform the exploration of niche roles for autophagy machinery in more complex eukaryotes and reveal insights relevant across species.
    Keywords:  ATG9A; Cryo-EM; autophagy; membrane protein dynamics; phagophore; scramblase; single-particle analysis
    DOI:  https://doi.org/10.1080/15548627.2023.2275905
  15. Curr Med Sci. 2023 Nov 04.
    Resolvin D1 Induces mTOR-independent and ATG5-dependent Autophagy in BV-2 Microglial Cells.
    Shang-Wen Pan, Li-Sha Hu, Han Wang, Rui-Ting Li, Ya-Jun He, You Shang, Zhong-Liang Dai, Li-Xin Chen, Wei Xiong.
       OBJECTIVE: The activation state of microglia is known to occupy a central position in the pathophysiological process of cerebral inflammation. Autophagy is a catabolic process responsible for maintaining cellular homeostasis. In recent years, autophagy has been demonstrated to play an important role in neuroinflammation. Resolvin D1 (RvD1) is a promising therapeutic mediator that has been shown to exert substantial anti-inflammatory and proresolving activities. However, whether RvD1-mediated resolution of inflammation in microglia is related to autophagy regulation needs further investigation. The present study aimed to explore the effect of RvD1 on microglial autophagy and its corresponding pathways.
    METHODS: Mouse microglial cells (BV-2) were cultured, treated with RvD1, and examined by Western blotting, confocal immunofluorescence microscopy, transmission electron microscopy, and flow cytometry.
    RESULTS: RvD1 promoted autophagy in both BV-2 cells and mouse primary microglia by favoring the maturation of autophagosomes and their fusion with lysosomes. Importantly, RvD1 had no significant effect on the activation of mammalian target of rapamycin (mTOR) signaling. Furthermore, RvD1-induced mTOR-independent autophagy was confirmed by observing reduced cytoplasmic calcium levels and suppressed calcium/calmodulin-dependent protein kinase II (CaMK II) activation. Moreover, by downregulating ATG5, the increased phagocytic activity induced by RvD1 was demonstrated to be tightly controlled by ATG5-dependent autophagy.
    CONCLUSION: The present work identified a previously unreported mechanism responsible for the role of RvD1 in microglial autophagy, highlighting its therapeutic potential against neuroinflammation.
    Keywords:  ATG5-dependent autophagy; mTOR-independent autophagy; microglia; phagocytosis; resolvin D1
    DOI:  https://doi.org/10.1007/s11596-023-2787-5
  16. J Biomed Sci. 2023 Nov 07. 30(1): 91
    Spatiotemporal roles of AMPK in PARP-1- and autophagy-dependent retinal pigment epithelial cell death caused by UVA.
    Anthony Yan-Tang Wu, Ponarulselvam Sekar, Duen-Yi Huang, Shu-Hao Hsu, Chi-Ming Chan, Wan-Wan Lin.
       BACKGROUND: Although stimulating autophagy caused by UV has been widely demonstrated in skin cells to exert cell protection, it remains unknown the cellular events in UVA-treated retinal pigment epithelial (RPE) cells.
    METHODS: Human ARPE-19 cells were used to measure cell viability, mitochondrial reactive oxygen species (ROS), mitochondrial membrane potential (MMP), mitochondrial mass and lysosomal mass by flow cytometry. Mitochondrial oxygen consumption rate (OCR) was recorded using Seahorse XF flux analyzer. Confocal microscopic images were performed to indicate the mitochondrial dynamics, LC3 level, and AMPK translocation after UVA irradiation.
    RESULTS: We confirmed mitochondrial ROS production and DNA damage are two major features caused by UVA. We found the cell death is prevented by autophagy inhibitor 3-methyladenine and gene silencing of ATG5, and UVA induces ROS-dependent LC3II expression, LC3 punctate and TFEB expression, suggesting the autophagic death in the UVA-stressed RPE cells. Although PARP-1 inhibitor olaparib increases DNA damage, ROS production, and cell death, it also blocks AMPK activation caused by UVA. Interestingly we found a dramatic nuclear export of AMPK upon UVA irradiation which is blocked by N-acetylcysteine and olaparib. In addition, UVA exposure gradually decreases lysosomal mass and inhibits cathepsin B activity at late phase due to lysosomal dysfunction. Nevertheless, cathepsin B inhibitor, CA-074Me, reverses the death extent, suggesting the contribution of cathepsin B in the death pathway. When examining the role of EGFR in cellular events caused by UVA, we found that UVA can rapidly transactivate EGFR, and treatment with EGFR TKIs (gefitinib and afatinib) enhances the cell death accompanied by the increased LC3II formation, ROS production, loss of MMP and mass of mitochondria and lysosomes. Although AMPK activation by ROS-PARP-1 mediates autophagic cell death, we surprisingly found that pretreatment of cells with AMPK activators (A769662 and metformin) reverses cell death. Concomitantly, both agents block UVA-induced mitochondrial ROS production, autophagic flux, and mitochondrial fission without changing the inhibition of cathepsin B.
    CONCLUSION: UVA exposure rapidly induces ROS-PARP-1-AMPK-autophagic flux and late lysosomal dysfunction. Pre-inducing AMPK activation can prevent cellular events caused by UVA and provide a new protective strategy in photo-oxidative stress and photo-retinopathy.
    Keywords:  AMPK; Autophagic cell death; EGFR; Lysosome dysfunction; PARP; ROS; RPE; UVA
    DOI:  https://doi.org/10.1186/s12929-023-00978-4
  17. Autophagy. 2023 Nov 05. 1-3
    SREBF1/SREBP-1 concurrently regulates lipid synthesis and lipophagy to maintain lipid homeostasis and tumor growth.
    Feng Geng, Deliang Guo.
      Cholesterol is an essential structural component of the cell membrane, whereas excess cholesterol can be toxic and thus is stored in intracellular lipid droplets (LDs). Malignant tumor cells grow rapidly and require abundant cholesterol to build new membranes. How they maintain cholesterol homeostasis is largely unknown. We recently revealed that SREBF1/SREBP-1 (sterol regulatory element binding transcription factor 1), a key lipogenic transcription factor, plays a critical role in maintaining cholesterol homeostasis in tumor cells. We found that in addition to activation of de novo lipid synthesis and cholesterol uptake, SREBF1 also upregulates macroautophagy/autophagy to hydrolyze LDs, and increases the expression of NPC2, a lysosome cholesterol transporter, actively mobilizing LD-stored cholesterol and fatty acids to promote tumor growth. Our study demonstrates that SREBF1 controls the balance of lipid synthesis, uptake, storage and liberation to maintain lipid homeostasis for rapid tumor growth, while suggesting it as a very promising molecular target for cancer treatment.
    Keywords:  Autophagy; cancer; cholesterol; glioblastoma; lipid droplets; lipophagy
    DOI:  https://doi.org/10.1080/15548627.2023.2275501
  18. Elife. 2023 Nov 06. pii: e80944. [Epub ahead of print]12
    Glucagon-like peptide-1 receptor activation stimulates PKA-mediated phosphorylation of raptor and this contributes to the weight loss effect of liraglutide.
    Thao D V Le, Dianxin Liu, Gai-Linn K Besing, Ritika Raghavan, Blair J Ellis, Ryan P Ceddia, Sheila Collins, Julio E Ayala.
