Autophagy最新文献

During the maternal-to-zygotic transition (MZT), the programmed decay of maternal mRNAs is critical for successful embryonic development. Although autophagy is known to participate in early embryonic development, its specific role in maternal mRNA clearance remains unclear. MAP1LC3B/LC3B, a key autophagy-related protein, has recently been identified as an RNA-binding protein; however, whether it contributes to maternal mRNA degradation has not been established. Through integrative analyses combining RIP-seq, RNA-seq, and CUT&Tag in early embryos, we identified LC3B as a maternal mRNA-binding protein essential for mRNA degradation. LC3B-mediated mRNA decay exhibited faster kinetics than the classical BTG4-CCR4-NOT pathway. Knockdown of LC3B or inhibition of autophagy significantly delayed maternal mRNA clearance, resulting in impaired zygotic genome activation (ZGA) and developmental arrest. Further analysis revealed the maternal Suv39h2 as a key LC3B-target gene, whose abnormal persistence correlates with developmental failure. Our findings revealed an autophagy-dependent mRNA clearance pathway mediated by LC3B, providing novel mechanistic insights into maternal mRNA decay and developmental regulation during mammalian MZT.Abbreviations: BTG4: BTG anti-proliferation factor 4; E2C: early 2-cell; GV: germinal vesicle; H3K9me3: histone H3 lysine 9 trimethylation; L2C: late 2-cell; MII: metaphase II; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MD: maternal mRNAs decay; MERVL: murine endogenous retrovirus-L; MZT: maternal-to-zygotic transition; PN5: pronuclear stage 5; Suv39h2: suppressor of variegation 3-9 2; TUT7: terminal uridylyl transferase 7; TUT4: terminal uridylyl transferase 4; ZGA: zygotic genome activation.

Mitochondrial reactive oxygen species (mtROS) are typically viewed as harmful byproducts of stress. However, our recent study establishes their fundamental role as essential signaling molecules that activate a protective adaptive response. We discovered that mtROS serve as the specific trigger to activate the ATM-CHEK2/CHK2 DNA damage response pathway, which in turn coordinates the key steps of PINK1-PRKN/Parkin-dependent mitophagy. Upon activation by mtROS, CHEK2 phosphorylates ATAD3A to initiate PINK1 import arrest, OPTN to enhance cargo recognition, and BECN1 (beclin 1) to promote autophagosome formation. This work reveals a novel mtROS-driven signaling cascade, expanding the function of the ATM-CHEK2 pathway beyond the nucleus and positioning it as a central integrator of cellular homeostasis by responding to both genomic and mitochondrial stress.

Glioblastoma is the most aggressive form of primary brain malignancy and is defined as IDH/isocitrate dehydrogenase wild-type tumors. Upregulation of IDH1 is associated with poor prognosis; however, the mechanisms that regulate IDH1 expression in glioblastoma pathogenesis are poorly understood. In this study, we identified chaperone-mediated autophagy (CMA) as a critical regulator of IDH1 in glioblastoma progression. We determined that wild-type IDH1 contained a conserved CMA-targeting motif and directly interacted with the CMA chaperone HSPA8/HSC70 (heat shock protein family A (Hsp70) member 8). Our findings indicated that genetic or pharmacological inhibition of CMA resulted in IDH1 accumulation, which in turn increased α-ketoglutarate (α-KG) production. This metabolic shift upregulated CCND1 (cyclin D1), disrupted the RB1 (RB transcriptional corepressor 1) cell cycle checkpoint, and accelerated the G₁-S phase transition, thereby promoting tumor growth. Analysis of clinical glioma specimens revealed widespread CMA dysfunction concurrent with IDH1 overexpression. This phenotype was further exacerbated by chronic temozolomide treatment in both in vitro and in vivo glioblastoma models. Notably, CMA-activating compounds, including the RARA (retinoic acid receptor alpha) antagonist CA77.1, the class I phosphoinositide 3-kinase (PI3K) inhibitor paxalisib, and metformin, effectively reduced IDH1 and CCND1 levels while suppressing glioblastoma cell growth. Together, our findings suggest that dysfunction of the CMA-IDH1-CCND1 regulatory cascade drives progression of IDH1-wild-type glioblastoma and provide a mechanistic basis for repurposing CMA activators as potential therapeutic agents for these tumors.Abbreviations: α-KG: α-ketoglutarate; CCND1: cyclin D1; CMA: chaperone-mediated autophagy; E2F1: E2F transcription factor 1; GSC: glioblastoma stem cells; HSPA8/HSC70: heat shock protein family A (Hsp70) member 8; LAMP1: lysosomal associated membrane protein 1; LAMP2A: lysosomal associated membrane protein 2A; IDH1: isocitrate dehydrogenase (NADP(+)) 1; PI3K: phosphoinositide 3-kinase; RARA: retinoic acid receptor alpha; RB1: RB transcriptional corepressor 1; TMZ: temozolomide.

