bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2023‒09‒24
fifty papers selected by
Viktor Korolchuk, Newcastle University
  1. Evolutionarily acquired response of selective autophagy receptors provides resilience against oxidative stress.
  2. Cogs in the autophagic machine-equipped to combat dementia-prone neurodegenerative diseases.
  3. Ksp1 is an autophagic receptor protein for the Snx4-assisted autophagy of Ssn2/Med13.
  4. mTOR signaling and Alzheimer's disease: What we know and where we are?
  5. A mechanism that ensures non-selective cytoplasm degradation by autophagy.
  6. ATPase-regulated autophagosome biogenesis.
  7. Neuronal mTORC1 inhibition promotes longevity without suppressing anabolic growth and reproduction in C. elegans.
  8. Cell-specific alterations in autophagy-lysosomal activity near the chronically implanted microelectrodes.
  9. FGF21 and autophagy coordinately counteract kidney disease progression during aging and obesity.
  10. Dysregulation of the Progranulin-driven Autophagy-lysosomal Pathway Mediates Secretion of the Nuclear Protein TDP-43.
  11. Opposing roles of RUBCN isoforms in autophagy and memory B cell generation.
  12. A toxic gain-of-function mechanism in C9orf72 ALS impairs the autophagy-lysosome pathway in neurons.
  13. Depletion of mTOR ameliorates CD4+ T cell pyroptosis by promoting autophagy activity in septic mice.
  14. AZI2 mediates TBK1 activation at unresolved selective autophagy cargo receptor complexes with implications for CD8 T-cell infiltration in breast cancer.
  15. Autophagy and LC3-associated phagocytosis contribute negatively to the killing capability of THP-1-derived macrophages against Candida albicans at the mid-stage.
  16. Autophagy in colitis-associated colon cancer: exploring its potential role in reducing initiation and preventing IBD-Related CAC development.
  17. Enhancing Efficacy of Albumin-Bound Paclitaxel for Human Lung and Colorectal Cancers through Autophagy Receptor Sequestosome 1 (SQSTM1)/p62-Mediated Nanodrug Delivery and Cancer therapy.
  18. Autophagy in Intracerebral Hemorrhage: From Mechanism to Regulation.
  19. Inhibition of PRKAA/AMPK (Ser485/491) phosphorylation by crizotinib induces cardiotoxicity via perturbing autophagosome-lysosome fusion.
  20. The post-translational regulation of transcription factor EB (TFEB) in health and disease.
  21. Dynamic modelling and tristability analysis of misfolded α-synuclein degraded via autophagy in Parkinson's disease.
  22. Toxoplasma gondii autophagy-related protein ATG7 maintains apicoplast inheritance by stabilizing and lipidating ATG8.
  23. A new vulnerability to BET inhibition due to enhanced autophagy in BRCA2 deficient pancreatic cancer.
  24. Construction of a Dual-Emissive Probe for Discriminative Visualization of Lysosomal and Mitochondrial Dysfunction.
  25. Autophagy in liver regeneration: Unravelling the endothelial cell's role and therapeutic prospects.
  26. Hyperoside attenuates pyrrolizidine alkaloids-induced liver injury by ameliorating TFEB-mediated mitochondrial dysfunction.
  27. Iditarod, a Drosophila homolog of the Irisin precursor FNDC5, is critical for exercise performance and cardiac autophagy.
  28. Regulation of nucleo-cytosolic 26S proteasome translocation by aromatic amino acids via mTOR is essential for cell survival under stress.
  29. Neuronal MML-1/MXL-2 regulates systemic aging via glutamate transporter and cell nonautonomous autophagic and peroxidase activity.
  30. Rebalancing of mitochondrial homeostasis through an NAD+-SIRT1 pathway preserves intestinal barrier function in severe malnutrition.
  31. Malignant Brain Aging: The Formidable Link Between Dysregulated Signaling Through Mechanistic Target of Rapamycin Pathways and Alzheimer's Disease (Type 3 Diabetes).
  32. Elucidating the molecular mechanisms underlying the induction of autophagy by antidepressant-like substances in C57BL/6J mouse testis model upon LPS challenge.
  33. DAP1 regulates osteoblast autophagy via the ATG16L1-LC3 axis in Graves' disease-induced osteoporosis.
  34. Porphyromonas gingivalis, a periodontal pathogen, impairs post-infarcted myocardium by inhibiting autophagosome-lysosome fusion.
  35. Parkinson's disease-linked parkin mutation disrupts recycling of synaptic vesicles in human dopaminergic neurons.
  36. The Lysosomal Calcium Channel TRPML1 Maintains Mitochondrial Fitness in NK Cells through Interorganelle Cross-Talk.
  37. Activity of granulomatosis with polyangiitis and its correlation with mTOR phosphoproteomics in neutrophils.
  38. mTOR signaling in hair follicle and hair diseases: recent progress.
  39. Synaptotagmin-7 Mediates Cardiac Hypertrophy by Targeting Autophagy.
  40. Selective retention of dysfunctional mitochondria during asymmetric cell division in yeast.
  41. Crosstalk among Reactive Oxygen Species, Autophagy and Metabolism in Myocardial Ischemia and Reperfusion Stages.
  42. ER stress elicits non-canonical CASP8 (caspase 8) activation on autophagosomal membranes to induce apoptosis.
  43. Deletion of the Homocysteine Thiolactone Detoxifying Enzyme Bleomycin Hydrolase, in Mice, Causes Memory and Neurological Deficits and Worsens Alzheimer's Disease-Related Behavioral and Biochemical Traits in the 5xFAD Model of Alzheimer's Disease.
  44. TORC1 mediated regulation of mitochondrial integrity and calcium ion homeostasis by Wat1/mLst8 in S. pombe.
  45. The role of autophagy in mitigating osteoarthritis progression via regulation of chondrocyte apoptosis: a review.
  46. CSNK1A1/CK1α suppresses autoimmunity by restraining the CGAS-STING1 signaling.
  47. Extracellular Glutamine Promotes Intestinal Porcine Epithelial Cell Proliferation via Arf1-mTORC1 Pathway Independently of Rag GTPases.
  48. Temporal landscape of mitochondrial proteostasis governed by the UPRmt.
  49. Gemigliptin, a DPP4 inhibitor, ameliorates nonalcoholic steatohepatitis through AMP-activated protein kinase-independent and ULK1-mediated autophagy.
  50. A monocarboxylate transporter rescues frontotemporal dementia and Alzheimer's disease models.
  1. Bioessays. 2023 Sep 19. e2300168
    Evolutionarily acquired response of selective autophagy receptors provides resilience against oxidative stress.
    Fazilet Bekbulat.
      
    Keywords:  aggrephagy; aging; autophagy; mitophagy; neurodegeneration; oxidative stress; selective autophagy receptors
    DOI:  https://doi.org/10.1002/bies.202300168
  2. Front Mol Neurosci. 2023 ;16 1225227
    Cogs in the autophagic machine-equipped to combat dementia-prone neurodegenerative diseases.
    Sholto de Wet, Rensu Theart, Ben Loos.
      Neurodegenerative diseases are often characterized by hydrophobic inclusion bodies, and it may be the case that the aggregate-prone proteins that comprise these inclusion bodies are in fact the cause of neurotoxicity. Indeed, the appearance of protein aggregates leads to a proteostatic imbalance that causes various interruptions in physiological cellular processes, including lysosomal and mitochondrial dysfunction, as well as break down in calcium homeostasis. Oftentimes the approach to counteract proteotoxicity is taken to merely upregulate autophagy, measured by an increase in autophagosomes, without a deeper assessment of contributors toward effective turnover through autophagy. There are various ways in which autophagy is regulated ranging from the mammalian target of rapamycin (mTOR) to acetylation status of proteins. Healthy mitochondria and the intracellular energetic charge they preserve are key for the acidification status of lysosomes and thus ensuring effective clearance of components through the autophagy pathway. Both mitochondria and lysosomes have been shown to bear functional protein complexes that aid in the regulation of autophagy. Indeed, it may be the case that minimizing the proteins associated with the respective neurodegenerative pathology may be of greater importance than addressing molecularly their resulting inclusion bodies. It is in this context that this review will dissect the autophagy signaling pathway, its control and the manner in which it is molecularly and functionally connected with the mitochondrial and lysosomal system, as well as provide a summary of the role of autophagy dysfunction in driving neurodegenerative disease as a means to better position the potential of rapamycin-mediated bioactivities to control autophagy favorably.
    Keywords:  autophagy; lysosomes; mitochondrial function; mitophagy; neurodegenerative diseases; proteostasis
    DOI:  https://doi.org/10.3389/fnmol.2023.1225227
  3. Autophagy. 2023 Sep 21.
    Ksp1 is an autophagic receptor protein for the Snx4-assisted autophagy of Ssn2/Med13.
    Sara E Hanley, Stephen D Willis, Steven J Doyle, Randy Strich, Katrina F Cooper.
      Ksp1 is a casein II-like kinase whose activity prevents aberrant macroautophagy/autophagy induction in nutrient-rich conditions in yeast. Here, we describe a kinase-independent role of Ksp1 as a novel autophagic receptor protein for Ssn2/Med13, a known cargo of Snx4-assisted autophagy of transcription factors. In this pathway, a subset of conserved transcriptional regulators, Ssn2/Med13, Rim15, and Msn2, are selectively targeted for vacuolar proteolysis following nitrogen starvation, assisted by the sorting nexin heterodimer Snx4-Atg20. Here we show that phagophores also engulf Ksp1 alongside its cargo for vacuolar proteolysis. Ksp1 directly associates with Atg8 following nitrogen starvation at the interface of an Atg8-family interacting motif (AIM)/LC3-interacting region (LIR) in Ksp1 and the LIR/AIM docking site (LDS) in Atg8. Mutating the LDS site prevents the autophagic degradation of Ksp1. However, deletion of the C terminal canonical AIM still permitted Ssn2/Med13 proteolysis, suggesting that additional non-canonical AIMs may mediate the Ksp1-Atg8 interaction. Ksp1 is recruited to the perivacuolar phagophore assembly site by Atg29, a member of the trimeric scaffold complex. This interaction is independent of Atg8 and Snx4, suggesting that Ksp1 is recruited early to phagophores, with Snx4 delivering Ssn2/Med13 thereafter. Finally, normal cell survival following prolonged nitrogen starvation requires Ksp1. Together, these studies define a kinase-independent role for Ksp1 as an autophagic receptor protein mediating Ssn2/Med13 degradation. They also suggest that phagophores built by the trimeric scaffold complex are capable of receptor-mediated autophagy. These results demonstrate the dual functionality of Ksp1, whose kinase activity prevents autophagy while it plays a scaffolding role supporting autophagic degradation.
    Keywords:  Atg8; Ksp1; Ssn2/Med13; phagophore assembly site (PAS); receptor proteins; trimeric scaffold complex (17C); vacuolar degradation
    DOI:  https://doi.org/10.1080/15548627.2023.2259708
  4. CNS Neurosci Ther. 2023 Sep 18.
    mTOR signaling and Alzheimer's disease: What we know and where we are?
    Samin Davoody, Afsaneh Asgari Taei, Pariya Khodabakhsh, Leila Dargahi.
      Despite the great body of research done on Alzheimer's disease, the underlying mechanisms have not been vividly investigated. To date, the accumulation of amyloid-beta plaques and tau tangles constitutes the hallmark of the disease; however, dysregulation of the mammalian target of rapamycin (mTOR) seems to be significantly involved in the pathogenesis of the disease as well. mTOR, as a serine-threonine protein kinase, previously known for controlling many cellular functions such as cell size, autophagy, and metabolism. In this regard, mammalian target of rapamycin complex 1 (mTORC1) may leave anti-aging impacts by robustly inhibiting autophagy, a mechanism that inhibits the accumulation of damaged protein aggregate and dysfunctional organelles. Formation and aggregation of neurofibrillary tangles and amyloid-beta plaques seem to be significantly regulated by mTOR signaling. Understanding the underlying mechanisms and connection between mTOR signaling and AD may suggest conducting clinical trials assessing the efficacy of rapamycin, as an mTOR inhibitor drug, in managing AD or may help develop other medications. In this literature review, we aim to elaborate mTOR signaling network mainly in the brain, point to gaps of knowledge, and define how and in which ways mTOR signaling can be connected with AD pathogenesis and symptoms.
    Keywords:  Alzheimer's disease; mammalian target of rapamycin; pathogenesis; rapamycin
    DOI:  https://doi.org/10.1111/cns.14463
  5. Nat Commun. 2023 09 19. 14(1): 5815
    A mechanism that ensures non-selective cytoplasm degradation by autophagy.
