bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2024–11–24
fifty-four papers selected by
Viktor Korolchuk, Newcastle University
  1. mTORC1, the maestro of cell metabolism and growth.
  2. PINK1 controls RTN3L-mediated ER autophagy by regulating peripheral tubule junctions.
  3. Starvation-induced metabolic rewiring affects mTORC1 composition in vivo.
  4. Structure of the human TSC:WIPI3 lysosomal recruitment complex.
  5. Mechanisms of autophagy and their implications in dermatological disorders.
  6. Autophagic stress activates distinct compensatory secretory pathways in neurons.
  7. Induction of Ca2+-dependent autophagy and concurrent lysosomal alkalinization underlies the cytotoxic effects of NNC-55-0396 on glioblastoma cells.
  8. Phagolysosomes break down the membrane of a non-apoptotic corpse independent of macroautophagy.
  9. Mechanistic role for mTORC1 signaling in profibrotic toxicity of low-dose cadmium.
  10. AMPK: Balancing mitochondrial quality and quantity through opposite regulation of mitophagy pathways.
  11. PKN2 Promotes Peripheral Nerve Repair by Regulating Autophagy via Activation of the AKT-mTOR Pathway: An In Vitro Study.
  12. Sex and Region-Specific Disruption of Autophagy and Mitophagy in Alzheimer's Disease: Linking Cellular Dysfunction to Cognitive Decline.
  13. TEX264-mediated selective autophagy directs DNA damage repair.
  14. Nutrient control of growth and metabolism through mTORC1 regulation of mRNA splicing.
  15. Phytochrome-interacting factors PIF4 and PIF5 directly regulate autophagy during leaf senescence in Arabidopsis.
  16. Overexpression of autophagy enhancer PACER/RUBCNL in neurons accelerates disease in the SOD1G93A ALS mouse model.
  17. Chaperone-Mediated Autophagy Alleviates Cerebral Ischemia-Reperfusion Injury by Inhibiting P53-Mediated Mitochondria-Associated Apoptosis.
  18. A Novel Human TBCK- Neuronal Cell Model Results in Severe Neurodegeneration and Partial Rescue with Mitochondrial Fission Inhibition.
  19. Adverse outcome pathway of Alzheimer's disease-like changes resulting from autophagy flux blockade after MC-LR exposure.
  20. Neuronal fatty acid-binding protein enhances autophagy and suppresses amyloid-β pathology in a Drosophila model of Alzheimer's disease.
  21. MicroRNA-mediated autophagy and drug resistance in cancer: mechanisms and therapeutic strategies.
  22. EYA3 promotes the tumorigenesis of gastric cancer through activation of the mTORC1 signaling pathway and inhibition of autophagy.
  23. WAC Facilitates Mitophagy-mediated MSC Osteogenesis and New Bone Formation via Protecting PINK1 from Ubiquitination-Dependent Degradation.
  24. Itaconic acid ameliorates necrotizing enterocolitis through the TFEB-mediated autophagy-lysosomal pathway.
  25. NDR2 is critical for the osteoclastogenesis by regulating ULK1-mediated mitophagy.
  26. Autophagy modulates Arabidopsis male gametophyte fertility and controls actin organization.
  27. Exploring heat shock proteins as therapeutic targets for Parkinson's disease.
  28. Plasmodium berghei liver stage parasites exploit host GABARAP proteins for TFEB activation.
  29. Trimetazidine restores autophagy via lncRNA H19/AMPK in diabetic heart: Implications for its therapeutic value against diabetic cardiomyopathy.
  30. Deficiency of mitophagy mediator Parkin in aortic smooth muscle cells exacerbates abdominal aortic aneurysm.
  31. Intermittent Hypoxia Impairs Cognitive Function and Promotes Mitophagy and Lysophagy in Obstructive Sleep Apnea-Hypopnea Syndrome Rat Model.
  32. A multi-subunit autophagic capture complex facilitates degradation of ER stalled MHC-I in pancreatic cancer.
  33. Ivermectin inhibits the growth of ESCC by activating the ATF4-mediated endoplasmic reticulum stress-autophagy pathway.
  34. The roles of mTORC1 in parathyroid gland function in chronic kidney disease-induced secondary hyperparathyroidism: Evidence from male genetic mouse models and clinical data.
  35. Irisin reduces senile osteoporosis by inducing osteocyte mitophagy through Ampk activation.
  36. Astrocytic Proteostasis in the Tale of Aging and Neurodegeneration.
  37. Inhibition of TrkB kinase activity impairs autophagy in cervical motor neurons of young but not old mice.
  38. Naked cuticle homolog 2 controls the differentiation of osteoblasts and osteoclasts and ameliorates bone loss in ovariectomized mice.
  39. Residual microglia following short-term PLX5622 treatment in 5xFAD mice exhibit diminished NLRP3 inflammasome and mTOR signaling, and enhanced autophagy.
  40. Sestrin2 balances mitophagy and apoptosis through the PINK1-Parkin pathway to attenuate severe acute pancreatitis.
  41. Neurotoxicity of Realgar: Crosstalk Between UBXD8-DRP1-Regulated Mitochondrial Fission and PINK1-Parkin-Mediated Mitophagy.
  42. Small-Molecule Inhibitors in WNT Signalling Pathway for Targeted Cancer Therapy: Interplay between WNT, Autophagy and Apoptosis.
  43. Virtual Screening and Biological Evaluation of Natural Products as Novel VPS34 Inhibitors that Modulate Autophagy.
  44. Gnetupendin A protects against ischemic stroke through activating the PI3K/AKT/mTOR-dependent autophagy pathway.
  45. Autophagy-dependent ferroptosis mediates multiple sclerosis.
  46. Exploring Arylidene-Indolinone Ligands of Autophagy Proteins LC3B and GABARAP.
  47. Targeted protein degradation: expanding the technology to facilitate the clearance of neurotoxic proteins in neurodegenerative diseases.
  48. MT1G promotes iron autophagy and inhibits the function of gastric cancer cell lines by intervening in GPX4/SQSTM1.
  49. Aloperine Attenuates UVB-induced Damage in Skin Fibroblasts Via Activating TFE3/Beclin-1-Mediated Autophagy.
  50. Endoplasmic reticulum stress-mediated apoptosis and autophagy in osteoarthritis: from molecular mechanisms to therapeutic applications.
  51. SIRT3 Deficiency Promotes Lung Endothelial Pyroptosis Through Impairing Mitophagy to Activate NLRP3 Inflammasome During Sepsis-Induced Acute Lung Injury.
  52. Peripheral Lysosomal Positioning in Inflamed Odontoblasts Facilitates Mineralization.
  53. PDCD6 regulates lactate metabolism to modulate LC3-associated phagocytosis and antibacterial defense.
  54. Endogenous mitochondrial NAD(P)H fluorescence can predict lifespan.
  1. Genes Dev. 2024 Nov 21.
    mTORC1, the maestro of cell metabolism and growth.
    Long He, Sungyun Cho, John Blenis.
      The mechanistic target of rapamycin (mTOR) pathway senses and integrates various environmental and intracellular cues to regulate cell growth and proliferation. As a key conductor of the balance between anabolic and catabolic processes, mTOR complex 1 (mTORC1) orchestrates the symphonic regulation of glycolysis, nucleic acid and lipid metabolism, protein translation and degradation, and gene expression. Dysregulation of the mTOR pathway is linked to numerous human diseases, including cancer, neurodegenerative disorders, obesity, diabetes, and aging. This review provides an in-depth understanding of how nutrients and growth signals are coordinated to influence mTOR signaling and the extensive metabolic rewiring under its command. Additionally, we discuss the use of mTORC1 inhibitors in various aging-associated metabolic diseases and the current and future potential for targeting mTOR in clinical settings. By deciphering the complex landscape of mTORC1 signaling, this review aims to inform novel therapeutic strategies and provide a road map for future research endeavors in this dynamic and rapidly evolving field.
    Keywords:  cancer; cellular signaling; mT; mTOR complex 1; mTORC1
    DOI:  https://doi.org/10.1101/gad.352084.124
  2. J Cell Biol. 2024 Dec 02. pii: e202407193. [Epub ahead of print]223(12):
    PINK1 controls RTN3L-mediated ER autophagy by regulating peripheral tubule junctions.
    Ravi Chidambaram, Kamal Kumar, Smriti Parashar, Gowsalya Ramachandran, Shuliang Chen, Susan Ferro-Novick.
      Here, we report that the RTN3L-SEC24C endoplasmic reticulum autophagy (ER-phagy) receptor complex, the CUL3KLHL12 E3 ligase that ubiquitinates RTN3L, and the FIP200 autophagy initiating protein, target mutant proinsulin (Akita) condensates for lysosomal delivery at ER tubule junctions. When delivery was blocked, Akita condensates accumulated in the ER. In exploring the role of tubulation in these events, we unexpectedly found that loss of the Parkinson's disease protein, PINK1, reduced peripheral tubule junctions and blocked ER-phagy. Overexpression of the PINK1 kinase substrate, DRP1, increased junctions, reduced Akita condensate accumulation, and restored lysosomal delivery in PINK1-depleted cells. DRP1 is a dual-functioning protein that promotes ER tubulation and severs mitochondria at ER-mitochondria contact sites. DRP1-dependent ER tubulating activity was sufficient for suppression. Supporting these findings, we observed PINK1 associating with ER tubules. Our findings show that PINK1 shapes the ER to target misfolded proinsulin for RTN3L-SEC24C-mediated macro-ER-phagy at defined ER sites called peripheral junctions. These observations may have important implications for understanding Parkinson's disease.
    DOI:  https://doi.org/10.1083/jcb.202407193
  3. Sci Rep. 2024 11 16. 14(1): 28296
    Starvation-induced metabolic rewiring affects mTORC1 composition in vivo.
    Kaade Edgar, Mausbach Simone, Erps Nina, Sylvester Marc, Shakeri Farhad, Ron D Jachimowicz, Gieselmann Volkmar, Thelen Melanie.
      Lysosomes play a crucial role in metabolic adaptation to starvation, but detailed in vivo studies are scarce. Therefore, we investigated the changes of the proteome of liver lysosomes in mice starved short-term for 6h or long-term for 24h. We verified starvation-induced catabolism by weight loss, ketone body production, drop in blood glucose and an increase of 3-methylhistidine. Deactivation of mTORC1 in vivo after short-term starvation causes a depletion of mTORC1 and the associated Ragulator complex in hepatic lysosomes, resulting in diminished phosphorylation of mTORC1 target proteins. While mTORC1 lysosomal protein levels and activity in liver were restored after long-term starvation, the lysosomal levels of Ragulator remained constantly reduced. To determine whether this mTORC1 activity pattern may be organ-specific, we further investigated the key metabolic organs muscle and brain. mTORC1 inactivation, but not re-activation, occurred in muscle after a starvation of 12 h or longer. In brain, mTORC1 activity remained unchanged during starvation. As mTORC1 deactivation is known to induce autophagy, we further investigated the more than 150 non-lysosomal proteins enriched in the lysosomal fraction upon starvation. Proteasomal, cytosolic and peroxisomal proteins dominated after short-term starvation, while after long-term starvation, mainly proteasomal and mitochondrial proteins accumulated, indicating ordered autophagic protein degradation.
    DOI:  https://doi.org/10.1038/s41598-024-78873-7
  4. Sci Adv. 2024 Nov 22. 10(47): eadr5807
    Structure of the human TSC:WIPI3 lysosomal recruitment complex.
    Charles Bayly-Jones, Christopher J Lupton, Laura D'Andrea, Yong-Gang Chang, Gareth D Jones, Joel R Steele, Hari Venugopal, Ralf B Schittenhelm, Michelle L Halls, Andrew M Ellisdon.
      Tuberous sclerosis complex (TSC) is targeted to the lysosomal membrane, where it hydrolyzes RAS homolog-mTORC1 binding (RHEB) from its GTP-bound to GDP-bound state, inhibiting mechanistic target of rapamycin complex 1 (mTORC1). Loss-of-function mutations in TSC cause TSC disease, marked by excessive tumor growth. Here, we overcome a high degree of continuous conformational heterogeneity to determine the 2.8-Å cryo-electron microscopy (cryo-EM) structure of the complete human TSC in complex with the lysosomal recruitment factor WD repeat domain phosphoinositide-interacting protein 3 (WIPI3). We discover a previously undetected amino-terminal TSC1 HEAT repeat dimer that clamps onto a single TSC wing and forms a phosphatidylinositol phosphate (PIP)-binding pocket, which specifically binds monophosphorylated PIPs. These structural advances provide a model by which WIPI3 and PIP-signaling networks coordinate to recruit TSC to the lysosomal membrane to inhibit mTORC1. The high-resolution TSC structure reveals previously unrecognized mutational hotspots and uncovers crucial insights into the mechanisms of TSC dysregulation in disease.
    DOI:  https://doi.org/10.1126/sciadv.adr5807
  5. Front Immunol. 2024 ;15 1486627
    Mechanisms of autophagy and their implications in dermatological disorders.
    Shenghao Xue, Yumeng Lin, Haoran Chen, Zhengyu Yang, Junting Zha, Xuan Jiang, Zhongyu Han, Ke Wang.
