Autophagy最新文献

Macroautophagy (hereafter, autophagy) is essential for the degradation of mitochondria from yeast to humans. Mitochondrial autophagy in yeast is initiated when the selective autophagy scaffolding protein Atg11 is recruited to mitochondria through its interaction with the selective autophagy receptor Atg32. This also results in the recruitment of small 30-nm vesicles that fuse to generate the initial phagophore membrane. We demonstrate that Atg11 can bind to autophagic-like membranes in vitro in a curvature-dependent manner in part via a predicted amphipathic helix. Deletion of the amphipathic helix from Atg11 results in a delay in the formation of mitophagy initiation sites in yeast. Furthermore, using a novel biochemical approach, we demonstrate that the interaction between Atg11 and Atg32 results in the tethering of autophagic-like vesicles in clusters to giant unilamellar vesicles containing a lipid composition designed to mimic the outer mitochondrial membrane. We also demonstrate that the N-terminal region of Atg11 is an important mediator of vesicle tethering to cargo mimetics and that clustering of autophagic-like vesicles requires the C-terminal region of Atg11. Taken together, our results reveal that Atg11 clusters into high-order oligomers, can tether autophagic-like membranes and due to its ability to oligomerize can cluster vesicles on the surface of cargo mimetics. This work provides new insight into the mechanisms of protein and membrane clustering by Atg11. Given the increasing importance of protein oligomerization and clustering in autophagy, these results have important implications in the initiation of mitochondrial autophagy.Abbreviations Atg11: autophagy related 11; Atg11-Cterm: C-terminal region of Atg11; Atg11-Nterm: N-terminal region of Atg11; Atg32: autophagy related 32; COV: coefficient of variance; DOPC: 1,2-dioleoyl-sn-glycero-3-phosphocholine; DOPE: 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine; DOPS: 1,2-dioleoyl-sn-glycero-3-phospho-L-serine; FRAP: fluorescence recovery after photobleaching; GLT: GUV and liposome tethering; GUV: giant unilamellar vesicle; MKO: multiple knockout; OMM: outer mitochondrial membrane; PC: phosphatidylcholine; PE: phosphatidylethanolamine; PtdIns: phosphatidylinositol; PtdIns3P: phosphatidylinositol-3-phosphate; RhPE: rhodamine phosphatidylethanolamine; SAR: selective autophagy receptor; SEC: size-exclusion chromatography; SLB: supported lipid bilayers; SMrT: supported membrane templates; YPL: yeast polar lipids.

Radiotherapy is a fundamental step in the combined treatment of glioblastoma (GBM), while radioresistance of GBM causes limitation of therapeutic efficacy. Natural killer (NK) cells, a potential target of immunotherapy, have attracted considerable attention due to the robust cancer cell-targeted cytotoxicity in combined treatment with radiotherapy, suggesting NK cell regulation might be a radiosensitization strategy. Here we show that a cytotoxic subset of NK cells could be stimulated by ionizing radiation (IR) and accumulate in the GBM tumor microenvironment (TME). Co-culturing with NK cells significantly enhances the GBM cell response to IR, and pharmaceutically depleting NK cells in mice elevates IR-induced tumor growth delay. Specifically, GZMB should be the radiosensitization effector secreted by NK cells. Suppressing GZMB activity remarkably impairs NK-mediated GBM radiosensitization. Meanwhile, administrating exogenous GZMB improves irradiation dose-survival response in vitro or in a xenograft model. Mechanically, GZMB blocks autophagosome-lysosome fusion in GBM cells by directly recognizing and cleaving SDC1, a key regulator of autophagosome maturation, at the valine 225 and aspartate 228 sites. Uncleavable mutation of SDC1 reverses GZMB-mediated radiosensitization in GBM. Further studies demonstrate that cleavage of SDC1 obstructs the localization of TGM2, a key MAP1LC3/LC3 recognizer, on the lysosome surface. Clinical data reveal GBM patients with an SDC1 valine 225 or aspartate 228 mutation display lower response to radiotherapy. In this study, we disclose the critical role of NK cells in tumor radiotherapy through secreting GZMB and impeding autophagosome maturation, as well as propose a potential strategy combining radiotherapy and NK-based immunotherapy against radioresistant GBM.Abbreviations: DEGs: differentially expressed genes; GBM: glioblastoma; GZMB: granzyme B; IL: interleukin; IR: ionizing radiation; IRS: immunoreactive score; LAMP: lysosomal associated membrane protein; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; mSDC1: mutant SDC1; NK: natural killer; PRF1: perforin 1; SDC1: syndecan 1; SNAP29: synaptosome associated protein 29; SQSTM1: sequestosome 1; STX17: syntaxin 17; TGM2: transglutaminase 2; TME: tumor microenvironment; TGD: tumor growth delay; VAMP8: vesicle associated membrane protein 8; WT: wild type.