Mitochondria maintain homeostasis through dynamic remodeling and stress-responsive pathways, including the formation of specialized subdomains. Peripheral mitochondrial fission generates small MTFP1-enriched mitochondria (SMEM), which encapsulate damaged mtDNA and facilitate its macroautophagic/autophagic degradation. However, the underlying mechanism governing SMEM biogenesis remains unclear. In our recent study, we identified C3orf33/CG30159/MISO as a conserved regulator of mitochondrial dynamics and stress-induced subdomain formation in Drosophila and mammalian cells. C3orf33/MISO is an integral inner mitochondrial membrane (IMM) protein that assembles into discrete subdomains, which we confirm as small MTFP1-enriched mitochondria (SMEM). Mechanistically, C3orf33/MISO promotes mitochondrial fission by recruiting MTFP1 to activate the FIS1-DNM1L pathway while suppressing fusion via OPA1 exclusion. Under basal conditions, MISO is rapidly turned over and contributes to mitochondrial morphology maintenance. Upon specific IMM stresses (e.g. mtDNA damage, OXPHOS dysfunction, cristae disruption), C3orf33/MISO is stabilized, thereby initiating SMEM assembly. These SMEM compartments function as stress-responsive hubs that spatially coordinate IMM reorganization and target damaged mtDNA to the periphery for lysosome-mediated clearance via mitophagy. Together, we address these fundamental gaps by identifying C3orf33/MISO as the key protein that controls SMEM formation to preserve mitochondrial homeostasis under stress.

Autophagy preserves neuronal integrity by clearing damaged proteins and organelles, but its efficiency declines with aging and neurodegeneration. Depletion of the oxidized form of nicotinamide adenine dinucleotide (NAD⁺) is a hallmark of this decline, yet how metabolic restoration enhances autophagic control has remained obscure. Meanwhile, alternative RNA splicing errors accumulate in aging brains, compromising proteostasis. Here, we identify a metabolic - transcriptional mechanism linking NAD⁺ metabolism to autophagic proteostasis through the NAD⁺ -EVA1C axis. Cross-species analyses in C. elegans, mice, and human samples reveal that NAD⁺ supplementation corrects hundreds of age- or Alzheimer-associated splicing errors, notably restoring balanced expression of EVA1C isoforms. Loss of EVA1C impairs the memory and proteostatic benefits of NAD⁺, underscoring its essential role in neuronal resilience. Mechanistically, NAD⁺ rebalances EVA1C isoforms that interact with chaperones BAG1 and HSPA/HSP70, reinforcing their network to facilitate chaperone-assisted selective macroautophagy and proteasomal degradation of misfolded proteins such as MAPT/tau. Thus, NAD⁺ restoration coordinates RNA splicing fidelity with downstream proteostatic systems, establishing a metabolic - transcriptional checkpoint for neuronal quality control. This finding expands the paradigm of autophagy regulation, positioning metabolic splice-switching as a crucial mechanism to maintain proteostasis and suggesting new strategies to combat aging-related neurodegenerative diseases.

Macroautophagy/autophagy is a highly conserved pathway responsible for the bulk degradation of cytoplasmic material through the formation of a double-membrane structure known as the autophagosome. However, the precise mechanisms governing the transport of autophagosomes to the vacuole for degradation in plants remain largely elusive. There exists an ongoing debate about whether RAB7, a key regulatory protein, is involved in the plant autophagy pathway. In this study, we demonstrate that upon autophagy induction by BTH treatment, RABG3e, a member of the RAB7 family, exhibits a partial localization with late-stage autophagosomes in Arabidopsis root cells, and its dysfunction leads to the accumulation of enlarged multilayered autophagosomes and a significant reduction in autophagic flux. We also showed that RABG3e is recruited to autophagosomes by its guanine nucleotide exchange factor (GEF) complex, MON1-CCZ1, which is targeted through the interaction between CCZ1 and SH3P2 (SH3 DOMAIN-CONTAINING PROTEIN 2), a plant-specific autophagy regulator. Subsequently, RABG3e recruits downstream effectors such as VPS39, which in turn promotes the recruitment of soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNARE) proteins, including SYP21, VTI12, SYP51, and VAMP711, that are essential for the fusion process. Arabidopsis mutants with dysfunction in the autophagosome-vacuole fusion process exhibit accelerated senescence and increased sensitivity to nitrogen starvation. Collectively, our findings provide new insights into the regulation of autophagosome-vacuole fusion in Arabidopsis, highlighting the essential roles of SH3P2-dependent targeting of the CCZ1-MON1-RABG3e module to late-stage autophagosomes as well as RABG3e effectors and a unique SNARE complex.