      The canonical target of the glucagon-like peptide-1 receptor (GLP-1R), Protein Kinase A (PKA), has been shown to stimulate mechanistic Target of Rapamycin Complex 1 (mTORC1) by phosphorylating the mTOR-regulating protein Raptor at Ser791 following β-adrenergic stimulation. The objective of these studies is to test whether GLP-1R agonists similarly stimulate mTORC1 via PKA phosphorylation of Raptor at Ser791 and whether this contributes to the weight loss effect of the therapeutic GLP-1R agonist liraglutide. We measured phosphorylation of the mTORC1 signaling target ribosomal protein S6 in Chinese Hamster Ovary cells expressing GLP-1R (CHO-Glp1r) treated with liraglutide in combination with PKA inhibitors. We also assessed liraglutide-mediated phosphorylation of the PKA substrate RRXS*/T* motif in CHO-Glp1r cells expressing Myc-tagged wild-type (WT) Raptor or a PKA-resistant (Ser791Ala) Raptor mutant. Finally, we measured the body weight response to liraglutide in WT mice and mice with a targeted knock-in of PKA-resistant Ser791Ala Raptor. Liraglutide increased phosphorylation of S6 and the PKA motif in WT Raptor in a PKA-dependent manner but failed to stimulate phosphorylation of the PKA motif in Ser791Ala Raptor in CHO-Glp1r cells. Lean Ser791Ala Raptor knock-in mice were resistant to liraglutide-induced weight loss but not setmelanotide-induced (melanocortin-4 receptor-dependent) weight loss. Diet-induced obese Ser791Ala Raptor knock-in mice were not resistant to liraglutide-induced weight loss; however, there was weight-dependent variation such that there was a tendency for obese Ser791Ala Raptor knock-in mice of lower relative body weight to be resistant to liraglutide-induced weight loss compared to weight-matched controls. Together, these findings suggest that PKA-mediated phosphorylation of Raptor at Ser791 contributes to liraglutide-induced weight loss.
    Keywords:  cell biology; medicine; mouse
    DOI:  https://doi.org/10.7554/eLife.80944
  19. J Huntingtons Dis. 2023 Oct 27.
    Upregulated Chaperone-Mediated Autophagy May Perform a Key Role in Reduced Cancer Incidence in Huntington's Disease.
    Lis Frydenreich Hasholt.
      Incidence of cancer is markedly reduced in patients with the hereditary neurodegenerative polyglutamine (polyQ) diseases. We have very poor knowledge of the underlying molecular mechanisms, but the expanded polyQ sequence is assumed to play a central role, because it is common to the respective disease related proteins. The inhibition seems to take place in all kinds of cells, because the lower cancer frequency applies to nearly all types of tumors and is not related with the characteristic pathological changes in specific brain tissues. Further, the cancer repressing mechanisms appear to be active early in life including in pre-symptomatic and early phase polyQ patients. Autophagy plays a central role in clearing proteins with expanded polyQ tracts, and autophagy modulation has been demonstrated and particularly investigated in Huntington's disease (HD). Macroautophagy may be dysfunctional due to defects in several steps of the process, whereas increased chaperone-mediated autophagy (CMA) has been shown in HD patients, cell and animal models. Recently, CMA is assumed to play a key role in prevention of cellular transformation of normal cells into cancer cells. Investigations of normal cells from HD and other polyQ carriers could therefore add further insight into the protective mechanisms of CMA in tumorigenesis, and be important for development of autophagy based strategies to prevent malignant processes leading to cancer and neurodegeneration.
    Keywords:  Polyglutamine disease; chaperone-mediated autophagy; huntingtin; reduced cancer risk
    DOI:  https://doi.org/10.3233/JHD-230586
  20. Autophagy. 2023 Nov 06. 1-15
    Seneca Valley virus 3C protease cleaves OPTN (optineurin) to Impair selective autophagy and type I interferon signaling.
    Jiangwei Song, Yitong Guo, Dan Wang, Rong Quan, Jing Wang, Jue Liu.
      Seneca Valley virus (SVV) causes vesicular disease in pigs, posing a threat to global pork production. OPTN (optineurin) is a macroautophagy/autophagy receptor that restricts microbial propagation by targeting specific viral or bacterial proteins for degradation. OPTN is degraded and cleaved at glutamine 513 following SVV infection via the activity of viral 3C protease (3C[pro]), resulting in N-terminal and a C-terminal OPTN fragments. Moreover, OPTN interacts with VP1 and targets VP1 for degradation to inhibit viral replication. The N-terminal cleaved OPTN sustained its interaction with VP1, whereas the degradation capacity targeting VP1 decreased. The inhibitory effect of N-terminal OPTN against SVV infection was significantly reduced, C-terminal OPTN failed to inhibit viral replication, and degradation of VP1 was blocked. The knockdown of OPTN resulted in reduced TBK1 activation and phosphorylation of IRF3, whereas overexpression of OPTN led to increased TBK1-IRF3 signaling. Additionally, the N-terminal OPTN diminished the activation of the type I IFN (interferon) pathway. These results show that SVV 3C[pro] targets OPTN because its cleavage impairs its function in selective autophagy and type I IFN production, revealing a novel model in which the virus develops diverse strategies for evading host autophagic machinery and type I IFN response for survival.Abbreviations: Co-IP: co-immunoprecipitation; GFP-green fluorescent protein; hpi: hours post-infection; HRP: horseradish peroxidase; IFN: interferon; IFNB/IFN-β: interferon beta; IRF3: interferon regulatory factor 3; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MOI: multiplicity of infection; OPTN: optineurin; PBS: phosphate-buffered saline; SVV: Seneca Valley virus; SQSTM1: sequestosome 1; TAX1BP1: Tax1 binding protein 1; TBK1: TANK binding kinase 1; TCID50: 50% tissue culture infectious doses; UBAN: ubiquitin binding in TNIP/ABIN (TNFAIP3/A20 and inhibitor of NFKB/NF-kB) and IKBKG/NEMO; UBD: ubiquitin-binding domain; ZnF: zinc finger.
    Keywords:  3C protease (3C[pro]); OPTN (optineurin); Seneca Valley virus (SVV); cleavage; selective autophagy; type I interferon (IFN)
    DOI:  https://doi.org/10.1080/15548627.2023.2277108
  21. Cell Death Dis. 2023 11 04. 14(11): 719
    c-MYC-dependent transcriptional inhibition of autophagy is implicated in cisplatin sensitivity in HPV-positive head and neck cancer.
    Alessandro Medda, Micaela Compagnoni, Giorgio Spini, Simona Citro, Ottavio Croci, Stefano Campaner, Marta Tagliabue, Mohssen Ansarin, Susanna Chiocca.
      Autophagy is important for the removal, degradation and recycling of damaged organelles, proteins, and lipids through the degradative action of lysosomes. In addition to its catabolic function, autophagy is important in cancer and viral-mediated tumorigenesis, including Human Papillomavirus (HPV) positive cancers. HPV infection is a major risk factor in a subset of head and neck cancer (HNC), for which no targeted therapies are currently available. Herein, we assessed autophagy function in HPV-positive HNC. We showed that HPV-positive HNC cells presented a transcriptional and functional impairment of the autophagic process compared to HPV-negative cells, which were reactivated by knocking down HPV E6/E7 oncoproteins, the drivers of cellular transformation. We found that the oncoprotein c-MYC was stabilized and triggered in HPV-positive cell lines. This resulted in the reduced binding of the MiT/TFE transcription factors to their autophagy targets due to c-MYC competition. Thus, the knock-down of c-MYC induced the upregulation of autophagic and lysosomal genes in HPV-positive HNC cells, as well as the increase of autophagic markers at the protein level. Moreover, HPV oncoprotein E7 upregulated the expression of the phosphatase inhibitor CIP2A, accounting for c-MYC upregulation and stability in HPV+ HNC cells. CIP2A mRNA expression negatively correlated with autophagy gene expression in tumor tissues from HNC patients, showing, for the first time, its implication in a transcriptional autophagic context. Both CIP2A and c-MYC knock-down, as well as pharmacological downregulation of c-MYC, resulted in increased resistance to cisplatin treatment. Our results not only show a novel way by which HPV oncoproteins manipulate the host machinery but also provide more insights into the role of autophagy in chemoresistance, with possible implications for targeted HPV-positive HNC therapy.
    DOI:  https://doi.org/10.1038/s41419-023-06248-3
  22. Stem Cells. 2023 Nov 01. pii: sxad079. [Epub ahead of print]
    Selective Inhibition of mTORC1 Signaling Supports the Development and Maintenance of Pluripotency.
    Jin Koo Kim, Luis G Villa-Diaz, Thomas L Saunders, Ruiz P Saul, Suraj Timilsina, Fei Liu, Yuji Mishina, Paul H Krebsbach.
