Autophagy最新文献

TBCK syndrome is a severe neurodevelopmental disorder characterized by hypotonia, intellectual disability, and progressive neurodegeneration. While the TBCK gene has been implicated in MTOR signaling, its primary molecular function has remained controversial. In a recent study, we identify TBCK as the catalytic core of a heterotrimeric complex comprising TBCK, PPP1R21, and FERRY3/C12orf4. This complex functions as a specific GTPase-activating protein (GAP) for RAB5. TBCK deficiency or missense mutations of its key residues in the RABGAP-TBC domain lead to constitutive RAB5 hyperactivation, which blocks the transition from early to late endosomes and results in the formation of massively enlarged RAB5-positive endosomes. Furthermore, this RAB5 hyperactivation drives the constitutive activation of the PIK3C3/VPS34 complex. These defects culminate in a failure of lysosomal enzyme delivery and a secondary collapse of macroautophagic/autophagic flux. These findings redefine TBCK syndrome as a primary disorder of endosomal dynamics and highlight the TBCK-PPP1R21-FERRY3 axis as a critical "brake" for maintaining neuronal homeostasis.

Obesity is a feature of only a subset of ciliopathies, including Alström syndrome, a rare genetic disorder caused by ALMS1 deficiency. In our recent work, we applied integrative multi-omics network analysis to one of these ciliopathies that develop with obesity, the Alms1-deficient mouse model and identified DBI/ACBP (diazepam binding inhibitor, acyl-CoA binding protein) as a central driver of ciliopathy-associated obesity. We found that ALMS1 deficiency induces early hepatic dyslipidemia accompanied by impaired macroautophagy/autophagy and pathological accumulation of DBI/ACBP, preceding overt obesity. Importantly, prophylactic DBI/ACBP neutralization with monoclonal antibodies prevents weight gain and metabolic alterations without restoring autophagic markers, indicating that DBI/ACBP acts as an obesogenic effector downstream of, or parallel to, defective autophagy. These findings position DBI/ACBP as a metabolically relevant autophagy-associated regulator in ciliopathy and suggest that therapeutic benefit can be achieved by targeting autophagy-linked effectors without directly correcting autophagic flux. This punctum discusses our results in the context of hepatic autophagy and lipid metabolism, highlighting DBI/ACBP as a mechanistic link between ciliary dysfunction, altered autophagy, and metabolic disease.

Autophagy, a conserved lysosomal degradation pathway, is increasingly recognized as a central regulator of metabolic health. Its impairment contributes directly to obesity and type 2 diabetes by disrupting nutrient sensing, stress adaptation, and organelle quality control. Hyperactivation of MTORC1 with insufficient AMPK and SIRT1 signaling suppresses autophagic flux, driving lipid accumulation, insulin resistance, and mitochondrial dysfunction. Clinically relevant consequences include adipose inflammation and hypertrophy, hepatic steatosis with impaired β-oxidation, pancreatic β-cell failure from unresolved ER stress, and skeletal muscle atrophy due to loss of proteostasis. Moreover, defective autophagy across the gut - liver - brain axis exacerbates intestinal barrier dysfunction, endotoxemia, and neuroendocrine imbalance, amplifying systemic metabolic deterioration. Emerging interventions that restore autophagic capacity, including exercise-induced AMPK activation, dietary modulation of unsaturated fatty acids, pharmacological inducers, and nanotechnology-based lysosomal re-acidification show promise in preclinical models. However, the tissue-specific duality of autophagy, where suppression may be beneficial in some contexts but harmful in others, highlights the complexity of therapeutic targeting. This review highlights current mechanistic and translational insights to position autophagy as a therapeutic linchpin in obesity-associated metabolic disease. By aligning molecular pathways with clinical outcomes, we herein highlight opportunities to develop precision strategies that harness autophagy to combat the global burden of obesity and metabolic disorders.Abbreviation: AGEs: advanced glycation endproducts; ALR: autophagic lysosomal reformation; AMPK: AMP-activated protein kinase; AT: adipose tissue; BAT: brown adipose tissue; CMA: chaperone-mediated autophagy; CR: caloric reduction/restriction; DC: diabetic cardiomyopathy; DN: diabetic nephropathy; ER: endoplasmic reticulum; ESCRT: endosomal sorting complexes required for transport; FFAs: free fatty acids; HFD: high-fat diet; HOPS: homotypic fusion and vacuole protein sorting; KO: knockout; LAMs: Lipid-associated macrophages; LD: lipid droplet; MBH: mediobasal hypothalamus; Med diet: Mediterranean diet; MDBs: Mallory-Denk bodies; MEFs: mouse embryonic fibroblasts; MTORC1: mechanistic target of rapamycin kinase complex 1; PI3K: phosphoinositide 3-kinase; PtdIns3K-CI: class III phosphatidylinositol 3-kinase complex I; T1D: type 1 diabetes; T2D: type 2 diabetes; TASCC: TOR-autophagy spatial coupling compartment; TRE: time-restricted eating; WAT: white adipose tissue.