    Tetsuya Kotani, Yuji Sakai, Hiromi Kirisako, Chika Kakuta, Soichiro Kakuta, Yoshinori Ohsumi, Hitoshi Nakatogawa.
      In autophagy, a membrane cisterna called the isolation membrane expands, bends, becomes spherical, and closes to sequester cytoplasmic constituents into the resulting double-membrane vesicle autophagosome for lysosomal/vacuolar degradation. Here, we discover a mechanism that allows the isolation membrane to expand with a large opening to ensure non-selective cytoplasm sequestration within the autophagosome. A sorting nexin complex that localizes to the opening edge of the isolation membrane plays a critical role in this process. Without the complex, the isolation membrane expands with a small opening that prevents the entry of particles larger than about 25 nm, including ribosomes and proteasomes, although autophagosomes of nearly normal size eventually form. This study sheds light on membrane morphogenesis during autophagosome formation and selectivity in autophagic degradation.
    DOI:  https://doi.org/10.1038/s41467-023-41525-x
  6. Autophagy. 2023 Sep 18. 1-2
    ATPase-regulated autophagosome biogenesis.
    Viola Nähse, Kay O Schink, Harald Stenmark.
      Omega-shaped domains of the endoplasmic reticulum, known as omegasomes, have been suggested to contribute to autophagosome biogenesis, although their exact function is not known. Omegasomes are characterized by the presence of the double FYVE domain containing protein ZFYVE1/DFCP1, but it has remained a paradox that depletion of ZFYVE1 does not prevent bulk macroautophagy/autophagy. We recently showed that ZFYVE1 contains an N-terminal ATPase domain which dimerizes upon ATP binding. Mutations in the ATPase domain that inhibit ATP binding or hydrolysis do not prevent omegasome expansion and maturation. However, omegasome constriction is inhibited by these mutations, which results in an increased lifetime and thereby higher number of omegasomes. Interestingly, whereas ZFYVE1 knockout or mutations do not significantly affect bulk autophagy, selective autophagy of mitochondria, protein aggregates and micronuclei is inhibited. We propose that ATP binding and hydrolysis control the di- or multimerization state of ZFYVE1 which could provide the mechanochemical energy to drive large omegasome constriction and autophagosome completion.
    Keywords:  Aggrephagy; Atpase; autophagosome; micronucleophagy; mitophagy; omegasome
    DOI:  https://doi.org/10.1080/15548627.2023.2255967
  7. PLoS Genet. 2023 Sep 18. 19(9): e1010938
    Neuronal mTORC1 inhibition promotes longevity without suppressing anabolic growth and reproduction in C. elegans.
    Hannah J Smith, Anne Lanjuin, Arpit Sharma, Aditi Prabhakar, Ewelina Nowak, Peter G Stine, Rohan Sehgal, Klement Stojanovski, Benjamin D Towbin, William B Mair.
      mTORC1 (mechanistic target of rapamycin complex 1) is a metabolic sensor that promotes growth when nutrients are abundant. Ubiquitous inhibition of mTORC1 extends lifespan in multiple organisms but also disrupts several anabolic processes resulting in stunted growth, slowed development, reduced fertility, and disrupted metabolism. However, it is unclear if these pleotropic effects of mTORC1 inhibition can be uncoupled from longevity. Here, we utilize the auxin-inducible degradation (AID) system to restrict mTORC1 inhibition to C. elegans neurons. We find that neuron-specific degradation of RAGA-1, an upstream activator of mTORC1, or LET-363, the ortholog of mammalian mTOR, is sufficient to extend lifespan in C. elegans. Unlike raga-1 loss of function genetic mutations or somatic AID of RAGA-1, neuronal AID of RAGA-1 robustly extends lifespan without impairing body size, developmental rate, brood size, or neuronal function. Moreover, while degradation of RAGA-1 in all somatic tissues alters the expression of thousands of genes, demonstrating the widespread effects of mTORC1 inhibition, degradation of RAGA-1 in neurons only results in around 200 differentially expressed genes with a specific enrichment in metabolism and stress response. Notably, our work demonstrates that targeting mTORC1 specifically in the nervous system in C. elegans uncouples longevity from growth and reproductive impairments, and that many canonical effects of low mTORC1 activity are not required to promote healthy aging. These data challenge previously held ideas about the mechanisms of mTORC1 lifespan extension and underscore the potential of promoting longevity by neuron-specific mTORC1 modulation.
    DOI:  https://doi.org/10.1371/journal.pgen.1010938
  8. Biomaterials. 2023 Sep 11. pii: S0142-9612(23)00324-1. [Epub ahead of print]302 122316
    Cell-specific alterations in autophagy-lysosomal activity near the chronically implanted microelectrodes.
    Keying Chen, Camila Garcia Padilla, Kirill Kiselyov, Takashi D Y Kozai.
      Intracortical microelectrodes that can record and stimulate brain activity have become a valuable technique for basic science research and clinical applications. However, long-term implantation of these microelectrodes can lead to progressive neurodegeneration in the surrounding microenvironment, characterized by elevation in disease-associated markers. Dysregulation of autophagy-lysosomal degradation, a major intracellular waste removal process, is considered a key factor in the onset and progression of neurodegenerative diseases. It is plausible that similar dysfunctions in autophagy-lysosomal degradation contribute to tissue degeneration following implantation-induced focal brain injury, ultimately impacting recording performance. To understand how the focal, persistent brain injury caused by long-term microelectrode implantation impairs autophagy-lysosomal pathway, we employed two-photon microscopy and immunohistology. This investigation focused on the spatiotemporal characterization of autophagy-lysosomal activity near the chronically implanted microelectrode. We observed an aberrant accumulation of immature autophagy vesicles near the microelectrode over the chronic implantation period. Additionally, we found deficits in autophagy-lysosomal clearance proximal to the chronic implant, which was associated with an accumulation of autophagy cargo and a reduction in lysosomal protease level during the chronic period. Furthermore, our evidence demonstrates reactive astrocytes have myelin-containing lysosomes near the microelectrode, suggesting its role of myelin engulfment during acute implantation period. Together, this study sheds light on the process of brain tissue degeneration caused by long-term microelectrode implantation, with a specific focus on impaired intracellular waste degradation.
    Keywords:  Brain-computer interface; Glial reactivity; Neuron survival; Tissue homeostasis; brain metabolism
    DOI:  https://doi.org/10.1016/j.biomaterials.2023.122316
  9. Autophagy. 2023 Sep 18.
    FGF21 and autophagy coordinately counteract kidney disease progression during aging and obesity.
    Satoshi Minami, Shinsuke Sakai, Takeshi Yamamoto, Yoshitsugu Takabatake, Tomoko Namba-Hamano, Atsushi Takahashi, Jun Matsuda, Hiroaki Yonishi, Jun Nakamura, Shihomi Maeda, Sho Matsui, Isao Matsui, Yoshitaka Isaka.
      Chronic kidney disease (CKD) has reached epidemic proportions worldwide, partly due to the increasing population of elderly and obesity. Macroautophagy/autophagy counteracts CKD progression, whereas autophagy is stagnated owing to lysosomal overburden during aging and obesity, which promotes CKD progression. Therefore, for preventing CKD progression during aging and obesity, it is important to elucidate the compensation mechanisms of autophagy stagnation. We recently showed that FGF21 (fibroblast growth factor 21), which is a prolongevity and metabolic hormone, is induced by autophagy deficiency in kidney proximal tubular epithelial cells (PTECs); however, its pathophysiological role remains uncertain. Here, we investigated the interplay between FGF21 and autophagy and the direct contribution of endogenous FGF21 in the kidney during aging and obesity using PTEC-specific fgf21- and/or atg5-deficient mice at 24 months (aged) or under high-fat diet (obese) conditions. PTEC-specific FGF21 deficiency in young mice increased autophagic flux due to increased demand of autophagy, whereas fgf21-deficient aged or obese mice exacerbated autophagy stagnation due to severer lysosomal overburden caused by aberrant autophagy. FGF21 was robustly induced by autophagy deficiency, and aged or obese PTEC-specific fgf21- and atg5-double deficient mice deteriorated renal histology compared with atg5-deficient mice. Mitochondrial function was severely disturbed concomitant with exacerbated oxidative stress and downregulated TFAM (transcription factor A, mitochondrial) in double-deficient mice. These results indicate that FGF21 is robustly induced by autophagy disturbance and protects against CKD progression during aging and obesity by alleviating autophagy stagnation and maintaining mitochondrial homeostasis, which will pave the way to a novel treatment for CKD. (249 words).
    Keywords:  Ageing; FGF21; autophagy stagnation; lysosome; mitochondria; obesity
    DOI:  https://doi.org/10.1080/15548627.2023.2259282
  10. J Biol Chem. 2023 Sep 20. pii: S0021-9258(23)02300-1. [Epub ahead of print] 105272
    Dysregulation of the Progranulin-driven Autophagy-lysosomal Pathway Mediates Secretion of the Nuclear Protein TDP-43.
    Yoshinori Tanaka, Shun-Ichi Ito, Yuki Honma, Masato Hasegawa, Fuyuki Kametani, Genjiro Suzuki, Lina Kozuma, Kosuke Takeya, Masumi Eto.
      The cytoplasmic accumulation of the nuclear protein TDP-43 has been linked to the progression of amyotrophic lateral sclerosis and frontotemporal lobar degeneration (FTLD). TDP-43 secreted into the extracellular space has been suggested to contribute to the cell-to-cell spread of the cytoplasmic accumulation of TDP-43 throughout the brain; however, the underlying mechanisms remain unknown. We herein demonstrated that the secretion of TDP-43 was stimulated by the inhibition of the autophagy-lysosomal pathway driven by progranulin (PGRN), a causal protein of FTLD. Among modulators of autophagy, only vacuolar-ATPase inhibitors, such as bafilomycin A1 (Baf), increased the levels of the full-length and cleaved forms of TDP-43 and the autophagosome marker LC3-II in extracellular vesicle fractions prepared from the culture media of HeLa, SH-SY5Y or NSC-34 cells, whereas vacuolin-1, MG132, chloroquine, rapamycin, and serum starvation did not. The C-terminal fragment of TDP-43 was required for Baf-induced TDP-43 secretion. The Baf treatment induced the translocation of the aggregate-prone GFP-tagged C-terminal fragment of TDP-43 and mCherry-tagged LC3 to the plasma membrane. The Baf-induced secretion of TDP-43 was attenuated in autophagy-deficient ATG16L1 knockout HeLa cells. The knockdown of PGRN induced the secretion of cleaved TDP-43 in an autophagy-dependent manner in HeLa cells. The knockout of PGRN in MEFs increased the secretion of the cleaved forms of TDP-43 and LC3-II. The treatment inducing TDP-43 secretion increased the nuclear translocation of GFP-tagged TFEB, a master regulator of the autophagy-lysosomal pathway in SH-SY5Y cells. These results suggest that the secretion of TDP-43 is promoted by dysregulation of the PGRN-driven autophagy-lysosomal pathway.
    Keywords:  TAR DNA‐binding protein 43 (TDP‐43); amyotrophic lateral sclerosis (ALS); autolysosome; autophagosome; autophagy; extracellular vesicles; frontotemporal lobar degeneration (FTLD); lysosome; progranulin
    DOI:  https://doi.org/10.1016/j.jbc.2023.105272
  11. Sci Signal. 2023 Sep 19. 16(803): eade3599
    Opposing roles of RUBCN isoforms in autophagy and memory B cell generation.
    Chao-Yuan Tsai, Shuhei Sakakibara, Yu-Diao Kuan, Hiroko Omori, Maruwa Ali El Hussien, Daisuke Okuzaki, Shiou-Ling Lu, Takeshi Noda, Keisuke Tabata, Shuhei Nakamura, Tamotsu Yoshimori, Hitoshi Kikutani.
      RUBCN (also known as Rubicon) was originally identified as a negative regulator of autophagy, a process by which cells degrade and recycle damaged components or organelles and that requires the activity of the class III PI3K VPS34 and the mTORC1 protein complex. Here, we characterized the role of a shorter isoform, RUBCN100, as an autophagy-promoting factor in B cells. RUBCN100 was translated from alternative translation initiation sites and lacked the RUN domain of the longer, previously characterized RUBCN130 isoform. Specific deficiency of RUBCN130 in B cells enhanced autophagy, which promoted memory B cell generation. In contrast to RUBCN130, which is localized in late endosomes and lysosomes and suppresses the enzymatic activity of VPS34, an effect thought to mediated by its RUN domain, RUBCN100 was preferentially located in early endosomes and enhanced VPS34 activity, presumably because of the absence of the RUN domain. Furthermore, RUBCN100, but not RUBCN130, enhanced autophagy and suppressed mTORC1 activation. Our findings reveal that the opposing roles of two RUBCN isoforms are critical for autophagy regulation and memory B cell differentiation.