      Insight into the molecular mechanisms governing the development and maintenance of pluripotency is important for understanding early development and the use of stem cells in regenerative medicine. We demonstrate the selective inhibition of mTORC1 signaling is important for developing the inner cell mass (ICM) and the self-renewal of human embryonic stem cells. S6K suppressed the expression and function of pluripotency-related transcription factors (PTFs) OCT4, SOX2, and KLF4 through phosphorylation and ubiquitin proteasome-mediated protein degradation, indicating that S6K inhibition is required for pluripotency. PTFs inhibited mTOR signaling. The phosphorylation of S6 was decreased in PTF-positive cells of the ICM in embryos. Activation of mTORC1 signaling blocked ICM formation and the selective inhibition of S6K by rapamycin increased the ICM size in mouse blastocysts. Thus, selective inhibition of mTORC1 signaling supports the development and maintenance of pluripotency.
    Keywords:  4E-BP1; Human pluripotent stem cells (hPSCs); S6; S6K; inner cell mass (ICM); pluripotency-related transcription factors (PTFs)
    DOI:  https://doi.org/10.1093/stmcls/sxad079
  23. Front Neurosci. 2023 ;17 1202167
    Modulating mitochondrial calcium channels (TRPM2/MCU/NCX) as a therapeutic strategy for neurodegenerative disorders.
    Gretchen A Johnson, Raghu R Krishnamoorthy, Dorota L Stankowska.
      Efficient cellular communication is essential for the brain to regulate diverse functions like muscle contractions, memory formation and recall, decision-making, and task execution. This communication is facilitated by rapid signaling through electrical and chemical messengers, including voltage-gated ion channels and neurotransmitters. These messengers elicit broad responses by propagating action potentials and mediating synaptic transmission. Calcium influx and efflux are essential for releasing neurotransmitters and regulating synaptic transmission. Mitochondria, which are involved in oxidative phosphorylation, and the energy generation process, also interact with the endoplasmic reticulum to store and regulate cytoplasmic calcium levels. The number, morphology, and distribution of mitochondria in different cell types vary based on energy demands. Mitochondrial damage can cause excess reactive oxygen species (ROS) generation. Mitophagy is a selective process that targets and degrades damaged mitochondria via autophagosome-lysosome fusion. Defects in mitophagy can lead to a buildup of ROS and cell death. Numerous studies have attempted to characterize the relationship between mitochondrial dysfunction and calcium dysregulation in neurodegenerative diseases such as Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, Amyotrophic lateral sclerosis, spinocerebellar ataxia, and aging. Interventional strategies to reduce mitochondrial damage and accumulation could serve as a therapeutic target, but further research is needed to unravel this potential. This review offers an overview of calcium signaling related to mitochondria in various neuronal cells. It critically examines recent findings, exploring the potential roles that mitochondrial dysfunction might play in multiple neurodegenerative diseases and aging. Furthermore, the review identifies existing gaps in knowledge to guide the direction of future research.
    Keywords:  ROS; aging; calcium; mitochondria; neurodegeneration
    DOI:  https://doi.org/10.3389/fnins.2023.1202167
  24. Neuroscience. 2023 Nov 03. pii: S0306-4522(23)00487-6. [Epub ahead of print]
    Rapamycin exerts an antidepressant effect and enhances myelination in the prefrontal cortex of chronic restraint stress mice.
    Jin Zhang, Weifen Li, Qi Yue, Luping Liu, Sheng-Tao Hou, Jun Ju.
      Depressive disorder is a psychiatric condition that is characterized by the core symptoms of anhedonia and learned helplessness. Myelination loss was recently found in the prefrontal cortex (PFC) of patients with depression and animal models, but the mechanism of this loss is unclear. In our previous study, chronic restraint stress (CRS) mice showed depressive-like symptoms. In this study, we found that myelin was reduced in the PFC of CRS mice. We also observed increased mammalian target of rapamycin (mTOR) phosphorylation levels in the PFC. Chronic injections of rapamycin, a mTOR complex inhibitor, prevented depressive behavior as shown by the forced swimming test and sucrose preference test. Rapamycin also increased myelination in the PFC of CRS mice. In summary, we found that CRS enhanced mTOR signaling and reduced myelination in the PFC and that rapamycin could prevent it. Our study provides the etiology of reduced myelin in depressive symptoms and suggests that mTOR signaling could be a target for treating depression or improving myelination deficits in depressive disorders.
    Keywords:  Depressive disorder; mTOR signaling; myelination; prefrontal cortex; rapamycin
    DOI:  https://doi.org/10.1016/j.neuroscience.2023.10.025
  25. Calcif Tissue Int. 2023 Nov 05.
    Mitophagy Activation by Urolithin A to Target Muscle Aging.
    Julie Faitg, Davide D'Amico, Chris Rinsch, Anurag Singh.
      The age-related loss of skeletal muscle function starts from midlife and if left unaddressed can lead to an impaired quality of life. A growing body of evidence indicates that mitochondrial dysfunction is causally involved with muscle aging. Muscles are tissues with high metabolic requirements, and contain rich mitochondria supply to support their continual energy needs. Cellular mitochondrial health is maintained by expansing of the mitochondrial pool though mitochondrial biogenesis, by preserving the natural mitochondrial dynamic process, via fusion and fission, and by ensuring the removal of damaged mitochondria through mitophagy. During aging, mitophagy levels decline and negatively impact skeletal muscle performance. Nutritional and pharmacological approaches have been proposed to manage the decline in muscle function due to impaired mitochondria bioenergetics. The natural postbiotic Urolithin A has been shown to promote mitophagy, mitochondrial function and improved muscle function across species in different experimental models and across multiple clinical studies. In this review, we explore the biology of Urolithin A and the clinical evidence of its impact on promoting healthy skeletal muscles during age-associated muscle decline.
    Keywords:  Aging; Mitochondria; Mitophagy; Muscle health; Urolithin A
    DOI:  https://doi.org/10.1007/s00223-023-01145-5
  26. Cells. 2023 Nov 02. pii: 2566. [Epub ahead of print]12(21):
    The Small GTPase Rab7 Regulates Antigen Processing in B Cells in a Possible Interplay with Autophagy Machinery.
    Marika Runsala, Elina Kuokkanen, Eveliina Uski, Vid Šuštar, Meryem Özge Balci, Johanna Rajala, Vilma Paavola, Pieta K Mattila.
      In B cells, antigen processing and peptide-antigen (pAg) presentation is essential to ignite high-affinity antibody responses with the help of cognate T cells. B cells efficiently internalize and direct specific antigens for processing and loading onto MHCII. This critical step, which enables pAg presentation, occurs in MHCII compartments (MIICs) which possess the enzymatic machinery for pAg loading on MHCII. The intracellular transport systems that guide antigen and maintain this unique compartment remain enigmatic. Here, we probed the possible functional role of two known endosomal proteins, the Rab family small GTPases Rab7 and Rab9, that are both reported to colocalize with internalized antigen. As compared to Rab9, we found Rab7 to exhibit a higher overlap with antigen and MIIC components. Rab7 also showed a higher association with antigen degradation. The inhibition of Rab7 drastically decreased pAg presentation. Additionally, we detected the strong colocalization of perinuclearly clustered and presumably MIIC-associated antigen with autophagy protein LC3. When we pharmacologically inhibited autophagy, pAg presentation was inhibited. Together, our data promote Rab7 as an important regulator of antigen processing and, considering the previously reported functions of Rab7 in autophagy, this also raises the possibility of the involvement of autophagy-related machinery in this process.
    Keywords:  B cell activation; B cell receptor; BCR; MHCII; Rab7; adaptive immune system; antigen processing; autophagy; endosomes; lysosomes; vesicle traffic
    DOI:  https://doi.org/10.3390/cells12212566
  27. Mol Biotechnol. 2023 Nov 08.
    Hyperoxia can Induce Lung Injury by Upregulating AECII Autophagy and Apoptosis Via the mTOR Pathway.
    Yingcong Ren, Song Qin, Xinxin Liu, Banghai Feng, Junya Liu, Jing Zhang, Ping Yuan, Kun Yu, Hong Mei, Miao Chen.
