Autophagy最新文献

Studies using mitophagy reporter mice have established steady-state landscapes of mitochondrial destruction in mammalian tissues, sparking intense interest in basal mitophagy. Yet how basal mitophagy is modified by healthy aging in diverse brain cell types has remained a mystery. We present a comprehensive spatiotemporal analysis of mitophagy and macroautophagy dynamics in the aging mammalian brain, reporting critical region- and cell-specific turnover trajectories in a longitudinal study. We demonstrate that the physiological regulation of mitophagy in the mammalian brain is cell-specific, dynamic and complex. Mitophagy increases significantly in the cerebellum and hippocampus during midlife, while remaining unchanged in the prefrontal cortex (PFC). Conversely, macroautophagy decreases in the hippocampus and PFC, but remains stable in the cerebellum. We also describe emergent lysosomal heterogeneity, with subsets of differential acidified lysosomes accumulating in the aging brain. We further establish midlife as a critical inflection point for autophagy regulation, which may be important for region-specific vulnerability and resilience to aging. By mapping in vivo autophagy dynamics at the single cell level within projection neurons, interneurons and microglia, to astrocytes and secretory cells, we provide a new framework for understanding brain aging and offer potential targets and timepoints for further study and intervention in neurodegenerative diseases.

The NLRP3 inflammasome is a multiprotein complex that plays a vital role in the innate immune system in response to microbial infections and endogenous danger signals. Aberrant activation of the NLRP3 inflammasome is implicated in a spectrum of inflammatory and autoimmune diseases, emphasizing the necessity for precise regulation of the NLRP3 inflammasome to maintain immune homeostasis. The protein level of NLRP3 is a limiting step for inflammasome activation, which must be tightly controlled to avoid detrimental consequences. Here, we demonstrate that ABHD8, a member of the α/β-hydrolase domain-containing (ABHD) family, interacts with NLRP3 and promotes its degradation through the chaperone-mediated autophagy (CMA) pathway. ABHD8 acts as a scaffold to recruit palmitoyltransferase ZDHHC12 to NLRP3 for its palmitoylation as well as subsequent CMA-mediated degradation. Notably, ABHD8 deficiency results in the stabilization of NLRP3 protein and promotes NLRP3 inflammasome activation. We further confirm that ABHD8 overexpression ameliorates LPS- or alum-triggered NLRP3 inflammasome activation in vivo. Interestingly, the nucleocapsid (N) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) impairs the ABHD8-NLRP3 association, resulting in an elevation in NLRP3 protein level and excessive inflammasome activation. These findings demonstrate that ABHD8 May represent a potential therapeutic target in conditions associated with NLRP3 inflammasome dysregulation.Abbreviations: 3-MA: 3-methyladenine; ABHD: α/β-hydrolase domain-containing; BMDMs: Bone marrow-derived macrophages; CFZ: carfilzomib; CHX: cycloheximide; CMA: chaperone-mediated autophagy; CQ: chloroquine; DAMPs: danger/damage-associated molecular patterns; HSPA8/HSC70: heat shock protein family A (Hsp70) member 8; LAMP2A: lysosomal associated membrane protein 2A; NH₄Cl: ammonium chloride; NLRP3: NLR family pyrin domain containing 3; PAMPs: pathogen-associated molecular patterns; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2.

Reticulophagy selectively degrades fragments of the endoplasmic reticulum (ER) through macroautophagy/autophagy to maintain ER homeostasis. The deficiency of reticulophagy results in the unfolded protein response (UPR), which is a crucial clue to the pathogenesis of inflammatory diseases. However, the detailed mechanism underlying the cross-regulation between reticulophagy and inflammatory diseases remains largely unclear. Recently, we have revealed that UBAC2 (UBA domain containing 2) is essential for controlling ER homeostasis as a novel reticulophagy receptor. MARK2 catalyzes the phosphorylation of UBAC2 at serine (S) 223, hence facilitating the progression of reticulophagy and inhibiting ER stress-induced inflammatory responses.