    DOI:  https://doi.org/10.1126/scisignal.ade3599
  12. Acta Neuropathol Commun. 2023 Sep 18. 11(1): 151
    A toxic gain-of-function mechanism in C9orf72 ALS impairs the autophagy-lysosome pathway in neurons.
    Jimmy Beckers, Arun Kumar Tharkeshwar, Laura Fumagalli, Matilde Contardo, Evelien Van Schoor, Raheem Fazal, Dietmar Rudolf Thal, Siddharthan Chandran, Renzo Mancuso, Ludo Van Den Bosch, Philip Van Damme.
      BACKGROUND: Motor neurons (MNs), which are primarily affected in amyotrophic lateral sclerosis (ALS), are a specialized type of neurons that are long and non-dividing. Given their unique structure, these cells heavily rely on transport of organelles along their axons and the process of autophagy to maintain their cellular homeostasis. It has been shown that disruption of the autophagy pathway is sufficient to cause progressive neurodegeneration and defects in autophagy have been associated with various subtypes of ALS, including those caused by hexanucleotide repeat expansions in the C9orf72 gene. A more comprehensive understanding of the dysfunctional cellular mechanisms will help rationalize the design of potent and selective therapies for C9orf72-ALS.METHODS: In this study, we used induced pluripotent stem cell (iPSC)-derived MNs from C9orf72-ALS patients and isogenic control lines to identify the underlying mechanisms causing dysregulations of the autophagy-lysosome pathway. Additionally, to ascertain the potential impact of C9orf72 loss-of-function on autophagic defects, we characterized the observed phenotypes in a C9orf72 knockout iPSC line (C9-KO).
    RESULTS: Despite the evident presence of dysfunctions in several aspects of the autophagy-lysosome pathway, such as disrupted lysosomal homeostasis, abnormal lysosome morphology, inhibition of autophagic flux, and accumulation of p62 in C9orf72-ALS MNs, we were surprised to find that C9orf72 loss-of-function had minimal influence on these phenotypes. Instead, we primarily observed impairment in endosome maturation as a result of C9orf72 loss-of-function. Additionally, our study shed light on the pathological mechanisms underlying C9orf72-ALS, as we detected an increased TBK1 phosphorylation at S172 in MNs derived from C9orf72 ALS patients.
    CONCLUSIONS: Our data provides further insight into the involvement of defects in the autophagy-lysosome pathway in C9orf72-ALS and strongly indicate that those defects are mainly due to the toxic gain-of-function mechanisms underlying C9orf72-ALS.
    Keywords:  Amyotrophic lateral sclerosis; Autophagy; C9orf72; Endosome; Human iPSC-derived spinal motor neurons; Lysosome; TBK1; p62
    DOI:  https://doi.org/10.1186/s40478-023-01648-0
  13. Int Immunopharmacol. 2023 Sep 20. pii: S1567-5769(23)01289-4. [Epub ahead of print]124(Pt B): 110964
    Depletion of mTOR ameliorates CD4+ T cell pyroptosis by promoting autophagy activity in septic mice.
    Ran Guo, Guoyu Zhao, Guangxu Bai, Jianwei Chen, Wen Han, Na Cui, Hao Wang.
      A reduction in the number of CD4+ T cells is a central part of the immunosuppression phase of sepsis and leads to impaired immune defense ability and increased mortality. Pyroptosis, a newly discovered programmed cell death, was confirmed to be an important mechanism of lymphocytopenia in a lot of human diseases and is under the regulation of autophagy. The mammalian target of rapamycin (mTOR) pathway is closely related to CD4+ T-cell survival. Whether the mTOR pathway influences CD4+ T cell pyroptosis by regulating autophagy remains unknown. In this study, a septic mouse model was developed using cecal ligation and puncture (CLP) to explore the degree of pyroptosis and autophagy of CD4+ T cells. T-cell-specific mTOR/TSC1-knockout mice were used to investigate the role of mTOR pathway in the regulation of CD4+ T cell pyroptosis. Bafilomycin, a specific autophagy inhibitor, was used to verify the regulatory effect of autophagy on pyroptosis in septic mice. We observed aggravated pyroptosis in CD4+ T cells in CLP mice accompanied by impaired autophagy activity and an overactivated mTOR signaling pathway. Depletion of mTOR relieved autophagy deficiency and reduced the proportion of pyroptotic CD4+ T cells. In T-cell-specific mTOR-knockout mice treated with bafilomycin, the protective effect of mTOR depletion vanished. This indicated that autophagy negatively regulates CD4+ T cell pyroptosis, which is under the control of the mTOR pathway. Taken together, our findings emphasize the importance of pyroptosis in sepsis-induced lymphopenia and reveal the regulatory effects of the mTOR pathway and the role of autophagy in this regulation.
    Keywords:  Autophagy; CD(4)(+) T cell; Pyroptosis; Sepsis; mTOR
    DOI:  https://doi.org/10.1016/j.intimp.2023.110964
  14. Autophagy. 2023 Sep 21.
    AZI2 mediates TBK1 activation at unresolved selective autophagy cargo receptor complexes with implications for CD8 T-cell infiltration in breast cancer.
    Syn Kok Yeo, Michael Haas, Kanakaraju Manupati, Mingang Hao, Fuchun Yang, Song Chen, Jun-Lin Guan.
      Most breast cancers do not respond to immune checkpoint inhibitors and there is an urgent need to identify novel sensitization strategies. Herein, we uncovered that activation of the TBK-IFN pathway that is mediated by the TBK1 adapter protein AZI2 is a potent strategy for this purpose. Our initial observations showed that RB1CC1 depletion leads to accumulation of AZI2, in puncta along with selective macroautophagy/autophagy cargo receptors, which are both required for TBK1 activation. Specifically, disrupting the selective autophagy function of RB1CC1 was sufficient to sustain AZI2 puncta accumulation and TBK1 activation. AZI2 then mediates downstream activation of DDX3X, increasing its interaction with IRF3 for transcription of pro-inflammatory chemokines. Consequently, we performed a screen to identify inhibitors that can induce the AZI2-TBK1 pathway, and this revealed Lys05 as a pharmacological agent that induced pro-inflammatory chemokine expression and CD8+ T cell infiltration into tumors. Overall, we have identified a distinct AZI2-TBK1-IFN signaling pathway that is responsive to selective autophagy blockade and can be activated to make breast cancers more immunogenic.
    Keywords:  AZI2; RB1CC1; TBK1; breast cancer; immune checkpoint inhibitor
    DOI:  https://doi.org/10.1080/15548627.2023.2259775
  15. Immunol Lett. 2023 Sep 15. pii: S0165-2478(23)00155-4. [Epub ahead of print]
    Autophagy and LC3-associated phagocytosis contribute negatively to the killing capability of THP-1-derived macrophages against Candida albicans at the mid-stage.
    Ding Li, Lin Wang, Zhihong Zhao, Changsen Bai, Xichuan Li.
      In innate immunity, macrophages play critical roles in defending against pathogens via the lysosomal degradation function of autophagy. Two distinct autophagy pathways have been identified in decades: canonical autophagy (referred to as autophagy) and LC3-associated phagocytosis (LAP). Since several conflicting findings about the anti-Candida capability of autophagy (or LAP) have been reported, they serve as the foe or friend for Candida survival is still unclearly. The current study showed that the fungicidal process of THP-1-derived macrophages (THP-1-MФ) against Candida albicans is divided into three stages as follows, the early stage (the first 12 h, increasing in the killing capability), the mid-stage (12-24 h, no change in killing capability), and the late stage (24-48 h, decreasing of the killing capability). Autophagic protein LC3B-II reached the peak in THP-1-MФ after 24 h inoculated either with C.albicans or whole glucan particles (WGP). Thus, both anti-Candida roles of autophagy and the LAP pathway have been detected at the mid-stage. For autophagy, after 24 h inoculation with C.albicans, ULK1 increased, but p-ATG13(s318) decreased obviously in THP-1-MФ, and the killing assay showed that autophagy is unhelpful for Candida killing capability. For the LAP pathway, Rubicon and ROS raised significantly in THP-1-MФ after 24 h inoculated with C.albicans; each inhibition would sharply cut down the LC3B-II accumulation, which indicated that LAP had been induced. However, mCherry-GFP-LC3 fluorescent assay exhibited that LAP phago-lysosomal fusion has been blocked, and Rubicon knockdown facilitated the Candida killing activity. These data indicated that autophagy presented as redundant to Candida defense, and LAP phago-lysosomal fusion obstruction impairs the Candida killing capability of THP-1-MФ at the mid-stage. That may explain the no change in Candida killing capability at the mid-stage.
    Keywords:  Autophagy; C. albicans; LAP; Macrophage; Mid-stage
    DOI:  https://doi.org/10.1016/j.imlet.2023.09.006
  16. Autophagy. 2023 Sep 18.
    Autophagy in colitis-associated colon cancer: exploring its potential role in reducing initiation and preventing IBD-Related CAC development.
    Xuanhong Jin, Liangkun You, Jincheng Qiao, Weidong Han, Hongming Pan.
      Colitis-associated colon cancer (CAC) is a distinct form of colorectal cancer that emerges from prolonged colitis in individuals with inflammatory bowel disease (IBD). Chronic inflammation is considered as the most critical contributor to the development and progression of CAC, with the degree and persistence of the inflammatory response being the primary drivers of CAC progression in individuals with IBD. Macroautophagy/autophagy, which is a cellular process that aids in preserving the intestinal mucosal barrier and regulating intestinal inflammation, is effective in reducing IBD progression. However, the precise contribution of impaired autophagy to CAC pathogenesis has yet to be fully elucidated. Nevertheless, it is thought that autophagy may reduce the risk of CAC by regulating intestinal inflammation and other factors. This review summarizes recent research on CAC development and investigates the possible functions of autophagy in reducing CAC initiation. Furthermore, we explore the functional transformation of autophagy after CAC transformation and propose that promoting autophagy as a means of attenuating CAC initiation may serve as a novel strategy for preventing IBD-related CAC.
    Keywords:  Autophagy; autophagy regulators; colitis-associated colon cancer; inflammatory bowel diseases; intestinal homeostasis
    DOI:  https://doi.org/10.1080/15548627.2023.2259214
  17. ACS Nano. 2023 Sep 22.
    Enhancing Efficacy of Albumin-Bound Paclitaxel for Human Lung and Colorectal Cancers through Autophagy Receptor Sequestosome 1 (SQSTM1)/p62-Mediated Nanodrug Delivery and Cancer therapy.
    Yu-Wei Lin, Tzu-Ting Lin, Chien-Hung Chen, Rou-Hsin Wang, Ya-Hui Lin, Tzu-Yen Tseng, Yan-Jun Zhuang, Sheng-Yueh Tang, Yen-Cheng Lin, Jiun-Yu Pang, Rajan Deepan Chakravarthy, Hsin-Chieh Lin, Shey-Cherng Tzou, Jui-I Chao.
      Selective autophagy is a defense mechanism by which foreign pathogens and abnormal substances are processed to maintain cellular homeostasis. Sequestosome 1 (SQSTM1)/p62, a vital selective autophagy receptor, recruits ubiquitinated cargo to form autophagosomes for lysosomal degradation. Nab-PTX is an albumin-bound paclitaxel nanoparticle used in clinical cancer therapy. However, the role of SQSTM1 in regulating the delivery and efficacy of nanodrugs remains unclear. Here we showed that SQSTM1 plays a crucial role in Nab-PTX drug delivery and efficacy in human lung and colorectal cancers. Nab-PTX induces SQSTM1 phosphorylation at Ser403, which facilitates its incorporation into the selective autophagy of nanoparticles, known as nanoparticulophagy. Nab-PTX increased LC3-II protein expression, which triggered autophagosome formation. SQSTM1 enhanced Nab-PTX recognition to form autophagosomes, which were delivered to lysosomes for albumin degradation, thereby releasing PTX to induce mitotic catastrophe and apoptosis. Knockout of SQSTM1 downregulated Nab-PTX-induced mitotic catastrophe, apoptosis, and tumor inhibition in vitro and in vivo and inhibited Nab-PTX-induced caspase 3 activation via a p53-independent pathway. Ectopic expression of SQSTM1 by transfection of an SQSTM1-GFP vector restored the drug efficacy of Nab-PTX. Importantly, SQSTM1 is highly expressed in advanced lung and colorectal tumors and is associated with poor overall survival in clinical patients. Targeting SQSTM1 may provide an important strategy to improve nanodrug efficacy in clinical cancer therapy. This study demonstrates the enhanced efficacy of Nab-PTX for human lung and colorectal cancers via SQSTM1-mediated nanodrug delivery.