      Oxygen therapy is a crucial medical intervention, but it is undeniable that it can lead to lung damage. The mTOR pathway plays a pivotal role in governing cell survival, including autophagy and apoptosis, two phenomena deeply entwined with the evolution of diseases. However, it is unclarified whether the mTOR pathway is involved in hyperoxic acute lung injury (HALI). The current study aims to clarify the molecular mechanism underlying the pathogenesis of HALI by constructing in vitro and in vivo models using H2O2 and hyperoxia exposure, respectively. To investigate the role of mTOR, the experiment was divided into five groups, including normal group, injury group, mTOR inhibitor group, mTOR activator group, and DMSO control group. Western blotting, Autophagy double labeling, TUNEL staining, and HE staining were applied to evaluate protein expression, autophagy activity, cell apoptosis, and pathological changes in lung tissues. Our data revealed that hyperoxia can induce autophagy and apoptosis in Type II alveolar epithelial cell (AECII) isolated from the treated rats, as well as injuries in the rat lung tissues; also, H2O2 stimulation increased autophagy and apoptosis in MLE-12 cells. Noticeably, the experiments performed in both in vitro and in vivo models proved that the mTOR inhibitor Rapamycin (Rapa) functioned synergistically with hyperoxia or H2O2 to promote AECII autophagy, which led to increased apoptosis and exacerbated lung injury. On the contrary, activation of mTOR with MHY1485 suppressed autophagy activity, consequently resulting in reduced apoptosis and lung injury in H2O2-challenged MLE-12 cells and hyperoxia-exposed rats. In conclusion, hyperoxia caused lung injury via mTOR-mediated AECII autophagy.
    Keywords:  Apoptosis; Autophagy; Hyperoxic acute lung injury; Type II alveolar epithelial cells; mTOR
    DOI:  https://doi.org/10.1007/s12033-023-00945-2
  28. J Cell Physiol. 2023 Nov 09.
    NDP52 SUMOylation contributes to low-dose X-rays-induced cardiac hypertrophy through PINK1/Parkin-mediated mitophagy via MUL1/SUMO2 signalling.
    Anbo Gao, Mengjie Wang, Xing Tang, Gangqing Shi, Kai Hou, Jinren Fang, Linlin Zhou, Hong Zhou, Weimin Jiang, Yukun Li, Fan Ouyang.
      Radiation-induced heart damage caused by low-dose X-rays has a significant impact on tumour patients' prognosis, with cardiac hypertrophy being the most severe noncarcinogenic adverse effect. Our previous study demonstrated that mitophagy activation promoted cardiac hypertrophy, but the underlying mechanisms remained unclear. In the present study, PARL-IN-1 enhanced excessive hypertrophy of cardiomyocytes and exacerbated mitochondrial damage. Isobaric tags for relative and absolute quantification-based quantitative proteomics identified NDP52 as a crucial target mediating cardiac hypertrophy induced by low-dose X-rays. SUMOylation proteomics revealed that the SUMO E3 ligase MUL1 facilitated NDP52 SUMOylation through SUMO2. Co-IP coupled with LC-MS/MS identified a critical lysine residue at position 262 of NDP52 as the key site for SUMO2-mediated SUMOylation of NDP52. The point mutation plasmid NDP52K262R inhibited mitophagy under MUL1 overexpression, as evidenced by inhibition of LC3 interaction with NDP52, PINK1 and LAMP2A. A mitochondrial dissociation study revealed that NDP52K262R inhibited PINK1 targeting to endosomes early endosomal marker (EEA1), late/lysosome endosomal marker (LAMP2A) and recycling endosomal marker (RAB11), and laser confocal microscopy confirmed that NDP52K262R impaired the recruitment of mitochondria to the autophagic pathway through EEA1/RAB11 and ATG3, ATG5, ATG16L1 and STX17, but did not affect mitochondrial delivery to lysosomes via LAMP2A for degradation. In conclusion, our findings suggest that MUL1-mediated SUMOylation of NDP52 plays a crucial role in regulating mitophagy in the context of low-dose X-ray-induced cardiac hypertrophy. Two hundred sixty-second lysine of NDP52 is identified as a key SUMOylation site for low-dose X-ray promoting mitophagy activation and cardiac hypertrophy. Collectively, this study provides novel implications for the development of therapeutic strategies aimed at preventing the progression of cardiac hypertrophy induced by low-dose X-rays.
    Keywords:  MUL1; NDP52; PINK1/Parkin; SUMOylation; mitophagy; radiation-induced heart damage
    DOI:  https://doi.org/10.1002/jcp.31145
  29. J Biochem. 2023 Nov 08. pii: mvad089. [Epub ahead of print]
    p62 bodies: cytosolic zoning by phase separation.
    Reo Kurusu, Hideaki Morishita, Masaaki Komatsu.
      Cellular zoning or partitioning is critical in preventing macromolecules from random diffusion and in orchestrating the spatiotemporal dynamics of biochemical reactions. Along with membranous organelles, membrane-less organelles contribute to the precise regulation of biochemical reactions inside cells. In response to environmental cues, membrane-less organelles rapidly form through liquid-liquid phase separation, sequester certain proteins and RNAs, mediate specific reactions, and dissociate. Among membrane-less organelles, ubiquitin-positive condensates, namely, p62 bodies, maintain cellular homeostasis through selective autophagy of themselves to contribute to intracellular quality control. p62 bodies also activate the anti-oxidative stress response regulated by the KEAP1-NRF2 system. In this review, we present an overview of recent advancements in cellular and molecular biology related to p62 bodies, highlighting their dynamic nature and functions.
    Keywords:  Autophagy; KEAP1-NRF2 system; intracellular quality control; liquid-liquid phase separation; p62 body
    DOI:  https://doi.org/10.1093/jb/mvad089
  30. J Infect Dis. 2023 Oct 31. pii: jiad478. [Epub ahead of print]
    Epithelial cell NOD1/IRGM recruits STX17 to Neisseria gonorrhoeae-containing endosomes to initiate lysosomal degradation.
    Shuai Gao, Dailin Yuan, Lingyu Gao, Fan Yang, Xu'ai Lin, Stijn van der Veen.
      Neisseria gonorrhoeae establishes tight interactions with mucosal epithelia through activity of its type IV pilus, while pilus-retraction forces furthermore activate autophagic responses towards invading gonococci. Here we studied pilus-independent epithelial cell responses and showed that pilus-negative gonococci residing in early and late endosomes are detected and targeted by nucleotide-binding oligomerization domain 1 (NOD1). NOD1 subsequently forms a complex with immunity-related guanosine triphosphatase M (IRGM) and autophagy related 16 like 1 (ATG16L1) to activate autophagy and recruit microtubule-associated protein light chain 3 (LC3) to the intracellular bacteria. IRGM furthermore directly recruits syntaxin 17 (STX17), which is able to form tethering complexes with the lysosome. Importantly, IRGM/STX17 interactions are enhanced by LC3, but still observed at lower levels in an LC3 knock-out cell line. These findings demonstrate key roles for NOD1 and IRGM in sensing of intracellular N. gonorrhoeae and subsequent directing of the bacterium to the lysosome for degradation.
    Keywords:   Neisseria gonorrhoeae ; ATG16L1; Autophagy; IRGM; LC3; LdcA; NOD1; STX17; endosome
    DOI:  https://doi.org/10.1093/infdis/jiad478
  31. PLoS Biol. 2023 Nov 08. 21(11): e3002372
    The ortholog of human REEP1-4 is required for autophagosomal enclosure of ER-phagy/nucleophagy cargos in fission yeast.
    Chen-Xi Zou, Zhu-Hui Ma, Zhao-Di Jiang, Zhao-Qian Pan, Dan-Dan Xu, Fang Suo, Guang-Can Shao, Meng-Qiu Dong, Li-Lin Du.