Macroautophagy/autophagy plays a crucial role in maintaining cellular homeostasis and protecting against osteoarthritis (OA). Its dysregulation contributes to OA progression by promoting chondrocyte senescence, inflammation, and cartilage degradation. Enhancing autophagic activity thus represents a promising therapeutic strategy for OA. In this study, we identified lactucopicrin (LCP) as an effective autophagy activator that alleviates OA progression in a mouse model induced by the destabilization of the medial meniscus, by reducing cartilage degeneration and preserving matrix integrity. Mechanistically, LCP enhances ZDHHC4-catalyzed palmitoylation of the cargo receptor CCDC50, facilitating the selective autophagic degradation of MAP2K4/MKK4, leading to the suppression of MAPK/JNK signaling and the attenuation of chondrocyte senescence. Structural analysis reveals that LCP directly binds to His72 of ZDHHC4 via its p-hydroxybenzoic acid moiety, boosting enzymatic activity and promoting selective autophagy. These findings establish a novel ZDHHC4-CCDC50-MAP2K4/MKK4-MAPK/JNK regulatory axis linking palmitoylation, autophagy, and senescence, and identify LCP as a promising agent for targeting this pathway to inhibit OA progression. Furthermore, this study provides mechanistic insights into the crosstalk between autophagy, protein palmitoylation, and cellular senescence in degenerative joint disease.Abbreviation: ABE: acyl-biotin exchange; ADAMTS5: ADAM metallopeptidase with thrombospondin type 1 motif 5; CCDC50: coiled-coil domain containing 50; COL2A1: collagen, type II, alpha 1; COL10A1: collagen, type X, alpha 1; DARTS: drug affinity responsive target stability; DHHC: Asp-His-His-Cys catalytic motif; GOT1/AST: glutamic-oxaloacetic transaminase 1, soluble; GPT/ALT: glutamic pyruvic transaminase, soluble; H₂O_2: hydrogen peroxide; LCP: lactucopicrin; IL6: interleukin 6; MAPK/JNK: mitogen-activated protein kinase; MAP2K4/MKK4: mitogen-activated protein kinase kinase 4; MMP13: matrix metallopeptidase 13; OA: osteoarthritis; p-MAPK/JNK: phosphorylated mitogen-activated protein kinase; SASP: senescence-associated secretory phenotype; SA-GLB1/β-gal: senescence-associated galactosidase, beta 1; ZDHHC: zinc finger, DHHC domain containing.

Haploinsufficiency of TBK1 causes familial ALS and frontotemporal dementia (FTD), yet the mechanisms by which TBK1 loss leads to neurodegeneration remain unclear. Using deep proteomics and phospho-proteomics, we demonstrate that TBK1 regulates select macroautophagy/autophagy factors, targeting cargo receptors and autophagy initiation factors, and also sustains the phosphorylation of the late endosomal marker RAB7A in stem cells and stem cell-derived excitatory neurons. We further uncovered novel TBK1-dependent phosphorylation sites in the key autophagy protein SQSTM1/p62. Loss of TBK1 function results in a cell-autonomous neurodegenerative phenotype characterized by impaired neurite outgrowth and lysosomal dysfunction.

The mechanistic target of rapamycin complex 1 (mTORC1) integrates environmental cues, especially amino acids, to regulate metabolism and ultimately cancer progression. Phosphoserine aminotransferase 1 (PSAT1) is a key enzyme in de novo serine synthesis and its overexpression has been reported to promote oncogenesis in various cancers. Knockdown of PSAT1 inhibits the proliferation and migration of cancer cells. However, our study found an interesting phenomenon that either PSAT1 overexpression or knockout promoted cell proliferation in lung adenocarcinoma (LUAD) which seemed to contradict traditional views. The mechanism was that PSAT1 preferentially bound to GTP-loaded RagB GTPases, preventing the formation of Rag heterodimers. This restricted the lysosome localization of mTORC1 and enhanced the basal level of macroautophagy/autophagy, which promoted the proliferative ability of LUAD cells. PSAT1 knockout resulted in Rag heterodimer formation and mTORC1 activation, promoting protein synthesis and cell proliferation. Additionally, PSAT1 knockout caused a compensatory upregulation of the serine transporter solute carrier family 1 member 5 (SLC1A5), increasing exogenous serine uptake. In conclusion, our study reveals a novel function of PSAT1 in regulation of mTORC1 that affects the proliferation of LUAD cells.Abbreviations: ATG5: autophagy-related 5; BECN1: Beclin 1; CQ: chloroquine; 4EBP1: eukaryotic translation initiation factor 4E binding protein 1; GAP: GTPase-activating protein; GDP: Guanosine nucleotide diphosphate; GTP: Guanosine triphosphate; GTPase: guanosine triphosphatase; LAMP2: lysosome-associated membrane protein 2; LC3: microtubule-associated protein 1 light chain-3, LUAD: lung adenocarcinoma; mTORC1: mechanistic target of rapamycin complex 1; PCC: Pearson's correlation coefficient; PSAT1: Phosphoserine aminotransferase 1; Rag: Ras-related GTP binding; Raptor: regulatory-associated protein of mTOR; S6: ribosomal protein S6; S6K1: substrates S6 kinase 1; SLC1A5: solute carrier family 1 member 5; SSP: serine biosynthetic pathway; ULK1: unc-51 like autophagy activating kinase 1.

