Autophagy最新文献

LAMP2 is a ubiquitously expressed protein critical for autophagy. Alternative splicing gives rise to three isoforms. However, the roles of major LAMP2 isoforms in the heart are not known. To address this knowledge gap, we generated lamp2a and lamp2b knockout (KO) mice to investigate the role of these isoforms in heart function and autophagy. Deletion of either Lamp2a or Lamp2b did not alter cardiac structure or function. Lack of all LAMP2 isoforms led to increased cardiac fibrosis and reduced survival during pressure overload, which were not observed in lamp2a or lamp2b KO mice. Also, LAMP2B loss did not affect levels of the autophagy markers LC3-II and SQSTM1/p62. Conversely, LAMP2A was upregulated in hearts lacking LAMP2B, potentially preserving autophagy and cardiac function. Reintroducing LAMP2A in lamp2 KO mice effectively reduced autophagosome accumulation and improved cardiac function. Overall, these data support LAMP2 isoform functional redundancy in the myocardium under pathological conditions.Abbreviations: AAV: adeno-associated virus; ACTA2: actin alpha 2, smooth muscle, aorta; CMA: chaperone-mediated autophagy; KO: knockout; LAMP2: lysosomal-associated membrane protein 2; LV: Left ventricle; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; NPPA: natriuretic peptide type A; NPPB: natriuretic peptide type B; SQSTM1/p62: sequestosome 1; PBS: phosphate-buffered saline; PCR: polymerase chain reaction; TAC: transverse aortic constriction; WT: wild type.

Adipose tissue macrophages (ATMs) are key cellular components that respond to nutritional excess, contributing to obesity-induced inflammation and insulin resistance. However, the mechanisms underlying macrophage polarization and recruitment in adipose tissue during obesity remain unclear. In this study, we investigated mitophagy-dependent metabolic reprogramming in ATMs and identified a crucial role of the mitophagy receptor BNIP3 in regulating macrophage polarization in response to obesity. Mitophagic flux in ATMs increased following 12 weeks of high-fat diet (HFD) feeding, with Bnip3 levels upregulated in a HIF1A dependent manner, without affecting other mitophagy receptors. Macrophage-specific bnip3 knockout reduced HFD-induced adipose tissue inflammation and improved glucose tolerance and insulin sensitivity. Mechanistically, hypoxic conditions in vitro induced HIF1A-BNIP3-mediated mitophagy and glycolytic shift in macrophages. Furthermore, HIF1A-BNIP3 signaling-enhanced lipopolysaccharide-induced pro-inflammatory activation in macrophages. These findings demonstrate that BNIP3-mediated mitophagy regulates the glycolytic shift and pro-inflammatory polarization in macrophages and suggest that BNIP3 could be a therapeutical target for obesity-related metabolic diseases.

The common occurrence of cognitive decline is one of the most significant manifestations of aging in the brain, with the hippocampus - critical for learning and memory - being one of the first regions to exhibit functional deterioration. BGLAP/OCN/osteocalcin (bone gamma-carboxyglutamate protein), a pro-youth systemic factor produced by the bone, improves age-related cognitive decline by boosting hippocampal neuronal autophagy. However, the mechanism by which hippocampal neurons detect BGLAP/OCN in the systemic milieu and adapt their downstream response was previously unknown. We determined that BGLAP/OCN modulates core primary cilia (PC) proteins, suggesting that this "extracellular antenna" may play a role in mediating BGLAP/OCN's anti-aging effects. Furthermore, selective downregulation of core PC proteins in the hippocampus impairs learning and memory by reducing neuronal macroautophagy/autophagy. In contrast, restoring core PC protein levels in the hippocampus of aged mice improved this phenotype and was necessary for the induction of autophagy machinery by BGLAP/OCN. Together, these findings reveal a novel mechanism through which pro-youth systemic factors, like BGLAP/OCN, can regulate neuronal autophagy and foster cognitive resilience during aging.

STING1 is an essential component of the innate immune defense against a wide variety of pathogens. Whereas induction of type I interferon (IFN) responses is one of the best-defined functions of STING1, our transcriptomic analysis revealed IFN-independent activities of STING1 in macrophages, including transcriptional upregulation of numerous lysosomal and autophagic genes. This upregulation was mediated by the STING1-induced activation of the transcription factors TFEB and TFE3, and led to increased autophagy, lysosomal biogenesis, and lysosomal acidification. TFEB and TFE3 also modulated IFN-dependent STING1 signaling by controlling IRF3 activation. IFN production and cell death were increased in TFEB- and TFE3-depleted iBMDMs. Conversely, TFEB overexpression led to reduced IRF3 activation and an almost complete inhibition of IFN synthesis and secretion, resulting in decreased CASP3 activation and increased cell survival. Our study reveals a key role of TFEB and TFE3 as regulators of STING1-mediated innate antiviral immunity.