      Selective macroautophagy of the endoplasmic reticulum (ER) and the nucleus, known as ER-phagy and nucleophagy, respectively, are processes whose mechanisms remain inadequately understood. Through an imaging-based screen, we find that in the fission yeast Schizosaccharomyces pombe, Yep1 (also known as Hva22 or Rop1), the ortholog of human REEP1-4, is essential for ER-phagy and nucleophagy but not for bulk autophagy. In the absence of Yep1, the initial phase of ER-phagy and nucleophagy proceeds normally, with the ER-phagy/nucleophagy receptor Epr1 coassembling with Atg8. However, ER-phagy/nucleophagy cargos fail to reach the vacuole. Instead, nucleus- and cortical-ER-derived membrane structures not enclosed within autophagosomes accumulate in the cytoplasm. Intriguingly, the outer membranes of nucleus-derived structures remain continuous with the nuclear envelope-ER network, suggesting a possible outer membrane fission defect during cargo separation from source compartments. We find that the ER-phagy role of Yep1 relies on its abilities to self-interact and shape membranes and requires its C-terminal amphipathic helices. Moreover, we show that human REEP1-4 and budding yeast Atg40 can functionally substitute for Yep1 in ER-phagy, and Atg40 is a divergent ortholog of Yep1 and REEP1-4. Our findings uncover an unexpected mechanism governing the autophagosomal enclosure of ER-phagy/nucleophagy cargos and shed new light on the functions and evolution of REEP family proteins.
    DOI:  https://doi.org/10.1371/journal.pbio.3002372
  32. Autophagy. 2023 Nov 08. 1-2
    Connecting reticulophagy and neuronal NTRK2/TrkB signaling.
    Patrick Lüningschrör, Michael Sendtner.
      Tightly regulated cell surface expression of NTRK2/TrkB provides a mechanism for fine-tuning cellular responses to the neurotrophic factor BDNF. Recently, the degradation of NTRK2 by reticulophagy has been identified as a mechanism to limit its availability for trafficking to the cell membrane. The ER-chaperone CANX (calnexin) delivers NTRK2 to the reticulophagy receptor RETREG1/Fam134b for lysosomal degradation. Upon phosphorylation of CANX, NTRK2 is released from this complex, which facilitates its cell surface transport. These results identify a novel role for CANX in regulating the cell surface expression of NTRK2 and imply a function for reticulophagy that goes beyond regulating the degradation of misfolded proteins within the ER.
    Keywords:  BDNF; Calnexin; EGF; ER-phagy; Fam134b; NTRK2/TrkB signaling
    DOI:  https://doi.org/10.1080/15548627.2023.2276630
  33. Tuberculosis (Edinb). 2023 Oct 17. pii: S1472-9792(23)00120-8. [Epub ahead of print]143 102422
    Pulmonary tuberculosis biomarker miR-215-5p inhibits autophagosome-lysosome fusion in macrophages.
    Feng Deng, Peng Xu, Jiahong Miao, Cheng Jin, Huihui Tu, Jianhua Zhang.
      The normal autophagy flux is beneficial for the rapid elimination of phagocytic pathogens by macrophages. However, Mycobacterium tuberculosis interferes with the autophagy flux of macrophages to weaken their immune function and evade immune surveillance. In this study, we found that miRNA-215-5p was downregulated in tuberculosis patients. A potential diagnostic model for tuberculosis was established by combining miRNA-215-5p with three others differentially expressed microRNAs (miRNA-145-5p, miRNA-486-5p and miRNA-628-3p). Furthermore, we discovered that the up-regulated miRNA-215-5p could inhibit the maturation of autophagy by preventing the fusion of autophagosomes with lysosomes in macrophages. The role of TB-specific miRNA-215-5p in inhibiting auto-lysosome formation provides evidence of its potential role in Host-directed therapy for tuberculosis.
    Keywords:  Autophagy maturation; Diagnosis; Host-directed therapy; Macrophage; Pulmonary tuberculosis; miR-215-5p
    DOI:  https://doi.org/10.1016/j.tube.2023.102422
  34. Med Oncol. 2023 Nov 08. 40(12): 350
    ATGL promotes colorectal cancer growth by regulating autophagy process and SIRT1 expression.
    Bao-Chang Su, Kang-Ming Xiao, Kang-Long Wang, Sheng-Fu Yang, Zhang-Xiong Huang, Ji-Wen Luo.
      CRC is a common malignant tumor in the gastrointestinal tract, and its incidence has increased significantly in recent years. Several studies revealed that lipid metabolism reprogramming contributed to tumorigenicity and malignancy by interfering with energy production, membrane formation, and signal transduction in cancers. ATGL is a kind of hydroxy fatty acid ester of fatty acid synthase, and its role in tumor remains controversial. We compared levels of adipose triglyceride lipase (ATGL) in human CRC specimens to adjacent specimens. To validate the effect of ATGL on the proliferation ability of CRC, CCK8 assay and clone formation assay were performed. To evaluate whether autophagy process takes part in the effect of ATGL on CRC proliferation, the value of LC3-II/LC3-I was detected by western blot and we blocked the SIRT1 to detect value of LC3-II/LC3-I and p62 via western blot. In the end, we detected the value of SIRT1 in CRC specimens. We found that ATGL showed high expression in CRC and positively correlated with clinical stage, indicating poor prognosis of CRC. Moreover, ATGL significantly promoted tumor cell proliferation in vitro. Mechanistically, ATGL promoted CRC cells proliferation by blocking mTOR signaling pathway and activating autophagy process. Further, ATGL regulated autophagy process through triggering SIRT1 expression. Our results reveal that ATGL promotes colorectal cancer growth by up regulating autophagy process and SIRT1 expression.
    Keywords:  ATGL; Autophagy; Colorectal cancer; LC3II/I; SIRT1; mTOR
    DOI:  https://doi.org/10.1007/s12032-023-02148-w
  35. J Neurophysiol. 2023 Nov 08.
    Autophagy protects against vocal fold injury-induced fibrosis.
    Haiyan Zhang, Linxue Yang, Jing Zhang, Qianqian Han, Wei Xu.
       BACKGROUND: Vocal fold scar formation due to vocal fold injury (VFI) is a common cause of surgery or trauma-induced voice disorders. Severe scar formation can lead to reduced voice quality or even be life-threatening. Here we investigated the role of autophagy in VFI, focusing on fibrosis as a consequence of autophagy in inducing VFI.
    METHODS: A VFI model was constructed in rats by dissecting the lamina propria tissue from the thyroarytenoid muscle. Real-time PCR and western blot were used to analyze expressions of autophagy markers, including Beclin1 and Atg7, in VFI. Tgfb1 and Col1a1 were assessed to determine the correlation of fibrosis with VFI progression and autophagy levels. Rat vocal fold fibroblasts were also treated with TGF-β1 or rapamycin, which activates and suppresses autophagy respectively, to explore how autophagy regulates fibrosis in VFI.
    RESULTS: Initially, we observed that autophagy was downregulated in vocal fold mucosa after VFI in rats. This was particularly evident by the time-dependent downregulation of Beclin1 and Atg7 following VFI. Concurrently, levels of Tgfb1 and Col1a1 also surged, hinting at elevated fibrosis levels. Furthermore, our experiments with TGF-β1 stimulation revealed that it inhibited autophagy in rat vocal fold fibroblasts. Interestingly, when we introduced rapamycin, this effect was reversed.
    CONCLUSIONS: Our data suggest that autophagy is a suppressor of VFI by alleviating fibrosis, making targeting autophagy a potential therapeutic route in VFI.
    Keywords:  Autophagy; fibrosis; vocal fold injury
    DOI:  https://doi.org/10.1152/jn.00332.2023
  36. Endocr Metab Immune Disord Drug Targets. 2023 Nov 01.
    Mitochondrial Inherited Disorders and their Correlation with Neurodegenerative Diseases.
    Sofjana Gushi, Dr Vasileios Balis PhD Mrsb.
      Mitochondria are essential organelles for the survival of a cell because they produce energy. The cells that need more mitochondria are neurons because they perform a variety of tasks that are necessary to support brain homeostasis. The build-up of abnormal proteins in neurons, as well as their interactions with mitochondrial proteins, or MAM proteins, cause serious health issues. As a result, mitochondrial functions, such as mitophagy, are impaired, resulting in the disorders described in this review. They are also due to mtDNA mutations, which alter the heritability of diseases. The topic of disease prevention, as well as the diagnosis, requires further explanation and exploration. Finally, there are treatments that are quite promising, but more detailed research is needed.