Mitochondrial dysfunction is widely recognized as a key driver of aging and neurodegenerative diseases, with mitophagy acting as an essential cellular mechanism for the selective clearance of damaged mitochondria. While pharmacological activation of mitophagy has been reported to exert beneficial effects across multiple neurodegenerative diseases, its functional relevance in amyotrophic lateral sclerosis (ALS) remains poorly characterized. Our recent study published in EMBO Molecular Medicine demonstrates that PINK1-PRKN-dependent mitophagy is markedly impaired in ALS motor neurons. Through high-content drug screening, we identified a potent mitophagy agonist isoginkgetin (ISO), a bioflavonoid from Ginkgo biloba that stabilizes the PINK1-TOMM complex on the outer mitochondrial membrane, enhances PINK1-PRKN-dependent mitophagy, and ameliorates motor neuron degeneration in ALS-like Caenorhabditis elegans, mouse models, and induced pluripotent stem cell-derived motor neurons. Consequently, ISO is able to alleviate ALS-associated phenotypes. In this commentary, we contextualize these findings broadly to discuss whether pharmacologically induced mitophagy can act as an effective therapeutic strategy, distinct from current clinical approaches, for the development of ALS-targeted treatments.

Macroautophagy/autophagy protects muscle from proteotoxic stress and maintains tissue homeostasis, yet skeletal muscle relies on it more than most organs. Adult fibers endure constant mechanical strain and require continuous turnover of long-lived proteins, while muscle stem cells (MuSCs) depend on autophagy to remain quiescent, activate after injury, and regenerate effectively. How autophagy is transcriptionally regulated in muscle has been unclear. We identified DEAF1 as a transcriptional brake on autophagy. In MuSCs, DEAF1 controls activation and regeneration and becomes aberrantly elevated with age, promoting protein aggregate formation and cell death. In muscle fibers, DEAF1 is chronically induced during aging, suppressing autophagy and driving functional decline. Exercise reverses DEAF1 induction, restoring autophagy and muscle function. These findings reveal DEAF1 as a key regulator linking autophagy to regeneration and aging, highlighting a therapeutically tractable axis for preserving muscle health.

Microautophagy involves the direct uptake of cytoplasmic materials by lysosomes, but its regulation, including substrate specificity, has remained largely unclear in mammalian cells. Microlipophagy, a form of lipid droplet microautophagy, has been suggested in mammalian cells, yet the molecular basis that links lysosomes to lipid droplets and supports their uptake has not been elucidated. In our recent study, we showed that the lysosomal membrane protein LAMP2B mediates this process via its cytoplasmic region, which can bind phosphatidic acid, a lipid present on lipid droplets. We also found that this pathway depends on the ESCRT machinery and proceeds independently of macroautophagy. In this commentary, we summarize these findings and describe how LAMP2B affects lipid droplet degradation in cells. We describe that LAMP2B overexpression protects mice from high-fat-diet-induced obesity and related disorders. We also outline a model of microautophagy and microautophagy-like processes in which LAMP2 isoforms use their cytoplasmic regions to recognize distinct cargos.

Transfer RNA-derived small RNAs (tDRs) have transcended their traditional roles in protein synthesis and have emerged as crucial regulators of cellular homeostasis. Li et al. (2025) underscored this by identifying tRNA-Asp-GTC-3'tDR as a tDR responsive to hypoxic conditions, which confers renal protection through a distinctive macroautophagy/autophagy mechanism. This tDR adopts a G-quadruplex structure that sequesters PUS7 (pseudouridine synthase 7), thereby disrupting the pseudouridylation of histone mRNAs and directing them toward degradation via autophagosome-lysosome pathways, a mechanism termed "RNautophagy." Clinically, elevated levels of tRNA-Asp-GTC-3'tDR in conditions such as preeclampsia and early chronic kidney disease suggest a conserved evolutionary pathway for renal protection in humans. Experimental studies in mice have demonstrated that therapeutic enhancement of tDR mitigates renal inflammation, fibrosis, and damage, whereas its inhibition exacerbates these conditions. This establishes a novel paradigm linking RNA biology and autophagy regulation, paving the way for innovative precision RNA-based therapies for kidney diseases.Abbreviations: mRNAs: messenger RNA; PUS7: pseudouridine synthase 7; tDRs: transfer RNA-derived small RNAs; tRNA-Asp-GTC-3'tDR: transferRNA-aspartic acid-GTC-codon-3'terminal deoxyribonucleotide.