Intracellular persistence caused by Staphylococcus aureus (S. aureus) is among the primary reasons for recurrence and difficulty in eradicating S. aureus infections. In this study, we identify the secreted protein Hla (α-hemolysin) by S. aureus as a key factor enabling its intracellular retention. We demonstrate that intracellular Hla secreted by S. aureus inhibits lysosome degradation via disrupting lysosomal function, which sustains the survival and proliferation of S. aureus within autophagosomes. Furthermore, we identify the interaction between Hla and intracellular LGALS3 (galectin 3) as crucial for sustaining intracellular survival of S. aureus, resolve the structure of the Hla-LGALS3 complex, and identify the Loop 68-75 region of Hla as the key binding domain with LGALS3. Moreover, the interaction between Hla and LGALS3 influences the recruitment of PDCD6IP/ALIX (programmed cell death 6 interacting protein) to the damaged lysosomal surface, resulting in disruption of lysosomal degradative function. Our results highlight an unknown role of Hla in the intracellular survival of S. aureus and suggest that interrupting the interaction between Hla and LGALS3 May be a potential therapeutic strategy for treating S. aureus infections.Abbreviations: 3 MA: 3-methyladenine; AECII: alveolar epithelial cells II; Agr: accessory gene regulator; ATG13: autophagy related 13; Baf A₁: bafilomycin A₁; BLI: biolayer interferometry; CFU: colony-forming units; ClfA: clumping factor A; Co-IP: co-immunoprecipitation; CRD: carbohydrate recognition domain; ER: endoplasmic reticulum; ESCRT: endosomal sorting complex required for transport; FnbA: fibronectin-binding protein A; FnbB: fibronectin-binding protein B; Hla: α-hemolysin; IP-MS: immunoprecipitation-mass spectrometry; LGALS3: galectin 3; LLoMe: L-leucyl-L-leucine methyl ester hydrobromide; LMP: lysosomal-membrane permeabilization; MOI: multiplicity of infection; PDCD6IP/ALIX: programmed cell death 6 interacting protein; S. aureus: Staphylococcus aureus; SPA: staphylococcal protein A; SSPA: staphylococcal surface protein A; TEM: transmission electron microscopy; TRAF3: TNF receptor associated factor 3; ULK1: unc-51 like autophagy activating kinase 1.

Neuronal axon regeneration is a complex and coordinated reorganization process that requires the involvement of mitochondria. Here, we demonstrated that FUNDC1 (FUN14 domain containing 1)-mediated mitophagy played a crucial role in determining the intrinsic capacity for axonal regrowth and peripheral nerve recovery. We found that acute nerve injury resulted in the accumulation of impaired mitochondria at the axonal injury site, accompanied by an increase in the expression of the mitophagy receptor FUNDC1. Strikingly, overexpression of FUNDC1 enhanced axonal regeneration both in vitro and in vivo, likely by maintaining a healthy mitochondrial population through mitophagy. Similarly, treatment with urolithin A (UA), a natural mitophagy inducer, promoted axon regrowth after injury. Conversely, fundc1 deletion impaired regeneration, an effect reversed by reintroducing wild type (WT) FUNDC1 in neurons but not an MAP1LC3B/LC3 (microtubule associated protein 1 light chain 3 beta)-interacting region (LIR) mutant. Metabolic profiling further demonstrated that FUNDC1-mediated mitophagy drives dorsal root ganglion (DRG) neurons regeneration through enhanced carnosine biosynthesis. Mechanistically, sciatic nerve injury (SNI) in Fundc1 transgenic (TG) mice upregulated NRF1 (nuclear respiratory factor 1) and PPARGC1A/PGC-1α (PPARG coactivator 1 alpha), which stimulated mitochondrial biogenesis and activated Carns1 (carnosine synthase 1) transcription. This increased carnosine biosynthesis, aiding peripheral nerve recovery through its antioxidant effects. Our findings highlighted FUNDC1-mediated mitophagy as a key mechanism in nerve regeneration, linking mitochondrial quality control, metabolic adaptation, and nerve regeneration.Abbreviations: Δψm: mitochondrial membrane potential; DIV: days in vitro; DRG: dorsal root ganglion; KO: knockout; LIR: LC3-interacting region; P60: postnatal day 60; PNS: peripheral nervous system; PSI: post sciatic nerve injury; ROS: reactive oxygen species; SD: standard deviation; SNI: sciatic nerve injury; TEM: transmission electron microscopy; TG: transgenic; TMRE: tetramethylrhodamine ethylester; UA: urolithin A; WT: wild type.