      Autophagy is a highly conserved cellular self-digestive process that underlies the maintenance of cellular homeostasis. Autophagy is classified into three types: macrophage, chaperone-mediated autophagy (CMA) and microphagy, which maintain cellular homeostasis through different mechanisms. Altered autophagy regulation affects the progression of various skin diseases, including psoriasis (PA), systemic lupus erythematosus (SLE), vitiligo, atopic dermatitis (AD), alopecia areata (AA) and systemic sclerosis (SSc). In this review, we review the existing literature focusing on three mechanisms of autophagy, namely macrophage, chaperone-mediated autophagy and microphagy, as well as the roles of autophagy in the above six dermatological disorders in order to aid in further studies in the future.
    Keywords:  atopic dermatitis; autophagy; pemphigus; psoriasis; systemic lupus erythematosus; systemic sclerosis; vitiligo
    DOI:  https://doi.org/10.3389/fimmu.2024.1486627
  6. bioRxiv. 2024 Nov 07. pii: 2024.11.07.621551. [Epub ahead of print]
    Autophagic stress activates distinct compensatory secretory pathways in neurons.
    Sierra D Palumbos, Jacob Popolow, Juliet Goldsmith, Erika L F Holzbaur.
      Autophagic dysfunction is a hallmark of neurodegenerative disease, leaving neurons vulnerable to the accumulation of damaged organelles and proteins. However, the late onset of diseases suggests that compensatory quality control mechanisms may be engaged to delay the deleterious effects induced by compromised autophagy. Neurons expressing common familial Parkinson's disease (PD)-associated mutations in LRRK2 kinase exhibit defective autophagy. Here, we demonstrate that both primary murine neurons and human iPSC-derived neurons harboring pathogenic LRRK2 upregulate the secretion of extracellular vesicles. We used unbiased proteomics to characterize the secretome of LRRK2 G2019S neurons and found that autophagic cargos including mitochondrial proteins were enriched. Based on these observations, we hypothesized that autophagosomes are rerouted toward secretion when cell-autonomous degradation is compromised, likely to mediate clearance of undegraded cellular waste. Immunoblotting confirmed the release of autophagic cargos and immunocytochemistry demonstrated that secretory autophagy was upregulated in LRRK2 G2019S neurons. We also found that LRRK2 G2019S neurons upregulate the release of exosomes containing miRNAs. Live-cell imaging confirmed that this upregulation of exosomal release was dependent on hyperactive LRRK2 activity, while pharmacological experiments indicate that this release staves off apoptosis. Finally, we show that markers of both vesicle populations are upregulated in plasma from mice expressing pathogenic LRRK2. In sum, we find that neurons expressing pathogenic LRRK2 upregulate the compensatory release of secreted autophagosomes and exosomes, to mediate waste disposal and transcellular communication, respectively. We propose that this increased secretion contributes to the maintenance of cellular homeostasis, delaying neurodegenerative disease progression over the short term while potentially contributing to increased neuroinflammation over the longer term.
    SIGNIFICANCE: A hallmark feature of many neurodegenerative diseases is autophagy dysfunction, resulting in the accumulation of damaged proteins and organelles that is detrimental to neuronal health. The late onset of neurodegenerative diseases, however, suggests alternative quality control mechanisms may delay neuronal degeneration. Here, we demonstrate that neurons expressing a Parkinson's Disease-causing mutation upregulate the release of two extracellular vesicle populations. First, we observe the increased expulsion of secreted autophagosomes to mediate cellular waste disposal. Second, we observe the increased release of exosomes, likely to facilitate transcellular communication. Thus, we propose that increases in secretory autophagy and exosome release are a homeostatic response in neurons undergoing chronic stress.
    DOI:  https://doi.org/10.1101/2024.11.07.621551
  7. Biomed Pharmacother. 2024 Nov 19. pii: S0753-3322(24)01576-2. [Epub ahead of print]181 117690
    Induction of Ca2+-dependent autophagy and concurrent lysosomal alkalinization underlies the cytotoxic effects of NNC-55-0396 on glioblastoma cells.
    Anna Visa, Maria Casals, Lía Alza, Judit Herreros, Carles Cantí.
      Diverse agents targeting (macro)autophagy, a critical metabolic stress response in cancer cells, have been proposed for cancer therapy. In previous studies, we showed that NNC-55-0396 (NNC) induces glioblastoma cell death by activating the Unfolded Protein Response (UPR) of ER stress and increasing cytosolic Ca2+ levels. Here, we report that NNC affects both ends of the autophagy process, causing extensive cytoplasmic vacuolation. Our results show that: (1) NNC induces autophagy downstream of UPR and Ca2+ signaling pathways, thus silencing IRE1α/JNK1 or inhibiting Ca2+/IP3R signaling prevents NNC-induced vacuolation. (2) Silencing ATG5 delays cell death, indicating that autophagy induction plays a role in NNC's cytotoxic effects. (3) NNC and other Ca2+-mobilizing agents transcriptionally upregulate p62/SQSTM1, an autophagosome cargo receptor, highlighting a role for this protein in the response to NNC. (4) Studies using tandem fluorescent-tagged LC3 and electron microscopy, however, further reveal that NNC blocks late-stage autophagy that leads to enlarged degradative compartments accumulating ubiquitin-tagged cargoes. (5) Finally, NNC impedes pro-cathepsin-B processing, an effect that is reversed with a weak acid co-treatment, suggesting that lysosomal dysfunction due to increased intraluminal pH is the underlying cause of the autophagy blockade. Together, these findings underscore a multi-level dysregulation of autophagy that contributes to NNC's anti-tumoral effects.
    Keywords:  Calcium; UPR; autophagy; cell death; glioblastoma; tetralines
    DOI:  https://doi.org/10.1016/j.biopha.2024.117690
  8. PLoS One. 2024 ;19(11): e0306435
    Phagolysosomes break down the membrane of a non-apoptotic corpse independent of macroautophagy.
    Shruti Kolli, Cassidy J Kline, Kimya M Rad, Ann M Wehman.
      Cell corpses must be cleared in an efficient manner to maintain tissue homeostasis and regulate immune responses. Ubiquitin-like Atg8/LC3 family proteins promote the degradation of membranes and internal cargo during both macroautophagy and corpse clearance, raising the question how macroautophagy contributes to corpse clearance. Studying the clearance of non-apoptotic dying polar bodies in Caenorhabditis elegans embryos, we show that the LC3 ortholog LGG-2 is enriched inside the polar body phagolysosome independent of autophagosome formation. We demonstrate that ATG-16.1 and ATG-16.2, which promote membrane association of lipidated Atg8/LC3 proteins, redundantly promote polar body membrane breakdown in phagolysosomes independent of their role in macroautophagy. We also show that the lipid scramblase ATG-9 is needed for autophagosome formation in early embryos but is dispensable for timely polar body membrane breakdown or protein cargo degradation. These findings demonstrate that macroautophagy is not required to promote polar body degradation, in contrast to recent findings with apoptotic corpse clearance in C. elegans embryos. Determining how factors regulating Atg8/LC3 promote the breakdown of different types of cell corpses in distinct cell types or metabolic states is likely to give insights into the mechanisms of immunoregulation during normal development, physiology, and disease.
    DOI:  https://doi.org/10.1371/journal.pone.0306435
  9. Toxicol Appl Pharmacol. 2024 Nov 16. pii: S0041-008X(24)00358-2. [Epub ahead of print] 117159
    Mechanistic role for mTORC1 signaling in profibrotic toxicity of low-dose cadmium.
    Choon-Myung Lee, Ho Young Lee, Zachery R Jarrell, Ryan M Smith, Dean P Jones, Young-Mi Go.
      Cadmium (Cd) is a toxic environmental metal that is naturally present in foods and drinking water. Cd is of increasing concern to human health due to its association with age-related diseases and long biologic half-life. Previous studies show that low-dose Cd exposure via drinking water induces mechanistic target of rapamycin complex 1 (mTORC1) signaling in mice; however, the role of mTORC1 pathway in Cd-induced pro-fibrotic responses has not been established. In the present study, we used human lung fibroblasts to examine whether inhibiting the mTORC1 pathway prevents lung fibrosis signaling induced by low-dose Cd exposure. Results show that rapamycin, a pharmacological inhibitor of mTORC1, inhibited Cd-dependent phosphorylation of ribosomal protein S6, a downstream marker of mTORC1 activation. Rapamycin also decreased Cd-dependent increases in pro-fibrotic markers, α-smooth muscle actin, collagen 1α1 and fibronectin. Cd activated mitochondrial spare respiratory capacity in association with increased cell proliferation. Rapamycin decreased these responses, showing that mTORC1 signaling supports mitochondrial energy supply for cell proliferation, an important step in fibroblast trans-differentiation into myofibroblasts. Collectively, these results establish a key mechanistic role for mTORC1 activation in environmental Cd-dependent lung fibrosis.
    Keywords:  Cadmium; Environmental exposure; Mammalian target of rapamycin; Mitochondrial function; Pulmonary fibrosis
    DOI:  https://doi.org/10.1016/j.taap.2024.117159
  10. Mol Cell. 2024 Nov 21. pii: S1097-2765(24)00880-3. [Epub ahead of print]84(22): 4261-4263
    AMPK: Balancing mitochondrial quality and quantity through opposite regulation of mitophagy pathways.
    Hui Jiang.
      In this issue of Molecular Cell, Longo et al.1 reveal that AMPK, a regulatory kinase activated by metabolic stress, inhibits NIX/BNIP3-dependent mitophagy to preserve mitochondrial quantity and activates PINK1/Parkin-dependent mitophagy to ensure mitochondrial quality.
    DOI:  https://doi.org/10.1016/j.molcel.2024.10.040
  11. J Biochem Mol Toxicol. 2024 Dec;38(12): e70063
    PKN2 Promotes Peripheral Nerve Repair by Regulating Autophagy via Activation of the AKT-mTOR Pathway: An In Vitro Study.
    Lin Wang, Yuan-Sheng Huang.
      This study aims to explore the role of Protein Kinase N2 (PKN2) in peripheral nerve injury (PNI) and evaluate its potential as a therapeutic target. The study employed a PC12 cell model to assess the effects of PKN2 overexpression on cell proliferation, migration, synaptic growth, and autophagic activity, with a focus on the regulatory role of the protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway. The results demonstrated that PKN2 overexpression significantly promoted PC12 cell proliferation and cell migration, while also enhancing synaptic growth. Additionally, a significant suppression of autophagy was observed. Mechanistic analysis revealed that PKN2 inhibited autophagic activity through the activation of the AKT/mTOR pathway. In summary, PKN2 plays a significant role in peripheral nerve repair by promoting cell proliferation, migration, and synaptic growth, while inhibiting autophagy through the AKT/mTOR pathway. These findings suggest that targeting PKN2 may represent an effective therapeutic strategy for the treatment of PNI.
    Keywords:  AKT/mTOR; PC12 cells; Protein Kinase N2 (PKN2); autophagy; peripheral nerve injury (PNI); synaptic growth
    DOI:  https://doi.org/10.1002/jbt.70063
  12. bioRxiv. 2024 Oct 31. pii: 2024.10.30.621097. [Epub ahead of print]
    Sex and Region-Specific Disruption of Autophagy and Mitophagy in Alzheimer's Disease: Linking Cellular Dysfunction to Cognitive Decline.
    Aida Adlimoghaddam, Fariba Fayazbakhsh, Mohsen Mohammadi, Zeinab Babaei, Amir Barzegar Behrooz, Farhad Tabasi, Teng Guan, Iman Beheshti, Mahmoud Aghaei, Daniel J Klionsky, Benedict C Albensi, Saeid Ghavami.
      Macroautophagy and mitophagy are critical processes in Alzheimer's disease (AD), yet their links to behavioral outcomes, particularly sex-specific differences, are not fully understood. This study investigates autophagy (LC3B-II, SQSTM1) and mitophagy (BNIP3L, BNIP3, BCL2L13) markers in the cortex and hippocampus of male and female 3xTg-AD mice, using western blotting, transmission electron microscopy (TEM), and behavioral tests (novel object recognition and novel object placement). Significant sex-specific differences emerged: female 3xTg-AD mice exhibited autophagosome accumulation due to impaired degradation in the cortex, while males showed fewer autophagosomes, especially in the hippocampus, without significant degradation changes. TEM analyses demonstrated variations in mitochondrial and mitophagosome numbers correlated with memory outcomes. Females had enhanced mitophagy, with higher BNIP3L and BCL2L13 levels, whereas males showed elevated BNIP3 dimers. Cognitive deficits in females correlated with mitochondrial dysfunction in the cortex, while in males, higher LC3B-II levels associated positively with cognitive performance, suggesting protective autophagy effects. Using machine learning, we predicted mitophagosome and mitochondrial numbers based on behavioral data, pioneering a predictive approach to cellular outcomes in AD. These findings underscore the importance of sex-specific regulation of autophagy and mitophagy in AD and support personalized therapeutic approaches targeting these pathways. Integrating machine learning emphasizes its potential to advance neurodegenerative research.
    Abstract Figure:
    DOI:  https://doi.org/10.1101/2024.10.30.621097
  13. Trends Biochem Sci. 2024 Nov 15. pii: S0968-0004(24)00252-4. [Epub ahead of print]
    TEX264-mediated selective autophagy directs DNA damage repair.
