A lysosomal delivery mechanism required for autophagosome degradation
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ABSTRACT:
PROVIDER: PRJEB62651 | ENA |
REPOSITORIES: ENA
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Project description:Autophagy is a finely orchestrated process required for the lysosomal degradation of cytosolic components. The final degradation step is essential for clearing autophagic cargo and recycling macromolecules. We identified a highly conserved transmembrane protein named RNAseK as a novel regulator of autophagosome degradation. Analyses of RNAseK knockout cells revealed that, while autophagosome maturation was intact, cargo degradation was severely disrupted. Importantly, lysosomal protease activity and acidification remained intact in the absence of RNAseK suggesting a specificity to autolysosome degradation. Analyses of lysosome fractions showed reduced levels of a subset of hydrolases in the absence of RNAseK. Of these, the knockdown of PLD3 led to a defect in autophagosome clearance. In addition, the lysosomal fraction of RNAseK-depleted cells exhibited an accumulation of the ESCRT-III complex component, VPS4a, which is required for the lysosomal targeting of PLD3. Altogether, our findings identified a lysosomal hydrolase delivery pathway required to mediate efficient autolysosome degradation.
2024-07-05 | PXD042727 | Pride
Project description:Autophagy is a finely orchestrated process required for the lysosomal degradation of cytosolic components. The final degradation step is essential for clearing autophagic cargo and recycling macromolecules. Using a CRISPR/Cas9-based screen, we identify RNAseK, a highly conserved transmembrane protein, as a regulator of autophagosome degradation. Analyses of RNAseK knockout cells reveal that, while autophagosome maturation is intact, cargo degradation is severely disrupted. Importantly, lysosomal protease activity and acidification remain intact in the absence of RNAseK suggesting a specificity to autolysosome degradation. Analyses of lysosome fractions show reduced levels of a subset of hydrolases in the absence of RNAseK. Of these, the knockdown of PLD3 leads to a defect in autophagosome clearance. Furthermore, the lysosomal fraction of RNAseK-depleted cells exhibits an accumulation of the ESCRT-III complex component, VPS4a, which is required for the lysosomal targeting of PLD3. Altogether, here we identify a lysosomal hydrolase delivery pathway required for efficient autolysosome degradation.
2024-08-02 | PXD042079 | Pride
Project description:Autophagy is a finely orchestrated process required for the lysosomal degradation of cytosolic components. The final degradation step is essential for clearing autophagic cargo and recycling macromolecules. Using a CRISPR/Cas9-based screen, we identify RNAseK, a highly conserved transmembrane protein, as a regulator of autophagosome degradation. Analyses of RNAseK knockout cells reveal that, while autophagosome maturation is intact, cargo degradation is severely disrupted. Importantly, lysosomal protease activity and acidification remain intact in the absence of RNAseK suggesting a specificity to autolysosome degradation. Analyses of lysosome fractions show reduced levels of a subset of hydrolases in the absence of RNAseK. Of these, the knockdown of PLD3 leads to a defect in autophagosome clearance. Furthermore, the lysosomal fraction of RNAseK-depleted cells exhibits an accumulation of the ESCRT-III complex component, VPS4a, which is required for the lysosomal targeting of PLD3. Altogether, here we identify a lysosomal hydrolase delivery pathway required for efficient autolysosome degradation.
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Project description:MiT/TFE transcriptional activity controls lysosomal biogenesis and is negatively regulated by the nutrient sensor mTORC1. Some tumors bypass this regulatory circuit via genetic alterations that drive MiT/TFE expression and activity; however, the mechanisms by which cells with intact or constitutive mTORC1 signaling maintain lysosomal catabolism remain to be elucidated. Using the murine epidermis as a model system, we find that epidermal Tsc1 deletion results in a wavy hair phenotype due to increased EGFR degradation. Unexpectedly, constitutive mTORC1 activation increases lysosomal content via up-regulated expression and activity of MiT/TFEs, while genetic or prolonged pharmacologic mTORC1 inactivation has the reverse effect. This paradoxical up-regulation of lysosomal biogenesis by mTORC1 is mediated by feedback inhibition of AKT, and a resulting suppression of AKT-induced MiT/TFE proteasomal degradation. These data suggest that oncogenic feedback loops work to restrain or maintain cellular lysosomal content during chronically inhibited or constitutively active mTORC1 signaling respectively, and reveal a mechanism by which mTORC1 regulates upstream receptor tyrosine kinase signaling.
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2024-10-25 | GSE246850 | GEO
Project description:The enzyme transport vehicle (ETV:IDS) is a lysosomal enzyme fused to iduronate 2-sulfatase (ETV:IDS), the lysosomal enzyme deficient in mucopolysaccharidosis type II (MPS II). ETV:IDS treatment significantly improved brain delivery of IDS in a preclinical model of disease, enabling enhanced distribution to neurons, astrocytes, and microglia throughout the brain. Improved brain exposure for ETV:IDS translated to a significant reduction in accumulated substrates in these CNS cell types and peripheral tissues, and in a complete correction of downstream disease-relevant pathologies in the brain, including secondary accumulation of lysosomal lipids, perturbed gene expression, neuroinflammation, and neuronal injury. These results highlight the therapeutic potential of the ETV approach as a new treatment paradigm for MPS II and for other CNS diseases more broadly.
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Project description:Cardiac dysfunction is a serious complication of sepsis-induced multiorgan failure in intensive care units and is characterized by an uncontrolled immune response to overwhelming infection. Type 2 innate lymphoid cells (ILC2s), as a part of the innate immune system, play a crucial role in the inflammatory process of heterogeneous cardiac disorders. However, the role of ILC2 in regulating sepsis-induced cardiac dysfunction and its underlying mechanism remain unknown. The present study demonstrated that autophagic flux blockage exacerbated inflammatory response and cardiac dysfunction, which was associated with mortality of sepsis. Using a cecal ligation and puncture (CLP) mouse sepsis model, we observed an expansion of ILC2s in the septic heart. Furthermore, IL-4 derived from ILC2 mitigated cardiac inflammatory responses and improved cardiac function during sepsis. Additionally, IL-4 restored the impaired autophagic flux and enhanced lysosomal-associated membrane protein 2 (LAMP2) expression to stabilize lysosomal homeostasis during sepsis. Notably, LAMP2 preferentially bound to Flotillin2 (FLOT2) after IL-4 exposure and the interaction enhanced autophagosome-lysosome fusion in cardiac endothelial cells. Loss of FLOT2 reversed the regulatory effects of LAMP2 on autophagy mediated by IL-4, leading to autophagosome accumulation and suppressed autophagosome clearance. Conclusively, these findings provide novel insights that ILC2 regulates incomplete autophagic flux to protect septic heart and expand our understanding of immunoregulation for sepsis.
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