    Keywords:  Nab-PTX; SQSTM1; cancer therapy; drug delivery; selective autophagy
    DOI:  https://doi.org/10.1021/acsnano.3c04739
  18. J Integr Neurosci. 2023 Sep 18. 22(5): 134
    Autophagy in Intracerebral Hemorrhage: From Mechanism to Regulation.
    Jia Zheng, Wei Zou, Xueping Yu.
      Intracerebral hemorrhage (ICH) is the most lethal type of stroke. Secondary injury from ICH determines the recovery, but there is still a lack of effective treatment. The identification of new therapeutic targets may address the current dilemma. The process of autophagy is mediated through the lysosomal pathway and is used to maintain cell homeostasis. Recent studies have advanced our knowledge of autophagy, and in particular its involvement in cell physiology and pathology. Autophagy involves multiple targets and signaling pathways and occurs in many brain cells. It also regulates oxidative stress and inflammation after ICH, both of which are important factors in secondary brain injury. An appropriate level of autophagy is protective in ICH, whereas excessive autophagy may be detrimental. In this review, we discuss the signaling pathways for autophagy in ICH and related factors that provide a theoretical basis for the discovery of new treatment targets.
    Keywords:  autophagy; intracerebral hemorrhage; molecular mechanisms; signaling pathway
    DOI:  https://doi.org/10.31083/j.jin2205134
  19. Autophagy. 2023 Sep 21.
    Inhibition of PRKAA/AMPK (Ser485/491) phosphorylation by crizotinib induces cardiotoxicity via perturbing autophagosome-lysosome fusion.
    Zhifei Xu, Zezheng Pan, Ying Jin, Zizheng Gao, Feng Jiang, Huangxi Fu, Xueqin Chen, Xiaochen Zhang, Hao Yan, Xiaochun Yang, Bo Yang, Qiaojun He, Peihua Luo.
      Crizotinib, a small-molecule tyrosine kinase inhibitor targeting ALK, MET and ROS1, is the first-line drug for ALK-positive metastatic non-small cell lung cancer and is associated with severe, sometimes fatal, cases of cardiac failure, which increases the risk of mortality. However, the underlying mechanism remains unclear, which causes the lack of therapeutic strategy. We established in vitro and in vivo models for crizotinib-induced cardiotoxicity and found that crizotinib caused left ventricular dysfunction, myocardial injury and pathological remodeling in mice and induced cardiomyocyte apoptosis and mitochondrial injury. In addition, we found that crizotinib prevented the degradation of MET protein by interrupting autophagosome-lysosome fusion and silence of MET or re-activating macroautophagy/autophagy flux rescued the cardiomyocytes death and mitochondrial injury caused by crizotinib, suggesting that impaired autophagy activity is the key reason for crizotinib-induced cardiotoxicity. We further confirmed that recovering the phosphorylation of PRKAA/AMPK (Ser485/491) by metformin re-activated autophagy flux in cardiomyocytes and metformin rescued crizotinib-induced cardiomyocyte injury and cardiac complications. In summary, we revealed a novel mechanism for crizotinib-induced cardiotoxicity, wherein the crizotinib-impaired autophagy process causes cardiomyocyte death and cardiac injury by inhibiting the degradation of MET protein, demonstrated a new function of impeded autophagosome-lysosome fusion in drugs-induced cardiotoxicity, pointed out the essential role of the phosphorylation of PRKAA (Ser485/491) in autophagosome-lysosome fusion and confirmed metformin as a potential therapeutic strategy for crizotinib-induced cardiotoxicity.
    Keywords:  Autophagosome-lysosome fusion; PRKAA/AMPK; autophagy; cardiotoxicity; crizotinib; metformin
    DOI:  https://doi.org/10.1080/15548627.2023.2259216
  20. EMBO Rep. 2023 Sep 20. e57574
    The post-translational regulation of transcription factor EB (TFEB) in health and disease.
    Michael Takla, Swati Keshri, David C Rubinsztein.
      Transcription factor EB (TFEB) is a basic helix-loop-helix leucine zipper transcription factor that acts as a master regulator of lysosomal biogenesis, lysosomal exocytosis, and macro-autophagy. TFEB contributes to a wide range of physiological functions, including mitochondrial biogenesis and innate and adaptive immunity. As such, TFEB is an essential component of cellular adaptation to stressors, ranging from nutrient deprivation to pathogenic invasion. The activity of TFEB depends on its subcellular localisation, turnover, and DNA-binding capacity, all of which are regulated at the post-translational level. Pathological states are characterised by a specific set of stressors, which elicit post-translational modifications that promote gain or loss of TFEB function in the affected tissue. In turn, the resulting increase or decrease in survival of the tissue in which TFEB is more or less active, respectively, may either benefit or harm the organism as a whole. In this way, the post-translational modifications of TFEB account for its otherwise paradoxical protective and deleterious effects on organismal fitness in diseases ranging from neurodegeneration to cancer. In this review, we describe how the intracellular environment characteristic of different diseases alters the post-translational modification profile of TFEB, enabling cellular adaptation to a particular pathological state.
    Keywords:  TFEB; autophagy; lysosome; mitochondria; post-translational modification
    DOI:  https://doi.org/10.15252/embr.202357574
  21. Biosystems. 2023 Sep 17. pii: S0303-2647(23)00211-3. [Epub ahead of print] 105036
    Dynamic modelling and tristability analysis of misfolded α-synuclein degraded via autophagy in Parkinson's disease.
    Bojie Yang, Zhuoqin Yang, Heng Liu, Hong Qi.
      The widely-accepted hallmark pathology of Parkinson's disease (PD) is the presence of Lewy bodies with characteristic abnormal aggregated α-synuclein (αSyn). Growing physiological evidence suggests that there is a pivotal role for the autophagy-lysosome pathway (ALP) in the clearance of misfolded αSyn (αSyn∗). This work establishes a mathematical model for αSyn∗ degradation through the ALP. Qualitative simulations are used to uncover the tristable behavior of αSyn∗, i.e., the lower, medium, and upper steady states, which correspond to the healthy, critical, and disease stages of PD, respectively. Time series and codimension-1 bifurcation analysis suggest that the system shows tristability dynamics. Furthermore, variations in the key parameters influence the tristable dynamic behavior, and the distribution of tristable regions is exhibited more comprehensively in codimension-2 bifurcation diagrams. In addition, robustness analysis demonstrates that tristability is a robust property of the system. These results may be valuable in therapeutic strategies for the prevention and treatment of PD.
    Keywords:  Autophagy; Parkinson's disease; Tristability; α-synuclein
    DOI:  https://doi.org/10.1016/j.biosystems.2023.105036
  22. Biochim Biophys Acta Mol Basis Dis. 2023 Sep 20. pii: S0925-4439(23)00257-0. [Epub ahead of print] 166891
    Toxoplasma gondii autophagy-related protein ATG7 maintains apicoplast inheritance by stabilizing and lipidating ATG8.
    Mimi Wu, Jiaqi Ying, Xuejing Lin, Chao Xu, Xiaozi Zheng, Yi Zheng, Zhouxi Fang, Baolong Yan, Nu Zhang, Yani Mou, Feng Tan.
      ATG8/LC3-mediated autophagosome formation is a key rate-limiting step in the process of autophagy. The parasitic protist Toxoplasma gondii possesses a single ATG8 homolog (TgATG8), which can localize to either cytosolic autophagosome involved in delivery of autophagic material in bradyzoites, or the outermost membrane of apicoplast, a nonphotosynthetic plastid-like organelle, responsible for maintaining homeostasis in tachyzoites. However, mechanisms that regulate TgATG8 remain insufficiently understood. Here, a TgATG7 conditional knockdown line that we have generated is severely impaired in parasite's growth and exhibits significant defects in the organelle level, strikingly with a fragmentation of the mitochondrial network and a loss of the apicoplast. Specific TgATG7C1133S point mutant complemented line showed that these defects were associated with its E1-type enzyme activity. Both depletion of TgATG7 and mutation of its catalytic cysteine 1133 hindered TgATG8 lipidation and apicoplast localization. Unexpectedly, we also found that depletion of TgATG7 reduced the unlipidated TgATG8 protein level. Subsequently, we determined that TgATG7 was able to interact with TgATG8 directly via its C-terminal domain and multi-monoubiquitination stimulated proteasome-dependent degradation of TgATG8, while TgATG7 could inhibit the degradation through stabilization of TgATG8. Additionally, we identified a putative TgATG8 interacting fragment of TgATG7, 1281-1290aa. Depletion of the fragment impaired the parasite growth and apicoplast inheritance. To our knowledge, our study is the first to elucidate the role of TgATG7 and the ubiquitin-proteasome system in synergistically regulating the non-lipidated pool of TgATG8, suggesting a potential homeostatic mechanism responsible for balancing autophagic activity in T. gondii.
    Keywords:  ATG7; ATG8; Apicoplast; Autophagy; Toxoplasma gondii; Ubiquitination
    DOI:  https://doi.org/10.1016/j.bbadis.2023.166891
  23. Cell Death Dis. 2023 Sep 21. 14(9): 620
    A new vulnerability to BET inhibition due to enhanced autophagy in BRCA2 deficient pancreatic cancer.
    EunJung Lee, Suyakarn Archasappawat, Keely Ji, Jocelyn Pena, Virneliz Fernandez-Vega, Ritika Gangaraju, Nitin Sai Beesabathuni, Martin Jean Kim, Qi Tian, Priya S Shah, Louis Scampavia, Timothy P Spicer, Chang-Il Hwang.
      Pancreatic cancer is one of the deadliest diseases in human malignancies. Among total pancreatic cancer patients, ~10% of patients are categorized as familial pancreatic cancer (FPC) patients, carrying germline mutations of the genes involved in DNA repair pathways (e.g., BRCA2). Personalized medicine approaches tailored toward patients' mutations would improve patients' outcome. To identify novel vulnerabilities of BRCA2-deficient pancreatic cancer, we generated isogenic Brca2-deficient murine pancreatic cancer cell lines and performed high-throughput drug screens. High-throughput drug screening revealed that Brca2-deficient cells are sensitive to Bromodomain and Extraterminal Motif (BET) inhibitors, suggesting that BET inhibition might be a potential therapeutic approach. We found that BRCA2 deficiency increased autophagic flux, which was further enhanced by BET inhibition in Brca2-deficient pancreatic cancer cells, resulting in autophagy-dependent cell death. Our data suggests that BET inhibition can be a novel therapeutic strategy for BRCA2-deficient pancreatic cancer.
    DOI:  https://doi.org/10.1038/s41419-023-06145-9
  24. Anal Chem. 2023 Sep 19.
    Construction of a Dual-Emissive Probe for Discriminative Visualization of Lysosomal and Mitochondrial Dysfunction.
    Wei Ge, Huina Wang, Xiaofen Wu, Baoli Dong, Ruoyao Zhang, Minggang Tian.
      Discriminatively visualizing mitochondrial and lysosomal dysfunction is crucial for an in-depth understanding of cell apoptosis regulation and relative biology. However, fluorescent probes for the separate visualization of lysosomal and mitochondria damages have not been reported yet. Herein, we have constructed a fluorescent probe [2-(4-hydroxystyryl)-1,3,3-trimethyl-3H-indol-1-ium iodide (HBSI)] for labeling mitochondria and lysosomes in dual emission colors and discriminatively imaging mitochondrial and lysosomal damage in two different sets of fluorescent signals. In living cells, HBSI targeted both lysosomes and mitochondria to give green and red emission, respectively. During mitochondrial damages, HBSI immigrated into lysosomes, and the red emission decreased. During lysosomal damage, HBSI immigrated into mitochondria, and the green emission decreased. With the robust probe, the different damaging sequences of mitochondria and lysosomes under different amounts of H2O2 and chloral hydrate have been revealed. The sequential damage of lysosomes and mitochondria during cell apoptosis induced by rotenone, paclitaxel, and colchicine has been discovered. Furthermore, the regulation of mitochondria, lysosome, and their interplay during autophagy was also observed with the probe.