    Keywords:  Mitochondria; diagnosis; heritability.; mitochondrial DNA; mitophagy; neurodegeneration; prevention; treatment
    DOI:  https://doi.org/10.2174/0118715303250271231018103202
  37. Arch Oral Biol. 2023 Nov 01. pii: S0003-9969(23)00228-5. [Epub ahead of print]157 105840
    Head and neck cancer stem cell maintenance relies on mTOR signaling, specifically involving the mechanistic target of rapamycin complexes 1 and 2 (mTORC1 and mTORC2).
    Luciana O Almeida, Luan César Silva, Carolina Emerick, Juliana Amorim Dos Santos, Rogerio M Castilho, Cristiane H Squarize.
       OBJECTIVE: Emerging evidence suggests that the modest response of head and neck squamous cell carcinoma (HNSCC) to treatment is associated with cancer stem cells (CSC). However, the signaling pathways that play a role in HNSCC CSC maintenance and therapy response are not well-understood. In this study, we investigate the response of CSCs to phosphatase and tensin homolog (PTEN) modulation and its potential dependency on the mammalian target of rapamycin (mTOR) signaling.
    DESIGN: PTEN deficiency was stably induced using short hairpin RNA (shRNA). Downregulation of RPTOR/mTORC1 and RICTOR/mTORC2 was achieved using small interfering RNA (siRNA). CSCs were evaluated through tumorsphere formation and were classified into various subtypes: parasphere, merosphere, and holosphere. We investigated the effect of rapamycin on CSC properties in both control and PTEN-deficient HNSCC cells.
    RESULTS: PTEN deficiency led to an accumulation of CSCs and enhanced a favorable response to rapamycin treatment. The viability of HNSCC CSCs was dependent on mTOR signaling. Deficiencies in both mTORC1 and mTORC2 reduced the number of CSCs. However, CSCs with PTEN deficiency had a greater reliance on mTORC1 signaling. Interestingly, when considering CSC subtypes, a deficiency in mTORC2 led to an increased number of paraspheres in both the control and PTEN-deficient groups.
    CONCLUSIONS: Loss of PTEN signaling increased the HNSCC CSC population, which can be targeted by rapamycin. However, the mTORC2 deficiency can induce a problematic selection of paraspheres CSCs subtype.
    Keywords:  Cancer stem cells; Chemotherapy; Head and neck tumors; Target therapy
    DOI:  https://doi.org/10.1016/j.archoralbio.2023.105840
  38. Nat Commun. 2023 Nov 03. 14(1): 7032
    Spliceosome component Usp39 contributes to hepatic lipid homeostasis through the regulation of autophagy.
    Donghai Cui, Zixiang Wang, Qianli Dang, Jing Wang, Junchao Qin, Jianping Song, Xiangyu Zhai, Yachao Zhou, Ling Zhao, Gang Lu, Hongbin Liu, Gang Liu, Runping Liu, Changshun Shao, Xiyu Zhang, Zhaojian Liu.
      Regulation of alternative splicing (AS) enables a single transcript to yield multiple isoforms that increase transcriptome and proteome diversity. Here, we report that spliceosome component Usp39 plays a role in the regulation of hepatocyte lipid homeostasis. We demonstrate that Usp39 expression is downregulated in hepatic tissues of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) subjects. Hepatocyte-specific Usp39 deletion in mice leads to increased lipid accumulation, spontaneous steatosis and impaired autophagy. Combined analysis of RNA immunoprecipitation (RIP-seq) and bulk RNA sequencing (RNA-seq) data reveals that Usp39 regulates AS of several autophagy-related genes. In particular, deletion of Usp39 results in alternative 5' splice site selection of exon 6 in Heat shock transcription factor 1 (Hsf1) and consequently its reduced expression. Importantly, overexpression of Hsf1 could attenuate lipid accumulation caused by Usp39 deficiency. Taken together, our findings indicate that Usp39-mediated AS is required for sustaining autophagy and lipid homeostasis in the liver.
    DOI:  https://doi.org/10.1038/s41467-023-42461-6
  39. Cell Metab. 2023 Nov 07. pii: S1550-4131(23)00380-7. [Epub ahead of print]35(11): 1872-1886
    Mitohormesis.
    Yu-Wei Cheng, Jie Liu, Toren Finkel.
      Perturbation of mitochondrial function can trigger a host of cellular responses that seek to restore cellular metabolism, cytosolic proteostasis, and redox homeostasis. In some cases, these responses persist even after the stress is relieved, leaving the cell or tissue in a less vulnerable state. This process-termed mitohormesis-is increasingly viewed as an important aspect of normal physiology and a critical modulator of various disease processes. Here, we review aspects of mitochondrial stress signaling that, among other things, can rewire the cell's metabolism, activate the integrated stress response, and alter cytosolic quality-control pathways. We also discuss how these pathways are implicated in various disease states from pathogen challenge to chemotherapeutic resistance and how their therapeutic manipulation can lead to new strategies for a host of chronic conditions including aging itself.
    DOI:  https://doi.org/10.1016/j.cmet.2023.10.011
  40. J Exp Med. 2024 Jan 01. pii: e20230367. [Epub ahead of print]221(1):
    ARL6IP1 gene delivery reduces neuroinflammation and neurodegenerative pathology in hereditary spastic paraplegia model.
    Jung Hwa Lim, Hyun Mi Kang, Dae Hun Kim, Bohyeon Jeong, Da Yong Lee, Jae-Ran Lee, Jeong Yeob Baek, Hyun-Soo Cho, Mi-Young Son, Dae Soo Kim, Nam-Soon Kim, Cho-Rok Jung.
      ARL6IP1 is implicated in hereditary spastic paraplegia (HSP), but the specific pathogenic mechanism leading to neurodegeneration has not been elucidated. Here, we clarified the molecular mechanism of ARL6IP1 in HSP using in vitro and in vivo models. The Arl6ip1 knockout (KO) mouse model was generated to represent the clinically involved frameshift mutations and mimicked the HSP phenotypes. Notably, in vivo brain histopathological analysis revealed demyelination of the axon and neuroinflammation in the white matter, including the corticospinal tract. In in vitro experiments, ARL6IP1 silencing caused cell death during neuronal differentiation and mitochondrial dysfunction by dysregulated autophagy. ARL6IP1 localized on mitochondria-associated membranes (MAMs) to maintain endoplasmic reticulum and mitochondrial homeostasis via direct interaction with LC3B and BCl2L13. ARL6IP1 played a crucial role in connecting the endoplasmic reticulum and mitochondria as a member of MAMs. ARL6IP1 gene therapy reduced HSP phenotypes and restored pathophysiological changes in the Arl6ip1 KO model. Our results established that ARL6IP1 could be a potential target for HSP gene therapy.
    DOI:  https://doi.org/10.1084/jem.20230367
  41. Cell Death Dis. 2023 Nov 10. 14(11): 729
    Aggregation of alpha-synuclein disrupts mitochondrial metabolism and induce mitophagy via cardiolipin externalization.
    Olivier Lurette, Rebeca Martín-Jiménez, Mehtab Khan, Razan Sheta, Stéphanie Jean, Mia Schofield, Maxime Teixeira, Raquel Rodriguez-Aller, Isabelle Perron, Abid Oueslati, Etienne Hebert-Chatelain.
      Accumulation of α-synuclein aggregates in the substantia nigra pars compacta is central in the pathophysiology of Parkinson's disease, leading to the degeneration of dopaminergic neurons and the manifestation of motor symptoms. Although several PD models mimic the pathological accumulation of α-synuclein after overexpression, they do not allow for controlling and monitoring its aggregation. We recently generated a new optogenetic tool by which we can spatiotemporally control the aggregation of α-synuclein using a light-induced protein aggregation system. Using this innovative tool, we aimed to characterize the impact of α-synuclein clustering on mitochondria, whose activity is crucial to maintain neuronal survival. We observed that aggregates of α-synuclein transiently and dynamically interact with mitochondria, leading to mitochondrial depolarization, lower ATP production, mitochondrial fragmentation and degradation via cardiolipin externalization-dependent mitophagy. Aggregation of α-synuclein also leads to lower mitochondrial content in human dopaminergic neurons and in mouse midbrain. Interestingly, overexpression of α-synuclein alone did not induce mitochondrial degradation. This work is among the first to clearly discriminate between the impact of α-synuclein overexpression and aggregation on mitochondria. This study thus represents a new framework to characterize the role of mitochondria in PD.