MAP1LC3/LC3 (microtubule associated protein 1 light chain 3) proteins have long been thought to carry out their cellular and organismal functions, including macroautophagy/autophagy, exclusively in their lipidated form, also referred to as Atg8ylation. They are anchored mainly to the phosphatidylethanolamine present in membranes through the action of two ubiquitin-like conjugation systems. Our recent work, however, uncovered a role of non-lipidated LC3s during influenza A virus (IAV) infection. We revealed that LC3s, together with the centrosomal scaffold protein PCNT (pericentrin), form a dynein adaptor complex that facilitates IAV uncoating at late endosomes (LEs). We also showed that co-opting the LC3s-PCNT complex is an alternative strategy to aggresome processing machinery (APM) hijacking via HDAC6, allowing IAV to exploit the force generated by dynein-dependent motors for virion uncoating and genome delivery in the host cytoplasm. Notably, the function of LC3s in IAV uncoating does not require their Atg8ylation or the core autophagy machinery, and PCNT's role is independent from its centrosomal localization. These findings redefine LC3s as multifunctional adaptor proteins and reveal how viruses can co-opt centrosome assembly machinery components for host invasion.Abbreviation: AKAP9/AKAP450- A-kinase anchoring protein 9; APM- aggresome processing machinery; IAV- influenza A virus; LC3s-I- non-lipidated LC3s; Les- late endosomes; MAP1LC3/LC3s-microtubule associated protein 1 light chain 3 proteins; MT-microtubule; NEU- neuraminidase; PCNT-pericentrin; TNPO1-transportin 1; vRNP-viral ribonucleoprotein.

A recent study published in Nature by Zhang et al. reported that cytosolic acetyl-CoA functions as a signaling metabolite that regulates NLRX1-dependent mitophagy during nutrient stress. This discovery reveals a metabolic checkpoint for mitochondrial quality control and provides new insights into KRAS inhibitor resistance.

Mitochondrial dynamics play critical roles in mitochondrial quality control to maintain mitochondrial function. In plants, mitochondria are typically discrete rather than networked, but how damaged mitochondrial contents can be efficiently removed remains unclear. In a recent study, we demonstrate that the plant-specific fission regulator ELM1, together with DRP3 and the autophagic adaptor SH3P2, orchestrates mitochondrial dynamics and mitophagosome assembly for piecemeal mitophagy under heat stress condition. Deficiency in mitochondrial fission activity delays mitophagosome formation and leads to an accumulation of megamitochondria that are partially sequestered by phagophore intermediates positive for ATG8 and NBR1. Further 3D electron tomography analysis reveals that phagophore fragments expand toward the constriction sites of the abnormal protrusions from the mitochondrial body. These findings highlight an unappreciated role of plant mitochondrial fission machinery in coupling with autophagy machinery for mitochondrial segregation and mitophagosome assembly, establishing a mechanistic framework for plant mitophagy in stress resilience.Abbreviations ATG, autophagy related; DRP3, dynamin related protein 3; ELM1, elongated mitochondria 1; HS, heat stress; NBR1, next to BRCA1 gene 1; SH3P2, SH3 domain-containing protein 2.

The liver orchestrates systemic metabolism, and its dysfunction drives diseases including metabolic dysfunction-associated steatotic liver disease (MASLD) and hepatocellular carcinoma (HCC). ATG9A, an autophagy-related transmembrane protein and lipid scramblase, regulates lipid dynamics, yet its role in hepatic pathogenesis remains unclear. Using multi-model approaches, we demonstrate that liver-specific ATG9A overexpression in mice enhanced autophagic flux but impaired autophagosome degradation. ATG9A disrupted hepatic lipid metabolism, reduced lipid droplet accumulation and exacerbated inflammation and fibrosis. Furthermore, we identified PLA2G6 as an ATG9A binding protein. ATG9A-PLA2G6 interaction accelerated phosphatidylcholine degradation, perturbing fatty acid metabolism and causing mitochondrial dysfunction. Besides, ATG9A promoted tumor growth in vivo, independent of canonical macroautophagy/autophagy. Our findings redefine ATG9A as a dual metabolic effector, driving liver disease progression through lipid remodeling and organelle stress. The ATG9A-PLA2G6 axis presents a therapeutic target for metabolic liver disorders and HCC.