    DOI:  https://doi.org/10.1021/acs.analchem.3c03024
  25. Liver Int. 2023 Oct;43(10): 2055-2056
    Autophagy in liver regeneration: Unravelling the endothelial cell's role and therapeutic prospects.
    Sarah Raevens.
      
    DOI:  https://doi.org/10.1111/liv.15694
  26. Arch Pharm Res. 2023 Sep 21.
    Hyperoside attenuates pyrrolizidine alkaloids-induced liver injury by ameliorating TFEB-mediated mitochondrial dysfunction.
    Jie Xu, Aizhen Xiong, Xunjiang Wang, Xing Yan, Yilin Chen, Xuanling Ye, Zhengtao Wang, Lili Ding, Li Yang.
      Pyrrolizidine alkaloids (PAs) are potent hepatotoxins that can cause liver damage. Hyperoside (Hyp), a natural flavonoid, can be extracted from medicinal plants. Hyp displays hepatoprotective activity in various liver diseases. However, the potential effect and mechanism of action of Hyp in ameliorating PA-induced liver injury remain obscure. This study aimed to explore the protective effect of Hyp against PA-induced hepatotoxicity and its underlying mechanism. We established an in vitro model of PAs in mouse primary hepatocytes and developed a mouse model of acute PA toxicity to investigate the protective effect of Hyp. We found that Hyp notably attenuated PA-induced hepatotoxicity. RNA-sequencing showed that the beneficial effect of Hyp against PA-induced hepatotoxicity was associated with the transcription factor EB (TFEB)-peroxisome proliferator-activated receptor-γ coactivator-1-α (PGC1α) pathway. Our results confirmed that both the autophagy-lysosomal pathway and mitochondrial biogenesis were induced by Hyp through TFEB nuclear translocation in PA-induced liver injury. Furthermore, we demonstrated that activation of the mechanistic target of rapamycin complex 1 (mTORC1) by MHY 1485 decreased TFEB nuclear translocation and abrogated the protective effect of Hyp against PA-induced liver injury in mice. In contrast, inhibition of mTORC1 activity increased the level of TFEB and reduced hepatotoxicity induced by PAs in mouse livers. Likewise, Hyp-induced TFEB activation was validated in vitro. In conclusion, Hyp can activate the TFEB-mediated autophagy-lysosomal pathway and mitochondrial biogenesis through inhibition of mTORC1 activity, alleviating the liver injury induced by PAs, thus suggesting the potential value of Hyp in the treatment of PA-induced hepatotoxicity.
    Keywords:  Hyperoside; Liver injury; Mitochondrial dysfunction; Pyrrolizidine alkaloids; Transcription factor EB
    DOI:  https://doi.org/10.1007/s12272-023-01460-3
  27. Proc Natl Acad Sci U S A. 2023 Sep 26. 120(39): e2220556120
    Iditarod, a Drosophila homolog of the Irisin precursor FNDC5, is critical for exercise performance and cardiac autophagy.
    Tyler Cobb, Irene Hwang, Michael Soukar, Sim Namkoong, Uhn-Soo Cho, Maryam Safdar, Myungjin Kim, Robert J Wessells, Jun Hee Lee.
      Mammalian FNDC5 encodes a protein precursor of Irisin, which is important for exercise-dependent regulation of whole-body metabolism. In a genetic screen in Drosophila, we identified Iditarod (Idit), which shows substantial protein homology to mouse and human FNDC5, as a regulator of autophagy acting downstream of Atg1/Atg13. Physiologically, Idit-deficient flies showed reduced exercise performance and defective cold resistance, which were rescued by exogenous expression of Idit. Exercise training increased endurance in wild-type flies, but not in Idit-deficient flies. Conversely, Idit is induced upon exercise training, and transgenic expression of Idit in wild-type flies increased endurance to the level of exercise trained flies. Finally, Idit deficiency prevented both exercise-induced increase in cardiac Atg8 and exercise-induced cardiac stress resistance, suggesting that cardiac autophagy may be an additional mechanism by which Idit is involved in the adaptive response to exercise. Our work suggests an ancient role of an Iditarod/Irisin/FNDC5 family of proteins in autophagy, exercise physiology, and cold adaptation, conserved throughout metazoan species.
    Keywords:  FNDC5; Irisin; autophagy; cardiac; exercise
    DOI:  https://doi.org/10.1073/pnas.2220556120
  28. Mol Cell. 2023 Sep 21. pii: S1097-2765(23)00652-4. [Epub ahead of print]83(18): 3333-3346.e5
    Regulation of nucleo-cytosolic 26S proteasome translocation by aromatic amino acids via mTOR is essential for cell survival under stress.
    Ido Livneh, Victoria Cohen-Kaplan, Bertrand Fabre, Ifat Abramovitch, Chen Lulu, Nishanth Belugali Nataraj, Ikrame Lazar, Tamar Ziv, Yosef Yarden, Yaniv Zohar, Eyal Gottlieb, Aaron Ciechanover.
      The proteasome is responsible for removal of ubiquitinated proteins. Although several aspects of its regulation (e.g., assembly, composition, and post-translational modifications) have been unraveled, studying its adaptive compartmentalization in response to stress is just starting to emerge. We found that following amino acid starvation, the proteasome is translocated from its large nuclear pool to the cytoplasm-a response regulated by newly identified mTOR-agonistic amino acids-Tyr, Trp, and Phe (YWF). YWF relay their signal upstream of mTOR through Sestrin3 by disrupting its interaction with the GATOR2 complex. The triad activates mTOR toward its downstream substrates p62 and transcription factor EB (TFEB), affecting both proteasomal and autophagic activities. Proteasome translocation stimulates cytosolic proteolysis which replenishes amino acids, thus enabling cell survival. In contrast, nuclear sequestration of the proteasome following mTOR activation by YWF inhibits this proteolytic adaptive mechanism, leading to cell death, which establishes this newly identified pathway as a key stress-coping mechanism.
    Keywords:  UPS; aromatic amino acids; mTOR; proteasome dynamics; protein quality control; proteolysis; stress response
    DOI:  https://doi.org/10.1016/j.molcel.2023.08.016
  29. Proc Natl Acad Sci U S A. 2023 Sep 26. 120(39): e2221553120
    Neuronal MML-1/MXL-2 regulates systemic aging via glutamate transporter and cell nonautonomous autophagic and peroxidase activity.
    Tatsuya Shioda, Ittetsu Takahashi, Kensuke Ikenaka, Naonobu Fujita, Tomotake Kanki, Toshihiko Oka, Hideki Mochizuki, Adam Antebi, Tamotsu Yoshimori, Shuhei Nakamura.
      Accumulating evidence has demonstrated the presence of intertissue-communication regulating systemic aging, but the underlying molecular network has not been fully explored. We and others previously showed that two basic helix-loop-helix transcription factors, MML-1 and HLH-30, are required for lifespan extension in several longevity paradigms, including germlineless Caenorhabditis elegans. However, it is unknown what tissues these factors target to promote longevity. Here, using tissue-specific knockdown experiments, we found that MML-1 and its heterodimer partners MXL-2 and HLH-30 act primarily in neurons to extend longevity in germlineless animals. Interestingly, however, the downstream cascades of MML-1 in neurons were distinct from those of HLH-30. Neuronal RNA interference (RNAi)-based transcriptome analysis revealed that the glutamate transporter GLT-5 is a downstream target of MML-1 but not HLH-30. Furthermore, the MML-1-GTL-5 axis in neurons is critical to prevent an age-dependent collapse of proteostasis and increased oxidative stress through autophagy and peroxidase MLT-7, respectively, in long-lived animals. Collectively, our study revealed that systemic aging is regulated by a molecular network involving neuronal MML-1 function in both neural and peripheral tissues.
    Keywords:  C. elegans; autophagy; longevity; redox homeostasis
    DOI:  https://doi.org/10.1073/pnas.2221553120
  30. EBioMedicine. 2023 Sep 20. pii: S2352-3964(23)00375-4. [Epub ahead of print]96 104809
    Rebalancing of mitochondrial homeostasis through an NAD+-SIRT1 pathway preserves intestinal barrier function in severe malnutrition.
    Catriona Ling, Christian J Versloot, Matilda E Arvidsson Kvissberg, Guanlan Hu, Nathan Swain, José M Horcas-Nieto, Emily Miraglia, Mehakpreet K Thind, Amber Farooqui, Albert Gerding, Karen van Eunen, Mirjam H Koster, Niels J Kloosterhuis, Lijun Chi, YueYing ChenMi, Miriam Langelaar-Makkinje, Celine Bourdon, Jonathan Swann, Marieke Smit, Alain de Bruin, Sameh A Youssef, Marjon Feenstra, Theo H van Dijk, Kathrin Thedieck, Johan W Jonker, Peter K Kim, Barbara M Bakker, Robert H J Bandsma.
      BACKGROUND: The intestine of children with severe malnutrition (SM) shows structural and functional changes that are linked to increased infection and mortality. SM dysregulates the tryptophan-kynurenine pathway, which may impact processes such as SIRT1- and mTORC1-mediated autophagy and mitochondrial homeostasis. Using a mouse and organoid model of SM, we studied the repercussions of these dysregulations on malnutrition enteropathy and the protective capacity of maintaining autophagy activity and mitochondrial health.METHODS: SM was induced through feeding male weanling C57BL/6 mice a low protein diet (LPD) for 14-days. Mice were either treated with the NAD+-precursor, nicotinamide; an mTORC1-inhibitor, rapamycin; a SIRT1-activator, resveratrol; or SIRT1-inhibitor, EX-527. Malnutrition enteropathy was induced in enteric organoids through amino-acid deprivation. Features of and pathways to malnutrition enteropathy were examined, including paracellular permeability, nutrient absorption, and autophagic, mitochondrial, and reactive-oxygen-species (ROS) abnormalities.
    FINDINGS: LPD-feeding and ensuing low-tryptophan availability led to villus atrophy, nutrient malabsorption, and intestinal barrier dysfunction. In LPD-fed mice, nicotinamide-supplementation was linked to SIRT1-mediated activation of mitophagy, which reduced damaged mitochondria, and improved intestinal barrier function. Inhibition of mTORC1 reduced intestinal barrier dysfunction and nutrient malabsorption. Findings were validated and extended using an organoid model, demonstrating that resolution of mitochondrial ROS resolved barrier dysfunction.
    INTERPRETATION: Malnutrition enteropathy arises from a dysregulation of the SIRT1 and mTORC1 pathways, leading to disrupted autophagy, mitochondrial homeostasis, and ROS. Whether nicotinamide-supplementation in children with SM could ameliorate malnutrition enteropathy should be explored in clinical trials.
    FUNDING: This work was supported by the Bill and Melinda Gates Foundation, the Sickkids Research Institute, the Canadian Institutes of Health Research, and the University Medical Center Groningen.
    Keywords:  Autophagy; Enteropathy; Malnutrition; Mitochondria; SIRT1
    DOI:  https://doi.org/10.1016/j.ebiom.2023.104809
  31. J Alzheimers Dis. 2023 Sep 11.
    Malignant Brain Aging: The Formidable Link Between Dysregulated Signaling Through Mechanistic Target of Rapamycin Pathways and Alzheimer's Disease (Type 3 Diabetes).
    Suzanne M de la Monte.
      Malignant brain aging corresponds to accelerated age-related declines in brain functions eventually derailing the self-sustaining forces that govern independent vitality. Malignant brain aging establishes the path toward dementing neurodegeneration, including Alzheimer's disease (AD). The full spectrum of AD includes progressive dysfunction of neurons, oligodendrocytes, astrocytes, microglia, and the microvascular systems, and is mechanistically driven by insulin and insulin-like growth factor (IGF) deficiencies and resistances with accompanying deficits in energy balance, increased cellular stress, inflammation, and impaired perfusion, mimicking the core features of diabetes mellitus. The underlying pathophysiological derangements result in mitochondrial dysfunction, abnormal protein aggregation, increased oxidative and endoplasmic reticulum stress, aberrant autophagy, and abnormal post-translational modification of proteins, all of which are signature features of both AD and dysregulated insulin/IGF-1-mechanistic target of rapamycin (mTOR) signaling. This article connects the dots from benign to malignant aging to neurodegeneration by reviewing the salient pathologies associated with initially adaptive and later dysfunctional mTOR signaling in the brain. Effective therapeutic and preventive measures must be two-pronged and designed to 1) address complex and shifting impairments in mTOR signaling through the re-purpose of effective anti-diabetes therapeutics that target the brain, and 2) minimize the impact of extrinsic mediators of benign to malignant aging transitions, e.g., inflammatory states, obesity, systemic insulin resistance diseases, and repeated bouts of general anesthesia, by minimizing exposures or implementing neuroprotective measures.
