Autophagy最新文献

Lysosomes are essential degradative organelles and signaling hubs within cells, playing a crucial role in the regulation of macroautophagy/autophagy. Dysfunction of lysosomes and impaired autophagy are closely associated with the development of various neurodegenerative diseases. Enhancing lysosomal activity and boosting autophagy levels holds great promise as effective strategies for treating these diseases. However, there remains a lack of methods to dynamically regulate lysosomal activity and autophagy levels in living cells or animals. In our recent work, we applied optogenetics to manipulate lysosomal physiology and function, developing three lysosome-targeted optogenetic tools: lyso-NpHR3.0, lyso-ArchT, and lyso-ChR2. These new actuators enable light-dependent regulation of key aspects such as lysosomal membrane potential, lumenal pH, hydrolase activity, degradation processes, and Ca²⁺ dynamics in living cells. Notably, lyso-ChR2 activation induces autophagy via the MTOR pathway while it promotes Aβ clearance through autophagy induction in cellular models of Alzheimer disease. Furthermore, lyso-ChR2 activation reduces Aβ deposition and alleviates Aβ-induced paralysis in Caenorhabditis elegans models of Alzheimer disease. Our lysosomal optogenetic actuators offer a novel method for dynamically regulating lysosomal physiology and autophagic activity in living cells and animals.

Prion disease is a fatal and infectious neurodegenerative disorder caused by the trans-conformation conversion of PRNP/PrP^C to PRNP/PrP^Sc. Accumulated PRNP/PrP^Sc-induced ER stress causes chronic unfolded protein response (UPR) activation, which is one of the fundamental steps in prion disease progression. However, the role of various ER-resident proteins in prion-induced ER stress is elusive. This study demonstrated that ARL6IP5 is compensatory upregulated in response to chronically activated UPR in the cellular prion disease model (RML-ScN2a). Furthermore, overexpression of ARL6IP5 overcomes ER stress by lowering the expression of chronically activated UPR pathway proteins. We discovered that ARL6IP5 induces reticulophagy to reduce the PRNP/PrP^Sc burden by releasing ER stress. Conversely, the knockdown of ARL6IP5 leads to inefficient macroautophagic/autophagic flux and elevated PRNP/PrP^Sc burden. Our study also uncovered that ARL6IP5-induced reticulophagy depends on Ca²⁺-mediated AMPK activation and can induce 3 MA-inhibited autophagic flux. The detailed mechanistic study revealed that ARL6IP5-induced reticulophagy involves interaction with soluble reticulophagy receptor CALCOCO1 and lysosomal marker LAMP1, leading to degradation in lysosomes. Here, we delineate the role of ARL6IP5 as a novel ER stress regulator and reticulophagy inducer that can effectively reduce the misfolded PRNP/PrP^Sc burden. Our research opens up a new avenue of selective autophagy in prion disease and represents a potential therapeutic target.Abbreviations: ARL6IP5: ADP ribosylation factor-like GTPase 6 interacting protein 5; AMPK: adenosine 5'-monophosphate (AMP)-activated protein kinase; CALCOCO1: calcium binding and coiled-coil domain 1; CQ: chloroquine; DAPI: 4'6-diamino-2-phenylindole; ER: endoplasmic reticulum; ERPHS: reticulophagy/ER-phagy sites; KD: knockdown; KD-CON: knockdown control; LAMP1: lysosomal-associated membrane protein 1; MAP1LC3/LC3, microtubule-associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; MβCD: methyl beta cyclodextrin; 3 MA: 3-methyladenine; OE: overexpression; OE-CON: empty vector control; PrDs: prion diseases; PRNP/PrP^C: cellular prion protein (Kanno blood group); PRNP/PrP^Sc: infectious scrapie misfolded PRNP; Tm: tunicamycin; UPR: unfolded protein response; UPS: ubiquitin-proteasome system.

GJA1/Cx43 (gap junction protein alpha 1) has long been associated with gap junctions-mediated communication between adjacent cells. However, recent data have defied this concept, with studies implicating GJA1 in other biological processes, such as macroautophagy/autophagy regulation, mitochondrial activity and extracellular vesicles biology. In our recent study we unveiled an additional role played by GJA1 in lysosomal trafficking. We demonstrate that GJA1 promotes the exocytosis of damaged lysosomes, through a mechanism that relies on ACTR2/ARP2-ACTR3/ARP3-dependent actin remodeling. Our findings ascribe to GJA1 an important role during pathogen infection and lysosomal storage disorders, favoring the release of dysfunctional lysosomes.