    Yuxia Qi, Sho W Suzuki.
      DNA is constantly subject to damage from endogenous and exogenous factors, leading to mutations and disease. While DNA is traditionally repaired in the nucleus, Lascaux et al. reveal a novel role for the lysosome in DNA repair, demonstrating that topoisomerase 1 (TOP1) cleavage complex (TOP1cc) DNA lesions are degraded via TEX264-mediated selective autophagy.
    Keywords:  DNA repair; TEX264; colorectal cancer; genome stability; selective autophagy; topoisomerase 1 cleavage complex
    DOI:  https://doi.org/10.1016/j.tibs.2024.10.012
  14. Mol Cell. 2024 Nov 15. pii: S1097-2765(24)00877-3. [Epub ahead of print]
    Nutrient control of growth and metabolism through mTORC1 regulation of mRNA splicing.
    Takafumi Ogawa, Meltem Isik, Ziyun Wu, Kiran Kurmi, Jin Meng, Sungyun Cho, Gina Lee, L Paulette Fernandez-Cardenas, Masaki Mizunuma, John Blenis, Marcia C Haigis, T Keith Blackwell.
      Cellular growth and organismal development are remarkably complex processes that require the nutrient-responsive kinase mechanistic target of rapamycin complex 1 (mTORC1). Anticipating that important mTORC1 functions remained to be identified, we employed genetic and bioinformatic screening in C. elegans to uncover mechanisms of mTORC1 action. Here, we show that during larval growth, nutrients induce an extensive reprogramming of gene expression and alternative mRNA splicing by acting through mTORC1. mTORC1 regulates mRNA splicing and the production of protein-coding mRNA isoforms largely independently of its target p70 S6 kinase (S6K) by increasing the activity of the serine/arginine-rich (SR) protein RSP-6 (SRSF3/7) and other splicing factors. mTORC1-mediated mRNA splicing regulation is critical for growth; mediates nutrient control of mechanisms that include energy, nucleotide, amino acid, and other metabolic pathways; and may be conserved in humans. Although mTORC1 inhibition delays aging, mTORC1-induced mRNA splicing promotes longevity, suggesting that when mTORC1 is inhibited, enhancement of this splicing might provide additional anti-aging benefits.
    Keywords:  C. elegans; SR proteins; development; gene expression; growth; human cell growth; longevity; mRNA splicing; mTORC1; metabolism; nutrient response
    DOI:  https://doi.org/10.1016/j.molcel.2024.10.037
  15. J Exp Bot. 2024 Nov 16. pii: erae469. [Epub ahead of print]
    Phytochrome-interacting factors PIF4 and PIF5 directly regulate autophagy during leaf senescence in Arabidopsis.
    Juhyeon Lee, Myeong Hoon Kang, Da-Min Choi, Anne Marmagne, Jeehye Park, Heeho Lee, Eunha Gwak, Jong Chan Lee, Jeong-Il Kim, Céline Masclaux-Daubresse, Pyung Ok Lim.
      During leaf senescence, autophagy plays a critical role by removing damaged cellular components and participating in nutrient remobilization to sink organs. However, how AUTOPHGAY (ATG) genes are regulated during natural leaf senescence remains largely unknown. In this study, we attempted to identify upstream transcriptional regulator(s) of ATGs and their molecular basis during leaf senescence in Arabidopsis through the combined analyses of promoter binding, autophagy flux, and genetic interactions. We found that PIF4 and PIF5 (PIF4/PIF5) directly bind to the promoters of the ATG5, ATG12a, ATG12b, ATG8a, ATG8e, ATG8f, and ATG8g, inducing their transcription. These target ATGs are downregulated in pif4, pif5, and pif4pif5 mutants, resulting in decreased autophagic activity and slower degradation of chloroplast proteins and chlorophyll. Conversely, overexpression of ATG8s accelerated protein degradation with early leaf senescence. Moreover, our data suggests partial suppression of the pif4pif5 phenotype by ATG8a overexpression. PIF4/PIF5 also influences senescence induced by nutrient starvation, another hallmark of the autophagy pathway. Furthermore, we observed that the PIF4/PIF5-ATG regulatory module may contribute to seed maturation. Our study not only unveils transcriptional regulators of autophagy in natural leaf senescence but also underscores the potential role of PIF4/PIF5 as functional regulators in leaf senescence and nutrient remobilization.
    Keywords:  Autophagy; Leaf senescence; Nutrient remobilization; Phytochrome-interacting factor; Starvation; Transcriptions Factors
    DOI:  https://doi.org/10.1093/jxb/erae469
  16. Biol Res. 2024 Nov 17. 57(1): 86
    Overexpression of autophagy enhancer PACER/RUBCNL in neurons accelerates disease in the SOD1G93A ALS mouse model.
    Luis Labrador, Leonardo Rodriguez, Sebastián Beltran, Fernanda Hernandez, Laura Gomez, Patricia Ojeda, Cristian Bergmann, Melissa Calegaro-Nassif, Bredford Kerr, Danilo B Medinas, Patricio Manque, Ute Woehlbier.
      Amyotrophic lateral sclerosis (ALS) is a debilitating and fatal paralytic disorder associated with motor neuron death. Mutant superoxide dismutase 1 (SOD1) misfolding and aggregation have been linked to familial ALS, with the accumulation of abnormal wild-type SOD1 species being also observed in postmortem tissue of sporadic ALS cases. Both wild-type and mutated SOD1 are reported to contribute to motoneuron cell death. The autophagic pathway has been shown to be dysregulated in ALS. Recent evidence suggests a dual time-dependent role of autophagy in the progression of the disease. PACER, also called RUBCNL (Rubicon-like), is an enhancer of autophagy and has been found diminished in its levels during ALS pathology in mice and humans. Pacer loss of function disturbs the autophagy process and leads to the accumulation of SOD1 aggregates, as well as sensitizes neurons to death. Therefore, here we investigated if constitutive overexpression of PACER in neurons since early development is beneficial in an in vivo model of ALS. We generated a transgenic mouse model overexpressing human PACER in neurons, which then was crossbred with the mutant SOD1G93A ALS mouse model. Unexpectedly, PACER/SOD1G93A double transgenic mice exhibited an earlier disease onset and shorter lifespan than did littermate SOD1G93A mice. The overexpression of PACER in neurons in vivo and in vitro increased the accumulation of SOD1 aggregates, possibly due to impaired autophagy. These results suggest that similar to Pacer loss-of function, Pacer gain-of function is detrimental to autophagy, increases SOD1 aggregation and worsens ALS pathogenesis. In a wider context, our results indicate the requirement to maintain a fine balance of PACER protein levels to sustain proteostasis.
    Keywords:  Amyotrophic lateral sclerosis; Autophagy; KIAA0226L; PACER; RUBCNL; SQSTM1; Superoxide dismutase 1; p62
    DOI:  https://doi.org/10.1186/s40659-024-00567-1
  17. Neurochem Res. 2024 Nov 22. 50(1): 29
    Chaperone-Mediated Autophagy Alleviates Cerebral Ischemia-Reperfusion Injury by Inhibiting P53-Mediated Mitochondria-Associated Apoptosis.
    Shaonan Yang, Lu Jiang, Ling Deng, Jingjing Luo, Xiaoling Zhang, Sha Chen, Zhi Dong.
      Ischemia-reperfusion is a complex brain disease involving multiple biological processes, including autophagy, oxidative stress, and mitochondria-associated apoptosis. Chaperone-mediated autophagy (CMA), a selective autophagy, is involved in the development of various neurodegenerative diseases and acute nerve injury, but its role in ischemia-reperfusion is unclear. Here, we used middle cerebral artery occlusion/reperfusion (MCAO/R) and oxygen-glucose deprivation/reoxygenation (OGD/R) models to simulate cerebral ischemic stroke in vivo and in vitro, respectively. LAMP2A (lysosome-associated membrane protein 2A), a key molecule of CMA, was dramatically downregulated in ischemia-reperfusion. Enhancement of CMA activity by LAMP2A overexpression reduced the neurological deficit, brain infarct volume, pathological features, and neuronal apoptosis of the cortex in vivo. Concomitantly, enhanced CMA activity alleviated OGD/R-induced apoptosis and mitochondrial membrane potential decline in vitro. In addition, we found that CMA inhibited the P53(Tumor protein p53) signaling pathway and reduced P53 translocation to mitochondria. The P53 activator, Nutlin-3, not only reversed the inhibitory effect of CMA on apoptosis, but also significantly weakened the protective effect of CMA on OGD/R and MCAO/R. Taken together, these results indicate that inhibition of P53-mediated mitochondria-associated apoptosis is essential for the neuroprotective effect of CMA against ischemia-reperfusion.
    Keywords:  Chaperone-mediated autophagy; Ischemia–reperfusion; Neuronal death; Tumor protein p53
    DOI:  https://doi.org/10.1007/s11064-024-04266-x
  18. bioRxiv. 2024 Oct 31. pii: 2024.10.30.621078. [Epub ahead of print]
    A Novel Human TBCK- Neuronal Cell Model Results in Severe Neurodegeneration and Partial Rescue with Mitochondrial Fission Inhibition.
    Rajesh Angireddy, Bhanu Chandra Karisetty, Kaitlin A Katsura, Abdias Díaz, Svathi Murali, Sarina Smith, Laura Ohl, Kelly Clark, Andrew V Kossenkov, Elizabeth J K Bhoj.
       Background and Objectives: TBCK syndrome is a rare fatal pediatric neurodegenerative disease caused by biallelic loss-of-function mutations in the TBCK gene. Previous studies by our lab and others have implicated mTOR, autophagy, lysosomes, and intracellular mRNA transport, however the exact primary pathologic mechanism is unknown. This gap has prevented the development of targeted therapies.
    Methods: We employed a human neural progenitor cell line (NPC), ReNcell VM, which can differentiate into neurons and astrocytes, to understand the role of TBCK in mTORC1 activity and neuronal autophagy and cellular mechanisms of pathology. We used shRNA technology to knockdown TBCK in ReNcells.
    Results: These data showed that loss of TBCK did not inhibit mTORC1 activity in neither NPC nor neurons. Additionally, analysis of eight patient-derived cells and TBCK knock down HeLa cells showed that mTORC1 inhibition is inconsistent across different patients and cell types. We showed that TBCK knockdown in ReNcells affected NPC differentiation to neurons and astrocytes. Specifically, differentiation defects are coupled to cell cycle defects in NPC and increased cell death during differentiation. RNAseq analysis indicated the downregulation of several different neurodevelopmental and differentiation pathways. We observed a higher number of LC3-positive vesicles in the soma and neurites of TBCK knockdown cells. Further, TBCK knockdown altered mitochondrial dynamics and membrane potential in NPC, neurons and astrocytes. We found partial mitochondrial rescue with the mitochondrial fission inhibitor mdivi- 1.
    Discussion: This work outlines a new Human Cell Model for TBCK-related neurodegeneration and the essential role of mitochondrial health and partial rescue with mitochondrial fission inhibitor. This data, along with human neurons and astrocytes, illuminate mechanisms of neurodegeneration and provide a possible novel therapeutic avenue for affected patients.
    DOI:  https://doi.org/10.1101/2024.10.30.621078
  19. Environ Pollut. 2024 Nov 15. pii: S0269-7491(24)02039-6. [Epub ahead of print]364(Pt 1): 125322
    Adverse outcome pathway of Alzheimer's disease-like changes resulting from autophagy flux blockade after MC-LR exposure.
    Yuhan Ma, Dihui Xu, Yibin Gan, Zining Chen, Yabing Chen, Xiaodong Han.
      Microcystins (MCs) pollution is a worldwide environmental issue concerning about human health. Microcystin-leucine-arginine (MC-LR), the most common type of MCs produced by cyanobacteria, could enter the brain and bring about damage to the nervous system. Up to date, it is not clear about the mechanism of MC-LR-induced neurotoxicity. Amyloid-β (Aβ) deposits are hallmark of Alzheimer's disease (AD). In this study, we revealed that MC-LR exposure at environment-related doses (1, 7.5, 15 μg/L) could promote Aβ accumulation in mouse brain. Mechanically, we firstly found that Aβ accumulation is closely associated with abnormal Aβ degradation due to autophagy flux blockade and lysosome dysfunctions in neurons after MC-LR exposure. Moreover, an adverse outcome pathway (AOP) framework oriented to neurotoxicity of MC-LR was conducted in this study. MC-LR inhibited the activity of protein phosphatase 2A (PP2A) in neurons, which is regarded as a molecular initiating event (MIE). In addition, the abnormalities in autophagy were observed after MC-LR exposure. The hindered autophagosome-lysosome fusion and disrupted lysosomal function were key events (KEs) after MC-LR exposure, which contributed to proteostasis dysregulation, ultimately leading to Aβ abnormal degradation and learning deficits as adverse outcomes (AO) of neurotoxicity. This study provided novel information about MC-LR neurotoxicity and new insights into understanding the mechanisms underlying the environmental chemicals-induced neurodegeneration diseases, which has deep implications for public health.