    DOI:  https://doi.org/10.1038/s41419-023-06251-8
  42. Cell Rep. 2023 Nov 08. pii: S2211-1247(23)01414-6. [Epub ahead of print]42(11): 113402
    ATM-CHK2-TRIM32 axis regulates ATG7 ubiquitination to initiate autophagy under oxidative stress.
    Jingwei Liu, Songming Lu, Lixia Zheng, Qiqiang Guo, Liangzi Cao, Yutong Xiao, Di Chen, Yu Zou, Xu Liu, Chengsi Deng, Siyi Zhang, Ruohan Yang, Yubang Wang, Ying Zhang, Naijin Zhang, Xiaoyu Song, Chengzhong Xing, Zhenning Wang, Liu Cao.
      Oxidative stress-induced autophagy helps to prevent cellular damage and to maintain homeostasis. However, the regulatory pathway that initiates autophagy remains unclear. We previously showed that reactive oxygen species (ROS) function as signaling molecules to activate the ATM-CHK2 pathway and promote autophagy. Here, we find that the E3 ubiquitin ligase TRIM32 functions downstream of ATM-CHK2 to regulate ATG7 ubiquitination. Under metabolic stress, ROS induce ATM phosphorylation at S1981, which in turn phosphorylates CHK2 at T68. We show that CHK2 binds and phosphorylates TRIM32 at the S55 site, which then mediates K63-linked ubiquitination of ATG7 at the K45 site to initiate autophagy. In addition, Chk2-/- mice show an aggravated infarction phenotype and reduced phosphorylation of TRIM32 and ubiquitination of ATG7 in a stroke model. We propose a molecular mechanism for autophagy initiation by ROS via the ATM-CHK2-TRIM32-ATG7 axis to maintain intracellular homeostasis and to protect cells exposed to pathological conditions from stress-induced tissue damage.
    Keywords:  ATG7; CP: Cell biology; CP: Molecular biology; ROS; autophagy; ubiquitination
    DOI:  https://doi.org/10.1016/j.celrep.2023.113402
  43. Cell Cycle. 2023 Nov 08. 1-13
    SNHG15 promotes gallbladder cancer progression by enhancing the autophagy of tumor cell under nutrition stress.
    He Min, Linhua Yang, Xinsen Xu, Yajun Geng, Fatao Liu, Yingbin Liu.
      Gallbladder cancer (GBC) is a major malignant carcinoma of the biliary tract with extremely poor prognosis. Currently, there is no useful therapy strategies for GBC treatment, indicating the unmet mechanism researches for GBC. In this study, our data showed that SNHG15 expression significantly up-regulated and its high expression associated with poor overall survival of patients suffer from GBC. Functional experiments showed that SNHG15 depletion delayed the proliferation and enhanced the apoptosis of GBC tumor cells under the nutrition stress condition, which further confirmed in the subcutaneous xenograft model and liver metastasis model. Mechanistically, SNHG15 could interact with AMPK and facilitate the phosphorylation of AMPK to Tuberous sclerosis complex TSC2, resulting in mTOR suppression and autophagy enhancement, and finally, conferring the GBC cell sustain proliferation under nutrition stress. Taken together, our findings revealed that SNHG15 promotes GBC tumor progression by enhancing the autophagy under poor nutrition tumor microenvironment, which could be a promising targets for GBC.
    Keywords:  Gallbladder cancer; SNHG15; TSC2; autophagy
    DOI:  https://doi.org/10.1080/15384101.2023.2278339
  44. J Pharm Pharmacol. 2023 Nov 02. pii: rgad100. [Epub ahead of print]
    Maackiain suppresses the development of cervical cancer via AMPK priming autophagy.
    Juan He, Lan Xiang, Tingting Zhu, Haiyan Wang, Yurong Huang, Hui Li, Chenggui Miao, Yali Zhuang, Yunxia Cao.
       BACKGROUND: Maackiain (Mac), a flavonoid analog isolated from Sophora flavescens, exhibits neuroprotective, anti-allergic, anti-inflammatory, and pro-apoptotic effects. It is not clear whether Mac has a therapeutic effect on cervical cancer.
    METHOD: In this work, we used RT-qPCR, western blot, immunofluorescence, and related methods to detect the therapeutic mechanism of Mac for cervical cancer.
    RESULTS: We demonstrated that Mac significantly inhibited the proliferation, migration, and invasion of human cervical cancer cell lines HeLa and SiHa. And, Mac enhanced the pro-apoptotic effects of cisplatin in treating cervical cancer cells. Mac has shown good efficacy in treating cervical cancer. Furthermore, Mac inhibited the mammalian target of the rapamycin (mTOR) pathway, thereby inducing autophagy in cervical cancer cells. The regulation of mTOR/autophagy pathway by Mac relied on the activation of AMP-activated protein kinase (AMPK), and the inhibition of the AMPK reversed the Mac's anti-cervical cancer activity. In addition, experimental study of Mac in mouse xenograft tumor model further confirmed its good anti-cervical cancer activity.
    CONCLUSION: Mac inhibits human cervical cancer by activating the AMPK/mTOR/autophagy pathway, indicating that it is a potential natural compound for the treatment of cervical cancer. This study also provides a feasible molecular mechanism for the treatment of cervical cancer.
    Keywords:  AMPK; Maackiain; autophagy; cervical cancer; mTOR pathway
    DOI:  https://doi.org/10.1093/jpp/rgad100
  45. Front Cell Neurosci. 2023 ;17 1274727
    Crucial role of autophagy in propofol-treated neurological diseases: a comprehensive review.
    Sicong Yu, Jian Liao, Xuezheng Lin, Yu Luo, Guangtao Lu.
      Neurological disorders are the leading cause of disability and death globally. Currently, there is a significant concern about the therapeutic strategies that can offer reliable and cost-effective treatment for neurological diseases. Propofol is a widely used general intravenous anesthetic in the clinic. Emerging studies demonstrate that propofol exerts neuroprotective effects on neurological diseases and disorders, while its underlying pathogenic mechanism is not well understood. Autophagy, an important process of cell turnover in eukaryotes, has been suggested to involve in the neuroprotective properties developed by propofol. In this narrative review, we summarized the current evidence on the roles of autophagy in propofol-associated neurological diseases. This study highlighted the effect of propofol on the nervous system and the crucial roles of autophagy. According to the 21 included studies, we found that propofol was a double-edged sword for neurological disorders. Several eligible studies reported that propofol caused neuronal cell damage by regulating autophagy, leading to cognitive dysfunction and other neurological diseases, especially high concentration and dose of propofol. However, some of them have shown that in the model of existing nervous system diseases (e.g., cerebral ischemia-reperfusion injury, electroconvulsive therapy injury, cobalt chloride-induced injury, TNF-α-induced injury, and sleep deprivation-induced injury), propofol might play a neuroprotective role by regulating autophagy, thus improving the degree of nerve damage. Autophagy plays a pivotal role in the neurological system by regulating oxidative stress, inflammatory response, calcium release, and other mechanisms, which may be associated with the interaction of a variety of related proteins and signal cascades. With extensive in-depth research in the future, the autophagic mechanism mediated by propofol will be fully understood, which may facilitate the feasibility of propofol in the prevention and treatment of neurological disorders.
    Keywords:  autophagy; mechanism; neurological disorders; propofol; treatment
    DOI:  https://doi.org/10.3389/fncel.2023.1274727
  46. Childs Nerv Syst. 2023 Nov 10.
    Treatment of tuberous sclerosis complex manifestations in children with mTOR inhibitors.
    Şule Yeşil, Burçak Kurucu, Melda Berber Hamamcı, Şükriye Yılmaz, Gürses Şahin.
       PURPOSE: Tuberous sclerosis complex (TSC) is a rare autosomal dominant genetic disorder that affects multiple organ systems. Mutations in the TSC1 and TSC2 genes result in the constitutive hyperactivation of the mammalian target of rapamycin (mTOR) pathway, contributing to the growth of benign tumors or hamartomas in various organs. Due to the implication of mTOR pathway dysregulation in the disease pathology, increasing evidence supports the use of mTOR inhibitors for treating multiple manifestations of TSC.
