Autophagy最新文献

PINK1-dependent activation of PRKN/parkin on depolarized mitochondria causes mitophagy. The deficiency of NME3, a nucleoside diphosphate kinase/NDPK on the outer mitochondria membrane (OMM), is associated with a fatal neurodegenerative disorder. Here, we report that NME3 deficiency impairs p-S65-ubiquitin (Ub)-dependent PRKN binding on depolarized mitochondria without involving the loss of Ub phosphorylation by PINK1. Our mechanistic investigation revealed that NME3 interacts with PLD6/MitoPLD to generate phosphatidic acid (PA) from cardiolipin on the OMM of damaged mitochondria after depolarization. This lipid signal is essential for positioning MFN2 nearby PINK1 for phosphorylation of Ub conjugates on MFN2, thus enabling the subsequent amplification of PRKN binding to mitochondria. We provide further evidence that mitochondria-endoplasmic reticulum (Mito-ER) tethering prohibits the proximity of MFN2 with PINK1 and PRKN amplification on mitochondria. Importantly, the loss of NME3-regulated PA signal causes Mito-ER tethering. Overall, our findings suggest that NME3 cooperates with PLD6 to generate PA as a critical step in Mito-ER untethering, allowing MFN2 access to PINK1 for p-S65-poly-Ub-dependent feedforward activation of PRKN.Abbreviation ACTB: actin beta; BDNF brain derived neurotrophic factor; CL: cardiolipin; CRISPR: clustered regularly interspaced short palindromic repeats; DAG: diacylglycerol; ER: endoplasmic reticulum; FCCP: carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone; FRET: Förster resonance energy transfer; IF: immunofluorescence; KO: knockout; KD: knockdown; LPIN1: lipin 1; MERCS: mitochondria-endoplasmic reticulum contact sites; MFN2: mitofusin 2; Mito: mitochondria; OMM: outer mitochondrial membrane; p-Ub: phosphorylated ubiquitin; PA: phosphatidic acid; PD: Parkinson disease; PINK1: PTEN induced kinase 1; PLA: proximity ligation assay; PLD6/MitoPLD: phospholipase D family member 6; PRKN: parkin RBR E3 ubiquitin protein ligase; RA: retinoic acid; RT-qPCR: reverse transcription-quantitative polymerase chain reaction; TEM: transmission electron microscopy; TN-NME3: TOMM20-NΔ-NME3; TOMM20: translocase of outer mitochondrial membrane 20; TUBB: tubulin beta class I; Ub: ubiquitin; VDAC: voltage dependent anion channel; WB: western blot.

Viral subversion of macroautophagy/autophagy is a well-established immune evasion strategy, with BCL2 homologs from γ-herpesviruses serving as prototypical inhibitors through BECN1 (beclin 1) sequestration. Yet the full spectrum of their functions remains incompletely understood. In our recent study, we uncovered a non-canonical role for the Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded BCL2 homolog (vBCL2) during late lytic replication. Unexpectedly, vBCL2 hijacks the host NDP kinase NME2/NM23-H2 to activate the mitochondrial fission GTPase DNM1L/DRP1, promoting mitochondrial fragmentation. This organelle remodeling dismantles MAVS-mediated antiviral signaling and facilitates virion assembly. A vBCL2 mutant unable to bind NME2 fails to induce fission or complete the viral lifecycle. These findings provide a long-sought answer to why vBCL2 is indispensable during lytic infection, and uncover a new immune evasion strategy centered on mitochondrial control. Our work expands the current view of virus-organelle interactions beyond canonical autophagy control and offers new targets for therapeutic intervention.

In metazoans, autophagosomes fuse with late endosomes (LEs)/multivesicular bodies (MVBs) to form a hybrid organelle known as an amphisome. Subsequently upon fusion with lysosomes the contents of amphisomes are degraded. While the formation of metazoan amphisomes has been well established, it has remained an open question whether amphisomes form and deliver their cargo to the central vacuole for degradation in plant cells. In this mini review, we provide an update on recent discoveries in the field of plant autophagy that demonstrate the formation of amphisome-like organelles that are generated through several distinct autophagosome/MVB fusion pathways.Abbreviations: CFS1: FYVE domain-containing protein; CORVET: core vacuole/endosome tethering; ER: endoplasmic reticulum; ESCRT: endosomal sorting complex required for transport; FYVE: Fab1p, YOTB, Vac1p, and EEA1; FREE1: FYVE domain protein required for endosomal sorting; HOPS: homotypic fusion and protein sorting; LEs: late endosomes; MVBs: multivesicular bodies; PtdIns3P: phosphatidylinositol-3-phosphate; SNAREs: soluble NSF attachment protein receptors; VAPVs: VPS41-associated phagic vacuoles.