    Keywords:  AOP; Amyloid-β; Autophagy; Lysosome; MC-LR; Neurotoxicity
    DOI:  https://doi.org/10.1016/j.envpol.2024.125322
  20. PLoS Genet. 2024 Nov;20(11): e1011475
    Neuronal fatty acid-binding protein enhances autophagy and suppresses amyloid-β pathology in a Drosophila model of Alzheimer's disease.
    Seokhui Jang, Byoungyun Choi, Chaejin Lim, Minkyoung Kim, Ji-Eun Lee, Hyungi Lee, Eunji Baek, Kyoung Sang Cho.
      Fatty acid-binding proteins (FABPs) are small cytoplasmic proteins involved in intracellular lipid transport and bind free fatty acids, cholesterol, and retinoids. FABP3, the major neuronal FABP in the adult brain, is upregulated in the CSF of patients with Alzheimer's disease (AD). However, the precise role of neuronal FABPs in AD pathogenesis remains unclear. This study investigates the contribution of fabp, the Drosophila homolog of FABP3 and FABP7, to amyloid β (Aβ) pathology using a Drosophila model. Neuronal knockdown of fabp shortened the lifespan of flies and increased age-related protein aggregates in the brain. In an AD model, fabp knockdown in neurons increased Aβ accumulation and Aβ-induced neurodegeneration, whereas fabp overexpression ameliorated Aβ pathology. Notably, fabp overexpression stimulated autophagy, which was inhibited by the knockdown of Eip75B, the Drosophila homolog of the peroxisome proliferator-activated receptor (PPAR). The PPAR activator rosiglitazone restored autophagy impaired by fabp knockdown and reduced fabp knockdown-induced increased Aβ aggregation and cell death. Furthermore, knockdown of either fabp or Eip75B in the wing imaginal disc or adult fly brain reduced the expression of Atg6 and Atg8a. Additionally, treatment of the fabp knockdown AD model flies with polyunsaturated fatty acids, such as docosahexaenoic acid or linoleic acid, partially alleviated cell death in the developing eye, restored impaired autophagy flux, reduced Aβ aggregation, and attenuated Aβ-induced cell death. Our results suggest that Drosophila fabp plays an important role in maintaining protein homeostasis during aging and protects neurons from Aβ-induced cell death by enhancing autophagy through the PPAR pathway. These findings highlight the potential importance of neuronal FABP function in AD pathogenesis.
    DOI:  https://doi.org/10.1371/journal.pgen.1011475
  21. Discov Oncol. 2024 Nov 16. 15(1): 662
    MicroRNA-mediated autophagy and drug resistance in cancer: mechanisms and therapeutic strategies.
    Jinxing Wei, Xianghui Wang, Duo Yu, Yanyang Tu, Yaoyu Yu.
      This paper provides an exhaustive overview of the intricate interplay between microRNAs (miRNAs) and autophagy in the context of human cancers, underscoring the pivotal role these non-coding RNAs play in modulating autophagic pathways and their implications for cancer development, progression, and resistance to therapy. MiRNAs, as critical regulators of gene expression post-transcription, influence various biological processes, including autophagy, a catabolic mechanism essential for cellular homeostasis, stress response, and survival. The review meticulously delineates the mechanisms through which miRNAs impact autophagy by targeting specific genes and signaling pathways, thereby affecting cancer cell proliferation, metastasis, and response to chemotherapy. It highlights several miRNAs with dual roles, acting either as oncogenes or tumor suppressors based on the cellular context and the specific autophagic pathways they regulate. The paper further explores the therapeutic potential of targeting miRNA-autophagy axis, offering insights into novel strategies for cancer treatment through modulation of this axis. Emphasizing the complexity of the miRNA-autophagy relationship, the review calls for more in-depth studies to unravel the nuanced regulatory networks between miRNAs and autophagy in cancer, which could pave the way for the development of innovative therapeutic interventions and diagnostic tools.
    Keywords:  Autophagy; Cancer therapy; Drug resistance; Epigenetic factors; Non-coding RNAs
    DOI:  https://doi.org/10.1007/s12672-024-01525-9
  22. Sci Rep. 2024 11 16. 14(1): 28355
    EYA3 promotes the tumorigenesis of gastric cancer through activation of the mTORC1 signaling pathway and inhibition of autophagy.
    Zhen Xu, Jianhua Liu, Mingjun Yang, Kaibin Huang.
      Gastric cancer (GC) is a leading cause of cancer-related mortality, with a high rate of postoperative recurrence and poor long-term survival. The Eyes Absent (EYA) protein family plays a significant role in cancer progression, with EYA3 being implicated in promoting GC cell proliferation and tumor growth. Utilizing the DepMap database, we identified EYA3 as a gene of interest in GC. We analyzed EYA3 expression in GC tissues and cell lines, performed in vitro assays to assess its role in cell proliferation, and conducted gene set enrichment analysis to explore its relationship with autophagy and the mTORC1 signaling pathway. In vivo, we used a xenograft tumor model to examine the effects of EYA3 expression on tumor progression. EYA3 was consistently upregulated in GC tissues, and its high expression correlated with a decrease in patient survival rates. Silencing EYA3 in GC cell lines resulted in reduced cell proliferation. Inhibition of autophagy and activation of the mTORC1 signaling pathway were observed as mechanisms by which EYA3 may promote GC cell growth. In vivo experiments supported the in vitro findings, showing slower tumor growth with reduced EYA3 expression. Our study confirms the upregulation of EYA3 in GC and its association with poor prognosis. EYA3 promotes GC cell proliferation and tumor growth by activating the mTORC1 signaling pathway and inhibiting autophagy. These findings highlight the potential of EYA3 as a therapeutic target for GC, providing a foundation for future research and treatment strategies. Despite the promising data, the limitations of sample size and the need for further mechanistic studies are acknowledged.
    Keywords:  Autophagy; EYA3; Gastric Cancer; Proliferation; mTORC1
    DOI:  https://doi.org/10.1038/s41598-024-80027-8
  23. Adv Sci (Weinh). 2024 Nov 18. e2404107
    WAC Facilitates Mitophagy-mediated MSC Osteogenesis and New Bone Formation via Protecting PINK1 from Ubiquitination-Dependent Degradation.
    Shuai Fan, Jinteng Li, Guan Zheng, Ziyue Ma, Xiaoshuai Peng, Zhongyu Xie, Wenjie Liu, Wenhui Yu, Jiajie Lin, Zepeng Su, Peitao Xu, Peng Wang, Yanfeng Wu, Huiyong Shen, Guiwen Ye.
      Osteogenic differentiation of mesenchymal stem cells (MSCs) plays a pivotal role in the pathogenesis and treatment of bone-related conditions such as osteoporosis and bone regeneration. While the WW domain-containing coiled-coil adaptor (WAC) protein is primarily associated with transcriptional regulation and autophagy, its involvement in MSC osteogenesis remains unclear. Here, the data reveal that the levels of WAC are diminished in both osteoporosis patients and osteoporosis mouse models. It plays a pivotal function in facilitating MSC osteogenesis and enhancing new bone formation both in vitro and in vivo. Mechanistically, WAC promotes MSC osteogenesis by protecting PINK1, a crucial initiator of mitophagy, from ubiquitination-dependent degradation thereby activating mitophagy. Interestingly, WAC interacts with the TM domains of PINK1 and prevents the K137 site from ubiquitination modification. The study elucidates the mechanism by which WAC modulates MSC osteogenesis, binds to PINK1 to protect it from ubiquitination, and identifies potential therapeutic targets for osteoporosis and bone defect repair.
    Keywords:  PINK1; WAC; mesenchymal stem cell; mitophagy; osteogenesis
    DOI:  https://doi.org/10.1002/advs.202404107
  24. Free Radic Biol Med. 2024 Nov 19. pii: S0891-5849(24)01069-4. [Epub ahead of print]
    Itaconic acid ameliorates necrotizing enterocolitis through the TFEB-mediated autophagy-lysosomal pathway.
    Baozhu Chen, Yufeng Liu, Shunchang Luo, Jialiang Zhou, Yijia Wang, Qiuming He, Guiying Zhuang, Hu Hao, Fei Ma, Xin Xiao, Sitao Li.
      Excessive autophagy has been implicated in the pathogenesis of necrotizing enterocolitis (NEC), yet the molecular underpinnings of the autophagy-lysosomal pathway (ALP) in NEC are not well characterized. This study aimed to elucidate alterations within the ALP in NEC by employing RNA sequencing on intestinal tissues obtained from affected infants. Concurrently, we established animal and cellular models of NEC to assess the therapeutic efficacy of itaconic acid (ITA). Our results indicate that the ALP is significantly disrupted in NEC. Notably, ITA was found to modulate the ALP, enhancing autophagic flux and lysosomal function, which consequently alleviated NEC symptoms. Further analysis revealed that ITA's beneficial effects are mediated through the promotion of TFEB nuclear translocation, thereby augmenting the ALP. These findings suggest that targeting the ALP with ITA to modulate TFEB activity may represent a viable therapeutic approach for NEC.
    Keywords:  Autophagy-lysosomal pathway; Itaconic acid; Lysosomal dysfunction; Necrotizing enterocolitis; TFEB
    DOI:  https://doi.org/10.1016/j.freeradbiomed.2024.11.035
  25. JCI Insight. 2024 Nov 19. pii: e180409. [Epub ahead of print]
    NDR2 is critical for the osteoclastogenesis by regulating ULK1-mediated mitophagy.
    Xiangxi Kong, Zhi Shan, Yihao Zhao, Siyue Tao, Jingyun Chen, Zhongyin Ji, Jiayan Jin, Junhui Liu, Wenlong Lin, Xiaojian Wang, Jian Wang, Fengdong Zhao, Bao Huang, Jian Chen.
      Bone homeostasis primarily stems from the balance between osteoblasts and osteoclasts, wherein an augmented number or heightened activity of osteoclasts is a prevalent etiological factor in the development of bone loss. Nuclear Dbf2-related kinase (NDR2), also known as STK38L, is a member of the Hippo family with serine/threonine kinase activity. We unveiled an upregulation of NDR2 expression during osteoclast differentiation. Manipulation of NDR2 levels through knockdown or overexpression facilitated or hindered osteoclast differentiation respectively, indicating a negative feedback role for NDR2 in the osteoclastogenesis. Myeloid NDR2-dificient mice (Lysm+NDR2f/f) showed lower bone mass and further exacerbated ovariectomy-induced or aging-related bone loss. Mechanically, NDR2 enhanced autophagy and mitophagy through mediating ULK1 instability. In addition, ULK1 inhibitor (ULK1-IN2) ameliorated NDR2 cKO-induced bone loss. Finally, we clarified a significant inverse association between NDR2 expression and the occurrence of osteoporosis in patients. In a word, NDR2-ULK1-mitophagy axis was a potential innovative therapeutic target for the prevention and management of bone loss.
    Keywords:  Autophagy; Bone marrow differentiation; Development; Metabolism; Osteoporosis
    DOI:  https://doi.org/10.1172/jci.insight.180409
  26. Nat Commun. 2024 Nov 21. 15(1): 10071
    Autophagy modulates Arabidopsis male gametophyte fertility and controls actin organization.
    He Yan, Zhen Lu, Xiaojuan Du, Zhengtao You, Mingkang Yang, Nianle Li, Xuequan Li, Zailue Ni, Hong Wu, Xiangfeng Wang, Lifeng Zhao, Hao Wang.
      Autophagy, a crucial mechanism for cellular degradation, is regulated by conserved autophagy-related (ATG) core proteins across species. Impairments in autophagy result in significant developmental and reproductive aberrations in mammals. However, autophagy is thought to be functionally dispensable in Arabidopsis thaliana since most of the ATG mutants lack severe growth and reproductive defects. Here, we challenge this perception by unveiling a role for autophagy in male gametophyte development and fertility in Arabidopsis. A detailed re-assessment of atg5 and atg7 mutants found that reduced autophagy activity in germinated pollen accompanied by partial aberrations in sperm cell biogenesis and pollen tube growth, leading to compromised seed formation. Furthermore, we revealed autophagy modulates the spatial organization of actin filaments via targeted degradation of actin depolymerization factors ADF7 and Profilin2 in pollen grains and tubes through a key receptor, Neighbor of BRCA1 (NBR1). Our findings advance the understanding of the evolutionary conservation and diversification of autophagy in modulating male fertility in plants contrasting to mammals.
    DOI:  https://doi.org/10.1038/s41467-024-54468-8
  27. Biochem Pharmacol. 2024 Nov 17. pii: S0006-2952(24)00633-6. [Epub ahead of print]230(Pt 3): 116633
    Exploring heat shock proteins as therapeutic targets for Parkinson's disease.
    Xiang Li, Wenjun Wang, Shi Pan, Xueqin Cao, Elizabeth Rosalind Thomas, Mingyu Xie, Chunxiang Zhang, Jianming Wu.