Protein homeostasis (proteostasis) refers to the balance of the cellular protein environment, tightly regulated by pathways governing protein synthesis, folding, trafficking, and degradation. Growing evidence supports the interconnection of these pathways to ensure the robustness of the proteo-stasis network. A recent study by Park et al. showed that, in macroautophagy/autophagy-deficient cells, the loss of proteasome or nuclear pore components causes synthetic lethality, as cytoplasmic proteins that accumulate under impaired autophagy are transported to the nucleus and degraded by nuclear proteasomes. The authors illustrated the mechanistic basis for why cells with conditions such as Huntington disease, where both autophagy and cytoplasm-to-nuclear shuttling are compromised, are more vulnerable to proteostasis perturbation.Abbreviation: UPR: unfolded protein response; UPS: ubiquitin-proteasome system.

The plasma concentration of the macroautophagy/autophagy inhibitor DBI/ACBP (diazepam binding inhibitor, acyl-CoA binding protein) increases with aging and body mass index (BMI). Both advanced age and obesity are among the most important risk factors for the development of cancer. We observed that patients with cancer predisposition syndromes due to mutations in BRCA1, BRCA2 and TP53 exhibit abnormally high plasma DBI/ACBP levels. Additionally, patients without known cancer predisposition syndromes also manifest higher DBI/ACBP levels before imminent cancer diagnosis (within 0-3 years) as compared to age and BMI-matched controls who remain cancer-free. Thus, supranormal plasma DBI/ACBP constitutes a risk factor for later cancer development. Mouse experimentation revealed that genetic or antibody-mediated DBI/ACBP inhibition can delay the development or progression of cancers. In the context of chemoimmunotherapy, DBI/ACBP neutralization enhances tumor infiltration by non-exhausted effector T cells but reduces infiltration by regulatory T cells. This resulted in better cancer control in models of breast cancer, non-small cell lung cancer and sarcoma. We conclude that DBI/ACBP constitutes an actionable autophagy checkpoint for improving cancer immunosurveillance. Abbreviation: BMI, body mass index; CTL, cytotoxic T lymphocyte; DBI, diazepam binding inhibitor, acyl-CoA binding protein; mAb, monoclonal antibody; NSCLC, non-small cell lung cancer; PDCD1/PD-1, programmed cell death 1; scRNA-seq, single-cell RNA sequencing; T_reg, regulatory T cell.

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly, with the non-neovascular or atrophic form being the most common. Current treatment options are limited, emphasizing the urgent need for new therapeutic strategies. Our key finding is that increased levels of AKT2 in the RPE cells impair lysosomal function and trigger secretory autophagy; a non-canonical macroautophagy/autophagy pathway where cellular materials are released via the plasma membrane rather than being degraded by lysosomes. We showed that this process involves a protein complex, AKT2-SYTL1-TRIM16-SNAP23, releasing factors contributing to drusen biogenesis, a clinical hallmark of AMD development. Importantly, SIRT5 can inhibit this pathway, potentially offering a protective effect. Understanding mechanisms by which this non-canonical autophagy pathway promotes extracellular waste accumulation could provide new insights into drusen biogenesis. Future therapies for atrophic AMD could focus on regulating secretory autophagy or manipulating proteins involved in this process.

Synaptic damage is a crucial pathological process in traumatic brain injury. However, the mechanisms driving this process remain poorly understood. In this report, we demonstrate that the accumulation of damaged mitochondria, resulting from impaired mitphagy, plays a significant role in causing synaptic damage. Moreover, copper induced downregulation of BNIP3 is a key player in regulating mitophagy. DMSA alleviates synaptic damage and mitochondrial dysfunction by promoting urinary excretion of copper. Mechanistically, we find that copper downregulate BNIP3 by increasing the nuclear translocation of NFKB, which is triggered by TRIM25-mediated ubiquitination-dependent degradation of NFKBIA. Our study underscores the importance of copper accumulation in the regulation of BNIP3-mediated mitophagy and suggests that therapeutic targeting of the copper-TRIM25-NFKB-BNIP3 axis holds promise to attenuate synaptic damage after traumatic brain injury.

Macroautophagy/autophagy maintains cellular homeostasis by degrading cytoplasmic components and its disruption is linked to Parkinson disease (PD), which is characterized by dopamine depletion and the accumulation of SNCA/α-synuclein aggregates in neurons. Therefore, activation of autophagy is considered a therapeutic strategy for PD; however, autophagy inducers have not yet been developed as therapeutic drugs because they are involved in a wide range of signaling pathways. Here, we focused on the lysosomal clustering around the microtubule-organizing center (MTOC) that can regulate the process of autophagosome-lysosome fusion, the final step of autophagy, and examined how lysosomal clustering affects protein degradation through autophagy. Our study identified six compounds from a high-content screen of 1,200 clinically approved drugs that induce both lysosomal clustering and autophagy. Notably, albendazole reduced SNCA aggregates in a PD model by lysosomal clustering and autophagy. These findings suggest that targeting lysosomal clustering could offer new therapeutic insights for PD.