    Keywords:  Aging; Alzheimer’s disease; brain; mTOR; neurodegeneration; neuroinflammation; type 3 diabetes; vascular disease; white matter
    DOI:  https://doi.org/10.3233/JAD-230555
  32. Cell Commun Signal. 2023 Sep 21. 21(1): 251
    Elucidating the molecular mechanisms underlying the induction of autophagy by antidepressant-like substances in C57BL/6J mouse testis model upon LPS challenge.
    Przemysław Sołek, Ewelina Czechowska, Magdalena Sowa-Kućma, Katarzyna Stachowicz, Piotr Kaczka, Anna Tabęcka-Łonczyńska.
      The treatment of depression with pharmaceuticals is associated with many adverse side effects, including male fertility problems. The precise mechanisms by which these agents affect testicular cells remain largely unknown, but they are believed to induce cellular stress, which is sensed by the endoplasmic reticulum (ER) and the Golgi apparatus. These organelles are responsible for maintaining cellular homeostasis and regulating signal pathways that lead to autophagy or apoptosis. Therefore, in this study, we aimed to investigate the autophagy, ER, and Golgi stress-related pathways in mouse testis following treatment with antidepressant-like substances (ALS) and ALS combined with lipopolysaccharide (LPS). We found that most ALS and activated proteins are associated with the induction of apoptosis. However, when imipramine (IMI) was combined with NS-398 (a cyclooxygenase-2 inhibitor) after LPS administration, we observed a marked increase in the BECLIN1, Bcl-2, ATG16L, and LC3 expression, which are marker proteins of autophagosome formation. The expression of the BECN1 and ATG16L genes was also high compared to the control, indicating the induction of autophagy processes that may potentially protect mouse testicular cells from death and regulate metabolism in the testis. Our findings may provide a better understanding of the stress-related effects of specific ALS on the testis. Video Abstract.
    Keywords:  Antidepressant-like substances; Autophagy; Depression; Endoplasmic reticulum; Golgi apparatus; Testis
    DOI:  https://doi.org/10.1186/s12964-023-01270-6
  33. J Orthop Surg Res. 2023 Sep 21. 18(1): 711
    DAP1 regulates osteoblast autophagy via the ATG16L1-LC3 axis in Graves' disease-induced osteoporosis.
    Mingdong Gao, Zouxi Du, Qianqian Dong, Shan Su, Limin Tian.
      OBJECTIVE: This study aimed to uncover a critical protein and its mechanisms in modulating autophagy in Graves' disease (GD)-induced osteoporosis (OP).METHODS: We discovered the target protein, death-associated protein 1 (DAP1), using bone proteomics analysis. Furthermore, genetic overexpression and knockdown (KD) of DAP1 in bone and MC3T3-E1 cells revealed DAP1 effects on autophagy and osteogenic markers, and autophagic vacuoles in cells were detected using transmission electron microscopy and the microtubule-associated protein 1 light chain 3 alpha (MAP1LC3/LC3) dual fluorescence system. An autophagy polymerase chain reaction (PCR) array kit was used to identify the key molecules associated with DAP1-regulated autophagy.
    RESULTS: DAP1 levels were significantly higher in the bone tissue of GD mice and MC3T3-E1 cells treated with triiodothyronine (T3). DAP1 overexpression reduced LC3 lipidation, autophagic vacuoles, RUNX family transcription factor 2 (RUNX2), and osteocalcin (OCN) expression in MC3T3-E1 cells, whereas DAP1 KD reversed these changes. In vivo experiments revealed that GD mice with DAP1 KD had greater bone mass than control mice. DAP1-overexpressing (OE) cells had lower levels of phosphorylated autophagy-related 16-like 1 (ATG16L1) and LC3 lipidation, whereas DAP1-KD cells had higher levels.
    CONCLUSIONS: DAP1 was found to be a critical regulator of autophagy homeostasis in GD mouse bone tissue and T3-treated osteoblasts because it negatively regulated autophagy and osteogenesis in osteoblasts via the ATG16L1-LC3 axis.
    Keywords:  Autophagy; Death-associated protein 1; Graves’ disease; Osteoblasts; Osteoporosis
    DOI:  https://doi.org/10.1186/s13018-023-04171-z
  34. Int J Oral Sci. 2023 09 18. 15(1): 42
    Porphyromonas gingivalis, a periodontal pathogen, impairs post-infarcted myocardium by inhibiting autophagosome-lysosome fusion.
    Yuka Shiheido-Watanabe, Yasuhiro Maejima, Shun Nakagama, Qintao Fan, Natsuko Tamura, Tetsuo Sasano.
      While several previous studies have indicated the link between periodontal disease (PD) and myocardial infarction (MI), the underlying mechanisms remain unclear. Autophagy, a cellular quality control process that is activated in several diseases, including heart failure, can be suppressed by Porphyromonas gingivalis (P.g.). However, it is uncertain whether autophagy impairment by periodontal pathogens stimulates the development of cardiac dysfunction after MI. Thus, this study aimed to investigate the relationship between PD and the development of MI while focusing on the role of autophagy. Neonatal rat cardiomyocytes (NRCMs) and MI model mice were inoculated with wild-type P.g. or gingipain-deficient P.g. to assess the effect of autophagy inhibition by P.g. Wild-type P.g.-inoculated NRCMs had lower cell viability than those inoculated with gingipain-deficient P.g. This study also revealed that gingipains can cleave vesicle-associated membrane protein 8 (VAMP8), a protein involved in lysosomal sensitive factor attachment protein receptors (SNAREs), at the 47th lysine residue, thereby inhibiting autophagy. Wild-type P.g.-inoculated MI model mice were more susceptible to cardiac rupture, with lower survival rates and autophagy activity than gingipain-deficient P.g.-inoculated MI model mice. After inoculating genetically modified MI model mice (VAMP8-K47A) with wild-type P.g., they exhibited significantly increased autophagy activation compared with the MI model mice inoculated with wild-type P.g., which suppressed cardiac rupture and enhanced overall survival rates. These findings suggest that gingipains, which are virulence factors of P.g., impair the infarcted myocardium by cleaving VAMP8 and disrupting autophagy. This study confirms the strong association between PD and MI and provides new insights into the potential role of autophagy in this relationship.
    DOI:  https://doi.org/10.1038/s41368-023-00251-2
  35. Neuron. 2023 Sep 13. pii: S0896-6273(23)00629-3. [Epub ahead of print]
    Parkinson's disease-linked parkin mutation disrupts recycling of synaptic vesicles in human dopaminergic neurons.
    Pingping Song, Wesley Peng, Veronique Sauve, Rayan Fakih, Zhong Xie, Daniel Ysselstein, Talia Krainc, Yvette C Wong, Niccolò E Mencacci, Jeffrey N Savas, D James Surmeier, Kalle Gehring, Dimitri Krainc.
      Parkin-mediated mitophagy has been studied extensively, but whether mutations in parkin contribute to Parkinson's disease pathogenesis through alternative mechanisms remains unexplored. Using patient-derived dopaminergic neurons, we found that phosphorylation of parkin by Ca2+/calmodulin-dependent protein kinase 2 (CaMK2) at Ser9 leads to activation of parkin in a neuronal-activity-dependent manner. Activated parkin ubiquitinates synaptojanin-1, facilitating its interaction with endophilin A1 and synaptic vesicle recycling. Neurons from PD patients with mutant parkin displayed defective recycling of synaptic vesicles, leading to accumulation of toxic oxidized dopamine that was attenuated by boosting endophilin A1 expression. Notably, combined heterozygous parkin and homozygous PTEN-induced kinase 1 (PINK1) mutations led to earlier disease onset compared with homozygous mutant PINK1 alone, further underscoring a PINK1-independent role for parkin in contributing to disease. Thus, this study identifies a pathway for selective activation of parkin at human dopaminergic synapses and highlights the importance of this mechanism in the pathogenesis of Parkinson's disease.
    Keywords:  CaMK2-mediated activation of parkin; PINK1-independent; Parkinson’s disease; human dopaminergic neurons; synaptic dysfunction; toxic oxidized dopamine
    DOI:  https://doi.org/10.1016/j.neuron.2023.08.018
  36. J Immunol. 2023 Sep 22. pii: ji2300406. [Epub ahead of print]
    The Lysosomal Calcium Channel TRPML1 Maintains Mitochondrial Fitness in NK Cells through Interorganelle Cross-Talk.
    Dennis Clement, Edina K Szabo, Silje Zandstra Krokeide, Merete Thune Wiiger, Marianna Vincenti, Daniel Palacios, Young-Tae Chang, Christian Grimm, Sandip Patel, Harald Stenmark, Andreas Brech, Rakesh Kumar Majhi, Karl-Johan Malmberg.
      Cytotoxic lymphocytes eliminate cancer cells through the release of lytic granules, a specialized form of secretory lysosomes. This compartment is part of the pleomorphic endolysosomal system and is distinguished by its highly dynamic Ca2+ signaling machinery. Several transient receptor potential (TRP) calcium channels play essential roles in endolysosomal Ca2+ signaling and ensure the proper function of these organelles. In this study, we examined the role of TRPML1 (TRP cation channel, mucolipin subfamily, member 1) in regulating the homeostasis of secretory lysosomes and their cross-talk with mitochondria in human NK cells. We found that genetic deletion of TRPML1, which localizes to lysosomes in NK cells, led to mitochondrial fragmentation with evidence of collapsed mitochondrial cristae. Consequently, TRPML1-/- NK92 (NK92ML1-/-) displayed loss of mitochondrial membrane potential, increased reactive oxygen species stress, reduced ATP production, and compromised respiratory capacity. Using sensitive organelle-specific probes, we observed that mitochondria in NK92ML1-/- cells exhibited evidence of Ca2+ overload. Moreover, pharmacological activation of the TRPML1 channel in primary NK cells resulted in upregulation of LC3-II, whereas genetic deletion impeded autophagic flux and increased accumulation of dysfunctional mitochondria. Thus, TRPML1 impacts autophagy and clearance of damaged mitochondria. Taken together, these results suggest that an intimate interorganelle communication in NK cells is orchestrated by the lysosomal Ca2+ channel TRPML1.
    DOI:  https://doi.org/10.4049/jimmunol.2300406
  37. Front Immunol. 2023 ;14 1227369
    Activity of granulomatosis with polyangiitis and its correlation with mTOR phosphoproteomics in neutrophils.
    Marcin Surmiak, Katarzyna Wawrzycka-Adamczyk, Joanna Kosałka-Węgiel, Anna Włudarczyk, Marek Sanak, Jacek Musiał.
      Introduction: Granulomatosis with polyangiitis (GPA) is a small vessel vasculitis with a complex pathomechanism. Organ damage in GPA is also mediated by extracellular trap formation (NETosis). We analyzed the functional status of phosphoproteins modulating NETosis in neutrophils by the mammalian target of rapamycin (mTOR) pathway in GPA along with NETosis biomarkers.Methods: Phosphoproteins levels measured in isolated neutrophils from 42 patients with GPA (exacerbation n=21; remission n=21) and 21 healthy controls were compared to serum biomarkers of the disease.
    Results: Neutrophils in active disease manifested lowered levels of phosphorylated mTOR(Ser2448), PTEN(Ser380) and ULK1(Ser555), whereas phosphorylated GSK-3α/β(Ser21/Ser9) was elevated. Exacerbation of GPA was characterized by elevated neutrophil dsDNA in serum, circulating mitochondrial DNA, and DNA-MPO complexes. A significant negative correlation between mTOR or PTEN phosphoproteins and biomarkers of GPA activity was also present, reflecting the clinical activity score of GPA. Positive correlations between phosphorylated GSK-3 α/β and circulating mtDNA, DNA-MPO complexes, neutrophil-released dsDNA, or circulating proteins were also significant. Increased serum levels of IGFBP-2, TFF-3, CD147, and CHI3L1 accompanied GPA exacerbation, whereas DPP-IV levels were the lowest in active GPA. Using a principal component analysis basigin, PTEN and mTOR had the highest loadings on the discrimination function, allowing classification between active, remission, and control subjects with 98% performance.
    Conclusions: We present evidence that inhibited mTOR signaling accompanies NETosis in patients with GPA. The functional status of phosphoproteins suggests simultaneous activation of NETosis and autophagy. These results give rise to the study of autophagy as a mechanism underlying granuloma formation in GPA.