      Parkinson's disease (PD) is characterized by the accumulation of misfolded α-synuclein (α-syn). Promoting the degradation of misfolded proteins has been shown to be an effective approach to alleviate PD. This review highlights the roles of specific heat shock proteins (HSPs) in modulating α-syn aggregation and neuronal survival. HSP27 prevents glycosylation-induced α-syn aggregation, disrupts copper ion interactions, inhibits mitochondrial apoptosis, and prevents dopaminergic neuronal cell death. HSP70 alleviates dopaminergic neuronal damage by promoting mitophagy and preventing neuronal apoptosis. HSC70 plays a critical role in chaperone-mediated autophagy and facilitates lysosomal degradation. GRP78 mitigates abnormal protein aggregation. The HSP70-HSP40-HSP110 system is capable of degrading α-syn amyloid fibers. Inhibition of HSP90 expression protects neurons. Further research should prioritize developing regulators of HSPs as treatments for PD. While HSPs offer promise in PD management, their complex roles necessitate cautious therapeutic development to harness their potential. Understanding the specific roles of different HSPs will be essential to developing effective therapies for α-syn clearance.
    Keywords:  HSPs; Mitophagy; Parkinson’ disease; Unfolded protein response; α-syn
    DOI:  https://doi.org/10.1016/j.bcp.2024.116633
  28. Commun Biol. 2024 Nov 21. 7(1): 1554
    Plasmodium berghei liver stage parasites exploit host GABARAP proteins for TFEB activation.
    Jacqueline Schmuckli-Maurer, Annina F Bindschedler, Rahel Wacker, Oliver M Würgler, Ruth Rehmann, Timothy Lehmberg, Leon O Murphy, Thanh N Nguyen, Michael Lazarou, Jlenia Monfregola, Andrea Ballabio, Volker T Heussler.
      Plasmodium, the causative agent of malaria, infects hepatocytes prior to establishing a symptomatic blood stage infection. During this liver stage development, parasites reside in a parasitophorous vacuole (PV), whose membrane acts as the critical interface between the parasite and the host cell. It is well-established that host cell autophagy-related processes significantly impact the development of Plasmodium liver stages. Expression of genes related to autophagy and lysosomal biogenesis is orchestrated by transcription factor EB (TFEB). In this study, we explored the activation of host cell TFEB in Plasmodium berghei-infected cells during the liver stage of the parasite. Our results unveiled a critical role of proteins belonging to the Gamma-aminobutyric acid receptor-associated protein subfamily (GABARAP) of ATG8 proteins (GABARAP/L1/L2 and LC3A/B/C) in recruiting the TFEB-blocking FLCN-FNIP (Folliculin-Folliculin-interacting protein) complex to the PVM. Remarkably, the sequestration of FLCN-FNIP resulted in a robust activation of TFEB, reliant on conjugation of ATG8 proteins to single membranes (CASM) and GABARAP proteins. Our findings provide novel mechanistic insights into host cell signaling occurring at the PVM, shedding light on the complex interplay between Plasmodium parasites and the host cell during the liver stage of infection.
    DOI:  https://doi.org/10.1038/s42003-024-07242-x
  29. Clin Exp Pharmacol Physiol. 2025 Jan;52(1): e70006
    Trimetazidine restores autophagy via lncRNA H19/AMPK in diabetic heart: Implications for its therapeutic value against diabetic cardiomyopathy.
    Wei Wei, Yadi Hu, Jing Gao, Danjun Fan, Xiaorong Ye, Yan Chen.
       OBJECTIVE: Previous studies have shown that trimetazidine (TMZ) alleviates diabetes-induced cardiac dysfunction. However, the underlying mechanism for its protective effects on cardiac function remains incompletely understood. Diminished autophagy was found in diabetic hearts, and restoration of autophagy generates cardioprotective effect. This study aims to investigate whether and how TMZ produces protective effect through increasing autophagic activity in the diabetic heart.
    METHOD: A high-fat diet and low-dose streptozotocin were applied to induce type 2 diabetes mellitus (T2DM) in male C57BL/6 mice, followed by treatment with TMZ for 14 weeks before cardiac function was evaluated. To mimic the diabetic condition, the neonatal rat cardiomyocytes (NRCMs) were exposed to high glucose/palmitic acid (HP) in the presence or absence of TMZ.
    RESULTS: We found that TMZ treatment promotes autophagic flux in cardiomyocytes, which is impaired in diabetes. We further found that the AMPK and lncRNA H19 played critical roles in mediating TMZ-induced enhancement of autophagy in cardiomyocyte. We showed that TMZ treatment restored the level of H19 and phosphorylated AMPK (p-AMPK T172) in diabetic heart and NRCMs exposed to HP. Of note, the effect of TMZ on autophagy and p-AMPK was abolished by knockdown of H19.
    CONCLUSION: These findings indicated that TMZ is able to recover the cardiac autophagic activity which is impaired by T2DM, and the underlying mechanism accounted for this ability is mostly likely attributed to the restored expression of H19 and AMPK activity.
    Keywords:  LncRNA H19; autophagy; cardiomyopathy; diabetes mellitus; trimetazidine
    DOI:  https://doi.org/10.1111/1440-1681.70006
  30. bioRxiv. 2024 Nov 01. pii: 2024.10.30.621201. [Epub ahead of print]
    Deficiency of mitophagy mediator Parkin in aortic smooth muscle cells exacerbates abdominal aortic aneurysm.
    Hui Wang, Mattew Kazaleh, Rachel Gioscia-Ryan, Jessica Millar, Gerard Temprano-Sagrera, Sherri Wood, Fran Van Den Bergh, Muriel G Blin, Kathleen M Wragg, Adrian Luna, Robert B Hawkins, Scott A Soleimanpour, Maria Sabater-Lleal, Chang Shu, Daniel A Beard, Gorav Ailawadi, Jane C Deng, Daniel R Goldstein, Morgan Salmon.
      Abdominal aortic aneurysms (AAAs) are a degenerative aortic disease and associated with hallmarks of aging, such as mitophagy. Despite this, the exact associations among mitophagy, aging, and AAA progression remain unknown. In our study, gene expression analysis of human AAA tissue revealed downregulation of mitophagy pathways, mitochondrial structure, and function-related proteins. Human proteomic analyses identified decreased levels of mitophagy mediators PINK1 and Parkin. Aged mice and, separately, a murine AAA model showed reduced mitophagy in aortic vascular smooth muscle cells (VSMCs) and PINK1 and Parkin expression. Parkin knockdown in VSMCs aggravated AAA dilation in murine models, with elevated mitochondrial ROS and impaired mitochondrial function. Importantly, inhibiting USP30, an antagonist of the PINK1/Parkin pathway, increased mitophagy in VSMCs, improved mitochondrial function, and reduced AAA incidence and growth. Our study elucidates a critical mechanism that proposes AAAs as an age-associated disease with altered mitophagy, introducing new potential therapeutic approaches.
    DOI:  https://doi.org/10.1101/2024.10.30.621201
  31. Mol Biotechnol. 2024 Nov 16.
    Intermittent Hypoxia Impairs Cognitive Function and Promotes Mitophagy and Lysophagy in Obstructive Sleep Apnea-Hypopnea Syndrome Rat Model.
    Jizu Ling, BoWen Li, XinHui Yuan, WenKai Yang, KeYang Sun.
      Autophagy regulates intermittent hypoxia (IH)-induced obstructive sleep apnea-hypopnea syndrome (OSAHS). We investigated the effects of IH and its withdrawal on cognitive function, autophagy, and lysophagy in OSAHS. An OSAHS rat model was established, and rats were divided into five groups: normoxia control, IH-4w (4-week IH), IH-6w (6-week IH), IH-8w (8-week IH), and IH-8w + 4w (8-week IH and 4-week normoxia). The cognitive behavior; mitochondrial and lysosomal morphology of the hippocampal tissue; mitochondrial respiratory function, permeability, and membrane potential; lysosomal function; autophagy- and lysophagy-related protein levels; and hypoxia-associated autophagy gene expression in rats were assessed. The cognitive function of rats in the IH-4w, IH-6w, and IH-8w groups was significantly impaired. In IH-8w cells, mitochondrial function was damaged with swollen morphology and decreased quantity, respiration, permeability, and membrane potential, along with significantly increased mitophagy-related protein ATG5 and LC3II/LC3 levels and decreased p62 levels. Expression of hypoxia-associated autophagy genes Becn1, Hif1, Bnip3, Bnip3l, and Fundc1 was significantly higher in the IH-8w group. Significantly increased LAMP2, CTSB, and ACP2 levels in IH-8w cells further indicated impaired lysosomal function. Lysophagy-related protein LAMP1, LC3II/LC3I, and TFEB levels were significantly increased in the IH-8w group, whereas p62 level was significantly decreased. The above listed evidence indicated damage to the mitochondria and lysosomes, as well as stimulation of mitophagy and lysophagy in IH-treatment OSAHS rat model. After withdrawing IH and culturing for 4 weeks in normal conditions, the cognitive function of rats improved, and mitophagy and lysophagy decreased. Our findings indicate that IH impairs cognitive function and promotes mitophagy and lysophagy in an OSAHS rat model, and IH withdrawal recovered the above effects.
    Keywords:  Cognitive function; Hippocampus; Lysophagy; Mitophagy; Obstructive sleep apnea–hypopnea syndrome
    DOI:  https://doi.org/10.1007/s12033-024-01319-y
  32. bioRxiv. 2024 Oct 29. pii: 2024.10.27.620516. [Epub ahead of print]
    A multi-subunit autophagic capture complex facilitates degradation of ER stalled MHC-I in pancreatic cancer.
    Marine Berquez, Alexander L Li, Matthew A Luy, Anthony C Venida, Thomas O'Loughlin, Gilles Rademaker, Abhilash Barpanda, Jingjie Hu, Julian Yano, Arun Wiita, Luke A Gilbert, Peter M Bruno, Rushika M Perera.
      Pancreatic ductal adenocarcinoma (PDA) evades immune detection partly via autophagic capture and lysosomal degradation of major histocompatibility complex class I (MHC-I). Why MHC-I is susceptible to capture via autophagy remains unclear. By synchronizing exit of proteins from the endoplasmic reticulum (ER), we show that PDAC cells display prolonged retention of MHC-I in the ER and fail to efficiently route it to the plasma membrane. A capture-complex composed of NBR1 and the ER-phagy receptor TEX264 facilitates targeting of MHC-I for autophagic degradation, and suppression of either receptor is sufficient to increase total levels and re-route MHC-I to the plasma membrane. Binding of MHC-I to the capture complex is linked to antigen presentation efficiency, as inhibiting antigen loading via knockdown of TAP1 or beta 2-Microglobulin led to increased binding between MHC-I and the TEX264-NBR1 capture complex. Conversely, expression of ER directed high affinity antigenic peptides led to increased MHC-I at the cell surface and reduced lysosomal degradation. A genome-wide CRISPRi screen identified NFXL1, as an ER-resident E3 ligase that binds to MHC-I and mediates its autophagic capture. High levels of NFXL1 are negatively correlated with MHC-I protein expression and predicts poor patient prognosis. These data highlight an ER resident capture complex tasked with sequestration and degradation of non-conformational MHC-I in PDAC cells, and targeting this complex has the potential to increase PDAC immunogenicity.
    DOI:  https://doi.org/10.1101/2024.10.27.620516
  33. Acta Biochim Biophys Sin (Shanghai). 2024 Nov 22.
    Ivermectin inhibits the growth of ESCC by activating the ATF4-mediated endoplasmic reticulum stress-autophagy pathway.
    Huiyang Liu, Zhirong Chai, Ya Gao, Yanming Wang, Mengmeng Lu.
      Esophageal squamous cell carcinoma (ESCC) is one of the most common forms of malignancy worldwide. However, there is currently a lack of effective chemotherapeutic drugs for ESCC. Ivermectin is a broad-spectrum antiparasitic drug with notable antitumor activity. However, the cellular and molecular mechanisms by which ivermectin inhibits cancer growth remain unclear. In this study, we elucidate the role of ivermectin in ESCC suppression by activating the endoplasmic reticulum (ER) stress and autophagy pathways. In transcriptome analyses, we find that activating transcription factor 4 (ATF4) and DNA damage inducible transcript 3 (DDIT3) are involved in the activation of ER stress by ivermectin. Moreover, ivermectin treatment suppresses the growth of ESCC xenograft tumors in nude mice. Taken together, our results establish the antitumor molecular role of ivermectin in targeting the ER stress-autophagy pathway and suggest that ivermectin is a potential drug candidate for the treatment of ESCC.
    Keywords:  ATF4; ER stress; ESCC; autophagy; ivermectin
    DOI:  https://doi.org/10.3724/abbs.2024210
  34. FASEB J. 2024 Nov 30. 38(22): e70184
    The roles of mTORC1 in parathyroid gland function in chronic kidney disease-induced secondary hyperparathyroidism: Evidence from male genetic mouse models and clinical data.
    Nareman Khalaily, Alia Hassan, Yasmeen Khream, Tally Naveh-Many, Iddo Z Ben-Dov.