In macroautophagy/autophagy, the inner membrane of the autophagosome and its contents are degraded within the autolysosome, while outer membrane proteins are recycled via a process known as autophagosomal components recycling (ACR). ACR is mediated by the recycler complex, powered by dynein-dynactin complexes, and regulated by RAB32-family small GTPases. However, it remains unknown whether ACR is subject to nutrient signal regulation or whether additional molecular components participate in the recycler complex. Our latest research identifies SNX16 as a new component of the recycler complex and reveals that MTORC1 phosphorylates SNX16, enabling SNX16 to function as a nutrient sensor that regulates ACR.

Macroautophagy/autophagy exerts multilayered protective functions in intestinal epithelial cells (IECs) while a loss-of-function genetic variant in ATG16L1 (autophagy related 16 like 1) is associated with risk for developing Crohn disease (CD). Westernization of diet, partly characterized by excess of long-chain fatty acids, contributes to CD, and a metabolic control of intestinal inflammation is emerging. Here, we report an unexpected inflammatory function for ATG16L1-mediated autophagy in Crohn-like metabolic enteritis of mice induced by polyunsaturated fatty acid (PUFA) excess in a western diet. Dietary PUFAs induce ATG16L1-mediated conventional autophagy in IECs, which is required for PUFA-induced chemokine production and metabolic enteritis. By transcriptomic and lipidomic profiling of IECs, we demonstrate that ATG16L1 is required for PUFA-induced inflammatory stress signaling specifically mediated by TLR2 (toll-like receptor 2) and the production of arachidonic acid metabolites. Our study identifies ATG16L1-mediated autophagy in IECs as an inflammatory hub driving metabolic enteritis, which challenges the perception of protective autophagy in the context of diet westernization.Abbreviations: AA: arachidonic acid; ATG16L1: autophagy related 16 like 1; CD: Crohn disease; CXCL1: C-X-C motif chemokine ligand 1; ER: endoplasmic reticulum; GFP: green fluorescent protein; GPX4: glutathione peroxidase 4; IBD: inflammatory bowel disease; IECs: intestinal epithelial cells; PTGS2/COX2: prostaglandin-endoperoxide synthase 2; PUFA: polyunsaturated fatty acid; SDA: stearidonic acid; TLR2: toll-like receptor 2; WT: wild-type.

Accumulation of lipid droplets (LDs) in cardiomyocytes contributes to developmentof septic cardiomyopathy, a fatal complication of critical illness in patients.Lipophagy is a selective autophagic mechanism for LD degradation. This processis inhibited by MTOR, but is activated by PNPLA2 via its binding with LC3-II toform LD-containing autophagosomes. However, optimum lipophagic interventions tomanage septic cardiomyopathy have not been developed, thus furtherinvestigation is required to identify novel regulators of lipophagy in theseptic heart. HSPA12A (heat shockprotein 12A) encodes an atypical member of the HSPA/HSP70family. Here, we report that sepsis decreased HSPA12Aexpression in cardiomyocytes, whereas cardiomyocyte-specific HSPA12Aoverexpression aggravated sepsis-induced cardiomyocyte death and cardiacdysfunction in mice. Notably, HSPA12A promoted sepsis-induced LD accumulationin cardiomyocytes. By contrast, HSPA12A inhibited lipophagy in septiccardiomyocytes, as reflected by a decreased level of LD-containing autophagosomes,a reduced content of LC3-II, and an increased level of SQSTM1/p62. In-depthmolecular analysis revealed that HSPA12A increased phosphorylation of MTOR andthus its binding to PNPLA2 on LDs. MTOR thereby competed against LC3-II inbinding with PNPLA2 to suppress LD-containing autophagosome formation subsequentlyimpairing lipophagy and ultimately promoting cardiomyocyte death to exaggerate septiccardiomyopathy. We demonstrated that MTOR competed against LC3-II in bindingwith PNPLA2 to inhibit lipophagy and also identified HSPA12A as a driver ofthis competition with MTOR to impair lipophagy for exaggerating septic cardiomyopathy. Strategiesthat inhibit HSPA12A in cardiomyocytes might be a potential therapeuticintervention for septic cardiomyopathy.

