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: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.
2020-04-14 | GSE124754 | GEO
Project description:Autophagy-lysosomal degradation is an evolutionarily conserved process key to cellular homeostasis, differentiation, and stress survival, which is particularly important to the pathophysiology of the cardiovascular system. What is more, both experimental and clinical observations indicate that autophagy-lysosomal degradation affects correct cardiac morphogenesis, and in particular valve development. However, it is still unclear which cells upregulate autophagy-lysosomal degradation and for which specific cellular processes it is required. Here, we introduce novel zebrafish transgenic models to visualize autophagosomes and lysosomes in vivo and to follow their temporal and cellular localization in the larval heart. This allowed us to determine the kinetics of autophagosome and lysosome vesicle formation and to observe significant accumulation of lysosomal vesicles during the development of the atrioventricular and bulboventricular valves. We then addressed the functional role of lysosomal degradation in cardiovascular development using a spns1 mutant as a zebrafish model of lysosomal impairment. We found that spns1 mutants displayed morphologically and functionally abnormal heart development, including abnormal endocardial organization, impaired cardiac valve formation and high incidence of retrograde blood flow. Single-nuclear transcriptome analysis revealed endocardial-specific differences in the expression of lysosome-related genes and alterations of notch1 signaling in the mutant larval heart. Further, endocardial-specific overexpression of spns1 and notch1 rescued features of valve formation and function as well as overall cardiac morphogenesis. Altogether, our study provides an improved description of the autophagy and lysosomal events that take place during zebrafish heart development and reveals a cell-autonomous role of lysosomal processing during cardiac valve formation upstream of notch1 signaling.
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.
2020-09-16 | GSE139001 | GEO
Project description:Small molecule targets TMED9, promotes lysosomal degradation to reverse proteinopathy
| PRJNA533310 | ENA
Project description:Blunted first-phase insulin secretion and insulin deficiency are indicators of β-cell dysfunction and diabetes manifestation. Thus, insights into molecular mechanisms that regulate insulin homeostasis might provide entry sites to replenish insulin content and restore β-cell function. Here, we identify the insulin inhibitory receptor (short: inceptor; encoded by the gene IIR) as an insulin-binding receptor that regulates insulin stores by lysosomal degradation. Using human induced pluripotent stem cell (iPSC)-derived islets, we show that IIR knockout (KO) results in enhanced stem cell (SC)-β-cell differentiation and survival. Strikingly, extended in vitro culture of IIR KO SC-β-cells leads to greatly increased insulin content and glucose-stimulated insulin secretion (GSIS). We find that inceptor localises to clathrin-coated vesicles (CCVs) close to the plasma membrane (PM) and in the trans-Golgi network (TGN), as well as in secretory granules (SGs), where it acts as a sorting receptor to direct proinsulin and insulin towards lysosomal degradation. Targeting inceptor using a monoclonal antibody (mAB) increases proinsulin and insulin content and improves SC-β-cell GSIS.
2024-09-16 | GSE226346 | GEO
Project description:An unbalanced karyotype, a condition known as aneuploidy, has a profound impact on cellular physiology and is a hallmark of cancer. Determining how aneuploidy affects cells is thus critical to understanding tumorigenesis. Here we show that aneuploidy interferes with the degradation of autophagosomes within lysosomes. Mis-folded proteins that accumulate in aneuploid cells due to aneuploidy-induced proteomic changes overwhelm the lysosome with cargo, leading to the observed lysosomal degradation defects. Importantly, aneuploid cells respond to lysosomal saturation. They activate a lysosomal stress pathway that specifically increases the expression of genes needed for autophagy-mediated protein degradation. Our results reveal lysosomal saturation as a universal feature of the aneuploid state that must be overcome during tumorigenesis. RPE-1 cells either untreated or treated with one of Reversine, Bafilomycin A1 or MG132, each condition was done in triplicate. D14-*_Control: untreated control D14-*_Rev: cells treated with 0.5uM Reversine for 24hrs and harvested 48hrs later D14-*_Baf: cells treated with 0.1uM BafA1 for 6hrs D14-*_Mg: cells treated with 1uM MG132 for 24 hrs
2015-10-26 | E-GEOD-60570 | biostudies-arrayexpress
Project description:Ammonia is a ubiquitous, toxic by-product of cell metabolism. Its high membrane permeability and proton affinity causes ammonia to accumulate inside acidic lysosomes in its poorly membrane-permeant form: ammonium (NH4+). Ammonium buildup compromises lysosomal function, suggesting the existence of mechanisms that protect cells from ammonium toxicity. Here, we identified SLC12A9 as a lysosomal regulator of ammonium export that preserves lysosomal homeostasis. SLC12A9 knockout cells showed grossly enlarged lysosomes and elevated ammonium content. These phenotypes were reversed upon removal of the metabolic source of ammonium or dissipation of the lysosomal pH gradient. Lysosomal chloride increased in SLC12A9 knockout cells and chloride binding by SLC12A9 was required for ammonium transport. Our data indicate that SLC12A9 function is central for the handling of lysosomal ammonium and chloride, an unappreciated, fundamental mechanism of lysosomal physiology that may have special relevance in tissues with elevated ammonia, such as tumors.
2024-09-12 | GSE276655 | GEO