    Keywords:  autophagy; granulomatosis with polyangiitis; mammalian target of rapamycin; mitochondrial DNA; neutrophil extracellular traps; neutrophils
    DOI:  https://doi.org/10.3389/fimmu.2023.1227369
  38. Front Med (Lausanne). 2023 ;10 1209439
    mTOR signaling in hair follicle and hair diseases: recent progress.
    Wei Tu, Yu-Wei Cao, Mang Sun, Qian Liu, Heng-Guang Zhao.
      Mammalian target of rapamycin (mTOR) signaling pathway is a major regulator of cell proliferation and metabolism, playing significant roles in proliferation, apoptosis, inflammation, and illness. More and more evidences showed that the mTOR signaling pathway affects hair follicle circulation and maintains the stability of hair follicle stem cells. mTOR signaling may be a critical cog in Vitamin D receptor (VDR) deficiency-mediated hair follicle damage and degeneration and related alopecia disorders. This review examines the function of mTOR signaling in hair follicles and hair diseases, and talks about the underlying molecular mechanisms that mTOR signaling regulates.
    Keywords:  VDR; hair disease; hair follicle; hair follicle cycles; mTOR signaling
    DOI:  https://doi.org/10.3389/fmed.2023.1209439
  39. FEBS J. 2023 Sep 19.
    Synaptotagmin-7 Mediates Cardiac Hypertrophy by Targeting Autophagy.
    Teng Sun, Yu Han, Jia-Lei Li, Shuang Wang, Zhi-Jie Jing, Zi Yan, Lan Zhou, Lin Zuo, Jun-Li Yang, Ji-Min Cao.
      Sustained cardiac hypertrophy damages the heart and weakens cardiac function, often leading to heart failure and even death. Pathological cardiac hypertrophy has become a central therapeutic target for many heart diseases including heart failure. However, the underlying mechanisms of cardiac hypertrophy, especially the involvement of autophagy program, are still ill-understood. Synaptotagmin-7 (Syt7), a multifunctional and high-affinity calcium sensor, plays a pivotal role in asynchronous neurotransmitter release, synaptic facilitation and vesicle pool regulation during synaptic transmission. However, little is known about whether Syt7 is expressed in the myocardium and involved in the pathogenesis of heart diseases. Here we showed that Syt7 was significantly upregulated in Ang II-treated hearts and cardiomyocytes. Homozygous syt7 knockout (syt7-/-) mice exhibited significantly attenuated cardiac hypertrophy and fibrosis and improved cardiac function. We further found that Syt7 exerted a pro-hypertrophic effect by suppressing the autophagy process. In exploring the upstream mechanisms, microRNA (miR)-93 was identified to participate in the regulation of Syt7 expression. MiR-93 protected hearts against Ang II-induced hypertrophy through targeting Syt7-autophagy pathway. In summary, our data reveal a new cardiac hypertrophy regulator and a novel hypertrophy regulating model composed of miR-93, Syt7 and autophagy program. These molecules may serve as potential therapeutic targets in the treatment of cardiac hypertrophy and heart failure.
    Keywords:  Angiotensin II; Autophagy; Cardiac hypertrophy; MiR-93; Synaptotagmin-7
    DOI:  https://doi.org/10.1111/febs.16961
  40. PLoS Biol. 2023 Sep 18. 21(9): e3002310
    Selective retention of dysfunctional mitochondria during asymmetric cell division in yeast.
    Xenia Chelius, Veronika Bartosch, Nathalie Rausch, Magdalena Haubner, Jana Schramm, Ralf J Braun, Till Klecker, Benedikt Westermann.
      Decline of mitochondrial function is a hallmark of cellular aging. To counteract this process, some cells inherit mitochondria asymmetrically to rejuvenate daughter cells. The molecular mechanisms that control this process are poorly understood. Here, we made use of matrix-targeted D-amino acid oxidase (Su9-DAO) to selectively trigger oxidative damage in yeast mitochondria. We observed that dysfunctional mitochondria become fusion-incompetent and immotile. Lack of bud-directed movements is caused by defective recruitment of the myosin motor, Myo2. Intriguingly, intact mitochondria that are present in the same cell continue to move into the bud, establishing that quality control occurs directly at the level of the organelle in the mother. The selection of healthy organelles for inheritance no longer works in the absence of the mitochondrial Myo2 adapter protein Mmr1. Together, our data suggest a mechanism in which the combination of blocked fusion and loss of motor protein ensures that damaged mitochondria are retained in the mother cell to ensure rejuvenation of the bud.
    DOI:  https://doi.org/10.1371/journal.pbio.3002310
  41. Aging Dis. 2023 Aug 24.
    Crosstalk among Reactive Oxygen Species, Autophagy and Metabolism in Myocardial Ischemia and Reperfusion Stages.
    Yajie Peng, Yachuan Tao, Lingxu Liu, Ji Zhang, Bo Wei.
      Myocardial ischemia is the most common cardiovascular disease. Reperfusion, an important myocardial ischemia tool, causes unexpected and irreversible damage to cardiomyocytes, resulting in myocardial ischemia/reperfusion (MI/R) injury. Upon stress, especially oxidative stress induced by reactive oxygen species (ROS), autophagy, which degrades the intracellular energy storage to produce metabolites that are recycled into metabolic pathways to buffer metabolic stress, is initiated during myocardial ischemia and MI/R injury. Excellent cardioprotective effects of autophagy regulators against MI and MI/R have been reported. Reversing disordered cardiac metabolism induced by ROS also exhibits cardioprotective action in patients with myocardial ischemia. Herein, we review current knowledge on the crosstalk between ROS, cardiac autophagy, and metabolism in myocardial ischemia and MI/R. Finally, we discuss the possible regulators of autophagy and metabolism that can be exploited to harness the therapeutic potential of cardiac metabolism and autophagy in the diagnosis and treatment of myocardial ischemia and MI/R.
    DOI:  https://doi.org/10.14336/AD.2023.0823-4
  42. Autophagy. 2023 Sep 21.
    ER stress elicits non-canonical CASP8 (caspase 8) activation on autophagosomal membranes to induce apoptosis.
    Tatsuya Hattori, Kevin A Fundora, Kouta Hamamoto, David M Opozda, Xinwen Liang, Xiaoming Liu, Jiawen Zhang, Yasin Uzun, Yoshinori Takahashi, Hong-Gang Wang.
      The VPS37A gene encodes a subunit of the endosomal sorting complex required for transport (ESCRT)-I complex that is frequently lost in a wide variety of human solid cancers. We have previously demonstrated the role of VPS37A in directing the ESCRT membrane scission machinery to seal the phagophore for autophagosome completion. Here, we report that VPS37A-deficient cells exhibit an accumulation of the apoptotic initiator CASP8 (caspase 8) on the phagophore and are primed to undergo rapid apoptosis through the intracellular death-inducing signaling complex (iDISC)-mediated CASP8 activation upon exposure to endoplasmic reticulum (ER) stress. Using CRISPR-Cas9 gene editing and comparative transcriptome analysis, we identified the ATF4-mediated stress response pathway as a crucial mediator to elicit iDISC-mediated apoptosis following the inhibition of autophagosome closure. Notably, ATF4-mediated iDISC activation occurred independently of the death receptor TNFRSF10B/DR5 upregulation but required the pro-apoptotic transcriptional factor DDIT3/CHOP to enhance the mitochondrial amplification pathway for full-activation of CASP8 in VPS37A-deficient cells stimulated with ER stress inducers. Our analysis also revealed the upregulation of NFKB/NF-kB signaling as a potential mechanism responsible for restraining iDISC activation and promoting cell survival upon VPS37A depletion. These findings have important implications for the future development of new strategies to treat human cancers, especially those with VPS37A loss.
    Keywords:  ATF4-mediated ER stress response; Autophagy; ESCRT-mediated phagophore closure; NFKB/NF-kB signaling; VPS37A-deficient cancer; iDISC-mediated apoptosis
    DOI:  https://doi.org/10.1080/15548627.2023.2258701
  43. J Alzheimers Dis. 2023 Sep 12.
    Deletion of the Homocysteine Thiolactone Detoxifying Enzyme Bleomycin Hydrolase, in Mice, Causes Memory and Neurological Deficits and Worsens Alzheimer's Disease-Related Behavioral and Biochemical Traits in the 5xFAD Model of Alzheimer's Disease.
    Łukasz Witucki, Kamila Borowczyk, Joanna Suszyńska-Zajczyk, Ewelina Warzych, Piotr Pawlak, Hieronim Jakubowski.
      BACKGROUND: Bleomycin hydrolase (BLMH), a homocysteine (Hcy)-thiolactone detoxifying enzyme, is attenuated in Alzheimer's disease (AD) brains. Blmh loss causes astrogliosis in mice while the loss of histone demethylase Phf8, which controls mTOR signaling, causes neuropathy in mice and humans.OBJECTIVE: To examine how Blmh gene deletion affects the Phf8/H4K20me1/mTOR/autophagy pathway, amyloid-β (Aβ) accumulation, and cognitive/neuromotor performance in mice.
    METHODS: We generated a new mouse model of AD, the Blmh -/- 5xFAD mouse. Behavioral assessments were conducted by cognitive/neuromotor testing. Blmh and Phf8 genes were silenced in mouse neuroblastoma N2a-APPswe cells by RNA interference. mTOR- and autophagy-related proteins, and AβPP were quantified by western blotting and the corresponding mRNAs by RT-qPCR. Aβ was quantified by western blotting (brains) and by confocal microscopy (cells).
    RESULTS: Behavioral testing showed cognitive/neuromotor deficits in Blmh -/-  and Blmh -/- 5xFAD mice. Phf8 was transcriptionally downregulated in Blmh -/-  and Blmh -/- 5xFAD brains. H4K20me1, mTOR, phospho-mTOR, and AβPP were upregulated while autophagy markers Becn1, Atg5, and Atg7 were downregulated in Blmh -/-  and Blmh -/- 5xFAD brains. Aβ was elevated in Blmh -/- 5xFAD brains. These biochemical changes were recapitulated in Blmh-silenced N2a-APPswe cells, which also showed increased H4K20me1-mTOR promoter binding and impaired autophagy flux (Lc3-I, Lc3-II, p62). Phf8-silencing or treatments with Hcy-thiolactone or N-Hcy-protein, metabolites elevated in Blmh -/-  mice, induced biochemical changes in N2a-APPswe cells like those induced by the Blmh-silencing. However, Phf8-silencing elevated Aβ without affecting AβPP.
    CONCLUSIONS: Our findings show that Blmh interacts with AβPP and the Phf8/H4K20me1/mTOR/autophagy pathway, and that disruption of those interactions causes Aβ accumulation and cognitive/neuromotor deficits.
    Keywords:  Alzheimer’s disease; Blmh -/- 5xFAD mouse; H4K20me1; N2a-APPswe mouse neuroblastoma cells; Phf8; amyloid-β protein precursor; autophagy; bleomycin hydrolase; homocysteine thiolactone; mTOR
    DOI:  https://doi.org/10.3233/JAD-230578
  44. Int J Biol Macromol. 2023 Sep 17. pii: S0141-8130(23)03804-7. [Epub ahead of print]253(Pt 3): 126907
    TORC1 mediated regulation of mitochondrial integrity and calcium ion homeostasis by Wat1/mLst8 in S. pombe.
    Simmi Anjum, Swati Srivastava, Lalita Panigrahi, Uzair Ahmad Ansari, Arun Kumar Trivedi, Shakil Ahmed.
      The mTOR complexes play a fundamental role in mitochondrial biogenesis and cellular homeostasis. Wat1, an ortholog of mammalian Lst8 is an important component of TOR complex and is essential for the regulation of downstream signaling. Earlier we reported the role of Wat1 in oxidative stress response. Here, we have shown that the abrogation of wat1 causes respiratory defects and mitochondrial depolarization that leads to a decrease in ATP production. The confocal and electron microscopy in wat1Δ cells revealed the fragmented mitochondrial morphology implying its role in mitochondrial fission. Furthermore, we also showed its role in autophagy and the maintenance of calcium ion homeostasis. Additionally, tor2-287 mutant cells also exhibit defects in mitochondrial integrity indicating the TORC1-dependent involvement of Wat1 in the maintenance of mitochondrial homeostasis. The interaction studies of Wat1 and Tor2 with Por1 and Mmm1 proteins revealed a plausible cross-talk between mitochondria and endoplasmic reticulum through the Mitochondria-associated membranes (MAM) and endoplasmic reticulum-mitochondria encounter structure (ERMES) complex, involving TORC1. Taken together, this study demonstrates the involvement of Wat1/mLst8 in harmonizing various mitochondrial functions, redox status, and Ca2+ homeostasis.