Mitochondrial nicotinamide adenine dinucleotide (NAD⁺) plays a central role in energy metabolism, yet its roles and mechanisms in mitophagy and innate immunity remain poorly understood. In this study, we identify mitochondrial NAD⁺ depletion that causes mitophagy dysfunction and inflammation. We find that depletion of mitochondrial NAD⁺ owing to deficiency of the mitochondrial NAD⁺ transporter SLC25A51 impairs BNIP3-mediated mitophagy. Loss of mitochondrial NAD⁺ inhibits SIRT3-mediated deacetylation of FOXO3, leading to transcriptional downregulation of BNIP3 and subsequent disruption of MAP1LC3B/LC3B recruitment. Notably, mitochondrial NAD⁺ depletion promotes mitochondrial DNA (mtDNA) release from mitochondria to the cytosol upon oxidative stress, thereby exacerbating the type I interferon response to free cytosolic mtDNA via activation of the CGAS-STING1 signaling pathway. Our findings reveal a novel mechanistic link among mitochondrial NAD⁺, mitophagy, and mtDNA-induced inflammation by genetic manipulation of cell lines, highlighting mitochondrial NAD⁺ as a potential therapeutic target for mitigating sterile inflammation triggered by free cytosolic mtDNA. Thus, the study provides new insights into the crosstalk among mitochondrial homeostasis, inflammation, and innate immunity.Abbreviations: Baf A1: bafilomycin A₁; BNIP3: BCL2 interacting protein 3; CCCP: carbonyl cyanide m-chlorophenyl-hydrazone; CCL5: C-C motif chemokine ligand 5; CGAS: cyclic GMP-AMP synthase; COX4/COX-IV: cytochrome c oxidase subunit 4; CXCL10: C-X-C motif chemokine ligand 10; D-LOOP: displacement loop; EBSS: Earle's balanced salt solution; ELISA: enzyme-linked immunosorbent assay; FIS1: fission, mitochondrial 1; FOXO3: forkhead box O3; IFN: interferon; IFNB/IFNβ: interferon beta; IRF3: interferon regulatory factor 3; KO: knockout; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; mtDNA: mitochondrial DNA; NAD: nicotinamide adenine dinucleotide; MT-ND1: mitochondrially encoded NADH dehydrogenase 1; RT-PCR: real-time polymerase chain reaction; SIRT3: sirtuin 3; SLC25A51: solute carrier family 25 member 51; SoNar: sensor of NAD⁺ and NADH redox; SQSTM1: sequestosome 1; STING1: stimulator of interferon response cGAMP interactor 1; TBK1: TANK binding kinase 1; TOMM20: translocase of outer mitochondrial membrane 20; VDAC2: voltage dependent anion channel 2.

Peroxisomes are essential for lipid metabolism and redox balance, with pexophagy playing a critical role in maintaining cellular homeostasis. However, the regulatory mechanisms of pexophagy remain unclear. Through functional screening, we identified MARCHF7 as a novel E3 ligase regulating pexophagy. MARCHF7 depletion impaired pexophagic flux under PEX1 knockdown conditions. MARCHF7 binds to PXMP4 and promotes its ubiquitination at lysine 20 in PEX1-deficient cells. Depletion of PXMP4 impairs pexophagy, and reconstitution with the PXMP4 lysine 20 ubiquitination-defective mutant failed to rescue pexophagy. PEX1 depletion also induces TBK1 phosphorylation at serine 172, activating TBK1, which subsequently phosphorylates MARCHF7. This activation is driven by ROS accumulation, which reduces PXMP4 ubiquitination and prevents peroxisome loss. Furthermore, downregulation of MARCHF7 or PXMP4 impairs NBR1 recruitment to peroxisomes, suggesting that ubiquitinated PXMP4 acts as a recognition signal for NBR1. Collectively, our findings establish the TBK1-MARCHF7-PXMP4-NBR1 axis as a key regulatory pathway for pexophagy in response to PEX1 depletion.

Chaperone-mediated autophagy (CMA), once considered a secondary or auxiliary degradation pathway, is now recognized as a central regulator of synaptic proteostasis. A recent study by Khawaja et al. (2025) in Nature Cell Biology provides compelling evidence that CMA actively remodels the synaptic proteome in a sex-specific manner. Using a conditional knockout strategy based on Lamp2a-floxed mice crossed with a Camk2a-Cre driver line to achieve excitatory neuron-specific deletion of Lamp2a in adult mice, the authors revealed sexually divergent synaptic phenotypes: females exhibit enhanced presynaptic neurotransmitter release and GRIN/NMDAR-mediated plasticity, while males show increased postsynaptic GRIA/AMPAR activity due to impaired receptor endocytosis. These changes are driven by sex-specific degradation of synaptic proteins such as SYN1 (synapsin I) in females and AP2A/α-Adaptin in males. Importantly, reactivation of CMA - either genetically or pharmacologically - rescues synaptic dysfunction, seizure susceptibility, and memory deficits in aged mice and Alzheimer disease models. This commentary contextualizes these findings within the broader framework of activity-dependent proteostasis, sex-specific autophagy modulation, and therapeutic potential of CMA in brain aging and neurodegeneration.