Despite the well-established role of equilibrative nucleoside transporters (ENTs) in salvaging nucleosides for DNA synthesis, the presence of multiple ENT subfamilies within a single genome suggests putative, non-redundant functions in maintaining cellular homeostasis. In this study, we demonstrate that, in contrast to endolysosomal SLC29A3/ENT3, which promotes macroautophagy/autophagy, cell surface-localized SLC29A1/ENT1 is capable of inhibiting autophagy by suppressing PRKAA/AMPK phosphorylation. Consistent with this, silencing SLC29A1 induces autophagy, whereas silencing SLC29A3 suppresses it. Treatment with adenosine (Ado), a shared substrate of SLC29A1 and SLC29A3, triggers PRKAA/AMPK phosphorylation and autophagy in a concentration-dependent manner. This effect is PRKAA-dependent, as Ado fails to induce autophagy in prkaa-null cells. Mechanistically, elevated SLC29A1 expression promotes increased efflux and decreased intracellular retention of Ado, thereby attenuating PRKAA/AMPK activation and autophagic flux. However, this effect is contingent upon the metabolic state of the cells. Importantly, SLC29A1's regulatory effect is tied to its transport function, as pharmacological inhibition of SLC29A1 transport enhances intracellular Ado accumulation, PRKAA/AMPK phosphorylation, and autophagy. Unlike SLC29A3, which modulates the MTOR pathway, SLC29A1 does not affect MTOR signaling. Instead, it promotes BECN1-BCL2 interaction, thereby inhibiting autophagosome formation. Notably, autophagy itself differentially regulates SLC29A1 and SLC29A3 expression, with compensatory upregulation observed when either is modulated. Finally, slc29a1^-/- and slc29a3^-/- mice display autophagic proficiency and deficiency, respectively. These findings underscore a dynamic and reciprocal regulatory relationship between SLC29A1 and SLC29A3 in autophagy, offering new avenues for therapeutic modulation in autophagy-related disorders.

Chaperone-mediated autophagy (CMA) is a selective autophagy pathway that targets specific proteins containing a KFERQ-like motif for lysosomal degradation. It has been shown by us and others that CMA decreases during physiological aging in most tissues, and its impairment is associated with increased incidence of age-related pathologies, such as cardiovascular disease, neurodegenerative disorders or sarcopenia. However, its involvement in age-related macular degeneration (AMD), a prevalent progressive maculopathy that leads to bilateral central vision loss, had not been explored. In the early stages of AMD, the retinal pigment epithelium (RPE), a monolayer of cells that provides trophic support to photoreceptors, already presents major morphological and functional alterations but the cause of this cell type-specific vulnerability is unknown. In our latest work, we analyzed human donor RPE samples and found that CMA is selectively impaired in the RPE of AMD patients compared to healthy donors. These alterations lead to the accumulation of undegraded CMA substrates and untimely recycling of other proteins. Crucially, these findings are conserved in donor-derived iPSC-RPE models. We used this clinically relevant model to assess the consequences of dysfunctional CMA in AMD and found that it caused proteotoxicity, increased oxidative damage, and altered metabolism. Most importantly, using the new-generation CMA activator CA77.1, we restored proteostasis in AMD iPSC-RPE. Our findings shed light on the selective vulnerability of the RPE in AMD and provide evidence in support of CMA as a novel druggable target against AMD.

