Project description:Understanding how cells mitigate lysosomal damage is critical for unraveling pathogenic mechanisms of lysosome-related diseases. Here we generated and characterized iPSC-derived neurons (i3Neuron) bearing Ceroid Lipofuscinosis Neuronal 4 (CLN4)-linked DNAJC5 mutations, which revealed extensive lysosomal abnormality in mutant neurons. In vitro membrane-damaging experiments establish lysosome damages, caused by lysosome-associated CLN4 mutant aggregates, as a critical pathogenic linchpin in CLN4-associated neurodegeneration. Intriguingly, in non-neuronal cells, a ubiquitin-dependent microautophagy mechanism downregulates CLN4 aggregates to counteract CLN4-associated lysotoxicity. Genome-wide CRISPR screens identify the ubiquitin ligase CHIP as a central microautophagy regulator that confers ubiquitin-dependent lysosome protection. Importantly, CHIP’s lysosome protection function is transferrable: ectopic CHIP improves lysosomal function in CLN4 i3Neurons and effectively alleviates lipofuscin accumulation and cell death in a Drosophila CLN4 disease model. Our study establishes CHIP-mediated microautophagy as a key organelle guardian that preserves lysosome integrity, offering new insights into therapeutic development for lysosome-related neurodegenerative diseases.
Project description:Understanding how cells mitigate lysosomal damage is critical for unraveling pathogenic mechanisms of lysosome-related diseases. Here we use organelle-specific proteomics in iPSC-derived neurons (i3Neuron) and an in vitro lysosome-damaging assay to demonstrate that lysosome damage, caused by the aggregation of Ceroid Lipofuscinosis Neuronal 4 (CLN4)-linked DNAJC5 mutants on lysosomal membranes, serves as a critical pathogenic linchpin in CLN4-associated neurodegeneration. Intriguingly, in non-neuronal cells, a ubiquitin-dependent microautophagy mechanism downregulates CLN4 aggregates to counteract CLN4-associated lysotoxicity. Genome-wide CRISPR screens identify the ubiquitin ligase CHIP as a central microautophagy regulator that confers ubiquitin-dependent lysosome protection. Importantly, CHIP's lysosome protection function is transferrable, as ectopic CHIP improves lysosomal function in CLN4 i3Neurons, and effectively alleviates lipofuscin accumulation and neurodegeneration in a Drosophila CLN4 disease model. Our study establishes CHIP-mediated microautophagy as a key organelle damage guardian that preserves lysosome integrity, offering new insights into therapeutic development for CLN4 and other lysosome-related neurodegenerative diseases.
Project description:Understanding how cells mitigate lysosomal damage is critical for unraveling pathogenic mechanisms of lysosome related diseases. Here we use organelle-specific proteomics in iPSC derived neurons (i3Neuron) and an in vitro lysosome damaging assay to demonstrate that lysosome damage, caused by the aggregation of Ceroid Lipofuscinosis Neuronal 4 (CLN4) linked DNAJC5 mutants on lysosomal membranes, serves as a critical pathogenic linchpin in CLN4 associated neurodegeneration. Intriguingly, in non neuronal cells, a ubiquitin dependent microautophagy mechanism downregulates CLN4 aggregates to counteract CLN4 associated lysotoxicity. Genome wide CRISPR screens identify the ubiquitin ligase CHIP as a central microautophagy regulator that confers ubiquitin dependent lysosome protection. Importantly, CHIP lysosome protection function is transferrable, as ectopic CHIP improves lysosomal function in CLN4 i3Neurons, and effectively alleviates lipofuscin accumulation and neurodegeneration in a Drosophila CLN4 disease model. Our study establishes CHIP mediated microautophagy as a key organelle damage guardian that preserves lysosome integrity, offering new insights into therapeutic development for CLN4 and other lysosome related neurodegenerative diseases.
Project description:We report that lysosomal damage is a hitherto unknown inducer of stress granule (SG) formation and that the process termed membrane atg8ylation coordinates SG formation with mTOR inactivation during lysosomal stress. SGs were induced by lysosome-damaging agents including SARS-CoV-2ORF3a, Mycobacterium tuberculosis, and proteopathic tau. During damage, mammalian ATG8s directly interacted with the core SG proteins NUFIP2 and G3BP1. Atg8ylation was needed for their recruitment to damaged lysosomes independently of SG condensates whereupon NUFIP2 contributed to mTOR inactivation via the Ragulator-RagA/B complex. Thus, cells employ membrane atg8ylation to control and coordinate SG and mTOR responses to lysosomal damage.
Project description:Plasma membrane damage-dependent senescence is a novel senescence subtype. Here, we compare the time-resolved proteomic profiles of plasma membrane damage-dependent senescence, DNA damage-dependent senescence, and replicative senescence to find the major differences between the senescence subtypes.
Project description:Lysosomal membrane permeabilization (LMP) or lysosomal membrane damage is commonly associated with aging and age-related diseases. In searching for cellular mechanisms in response to LMP, we used a proteomic approach to identify proteins enriched on damaged lysosomes. This unbiased approach identified a new phosphoinositide signaling pathway triggered by LMP to mediate rapid lysosomal repair. Specifically, LMP induces fast lysosomal recruitment of PI4K2A which generates high levels of the lipid messenger phosphatidylinositol-4-phosphate (PtdIns4P) on damaged lysosomes. Lysosomal PtdIns4P in turn recruits multiple oxysterol-binding protein (OSBP)-related protein (ORP) family members, including ORP9, ORP10, and ORP11, to orchestrate extensive membrane contact sites (MCSs) between damaged lysosomes and the endoplasmic reticulum (ER). The ORPs subsequently catalyze robust ER-to-lysosomal transport of phosphatidylserine (PS), which is critical for rapid lysosomal repair. The lipid transporter ATG2 is also recruited to damaged lysosomes, activated by PS, and is essential for rapid lysosomal repair. Our findings identify a phosphoinositide-dependent membrane tethering and lipid transport (PITT) pathway essential for the maintenance of lysosomal membrane integrity, with important implications for a wide range of diseases characterized by impaired lysosomal function.
Project description:Emerging evidences suggest that both function and position of organelles are pivotal for tumor cell dissemination. Among them, lysosomes stand out as they integrate metabolic sensing with gene regulation and secretion of proteases. Yet, how lysosomes function is linked to their position and thereby control metastatic progression remains elusive. Here, we analyzed lysosome subcellular distribution in micropatterned patient-derived melanoma cells and found that lysosome spreading scales with their aggressiveness. Peripheral lysosomes promote invadopodia-based matrix degradation and invasion of melanoma cells which is directly linked to their lysosomal and cell transcriptional programs. When controlling lysosomal positioning using chemo-genetical heterodimerization in melanoma cells, we demonstrated that perinuclear clustering impairs lysosomal secretion, matrix degradation and invasion. Impairing lysosomal spreading in a zebrafish metastasis model significantly reduces invasive outgrowth. Our study provides a mechanistic demonstration that lysosomal positioning controls cell invasion, illustrating the importance of organelle adaptation in carcinogenesis.
Project description:To investigate the comparison of senescence progression in plasma membrane damage-, calcium influx-, DNA damage- and telomere shortening-induced senescence in the normal human fibroblast cells.