Epilepsy is a common neurological condition that arises from dysfunctional neuronal circuit control due to either acquired or innate disorders. Autophagy is an essential neuronal housekeeping mechanism, which causes severe proteotoxic stress when impaired. Autophagy impairment has been associated to epileptogenesis through a variety of molecular mechanisms. Vici Syndrome (VS) is the paradigmatic congenital autophagy disorder in humans due to recessive variants in the ectopic P-granules autophagy tethering factor 5 (EPG5) gene that is crucial for autophagosome-lysosome fusion and autophagic clearance. Here, we used Drosophila melanogaster to study the importance of Epg5 in development, aging, and seizures. Our data indicate that proteotoxic stress due to impaired autophagic clearance and seizure-like behaviors correlate and are commonly regulated, suggesting that seizures occur as a direct consequence of proteotoxic stress and age-dependent neurodegenerative progression. We provide complementary evidence from EPG5-mutated patients demonstrating an epilepsy phenotype consistent with Drosophila predictions.Abbreviations: AD: Alzheimer's disease; ALS-FTD: Amyotrophic Lateral Sclerosis-FrontoTemoporal Dementia; DART: Drosophila Arousal Tracking; ECoG: electrocorticogram; EEG: electroencephalogram; EPG5: ectopic P-granules 5 autophagy tethering factor; KA: kainic acid; MBs: mushroom bodies; MRI magnetic resonance imaging; MTOR: mechanistic target of rapamycin kinase; PD: Parkinson's disease; TSC: TSC complex; VS: Vici syndrome.

The endoplasmic reticulum (ER) is the site of multiple cellular events and maintaining its quality control is thus crucial for cell homeostasis. Through a morphology-based gain-of-function screen, we identified the cytosolic protein FKBPL as a regulator of reticulophagy. With multiple protein-binding domains, FKBPL binds to the ER-resident CKAP4, acting as a bridge that connects the ER to the phagophore and facilitating the delivery of ER contents for lysosomal degradation. The FKBPL-CKAP4 axis is essential for both basal and stress-induced reticulophagy. Loss of the FKBPL-CKAP4 interaction attenuates reticulophagy and enhances protein secretion via microvesicle shedding. Here, we propose a dual role for the FKBPL-CKAP4 axis in regulating reticulophagy and protein secretion.

Glia contribute to the neuropathology of Parkinson disease (PD), but how they react opposingly to be beneficial or detrimental under pathological conditions, like promoting or eliminating SNCA/α-syn (synuclein alpha) inclusions, remains elusive. Here we present evidence that aux (auxilin), the Drosophila homolog of the PD risk factor GAK (cyclin G associated kinase), regulates the lysosomal degradation of SNCA/α-syn in glia. Lack of glial GAK/aux increases the lysosome number and size, regulates lysosomal acidification and hydrolase activity, and ultimately blocks the degradation of substrates including SNCA/α-syn. Whereas SNCA/α-syn accumulates prominently in lysosomes devoid of glial aux, levels of injected SNCA/α-syn preformed fibrils are further enhanced in the absence of microglial GAK. Mechanistically, aux mediates phosphorylation at the serine 543 of Vha44, the V₁ C subunit of the vacuolar-type H⁺-translocating ATPase (V-ATPase), and regulates its assembly to control proper acidification of the lysosomal milieu. Expression of Vha44, but not the Vha44 variant lacking S543 phosphorylation, restores lysosome acidity, locomotor deficits, and DA neurodegeneration upon glial aux depletion, linking this pathway to PD. Our findings identify a phosphorylation-dependent switch controlling V-ATPase assembly for lysosomal SNCA/α-syn degradation in glia. Targeting the clearance of glial SNCA/α-syn inclusions via this lysosomal pathway could potentially be a therapeutic approach to ameliorate the disease progression in PD.Abbreviation: aux: auxilin; GAK: cyclin G associated kinase; LTG: LysoTracker Green; LTR: LysoTracker Red; MR: Magic Red; PD: Parkinson disease; SNCA/a-syn: synuclein alpha; V-ATPase: vacuolar-type H⁺-translocating ATPase.

Induction of macroautophagy/autophagy has been established as an important function elicited by the CGAS-STING1 pathway during pathogen infection. However, it remains unknown whether lysosomal activity within the cell in these settings is concurrently enhanced to cope with the increased autophagic flux. Recently, we discovered that the CGAS-STING1 pathway elevates the degradative capacity of the cell by activating lysosome biogenesis. Intriguingly, we found that STING1-induced GABARAP lipidation, rather than TBK1 activation, serves as the key mediator triggering the nuclear translocation of transcription factor TFEB and enhances the expression of lysosome-related genes. Mechanistically, we demonstrated that lipidated GABARAP on single membranes, regulated by the V-ATPase-ATG16L1 axis, sequesters the FLCN-FNIP complex to abolish its function toward RRAGC and RRAGD, leading to a specific impairment of MTORC1-dependent phosphorylation of TFEB and resulting in its subsequent nuclear translocation. Functionally, we showed that STING1-induced lysosome biogenesis is essential for the clearance of cytoplasmic DNA and the elimination of invading pathogens. Collectively, our findings underscore the induction of lysosome biogenesis as a novel function of the CGAS-STING1 pathway.Abbreviation: ATG: autophagy-related; cGAMP: cyclic GMP-AMP; CGAS: cyclic GMP-AMP synthase; GABARAP: GABA type A receptor-associated protein; MEF: mouse embryonic fibroblast; MTOR: mechanistic target of rapamycin kinase; STING1: stimulator of interferon response cGAMP interactor 1; TBK1: TANK binding kinase 1; TFEB: transcription factor EB.