    Keywords:  Calcium homeostasis; Mitochondrial integrity; S. pombe; TOR complex; Wat1
    DOI:  https://doi.org/10.1016/j.ijbiomac.2023.126907
  45. Joint Bone Spine. 2023 Sep 20. pii: S1297-319X(23)00121-5. [Epub ahead of print] 105642
    The role of autophagy in mitigating osteoarthritis progression via regulation of chondrocyte apoptosis: a review.
    Peggy Kong, Raja Elina Ahmad, Amirah Zulkifli, Shaliny Hari Rama Krishnan, Hui Yin Nam, Tunku Kamarul.
      Osteoarthritis (OA) is the most prevalent chronic joint disease with an immense socioeconomic burden; however, no treatment has achieved complete success in effectively halting or reversing cartilage degradation, which is the central pathophysiological feature of OA. Chondrocytes loss or dysfunction is a significant contributing factor to the progressive cartilage deterioration as these sole resident cells have a crucial role to produce extracellular matrix proteins, thus maintaining cartilage structure and homeostasis. It has been previously suggested that death of chondrocytes occurring through apoptosis substantially contributes to cartilage degeneration. Although the occurrence of apoptosis in osteoarthritic cartilage and its correlation with cartilage degradation is evident, the causes of chondrocyte apoptosis leading to matrix loss are still not well-understood. Autophagy, an intracellular degradative mechanism that eliminates dysfunctional cytoplasmic components to aid cell survival in unfavourable conditions, is a potential therapeutic target to inhibit chondrocyte apoptosis and reduce OA severity. Despite accumulating evidence indicating significant cytoprotective effects of autophagy against chondrocyte apoptosis, the mechanistic link between autophagy and apoptosis in chondrocytes remains to be further explored. In this review, we summarize the relevant mechanistic events that perpetuate chondrocyte apoptosis and highlight the prominent role of autophagy in modulating these events to mitigate OA progression.
    Keywords:  Aging; Cartilage; Cell death; Endoplasmic reticulum stress; Inflammation; Mitochondria
    DOI:  https://doi.org/10.1016/j.jbspin.2023.105642
  46. Autophagy. 2023 Sep 18. 1-18
    CSNK1A1/CK1α suppresses autoimmunity by restraining the CGAS-STING1 signaling.
    Mingyu Pan, Tongyu Hu, Jiao Lyu, Yue Yin, Jing Sun, Quanyi Wang, Lingxiao Xu, Haiyang Hu, Chen Wang.
      STING1 (stimulator of interferon response cGAMP interactor 1) is the quintessential protein in the CGAS-STING1 signaling pathway, crucial for the induction of type I IFN (interferon) production and eliciting innate immunity. Nevertheless, the overactivation or sustained activation of STING1 has been closely associated with the onset of autoimmune disorders. Notably, the majority of these disorders manifest as an upregulated expression of type I interferons and IFN-stimulated genes (ISGs). Hence, strict regulation of STING1 activity is paramount to preserve immune homeostasis. Here, we reported that CSNK1A1/CK1α, a serine/threonine protein kinase, was essential to prevent the overactivation of STING1-mediated type I IFN signaling through autophagic degradation of STING1. Mechanistically, CSNK1A1 interacted with STING1 upon the CGAS-STING1 pathway activation and promoted STING1 autophagic degradation by enhancing the phosphorylation of SQSTM1/p62 at serine 351 (serine 349 in human), which was critical for SQSTM1-mediated STING1 autophagic degradation. Consistently, SSTC3, a selective CSNK1A1 agonist, significantly attenuated the response of the CGAS-STING1 signaling by promoting STING1 autophagic degradation. Importantly, pharmacological activation of CSNK1A1 using SSTC3 markedly repressed the systemic autoinflammatory responses in the trex1-/- mouse autoimmune disease model and effectively suppressed the production of IFNs and ISGs in the PBMCs of SLE patients. Taken together, our study reveals a novel regulatory role of CSNK1A1 in the autophagic degradation of STING1 to maintain immune homeostasis. Manipulating CSNK1A1 through SSTC3 might be a potential therapeutic strategy for alleviating STING1-mediated aberrant type I IFNs in autoimmune diseases.Abbreviations: BMDMs: bone marrow-derived macrophages; cGAMP: cyclic GMP-AMP; CGAS: cyclic GMP-AMP synthase; HTDNA: herring testes DNA; IFIT1: interferon induced protein with tetratricopeptide repeats 1; IFNA4: interferon alpha 4; IFNB: interferon beta; IRF3: interferon regulatory factor 3; ISD: interferon stimulatory DNA; ISGs: IFN-stimulated genes; MEFs: mouse embryonic fibroblasts; PBMCs: peripheral blood mononuclear cells; RSAD2: radical S-adenosyl methionine domain containing 2; SLE: systemic lupus erythematosus; STING1: stimulator of interferon response cGAMP interactor 1; TBK1: TANK binding kinase 1.
    Keywords:  Autoimmunity; CSNK1A1; STING1; autophagy; type I IFN
    DOI:  https://doi.org/10.1080/15548627.2023.2256135
  47. J Agric Food Chem. 2023 Sep 22.
    Extracellular Glutamine Promotes Intestinal Porcine Epithelial Cell Proliferation via Arf1-mTORC1 Pathway Independently of Rag GTPases.
    Ling Yan, Yong-Xia Fang, En-Qing Lu, E Xu, Yi-Yu Zhang, Xiang Chen, Min Zhu.
      Glutamine (Gln) is the major energy source of intestinal porcine epithelial cells (IPEC-J2 cells) and plays a critical role in the nutritional physiological function of the intestine. However, the underlying mechanism requires further investigation. Here, the Gln-sensing pathway in IPEC-J2 cells was investigated. The results showed that Gln increased the cell proliferation. Subsequently, an analysis of the phosphorylated proteome revealed that Gln markedly upregulated ribosomal protein S6 (RPS6) phosphorylation at serine 235/236, suggesting that Gln activated the mTORC1 pathway. mTOR inhibition revealed that Gln promotes cell proliferation through the mTORC1 pathway. Similarly, blocking ADP-ribosylation factor 1 (Arf1) activity indicated that Gln-induced mTORC1 activation promoted cell proliferation in an Arf1-dependent manner. Additionally, the RagA/B pathway did not participate in Gln-induced mTORC1 activation. Collectively, these findings suggest that Gln-induced mTORC1 activation promotes IPEC-J2 cell proliferation via Arf1, not Rag GTPases. These results broaden our understanding of functional-cell-sensing amino acids, particularly Gln, that are regulated by mTORC1.
    Keywords:  Arf1; glutamine; intestinal porcine epithelial cells; mTORC1
    DOI:  https://doi.org/10.1021/acs.jafc.3c00339
  48. Sci Adv. 2023 Sep 22. 9(38): eadh8228
    Temporal landscape of mitochondrial proteostasis governed by the UPRmt.
    Louise Uoselis, Runa Lindblom, Wai Kit Lam, Catharina J Küng, Marvin Skulsuppaisarn, Grace Khuu, Thanh N Nguyen, Danielle L Rudler, Aleksandra Filipovska, Ralf B Schittenhelm, Michael Lazarou.
      Breakdown of mitochondrial proteostasis activates quality control pathways including the mitochondrial unfolded protein response (UPRmt) and PINK1/Parkin mitophagy. However, beyond the up-regulation of chaperones and proteases, we have a limited understanding of how the UPRmt remodels and restores damaged mitochondrial proteomes. Here, we have developed a functional proteomics framework, termed MitoPQ (Mitochondrial Proteostasis Quantification), to dissect the UPRmt's role in maintaining proteostasis during stress. We find essential roles for the UPRmt in both protecting and repairing proteostasis, with oxidative phosphorylation metabolism being a central target of the UPRmt. Transcriptome analyses together with MitoPQ reveal that UPRmt transcription factors drive independent signaling arms that act in concert to maintain proteostasis. Unidirectional interplay between the UPRmt and PINK1/Parkin mitophagy was found to promote oxidative phosphorylation recovery when the UPRmt failed. Collectively, this study defines the network of proteostasis mediated by the UPRmt and highlights the value of functional proteomics in decoding stressed proteomes.
    DOI:  https://doi.org/10.1126/sciadv.adh8228
  49. Mol Metab. 2023 Sep 20. pii: S2212-8778(23)00140-0. [Epub ahead of print] 101806
    Gemigliptin, a DPP4 inhibitor, ameliorates nonalcoholic steatohepatitis through AMP-activated protein kinase-independent and ULK1-mediated autophagy.
    Youngmi Song, Hyekyung Yang, Juhee Kim, Yoonjin Lee, Sung-Ho Kim, In-Gu Do, Cheol-Young Park.
      OBJECTIVE: Abnormal autophagic function and activated inflammasomes are typical features in the liver of patients with non-alcoholic steatohepatitis (NASH). Here, we explored whether gemigliptin, a dipeptidyl peptidase 4 (DPP4) inhibitor for treatment of type 2 diabetes, can induce autophagy and regulate inflammasome activation as a potential NASH treatment independent of its anti-diabetic effect.METHODS: Expression analysis was performed using human liver samples obtained from 18 subjects who underwent hepatectomy. We explored the function and mechanism of gemigliptin using a methionine- and choline-deficient diet (MCD)-induced NASH mouse model and HepG2 cells cultured in MCD-mimicking medium.
    RESULTS: Autophagy was suppressed by marked decreases in the expression of ULK1 and LC3II/LC3I ratio in human NAFLD/NASH patients, a NASH mouse model, and HepG2 cells cultured with MCD-mimicking media. Surprisingly, we found that the expression of p-AMPK decreased in liver tissues from patients with steatosis but was restored in NASH patients. The expression of p-AMPK in the NASH mouse model was similar to that of the control group. Hence, these results indicate that autophagy was reduced in NASH via an AMPK-independent pathway. However, gemigliptin treatment attenuated lipid accumulation, inflammation, and fibrosis in the liver of MCD diet-fed mice with restoration of ULK1 expression and autophagy induction. In vitro, gemigliptin alleviated inflammasome activation through induction of ULK1-dependent autophagy. Furthermore, gemigliptin treatment upregulated ULK1 expression and activated AMPK even after siRNA-mediated knockdown of AMPKα1/2 and ULK1, respectively.
    CONCLUSIONS: Collectively, these results suggest that gemigliptin ameliorated NASH via AMPK-independent, ULK1-mediated effects on autophagy.
    Keywords:  Autophagy; DPP-4 inhibitor; Gemigliptin; Inflammasome; NASH; ULK-1
    DOI:  https://doi.org/10.1016/j.molmet.2023.101806
  50. PLoS Genet. 2023 Sep;19(9): e1010893
    A monocarboxylate transporter rescues frontotemporal dementia and Alzheimer's disease models.
    Dongwei Xu, Alec Vincent, Andrés González-Gutiérrez, Benjamin Aleyakpo, Sharifah Anoar, Ashling Giblin, Magda L Atilano, Mirjam Adams, Dunxin Shen, Annora Thoeng, Elli Tsintzas, Marie Maeland, Adrian M Isaacs, Jimena Sierralta, Teresa Niccoli.
      Brains are highly metabolically active organs, consuming 20% of a person's energy at resting state. A decline in glucose metabolism is a common feature across a number of neurodegenerative diseases. Another common feature is the progressive accumulation of insoluble protein deposits, it's unclear if the two are linked. Glucose metabolism in the brain is highly coupled between neurons and glia, with glucose taken up by glia and metabolised to lactate, which is then shuttled via transporters to neurons, where it is converted back to pyruvate and fed into the TCA cycle for ATP production. Monocarboxylates are also involved in signalling, and play broad ranging roles in brain homeostasis and metabolic reprogramming. However, the role of monocarboxylates in dementia has not been tested. Here, we find that increasing pyruvate import in Drosophila neurons by over-expression of the transporter bumpel, leads to a rescue of lifespan and behavioural phenotypes in fly models of both frontotemporal dementia and Alzheimer's disease. The rescue is linked to a clearance of late stage autolysosomes, leading to degradation of toxic peptides associated with disease. We propose upregulation of pyruvate import into neurons as potentially a broad-scope therapeutic approach to increase neuronal autophagy, which could be beneficial for multiple dementias.
    DOI:  https://doi.org/10.1371/journal.pgen.1010893
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