      Secondary hyperparathyroidism (SHP) associated with chronic kidney disease (CKD) contributes to morbidity and mortality, yet the related parathyroid signaling pathways are not fully understood. Previous studies have indicated that the parathyroid mTORC1 pathway is activated in both experimental CKD and hypocalcemia-induced SHP. Furthermore, mice with parathyroid-specific mTOR deficiency (PT-mTOR-/-) exhibit disrupted parathyroid glands, but maintain normal serum PTH levels. Conversely, PT-Tsc1-/- mice, with mTORC1 hyperactivation, have enlarged glands and high serum PTH and calcium levels. We now uncover links between mTORC1 function, parathyroid gland morphology, and the response to CKD. Despite impaired gland structure, PT-mTOR-/- mice increased serum PTH to levels similar to controls in response to CKD, but not to acute kidney injury (AKI), highlighting the adaptability of their parathyroid glands to chronic but not acute stimulation. PT-Tsc1-/- mice, with enlarged glands also exhibited a CKD-induced rise in serum PTH comparable to controls, but with a reduced magnitude, suggesting compromised secretion capacity. Parathyroid glands from PT-Tsc1-/- mice displayed sustained high PTH secretion in culture, with no further increase when exposed to calcium-depleted media, unlike control glands. Complementing these findings, human data from 106 healthcare organizations demonstrated that drug-induced mTORC1 inhibition is associated with reduced serum PTH and a lower incidence of SHP in kidney transplant recipients. Collectively, our findings underscore the complex interplay between mTORC1 signaling and gland structure in the pathogenesis of SHP.
    DOI:  https://doi.org/10.1096/fj.202401547RR
  35. iScience. 2024 Nov 15. 27(11): 111042
    Irisin reduces senile osteoporosis by inducing osteocyte mitophagy through Ampk activation.
    Honghan Li, Deqing Luo, Wei Xie, Wenbin Ye, Jinlong Chen, Paolo Alberton, Mingzhu Zhang, Eryou Feng, Denitsa Docheva, Dasheng Lin.
      Irisin, an exercise-induced myokine, is known to be able to regulate bone metabolism. However, the underlying mechanisms regarding the effects of irisin on senile osteoporosis have not been fully elucidated. Here, we demonstrated that irisin can inhibit bone mass loss and bone microarchitecture alteration in senile osteoporosis mouse model. In addition, irisin has effects on bone remodeling that is in favor of bone formation. Remarkably, irisin induced autophagy in osteocytes demonstrated by increased LC3-positive osteocytes, and increased autophagy-related genes and proteins. In vitro analysis revealed that Irisin can prevent mitochondrial oxidative damage. Furthermore, irisin can obviously induce osteocyte mitophagy and increased phosphorylation of Ampk and Ulk1. Inhibition of Ampk signaling recapitulated the biological effect of irisin loss, accompanied by the markedly lower expression of Ulk1. Taken together, our findings show that irisin reduces age-related bone loss by inducing osteocyte mitophagy via Ampk-dependent activation of Ulk1.
    Keywords:  Biological sciences; Molecular biology; Physiology
    DOI:  https://doi.org/10.1016/j.isci.2024.111042
  36. Ageing Res Rev. 2024 Nov 16. pii: S1568-1637(24)00398-2. [Epub ahead of print] 102580
    Astrocytic Proteostasis in the Tale of Aging and Neurodegeneration.
    Felipe Cabral-Miranda, Isadora Matias, Flávia Carvalho Alcantara Gomes.
      Homeostasis of proteins (proteostasis), which governs protein processing, folding, quality control, and degradation, is a fundamental cellular process that plays a pivotal role in various neurodegenerative diseases and in the natural aging process of the mammalian brain. While the role of neuronal proteostasis in neuronal physiology is well characterized, the contribution of proteostasis of glial cells, particularly of astrocytes, has received fairly less attention in this context. Here, we summarize recent data highlighting proteostasis dysfunction in astrocytes and its putative implication to neurodegenerative diseases and aging. We discuss how distinct proteostasis nodes and pathways in astrocytes may specifically contribute to brain function and different age-associated pathologies. Finally, we argue that the understanding of astrocytic proteostasis role in neuronal physiology and functional decay may arise as a potential new avenue of intervention in neurodegenerative diseases and grant relevant data in the biology of aging.
    Keywords:  Astrocyte; aging; neurodegenerative disease; protein folding; proteostasis
    DOI:  https://doi.org/10.1016/j.arr.2024.102580
  37. Exp Physiol. 2024 Nov 22.
    Inhibition of TrkB kinase activity impairs autophagy in cervical motor neurons of young but not old mice.
    Miguel Pareja-Cajiao, Heather M Gransee, Sepideh Jahanian, Gary C Sieck, Carlos B Mantilla.
      Ageing-related neuromuscular dysfunction is associated with reduced tropomyosin-related kinase receptor subtype B (TrkB) signalling and accumulation of damaged cytoplasmic aggregates in motor neurons. Autophagy functions to remove these damaged aggregates, and we previously reported increased cervical motor neuron expression of LC3 and p62 in old age. We hypothesized that inhibition of TrkB kinase activity results in an increase in the relative expression of both LC3 and p62 in cervical motor neurons, consistent with impaired progression of autophagy. TrkBF616A mice, which possess a mutation that renders TrkB kinase activity susceptible to rapid inhibition by 1NMPP1, were treated at 6, 18 or 24 months of age with vehicle or 1NMPP1 for 7 days. Immunofluorescence intensity was measured to determine LC3 and p62 expression in choline acetyltransferase-positive motor neurons in the cervical spinal cord. The effect of inhibiting TrkB kinase activity on progression of autophagy was age dependent. In 6-month-old mice, inhibiting TrkB kinase activity increased cervical motor neuron expression of LC3 by 11% (P < 0.001) and p62 by 8% (P = 0.019) compared with vehicle treatment. In 18- and 24-month-old mice, there was no effect of inhibiting TrkB kinase activity on motor neuron LC3 or p62 expression. We provide evidence that inhibition of TrkB signalling impairs progression of autophagy in motor neurons of young mice, similar to the response to ageing. Accordingly, a reduction of TrkB signalling in old age might contribute to neuromuscular dysfunction by impairing progression of autophagy in motor neurons.
    Keywords:  ageing; autophagy; motor neuron; neurotrophins
    DOI:  https://doi.org/10.1113/EP092095
  38. Genes Dis. 2025 Jan;12(1): 101209
    Naked cuticle homolog 2 controls the differentiation of osteoblasts and osteoclasts and ameliorates bone loss in ovariectomized mice.
    Liying Shan, Xiaoxia Liao, Xiaoli Yang, Endong Zhu, Hairui Yuan, Jie Zhou, Xiaoxia Li, Baoli Wang.
      Naked cuticle homolog 2 (NKD2) has been recognized as an antagonist of Wnt/β-catenin signaling and a tumor suppressor. The role of NKD2 in osteoblast and osteoclast differentiation and the mechanism are not fully understood. In this study, we identified the up-regulation of NKD2 during osteoblast and adipocyte differentiation. Functional experiments revealed that NKD2 stimulated osteoblast differentiation and suppressed adipocyte formation. Furthermore, NKD2 down-regulated the expression of receptor activator of nuclear factor-κB ligand in bone marrow mesenchymal stem cells and inhibited osteoclast formation from osteoclast precursor cells. Mechanistic investigations revealed that the regulation of osteoblast and adipocyte differentiation by NKD2 involved Wnt/β-catenin and tuberous sclerosis complex subunit 1 (TSC1)/mechanistic target of rapamycin complex 1 (mTORC1) signaling pathways. Unlike in undifferentiated mesenchymal cells where NKD2 promoted Dishevelled-1 degradation, in the cells differentiating toward osteoblasts or adipocytes NKD2 down-regulated secreted frizzled related protein 1/4 expression and failed to destabilize Dishevelled-1, thereby activating Wnt/β-catenin signaling. Moreover, NKD2 bound to TSC1 and inhibited mTORC1 signaling. Further investigation uncovered an interplay between TSC1/mTORC1 and Wnt/β-catenin signaling pathways. Finally, transplantation of NKD2-overexpressing bone marrow mesenchymal stem cells into the marrow of mice increased osteoblasts, reduced osteoclasts and marrow fat, and partially prevented bone loss in ovariectomized mice. This study provides evidence that NKD2 in mesenchymal stem/progenitor cells reciprocally regulates the differentiation of osteoblasts and adipocytes by modulating Wnt/β-catenin and mTORC1 pathways and inhibits osteoclast formation by down-regulating receptor activator of nuclear factor-κB ligand. It suggests that NKD2 up-regulation may ameliorate postmenopausal bone loss.
    Keywords:  Mechanistic target of rapamycin complex 1; Naked cuticle homolog 2; Osteoblast; Osteoclast; Receptor activator of nuclear factor κB ligand; Wnt/β-catenin
    DOI:  https://doi.org/10.1016/j.gendis.2024.101209
  39. Aging Cell. 2024 Nov 21. e14398
    Residual microglia following short-term PLX5622 treatment in 5xFAD mice exhibit diminished NLRP3 inflammasome and mTOR signaling, and enhanced autophagy.
    Maheedhar Kodali, Leelavathi N Madhu, Yogish Somayaji, Sahithi Attaluri, Charles Huard, Prashanta Kumar Panda, Goutham Shankar, Shama Rao, Bing Shuai, Jenny J Gonzalez, Chris Oake, Catherine Hering, Roshni Sara Babu, Sanya Kotian, Ashok K Shetty.
      While moderately activated microglia in Alzheimer's disease (AD) are pivotal in clearing amyloid beta (Aβ), hyperactivated microglia perpetuate neuroinflammation. Prior investigations reported that the elimination of ~80% of microglia through inhibition of the colony-stimulating factor 1 receptor (CSF1R) during the advanced stage of neuroinflammation in 5xFamilial AD (5xFAD) mice mitigates synapse loss and neurodegeneration. Furthermore, prolonged CSF1R inhibition diminished the development of parenchymal plaques. Nonetheless, the effects of short-term CSF1R inhibition during the early stages of neuroinflammation on residual microglia are unknown. Therefore, we investigated the effects of 10-day CSF1R inhibition using PLX5622 in three-month-old female 5xFAD mice, a stage characterized by the onset of neuroinflammation and minimal Aβ plaques. We observed ~65% microglia depletion in the hippocampus and cerebral cortex. The leftover microglia displayed a noninflammatory phenotype with reduced NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome complexes. Moreover, plaque-associated microglia were reduced with diminished Clec7a expression. Additionally, phosphorylated S6 ribosomal protein and the protein sequestosome 1 analysis suggested reduced mechanistic targets of rapamycin (mTOR) signaling and autophagy in microglia and neurons within the hippocampus and cerebral cortex. Biochemical assays validated the inhibition of NLRP3 inflammasome activation, decreased mTOR signaling in the hippocampus and cerebral cortex, and enhanced autophagy in the hippocampus. However, short-term CSF1R inhibition did not influence Aβ plaques, soluble Aβ-42 levels, astrocyte hypertrophy, or hippocampal neurogenesis. Thus, short-term CSF1R inhibition during the early stages of neuroinflammation in 5xFAD mice promotes the retention of homeostatic microglia with diminished inflammasome activation and mTOR signaling, alongside increased autophagy.
    Keywords:  Alzheimer's disease; activated microglia; amyloid‐beta plaques; autophagy; chronic neuroinflammation; hippocampal neurogenesis; inflammasomes; mTOR signaling
    DOI:  https://doi.org/10.1111/acel.14398
  40. Cell Signal. 2024 Nov 20. pii: S0898-6568(24)00493-5. [Epub ahead of print] 111518
    Sestrin2 balances mitophagy and apoptosis through the PINK1-Parkin pathway to attenuate severe acute pancreatitis.
    Yuxi Yang, Yiqiu Peng, Yingying Li, Tingjuan Shi, Ning Xu, Yingyi Luan, Chenghong Yin.
      Mitophagy serves as a mitochondrial quality control mechanism to maintain the homeostasis of mitochondria and the intracellular environment. Studies have shown that there is a close relationship between mitophagy and apoptosis. Sestrin2 (Sesn2) is a highly conserved class of stress-inducible proteins that play important roles in reducing oxidative stress damage, inflammation, and apoptosis. However, the potential mechanism of how Sesn2 regulates mitophagy and apoptosis in severe acute pancreatitis (SAP) remains unclear. In the study, RAW264.7 (macrophage cell Line) cellular inflammation model established by lipopolysaccharide (LPS) treatment as well as LPS and CAE-induced SAP mouse model (wild-type and Sen2 Knockout mouse) were used. Our study showed that LPS stimulation significantly increased the level of Sesn2 in RAW264.7 cells, Sesn2 increased mitochondrial membrane potential, decreased inflammation levels, mitochondrial superoxide levels and apoptosis, and also promoted monocyte macrophages toward the M2 anti-inflammatory phenotype, suggesting a protective effect of Sesn2 on mitochondria. Further, Sesn2 increased mitophagy and decreased apoptosis via modulating the PINK1-Parkin signaling. Meanwhile, knockout of Sesn2 exacerbated pancreatic, mitochondrial damage and inflammation in a mouse model of SAP. In addition, the protective effect of Sesn2 against SAP was shown to be associated with mitophagy conducted by the PINK1-Parkin pathway via inhibiting apoptosis. These findings reveal that Sesn2 in balancing mitochondrial autophagy and apoptosis by modulating the PINK1-Parkin signaling may present a new therapeutic strategy for the treatment of SAP.