Skeletal muscle is a heterogeneous tissue consisting of fibers with distinct contractile speeds, metabolic profiles, and cellular signaling. This heterogeneity may extend to mitochondrial quality control processes such as mitophagy. Using mt-Keima mice, we found that mitophagic activity was greater in the fast-twitch, glycolytic extensor digitorum longus (EDL) compared to the slow-twitch, oxidative soleus (SOL) muscle. Live imaging of quadriceps (QUAD) muscle revealed two distinct fiber populations: those with high total mt-Keima signal but low mitophagic activity, and others with low signal but higher mitophagic activity. Additionally, we observed skeletal muscle type and regional differences in autophagic and mitophagic protein content. Further, select mitophagic proteins strongly correlated with mitochondrial proteins across different regions of the gastrocnemius, while others did not. These findings highlight the complexity of mitophagy regulation in skeletal muscle and emphasize the importance of considering muscle phenotype, including fiber type, region, and mitochondrial content when studying mitophagy.Abbreviations: AIFM1: apoptosis inducing factor mitochondria associated 1; ATG: autophagy related; ATG7: autophagy related 7; BNIP3: BCL2 interacting protein 3; BNIP3L: BCL2 interacting protein 3 like; BCL2L13: BCL2 like 13; CSA: cross-sectional area; CYCS: cytochrome c, somatic; EDL: extensor digitorum longus; FUNDC1: FUN14 domain containing 1; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GAS: gastrocnemius; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MYH: myosin heavy chain; OXPHOS: oxidative phosphorylation; PINK1: PTEN induced kinase 1; PLANT: plantaris; PRKN: parkin RBR E3 ubiquitin protein ligase; QUAD: quadriceps; SLC25A4: solute carrier family 25 member 4; SOD2: superoxide dismutase 2; SOL: soleus; SQSTM1: sequestosome 1; TFAM: transcription factor A, mitochondrial; VDAC1: voltage dependent anion channel 1.

Iodinated contrast-induced acute kidney injury (CI-AKI) is a common clinical complication with poor prognostic outcomes, yet its molecular mechanisms remain incompletely understood. Ferroptosis, a regulated form of cell death driven by iron overload and lipid peroxidation, has been implicated in CI-AKI. However, its involvement and precise regulation in CI-AKI remain unclear. Here, we identify STING1 (stimulator of interferon response cGAMP interactor 1) as a key mediator of ferroptosis in renal proximal tubular cells (RPTCs). We demonstrate that iodinated contrast media (ICM) activate STING1, triggering ferroptosis. Using proximal tubule-specific sting1 knockout mice and primary RPTCs, we show that Sting1 deficiency mitigates ferroptosis and alleviates CI-AKI. Mechanistically, STING1 interacts with HSPA8/HSC70 (heat shock protein family A (Hsp70) member 8) in patients with acute tubular necrosis and experimental CI-AKI models, facilitating the chaperone-mediated autophagic degradation of FTH1 (ferritin heavy chain 1) and GPX4 (glutathione peroxidase 4). Notably, inhibition of chaperone-mediated autophagy (CMA) via LAMP2A (lysosomal associated membrane protein 2A) knockdown inhibits FTH1 and GPX4 degradation, and attenuates ferroptosis. These findings uncover a novel STING1-driven mechanism linking CMA to ferroptosis in CI-AKI and highlight the STING1 pathway as a potential therapeutic target for contrast-induced renal injury.Abbreviations: 3-MA: 3-methyladenine; AIFM2/FSP1: AIF family member 2, ferroptosis suppressor; CLBD: cytoplasmic ligand-binding domain; CGAS: cyclic GMP-AMP synthase; CI-AKI: contrast-induced acute kidney injury; CMA: chaperone-mediated autophagy; CQ: chloroquine; CTT: C-terminal tail; DHE: dihydroethidium; FTH1: ferritin heavy chain 1; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GPX4: glutathione peroxidase 4; GSH/GSSG: glutathione/glutathione oxidized; KO: knockout; HK-2 cell: human renal proximal tubular epithelial cell; HSPA8/HSC70: heat shock protein family A (Hsp70) member 8; IRI: ischemia-reperfusion injury; KFERQ: CMA recognition pentapeptide; LAMP2A: lysosomal associated membrane protein 2A; MDA: malondialdehyde; NCOA4: nuclear receptor coactivator 4; PT: proximal tubule; RPTCs: renal proximal tubule cells; ROS: reactive oxygen species; STING1: stimulator of interferon response cGAMP interactor 1; TMD: transmembrane domain; WT: wild-type.