The presence of neuronal Lewy bodies mainly composed of SNCA/α-synuclein aggregations is a pathological feature of Parkinson disease (PD), whereas reducing SNCA protein levels may slow the progression of this disease. We hypothesized that compounds enhancing SNCA's interaction with MAP1LC3/LC3 May increase its macroautophagic/autophagic degradation. Here, we conducted small molecule microarray (SMM)-based screening to identify such compounds and revealed that the compound R406 could decrease SNCA protein levels in an autophagy-dependent manner. We further validated the proposed mechanism, in which knockdown of essential gene ATG5 for autophagy formation and using the autophagy inhibitor chloroquine (CQ) blocked the effect of R406. Additionally, R406 also reduced the levels of phosphorylated serine 129 of SNCA (p-S129-SNCA) in SNCA preformed fibrils (PFFs)-induced cellular models and rescued neuron degeneration. Importantly, we confirmed that R406 could alleviate PD-relevant disease phenotypes in human SNCA PFFs-induced cellular models and PD patient-derived organoid models. Taken together, we demonstrated the possibility of lowering SNCA levels by enhancing its autophagic degradation by compounds increasing SNCA-LC3 interactions.Abbreviations: ATTEC: autophagy-tethering compounds; BafA1: bafilomycin A₁; BiFC: bimolecular fluorescence complementation; CQ: chloroquine; hMOs: human midbrain organoids; iPSC: induced pluripotent stem cells; MBP: maltose-binding protein; mHTT: mutant huntingtin; OI-RD: oblique-incidence reflectivity difference; PFFs: preformed fibrils; p-S129-SNCA: phosphorylated serine 129 of SNCA; PD: Parkinson disease; ROS: reactive oxygen species; siRNA: small interfering RNA; SMM: small molecule microarray; SNCA: synuclein alpha; SYK: spleen associated tyrosine kinase.

The chemotherapeutic agent cisplatin is widely utilized for the treatment of various solid tumors. However, its clinical utility is limited by nephrotoxicity. Although numerous studies have demonstrated the potential of enhancing macroautophagy/autophagy in alleviating cisplatin-induced acute kidney injury (AKI), the dynamics of the autophagic process during renal tubular injury remain to be elucidated. In our investigation, we observed that cisplatin treatment leads to increased expression of LC3-II, GABARAPL1, SQSTM1/p62 and NBR1 in mouse renal tubular epithelial cells and BUMPT cells. Moreover, ultrastructurally, there is extensive accumulation of autophagic vacuoles in AKI mice. These findings imply that cisplatin-induced AKI results in impaired autophagic flow within renal tubular cells. Furthermore, LGALS3 (galectin 3) was found to be enriched in lysosomes after cisplatin treatment, revealing a close association between autophagy dysfunction and impaired lysosomal membrane integrity. Given the damaging contents of lysosomes, lysosomal membrane permeabilization must be rapidly resolved. Our findings showed that ESCRT III subunit CHMP4A-mediated lysosomal membrane repair significantly ameliorates autophagic defects and protects against lysosomal damage-induced cell death in a cisplatin-induced AKI model. In conclusion, our study indicates that ESCRT III-mediated lysosomal repair can relieve cisplatin-induced cell apoptosis and restore normal autophagy function in renal tubular epithelial cells. This mechanism plays a protective role against cisplatin-induced AKI.Abbreviations: AAV: adeno-associated virus; AKI: acute kidney injury; CQ: chloroquine; ESCRT: endosomal sorting complex required for transport; LMP: lysosomal membrane permeabilization; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; PAS: periodic acid Schiff; PTECs: proximal renal tubule epithelial cells; TEM: transmission electron microscopy; TUNEL: terminal deoxynucleotidyl transferase dUTP nick end labeling.