    METHODS: In this study, we conducted a retrospective analysis of clinical findings and treatment data from 38 patients diagnosed with tuberous sclerosis who were followed up in the Pediatric Oncology Clinic between 2010 and 2020. We collected information on patients' ages, genders, affected sites, familial history, imaging findings, presence of tumors, and treatments.
    RESULTS: Among the patients, nine individuals with TSC manifestations were treated with mTOR inhibitors. Specifically, everolimus was successfully administered to five patients with inborn cardiac rhabdomyoma causing hemodynamic impairment. In addition, two patients with refractory seizures received everolimus in combination with anti-epileptic drugs. A patient with renal angiomyolipomas larger than 3 cm was treated with everolimus, while a patient with extensive facial angiofibroma received topical sirolimus. All patients tolerated the mTOR inhibitors well, and the side effects were deemed acceptable.
    CONCLUSION: The utilization of mTOR inhibition in TSC is expected to become more prevalent in clinical practice, as current research is anticipated to provide a better understanding of the therapeutic roles of these treatments in TSC.
    Keywords:  Treatment; Tuberous sclerosis complex; mTOR inhibitors
    DOI:  https://doi.org/10.1007/s00381-023-06218-2
  47. Biomed Pharmacother. 2023 Nov 01. pii: S0753-3322(23)01611-6. [Epub ahead of print]168 115813
    Liensinine alleviates LPS-induced acute lung injury by blocking autophagic flux via PI3K/AKT/mTOR signaling pathway.
    Cheng Wang, Kang Zou, Yunlian Diao, Chaoqi Zhou, Jia Zhou, Yuting Yang, Zhenguo Zeng.
      Acute lung injury (ALI) is a major pathological problem characterized by severe inflammatory reactions and is a critical disease with high clinical morbidity and mortality. Liensinine, a major isoquinoline alkaloid, is extracted from the green embryos of mature Nelumbonaceae seeds. It has been reported to have an inhibitory effect on tumors. However, the effects of liensinine on ALI have not been reported to-date. The aim of this study was to explore the inhibitory effects of liensinine on lipopolysaccharide (LPS)-induced ALI and its possible mechanism. We found that liensinine significantly reduced LPS-induced ALI and reduced the production of inflammatory factors IL-6, IL-8, and TNF-α. In addition, liensinine blocked autophagic flux and increased the number of autophagosomes by upregulating LC3-II/I and p62 protein levels. More importantly, pretreatment with the early stages autophagy inhibitor 3-Methyladenine (3-MA) can reverse the inhibitory effects of liensinine on the secretion of inflammatory factors in ALI. The PI3K/AKT/mTOR pathway is involved in LPS-induced autophagy regulated by liensinine in ALI. In summary, this study suggests that liensinine inhibits the production of inflammatory factors in LPS-induced ALI by regulating autophagy via the PI3K/AKT/mTOR pathway, which may provide a new therapeutic strategy to alleviate ALI.
    Keywords:  Acute lung injury; Autophagic flux; Liensinine; PI3K/AKT/mTOR pathway
    DOI:  https://doi.org/10.1016/j.biopha.2023.115813
  48. Nat Commun. 2023 Nov 03. 14(1): 7034
    Integrative analysis reveals a conserved role for the amyloid precursor protein in proteostasis during aging.
    Vanitha Nithianandam, Hassan Bukhari, Matthew J Leventhal, Rachel A Battaglia, Xianjun Dong, Ernest Fraenkel, Mel B Feany.
      Aβ peptides derived from the amyloid precursor protein (APP) have been strongly implicated in the pathogenesis of Alzheimer's disease. However, the normal function of APP and the importance of that role in neurodegenerative disease is less clear. We recover the Drosophila ortholog of APP, Appl, in an unbiased forward genetic screen for neurodegeneration mutants. We perform comprehensive single cell transcriptional and proteomic studies of Appl mutant flies to investigate Appl function in the aging brain. We find an unexpected role for Appl in control of multiple cellular pathways, including translation, mitochondrial function, nucleic acid and lipid metabolism, cellular signaling and proteostasis. We mechanistically define a role for Appl in regulating autophagy through TGFβ signaling and document the broader relevance of our findings using mouse genetic, human iPSC and in vivo tauopathy models. Our results demonstrate a conserved role for APP in controlling age-dependent proteostasis with plausible relevance to Alzheimer's disease.
    DOI:  https://doi.org/10.1038/s41467-023-42822-1
  49. Nat Commun. 2023 Nov 09. 14(1): 7246
    Cryo-electron tomography of NLRP3-activated ASC complexes reveals organelle co-localization.
    Yangci Liu, Haoming Zhai, Helen Alemayehu, Jérôme Boulanger, Lee J Hopkins, Alicia C Borgeaud, Christina Heroven, Jonathan D Howe, Kendra E Leigh, Clare E Bryant, Yorgo Modis.
      NLRP3 induces caspase-1-dependent pyroptotic cell death to drive inflammation. Aberrant activity of NLRP3 occurs in many human diseases. NLRP3 activation induces ASC polymerization into a single, micron-scale perinuclear punctum. Higher resolution imaging of this signaling platform is needed to understand how it induces pyroptosis. Here, we apply correlative cryo-light microscopy and cryo-electron tomography to visualize ASC/caspase-1 in NLRP3-activated cells. The puncta are composed of branched ASC filaments, with a tubular core formed by the pyrin domain. Ribosomes and Golgi-like or endosomal vesicles permeate the filament network, consistent with roles for these organelles in NLRP3 activation. Mitochondria are not associated with ASC but have outer-membrane discontinuities the same size as gasdermin D pores, consistent with our data showing gasdermin D associates with mitochondria and contributes to mitochondrial depolarization.
    DOI:  https://doi.org/10.1038/s41467-023-43180-8
  50. PLoS Genet. 2023 Nov 07. 19(11): e1011005
    Dominant negative variants in KIF5B cause osteogenesis imperfecta via down regulation of mTOR signaling.
    Undiagnosed Diseases Network
       BACKGROUND: Kinesin motor proteins transport intracellular cargo, including mRNA, proteins, and organelles. Pathogenic variants in kinesin-related genes have been implicated in neurodevelopmental disorders and skeletal dysplasias. We identified de novo, heterozygous variants in KIF5B, encoding a kinesin-1 subunit, in four individuals with osteogenesis imperfecta. The variants cluster within the highly conserved kinesin motor domain and are predicted to interfere with nucleotide binding, although the mechanistic consequences on cell signaling and function are unknown.
    METHODS: To understand the in vivo genetic mechanism of KIF5B variants, we modeled the p.Thr87Ile variant that was found in two patients in the C. elegans ortholog, unc-116, at the corresponding position (Thr90Ile) by CRISPR/Cas9 editing and performed functional analysis. Next, we studied the cellular and molecular consequences of the recurrent p.Thr87Ile variant by microscopy, RNA and protein analysis in NIH3T3 cells, primary human fibroblasts and bone biopsy.
    RESULTS: C. elegans heterozygous for the unc-116 Thr90Ile variant displayed abnormal body length and motility phenotypes that were suppressed by additional copies of the wild type allele, consistent with a dominant negative mechanism. Time-lapse imaging of GFP-tagged mitochondria showed defective mitochondria transport in unc-116 Thr90Ile neurons providing strong evidence for disrupted kinesin motor function. Microscopy studies in human cells showed dilated endoplasmic reticulum, multiple intracellular vacuoles, and abnormal distribution of the Golgi complex, supporting an intracellular trafficking defect. RNA sequencing, proteomic analysis, and bone immunohistochemistry demonstrated down regulation of the mTOR signaling pathway that was partially rescued with leucine supplementation in patient cells.
    CONCLUSION: We report dominant negative variants in the KIF5B kinesin motor domain in individuals with osteogenesis imperfecta. This study expands the spectrum of kinesin-related disorders and identifies dysregulated signaling targets for KIF5B in skeletal development.
    DOI:  https://doi.org/10.1371/journal.pgen.1011005
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