The nucleus is a highly specialized organelle that houses the cell's genetic material and regulates key cellular activities, including growth, metabolism, protein synthesis, and cell division. Its structure and function are tightly regulated by multiple mechanisms to ensure cellular integrity and genomic stability. Increasing evidence suggests that nucleophagy, a selective form of autophagy that targets nuclear components, plays a critical role in preserving nuclear integrity by clearing dysfunctional nuclear materials such as nuclear proteins (lamins, SIRT1, and histones), DNA-protein crosslinks, micronuclei, and chromatin fragments. Impaired nucleophagy has been implicated in aging and various pathological conditions, including cancer, neurodegeneration, autoimmune disorders, and neurological injury. In this review, we focus on nucleophagy in mammalian cells, discussing its mechanisms, regulation, and cargo selection, as well as evaluating its therapeutic potential in promoting human health and mitigating disease.Abbreviations: 5-FU: 5-fluorouracil; AMPK, AMP-activated protein kinase; ATG, autophagy related; CMA, chaperone-mediated autophagy; DRPLA: dentatorubral-pallidoluysian atrophy; ER, endoplasmic reticulum; ESCRT: endosomal sorting complex required for transport; HOPS, homotypic fusion and vacuole protein sorting; LIR: LC3-interacting region; MEFs: mouse embryonic fibroblasts; mRNA: messenger RNA; MTORC1: mechanistic target of rapamycin kinase complex 1; PCa: prostate cancer; PE: phosphatidylethanolamine; PI3K, phosphoinositide 3-kinase; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; rRNA: ribosomal RNA; SCI: spinal cord injury; SCLC: small cell lung cancer; SNARE: soluble N-ethylmaleimide-sensitive factor attachment protein receptor; SupraT: supraphysiological levels of testosterone; TOP1cc: TOP1 cleavage complexes.

The synthesis of membrane and secreted proteins is safeguarded by an endoplasmic reticulum-associated ribosome quality control (ER-RQC) that promotes the disposal of defective translation products by the proteasome or via a lysosome-dependent pathway involving the degradation of portions of the ER by macroautophagy (reticulophagy). The UFMylation of RPL26 on ER-stalled ribosomes is essential for activating the ER-RQC and reticulophagy. Here, we report that the viral deubiquitinase (vDUB) encoded in the N-terminal domain of the Epstein-Barr virus (EBV) large tegument protein BPLF1 hinders the UFMylation of RPL26 on ribosomes that stall at the ER, promotes the stabilization of ER-RQC substrates, and inhibits reticulophagy. The vDUB did not act as a de-UFMylase or interfere with the UFMylation of the ER membrane protein CYB5R3 by the UFL1 ligase. Instead, it copurified with ribosomes in sucrose gradients and abrogated a ZNF598- and LTN1-independent ubiquitination event required for RPL26 UFMylation. Physiological levels of BPLF1 impaired the UFMylation of RPL26 in productively EBV-infected cells, pointing to an important role of the enzyme in regulating the translation quality control that allows the efficient synthesis of viral proteins and the production of infectious virus.Abbreviation: BPLF1, BamH1 P fragment left open readingframe-1; CDK5RAP3, CDK5regulatory subunit associated protein 3; ChFP, mCherry fluorescent protein; DDRGK1, DDRGKdomain containing 1; EBV, Epstein-Barr virus; eGFP, enhancedGFP; ER-RQC, endoplasmicreticulum-associated ribosome quality control; LCL, EBV-carryinglymphoblastoid cell line; GFP, green fluorescent protein; RQC, ribosome quality control; SRP, signal recognition particle; UFM1, ubiquitin fold modifier 1; UFL1, UFM1 specific ligase 1.