Microplastics (MPs) induce mitochondrial dysfunction and iron accumulation, contributing to mitochondrial macroautophagy/autophagy and ferroptosis, which has increased susceptibility to the exacerbation of chronic obstructive pulmonary disease (COPD); however, the underlying mechanism remains unclear. We demonstrated that MPs intensified inflammation in COPD by enhancing autophagy-dependent ferroptosis (ADF) in vitro and in vivo. In the lung tissues of patients with COPD, the concentrations of MPs, especially polystyrene microplastics (PS-MPs), were significantly higher than that of the control group, as detected by pyrolysis gas chromatography mass spectrometry (Py-GCMS), with increased iron accumulation. The exposure to PS-MPs, 2 μm in size, resulted in their being deposited in the lungs of COPD model mice detected by optical in vivo imaging, and observed in bronchial epithelial cells traced by GFP-labeled PS-MPs. There were mitochondrial impairments accompanied by mitochondrial reactive oxygen species (mito-ROS) overproduction and significantly increased levels of lysosome biogenesis and acidification in pDHBE cells with PS-MP stimulation, triggering occurrence of ferritinophagy and enhancing ADF in COPD, which triggered acute exacerbation of COPD (AECOPD). Reestablishing autophagy-dependent ferroptosis via mitochondria-specific ROS scavenging or ferroptosis inhibition alleviated excessive inflammation and ameliorated AECOPD induced by PS-MPs. Collectively, our data initially revealed that MPs exacerbate ferroptosis via mito-ROS-mediated autophagy in COPD, which sheds light on further hazard assessments of MPs on human respiratory health and potential therapeutic agents for patients with COPD.Abbreviations: ADF: autophagy-dependent ferroptosis; AECOPD: acute exacerbation of chronic obstructive pulmonary disease; Cchord: static compliance; COPD: chronic obstructive pulmonary disease; CQ: chloroquine; CS: cigarette smoke; DEGs: differentially expressed genes; Fer-1: ferrostatin-1; FEV 0.1: forced expiratory volume in first 100 ms; FVC: forced vital capacity; GSH: glutathione; HE: hematoxylin and eosin; IL1B/IL-1β: interleukin 1 beta; IL6: interleukin 6; MDA: malondialdehyde; Mito-ROS: mitochondrial reactive oxygen species; MMA: methyl methacrylate; MMF: maximal mid-expiratory flow curve; MMP: mitochondrial membrane potential; MOI: multiplicity of infection; MPs: microplastics; MV: minute volume; PA: polyamide; PBS: phosphate-buffered saline; PC: polycarbonate; pDHBE: primary human bronchial epithelial cell from COPD patients; PET: polyethylene terephthalate; PIF: peak inspiratory flow; PLA: polylactic acid; pNHBE: primary normal human bronchial epithelial cell; PS-MPs: polystyrene microplastics; PVA: polyvinyl acetate; PVC: polyvinyl chloride; Py-GCMS: pyrolysis gas chromatography mass spectrometry; SEM: scanning electron microscopy; Te: expiratory times; Ti: inspiratory times; TNF/TNF-α: tumor necrosis factor.

Regulated cell death and xenophagy constitute fundamental cellular mechanisms against invading microorganisms. Staphylococcus aureus, a notorious pathogen, can invade and persist within host cells for extended periods. Here, we describe a novel mechanism by which S. aureus subverts these host defenses through the manipulation of the CASP8 (caspase 8) signaling pathway. Upon invasion, S. aureus triggers the assembly of a RIPK3 (receptor interacting serine/threonine kinase 3) complex to induce CASP8 autoprocessing. However, the bacterium inhibits CUL3 (cullin 3)-dependent K63-linked ubiquitination, leading to an atypical activation of CASP8. This non-canonical activation does not initiate the CASP8-CASP3 cascade but instead suppresses RIPK3-dependent necroptosis, a regulated cell death pathway typically activated when apoptosis fails. The resulting non-apoptotic, cleaved CASP8 redirects its enzymatic activity toward cleaving SQSTM1/p62, a selective macroautophagy/autophagy receptor, thus enabling S. aureus to evade antimicrobial xenophagy. The results of this study suggest that S. aureus reprograms the CASP8 signaling pathway from inducing cell death to preserving cell survival and inhibiting xenophagy, a critical strategy that supports its stealthy replication and persistence within host cells.Abbreviations: CASP3: caspase 3; CASP8: caspase 8; CFU: colony-forming units; CUL3: cullin 3; DUB: deubiquitinating enzyme; MAP1LC3B-II/LC3B-II: microtubule associated protein 1 light chain 3 beta-II; MOI: multiplicity of infection; RIPK1: receptor interacting protein kinase 1; RIPK3: receptor interacting protein kinase 3; S. aureus: Staphylococcus aureus.

Endurance exercise triggers adaptive responses especially in slow-twitch myofibers of skeletal muscles, leading to the remodeling of myofiber structure and the mitochondrial network. However, molecular mechanisms underlying these adaptive responses, with a focus on the fiber type-specific perspective, remains largely unknown. In this study we analyzed the alterations of transcriptomics and metabolomics in distinct skeletal myofibers in response to endurance exercise. We determined that genes associated with sphingolipid metabolism, namely those encoding SPHK1, S1PR1, and S1PR2, are enriched in slow-twitch but not fast-twitch myofibers from both mouse and human skeletal muscles, and found that the SPHK1-S1PR pathway is essential for adaptive responses of slow-twitch to endurance exercise. Importantly, we demonstrate that endurance exercise causes the accumulation of ceramides on stressed mitochondria, and the mitophagic degradation of ceramides results in an increase of the sphingosine-1-phosphate (S1P) level. The elevated S1P thereby facilitates mitochondrial adaptation and enhances endurance capacity via the SPHK1-S1PR1/S1PR2 axis in slow-twitch muscles. Moreover, administration of S1P improves endurance performance in muscle atrophy mice by emulating these adaptive responses. Our findings reveal that the SPHK1-S1P-S1PR1/S1PR2 axis through mitophagic degradation of ceramides in slow-twitch myofibers is the central mediator to endurance exercise and highlight a potential therapeutic target for ameliorating muscle atrophy diseases.