    Keywords:  apoptosis; mitophagy; monocyte macrophage; sestrin2; severe acute pancreatitis
    DOI:  https://doi.org/10.1016/j.cellsig.2024.111518
  41. Mol Neurobiol. 2024 Nov 21.
    Neurotoxicity of Realgar: Crosstalk Between UBXD8-DRP1-Regulated Mitochondrial Fission and PINK1-Parkin-Mediated Mitophagy.
    Rui Feng, Jieyu Liu, Tiantian Yao, Zhao Yang, Hong Jiang.
      Realgar is a toxic mineral medicine containing arsenic that is present in many traditional Chinese medicines. It has been reported that the abuse of drugs containing realgar has potential neurotoxicity, but its mechanism of toxicity has not been fully clarified. In this study, we demonstrated that arsenic in realgar promoted mitochondrial fission via UBXD8-mediated DRP1 translocation to the mitochondria and activated mitophagy via PINK1-Parkin, resulting in mitochondrial dysfunction and nerve cell death in the rat cortex. We used PC12 cells and treated them with inorganic arsenic (iAs). Mdivi-1, a mitochondrial fission inhibitor, and the siRNA UBXD8 or PINK1 were used as interventions to verify the precise mechanism by which arsenic affects realgar-induced mitochondrial instability. The results revealed that the arsenic in realgar accumulated in the brain and led to neurobehavioral abnormalities in the rats. We demonstrated that arsenic in realgar-induced high expression of UBXD8 promoted the translocation of DRP1 to the mitochondria, where it underwent phosphorylation, which led to the over-fission of the mitochondria and mitochondria-mediated apoptosis. Moreover, the over-fission of the mitochondria activates mitophagy, which is self-protective but only partially alleviates apoptosis and mitochondria dysfunction. Our findings revealed the crosstalk between mitochondrial fission and mitophagy in realgar-induced neurotoxicity. These results highlight the role of the transposition of DRP1 by UBXD8 in realgar-induced mitochondrial dysfunction and provide new ideas and data for the study of the mechanism of realgar-induced neurotoxicity.
    Keywords:  Mitochondrial fission; Mitophagy; Neurotoxicity; Realgar; UBXD8-DRP1 pathway
    DOI:  https://doi.org/10.1007/s12035-024-04635-1
  42. Eur J Pharmacol. 2024 Nov 15. pii: S0014-2999(24)00827-6. [Epub ahead of print] 177137
    Small-Molecule Inhibitors in WNT Signalling Pathway for Targeted Cancer Therapy: Interplay between WNT, Autophagy and Apoptosis.
    Nayana A Menon, Chethana D Kumar, Pournami Ramachandran, Britny Blaize, Mridul Gautam, Marco Cordani, Lekha Dinesh Kumar.
      Cancer represents an intricate and heterogeneous ailment that evolves from a multitude of epigenetic and genetic variations that disrupt normal cellular function. The WNT/β-catenin pathway is an essential one in maintaining the balance between cell renewal and differentiation in various tissues. Abnormal activation of this pathway can lead to uncontrolled cell growth and initiate cancer across a variety of tissues such as the colon, skin, liver, and ovary. It enhances characteristics that lead to cancer progression, including angiogenesis, invasion and metastasis. Processes like autophagy and apoptosis which regulate cell death and play a crucial role in maintaining cellular equilibrium are also intimately linked with WNT- β-catenin pathway. Thus, targeting WNT pathway has become a key strategy in developing antitumor therapies. Employing s has emerged as a targeted therapies to improve the clinical outcome compared to conventional cancer treatments. Many strategies for using small molecule inhibitors for modulating the WNT/β-catenin pathway, such as hindering WNT ligands' secretion or interaction, disrupting receptor complex, and blocking the nuclear translocation of β-catenin have been investigated. These interventions have shown promise in both preclinical and clinical settings. This review provides a comprehensive understanding of the role of WNT/β-catenin signalling pathway's role in cancer, emphasizing its regulation of autophagy and apoptosis. Our goal is to highlight the potential of specific small molecule inhibitors targeting this pathway, fostering the development of novel, tailored cancer treatments.
    Keywords:  Apoptosis; Autophagy; Cancer; Inhibitors; WNT signalling; small molecules
    DOI:  https://doi.org/10.1016/j.ejphar.2024.177137
  43. ChemMedChem. 2024 Nov 22. e202400580
    Virtual Screening and Biological Evaluation of Natural Products as Novel VPS34 Inhibitors that Modulate Autophagy.
    Xiaowen Feng, Baoming Wu, Hanyang Xu, Chu Chen, Jiqing Ye.
      VPS34 is a sole member of class III phosphoinositide 3-kinase involved in endosomal trafficking and autophagosome formation, making it an interesting target for cancer treatment. Here, we investigated 5,774 natural products using structure-based virtual screening against human VPS34. 10 natural products identified by virtual screening were purchased and tested in VPS34 ADP-Glo assay, yielding several potential VPS34 inhibitors. Amongst, Salvianolic acid A (4) and Ellagic acid (8) inhibited VPS34 with IC50 values of 2.46 and 3.12 uM, respectively, more potent than the positivity control 3-MA. Moreover, in vitro assays demonstrated that both of the compounds suppressed vesicle trafficking in cell-based assay. Significantly, Salvianolic acid (4) effectively prevented autophagy in Hela cells induced either by starvation or Rapamycin, an mTOR inhibitor. In addition, in silico analysis was done to elucidate the binding mechanisms of the ligand in complex with VPS34. Overall, this study highlights the efficacy of structure-based virtual screening and presents several natural products as VPS34 inhibitors that modulate autophagy.
    Keywords:  VPS34 inhibitors, autophagy, virtual screening, MD simulations, Salvianolic acid A
    DOI:  https://doi.org/10.1002/cmdc.202400580
  44. Phytomedicine. 2024 Nov 08. pii: S0944-7113(24)00890-0. [Epub ahead of print]135 156233
    Gnetupendin A protects against ischemic stroke through activating the PI3K/AKT/mTOR-dependent autophagy pathway.
    Danyang Mu, Jingyu Liu, Yan Mi, Dequan Wang, Libin Xu, Yuxin Yang, Yueyang Liu, Dong Liang, Yue Hou.
       BACKGROUND: Autophagy has been recently emerged as a prominent factor in the pathogenesis of ischemic stroke (IS) and is increasingly being considered as a potential therapeutic target for IS. Gnetum parvifolium has been identified as a potential therapeutic agent for inflammatory diseases such as rheumatism and traumatic injuries. However, the pharmacological effects of Gnetupindin A (GA), a stilbene compound isolated from Gnetum parvifolium, have not been fully elucidated until now.
    OBJECTIVE: Here we identified the therapeutic potential of GA for IS, deeply exploring the possible mechanisms related to its regulation of autophagy.
    METHODS: The mouse model of middle cerebral artery occlusion-reperfusion (MCAO/R) and the oxygen-glucose deprivation reperfusion (OGD/R)-exposed cells served as models to study the protection of GA against IS. The adeno-associated virus (AAV) encoding shAtg5, in conjunction with autophagy inhibitor 3-Methyladenine (3-MA) were utilized to explore the role of GA in regulating autophagy following IS. Molecular docking, CETSA, and DARTS were used to identify the specific therapeutic target of GA. PI3K inhibitor LY294002 was employed to test the participation of PI3K in GA-mediated autophagy and neuroprotective effects following IS.
    RESULTS: Our findings revealed that treatment with GA significantly alleviated the brain infract volume, edema, improved neurological deficits and attenuated apoptosis. Mechanistically, we found that GA promoted autophagic flow both in vivo and in vitro after IS. Notably, neural-targeted knockdown of Atg5 abolished the neuroprotective effects mediated by GA. Inhibition of autophagy using 3-MA blocked the attenuation on apoptosis induced by GA. Moreover, molecular docking, CETSA, and DARTS analysis demonstrated that GA specifically targeted PI3K and further inhibited the activation of PI3K/AKT/mTOR signaling pathway. LY294002, which inhibits PI3K, reversed GA-induced autophagy and neuroprotective effects on OGD/R-treated cells.
    CONCLUSION: We demonstrated, for the first time, that GA protects against IS through promoting the PI3K/AKT/mTOR-dependent autophagy pathway. Our findings provide a novel mechanistic insight into the anti-IS effect of GA in regulating autophagy.
    Keywords:  Autophagy; Gnetupendin A; Ischemic stroke; Neuronal damage; PI3K/AKT/mTOR signaling
    DOI:  https://doi.org/10.1016/j.phymed.2024.156233
  45. Autophagy. 2024 Nov 22. 1-3
    Autophagy-dependent ferroptosis mediates multiple sclerosis.
    Daolin Tang, Rui Kang, Daniel J Klionsky.
      A recent paper published in Cell by Woo et al. reported that autophagy-dependent ferroptosis mediated by STING1 is involved in neuronal death associated with multiple sclerosis (MS). This research broadens our understanding of the pathogenesis of MS and opens new avenues for therapeutic interventions.
    Keywords:  Cell death; GPX4; STING1; macroautophagy; neurons
    DOI:  https://doi.org/10.1080/15548627.2024.2419112
  46. bioRxiv. 2024 Oct 29. pii: 2024.02.25.581879. [Epub ahead of print]
    Exploring Arylidene-Indolinone Ligands of Autophagy Proteins LC3B and GABARAP.
    Alexandria N Leveille, Thomas Schwarzrock, Hawley Brown, Bennett True, Joanet Plasencia, Philipp Neudecker, Alina Üffing, Oliver H Weiergräber, Dieter Willbold, Joshua A Kritzer.
      We report the first structure-activity studies of arylidene-indolinone compound GW5074 which was reported as a ligand of autophagy-related protein LC3B. The literature has conflicting information on the binding affinity of this compound and there is some debate regarding its use as a component of autophagy-dependent degrader compounds. We developed an AlphaScreen assay to measure competitive inhibition of the binding of known peptide ligands to LC3B and its paralog GABARAP. 18 analogs were synthesized and tested against both proteins. Inhibitory potencies were found to be in the mid- to high micromolar range. 2D-NMR data revealed the binding site on GABARAP as hydrophobic pocket 1, where native peptide ligands bind with an aromatic side chain. Our results suggest that GW5074 binds LC3B and GABARAP with micromolar affinity. These affinities could support further exploration in targeted protein degradation, but only if off-target effects and poor solubility can be appropriately addressed.
    Keywords:  autophagy; protein-protein interactions; small-molecule inhibitors; structure-activity relationships
    DOI:  https://doi.org/10.1101/2024.02.25.581879
  47. Ageing Res Rev. 2024 Nov 17. pii: S1568-1637(24)00402-1. [Epub ahead of print]102 102584
    Targeted protein degradation: expanding the technology to facilitate the clearance of neurotoxic proteins in neurodegenerative diseases.
    Xin Wang, Wen Shuai, Panpan Yang, Yinyang Liu, Yiwen Zhang, Guan Wang.
      In neurodegenerative diseases (NDDs), disruptions in protein homeostasis hinder the clearance of misfolded proteins, causing the formation of misfolded protein oligomers and multimers. The accumulation of these abnormal proteins results in the onset and progression of NDDs. Removal of non-native protein is essential for cell to maintain proteostasis. In recent years, targeted protein degradation (TPD) technologies have become a novel means of treating NDDs by removing misfolded proteins through the intracellular protein quality control system. The TPD strategy includes the participation of two primary pathways, namely the ubiquitin-proteasome pathway (for instance, PROTAC, molecular glue and hydrophobic tag), and the autophagy-lysosome pathway (such as LYTAC, AUTAC and ATTEC). In this review, we systematically present the mechanisms of various TPD strategies employed for neurotoxic protein degradation in NDDs. The article provides an overview of the design, in vitro and in vivo anti-NDD activities and pharmacokinetic properties of these small-molecular degraders. Finally, the advantages, challenges and perspectives of these TPD technologies in NDDs therapy are discussed, providing ideas for further development of small molecule degraders in the realm of NDDs.
    Keywords:  Autophagy-lysosome pathway; Neurodegenerative diseases; Neurotoxic protein; Targeted protein degradation; Ubiquitin-proteasome pathway
    DOI:  https://doi.org/10.1016/j.arr.2024.102584
  48. Sci Rep. 2024 11 18. 14(1): 28539
    MT1G promotes iron autophagy and inhibits the function of gastric cancer cell lines by intervening in GPX4/SQSTM1.
    Kaiqiang Meng, Jian Song, Fan Qi, Jiamin Li, Zhichao Fang, Liang Song.
      Gastric cancer (GC) is the fifth most common cancer and the third most common cause of cancer death globally, with high invasiveness, high recurrence rate, and poor prognosis. Multiple studies have shown that Metallothionein-1G (MT1G) is closely associated with oxidative stress, ferroptosis, and autophagy. However, the role and potential mechanisms of MT1G in GC have not been fully elucidated. This study aims to explore the biological functions and regulatory mechanisms of MT1G in GC. Perform bioinformatics analysis using the TCGA database to investigate the expression of MT1G in GC. RT-qPCR and Western blot were used to detect the expression of MT1G, ferroptosis related proteins, autophagy related proteins and ARNTL clock autophagy related proteins in Hgc27, MKN45 and AGS cell lines. Exploring the biological functions of MT1G overexpressing GC cell lines through wound healing and transwell experiments. Use specific fluorescence probes to examine mitochondrial membrane potential and Fe2+ fluorescence intensity. Using immunoprecipitation analysis (CO-IP) to elucidate the association between GC cell lines GPX4, SQSTM and ARNTL. Use flow cytometry to detect ROS expression. Observation of autophagy related morphological changes in cells using transmission electron microscopy. Compared with gastric mucosal cell lines, the expression of MT1G is decreased in three gastric cancer cell lines (Hgc27, MKN45 and AGS). Overexpression of MT1G inhibits the proliferation, migration, and invasion functions of GC cells, reduces SOD and GSH content, increases MDA content, cause the mitochondrial membrane potential to weaken and promote the transformation of JC-1 aggregates to JC-1 monomer, increases Fe2+, affects ROS, and reduces GPX4 and SLC7A11 protein expression, promoting ferroptosis. Overexpression of MT1G promotes the transformation of LC3B I to LC3B II, reduces SQSTM1 protein expression, and leads to the appearance of more autophagosomes and autolysosomes at low magnification. At high magnification, mitochondrial autophagy, endoplasmic reticulum autophagy, lipid droplet autophagy, and wrinkled mitochondrial cristae are observed, promoting autophagy. Overexpression of MT1G inhibits GPX4, thereby affecting SQSTM1 as a vector to promote ARNTL autophagy and EGLN2, promoting ARNTL clock autophagy through the GPX4/SQSTM1 axis. Our research findings elucidate that overexpression of MT1G promotes iron autophagy centered around ARNTL in GC cells via the GPX4/SQSTM1 axis, thereby inhibiting GC cell function and providing a new molecular mechanism and therapeutic target for the development of GC.
    Keywords:  ARNTL; Autophagy; Clock autophagy; Ferroptosis; Gastric cancer; MT1G
    DOI:  https://doi.org/10.1038/s41598-024-80160-4
  49. Protein Pept Lett. 2024 Nov 15.
    Aloperine Attenuates UVB-induced Damage in Skin Fibroblasts Via Activating TFE3/Beclin-1-Mediated Autophagy.
    Mingning Qiu, Jianchang Li, Shuai Zhang, Jinglan Liang, Xuguang Wang, Jie Liu.
       BACKGROUND: Aloperine (ALO) is an important active ingredient in the traditional Chinese medicinal plant Sophora alopecuroides L and has a significant autophagy-stimulating effect. The effect of ALO on cytotoxicity caused by UVB radiation in skin fibroblasts and the potential mechanism remains unclear.
    OBJECTIVE: The present study aimed to assess the effect of ALO on UVB-induced damage in skin fibroblasts and investigate its possible mechanism.
    METHODS: Cell viability, cytotoxicity, caspase-Glo 3/7 activity, apoptosis, and protein expression were measured in UVB-treated skin fibroblasts in the presence or absence of ALO. Autophagy inhibitors (chloroquine and bafilomycin A1) and TFE3 siRNA transfection were used to elucidate the potential mechanisms further.
    RESULTS: These data demonstrate that ALO attenuated cell viability inhibition, apoptosis, cytotoxicity, and alterations in autophagy-related proteins caused by UVB exposure in skin fibroblasts. ALO stimulates autophagy activation and TFE3 nuclear localization in UVB-treated skin fibroblasts. Furthermore, treatment with autophagy inhibitors and TFE3 siRNA reversed the effects of ALO on UVB-treated skin fibroblasts.
    CONCLUSION: These results suggest that ALO protects skin fibroblasts against UVB-induced cytotoxicity by stimulating TFE3/Beclin-1-mediated autophagy.
    Keywords:  Aloperine; Beclin-1; TFE3; UVB-induced damage; autophagy; skin fibroblasts
    DOI:  https://doi.org/10.2174/0109298665335370241017055831
  50. Cell Stress Chaperones. 2024 Nov 19. pii: S1355-8145(24)00130-5. [Epub ahead of print]
    Endoplasmic reticulum stress-mediated apoptosis and autophagy in osteoarthritis: from molecular mechanisms to therapeutic applications.
    Yifan Lu, Jing Zhou, Hong Wang, Hua Gao, Eryu Ning, Zhiqiang Shao, Xing Yang, Yuefeng Hao.
      Osteoarthritis (OA) is characterized primarily by the degeneration of articular cartilage, with a high prevalence and disability rate. The functional phenotype of chondrocytes, as the sole cell type within cartilage, is vital for OA progression. Due to the avascular nature of cartilage and its limited regenerative capacity, repair following injury poses significant challenges. Various cellular stressors, including hypoxia, nutrient deprivation, oxidative stress, and collagen mutations, can lead to the accumulation of misfolded proteins in the endoplasmic reticulum (ER), resulting in ER stress (ERS). In response to restore ER homeostasis as well as cellular vitality and function, a series of adaptive mechanisms are triggered, including the unfolded protein response (UPR), ER-associated degradation (ERAD), and ER-phagy. Prolonged or severe ERS may exceed the adaptive capacity of cells, leading to dysregulation in apoptosis and autophagy-key pathogenic factors contributing to chondrocyte damage and OA progression. This review examines the relationship between ERS in OA chondrocytes and both apoptosis and autophagy in order to identify potential therapeutic targets and strategies for prevention and treatment of OA.
    Keywords:  Apoptosis; Autophagy; Chondrocyte; Endoplasmic reticulum stress; Osteoarthritis
    DOI:  https://doi.org/10.1016/j.cstres.2024.11.005
  51. Mol Cell Biol. 2024 Nov 18. 1-16
    SIRT3 Deficiency Promotes Lung Endothelial Pyroptosis Through Impairing Mitophagy to Activate NLRP3 Inflammasome During Sepsis-Induced Acute Lung Injury.
    Congmin Yan, Xin Lin, Jingting Guan, Wengang Ding, Ziyong Yue, Zhiqiang Tang, Xiangqi Meng, Bo Zhao, Zhiqiang Song, Dongmei Li, Tao Jiang.
      Acute lung injury (ALI) is a major cause of death in bacterial sepsis due to endothelial inflammation and endothelial permeability defects. Mitochondrial dysfunction is recognized as a key mediator in the pathogenesis of sepsis-induced ALI. Sirtuin 3 (SIRT3) is a histone protein deacetylase involved in preservation of mitochondrial function, which has been demonstrated in our previous study. Here, we investigated the effects of SIRT3 deficiency on impaired mitophagy to promote lung endothelial cells (ECs) pyroptosis during sepsis-induced ALI. We found that 3-TYP aggravated sepsis-induced ALI with increased lung ECs pyroptosis and enhanced NLRP3 activation. Mitochondrial reactive oxygen species (mtROS) and extracellular mitochondrial DNA (mtDNA) released from damaged mitochondria could be exacerbated in SIRT3 deficiency, which further elicit NLRP3 inflammasome activation in lung ECs during sepsis-induced ALI. Furthermore, Knockdown of SIRT3 contributed to impaired mitophagy via downregulating Parkin, which resulted in mitochondrial dysfunction. Moreover, pharmacological inhibition NLRP3 or restoration of SIRT3 attenuates sepsis-induced ALI and sepsis severity in vivo. Taken together, our results demonstrated SIRT3 deficiency facilitated mtROS production and cytosolic release of mtDNA by impaired Parkin-dependent mitophagy, promoting to lung ECs pyroptosis through the NLRP3 inflammasome activation, which providing potential therapeutic targets for sepsis-induced ALI.
    Keywords:  Acute lung injury; SIRT3; mitophagy; pyroptosis; sepsis
    DOI:  https://doi.org/10.1080/10985549.2024.2426282
  52. J Endod. 2024 Nov 20. pii: S0099-2399(24)00597-1. [Epub ahead of print]
    Peripheral Lysosomal Positioning in Inflamed Odontoblasts Facilitates Mineralization.
    Nuo Xu, Qian Gao, Chengcan Yang, Xiaona Song, Kai Yang, Zhuan Bian.
       INTRODUCTION: Odontoblasts, terminally differentiated dentin-producing cells, critically rely on lysosomal functions for intracellular recycling and renewal. Beyond their traditional degradative role, lysosomes actively orchestrate cellular responses to external stimuli through precise and rapid intracellular trafficking and positioning. This study aimed to explore the influence of lysosomal positioning on odontoblast mineralization and the underlying mechanisms implicated in carious inflammation.
    METHODS: Human dental pulp stem cells (hDPSCs) were induced to differentiate into human odontoblast-like cells (hOBLCs). hOBLCs were treated with various doses of LPS (0.1, 1, 5 μg/mL) to mimic carious inflammation. Lysosomal positioning was examined by immunofluorescence staining of LAMP1 in healthy and carious human teeth, LPS-treated hOBLCs, mouse lower incisors at postnatal day 2.5, and mineralization medium cultured hDPSCs. Lysosomal positioning was manipulated by knockdown or overexpression of SNAPIN or ARL8B. Mineralization was assessed by ARS staining and expression of DSPP and DMP1. Lysosomal exocytosis was examined by detection of lysosomal-plasma membrane fusion, surface exposure of LAMP1 luminal epitopes (1D4B) and extracellularly released lysosomal enzymes.
    RESULTS: Peripheral lysosomal positioning was markedly increased in odontoblasts within moderate and extensive carious lesions (P < .001) and in hOBLCs following LPS treatment. Increased peripheral dispersion of lysosomes was similarly observed during odontoblastic differentiation in vivo and in vitro. Moreover, peripheral lysosomal positioning promoted mineralization in inflamed hOBLCs, potentially via mTORC1 signaling pathway and lysosomal exocytosis.
    CONCLUSION: Inflammatory stimuli prompted a relocation of lysosomes in odontoblasts, redistributing them from perinuclear location towards the cell periphery, which in turn facilitated mineralization, potentially via mTORC1 signaling and lysosomal exocytosis.
    Keywords:  lysosomal exocytosis; lysosomal positioning; mTORC1; mineralization; odontoblast
    DOI:  https://doi.org/10.1016/j.joen.2024.11.006
  53. Nat Commun. 2024 Nov 23. 15(1): 10157
    PDCD6 regulates lactate metabolism to modulate LC3-associated phagocytosis and antibacterial defense.
    Lulu Sun, Sijin Wu, Hui Wang, Tianyu Zhang, Mengyu Zhang, Xuepeng Bai, Xiumei Zhang, Bingqing Li, Cai Zhang, Yan Li, Jun Zhou, Tianliang Li.
      LC3-associated phagocytosis (LAP) is critical in host defense against invading pathogens, but the molecular mechanism for LAP activation is still unclear. Here, we find programmed cell death 6 (PDCD6) as a negative regulator of LAP. PDCD6 deficiency in mice and macrophages induces enhanced bactericidal activity and LAP formation. In parallel, lactate dehydrogenase A (LDHA) activity and lactate production is induced in macrophages challenged with bacteria, Zymosan or Pam3CSK4, while genetic ablation or pharmacological inhibition of LDHA reduces lactate levels and impairs bactericidal activity in vivo and in vitro. Mechanistically, PDCD6 interacts with LDHA to downregulate lactate metabolism, leading to reduced RUBCN lactylation at lysine33 (K33). By contrast, PDCD6-deficiency increases RUBCN lactylation, thereby promotes RUBCN interaction with VPS34, LAP formation, and protective responses. Our results thus suggest a PDCD6-LDHA-lactate-RUBCN axis of innate immunity regulation that may both contribute to protection from infectious diseases and serve as targets for therapeutic development.
    DOI:  https://doi.org/10.1038/s41467-024-54377-w
  54. Commun Biol. 2024 Nov 21. 7(1): 1551
    Endogenous mitochondrial NAD(P)H fluorescence can predict lifespan.
    Christopher S Morrow, Pallas Yao, Carlos A Vergani-Junior, Praju Vikas Anekal, Paula Montero Llopis, Jeffrey W Miller, Bérénice A Benayoun, William B Mair.
      Many aging clocks have recently been developed to predict health outcomes and deconvolve heterogeneity in aging. However, existing clocks are limited by technical constraints, such as low spatial resolution, long processing time, sample destruction, and a bias towards specific aging phenotypes. Therefore, here we present a non-destructive, label-free and subcellular resolution approach for quantifying aging through optically resolving age-dependent changes to the biophysical properties of NAD(P)H in mitochondria through fluorescence lifetime imaging (FLIM) of endogenous NAD(P)H fluorescence. We uncover age-dependent changes to mitochondrial NAD(P)H across tissues in C. elegans that are associated with a decline in physiological function and construct non-destructive, label-free and cellular resolution models for prediction of age, which we refer to as "mito-NAD(P)H age clocks." Mito-NAD(P)H age clocks can resolve heterogeneity in the rate of aging across individuals and predict remaining lifespan. Moreover, we spatiotemporally resolve age-dependent changes to mitochondria across and within tissues, revealing multiple modes of asynchrony in aging and show that longevity is associated with a ubiquitous attenuation of these changes. Our data present a high-resolution view of mitochondrial NAD(P)H across aging, providing insights that broaden our understanding of how mitochondria change during aging and approaches which expand the toolkit to quantify aging.
    DOI:  https://doi.org/10.1038/s42003-024-07243-w
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