CHIP protects lysosomes from CLN4 mutant-induced membrane damage

Area of Science:

• Cell Biology
• Neuroscience
• Molecular Biology

Background:

• Lysosomal damage is central to neurodegenerative diseases.
• CLN4-linked DNAJC5 mutations cause lysosomal abnormalities and neurodegeneration.
• Cellular mechanisms for mitigating lysosomal damage are not fully understood.

Purpose of the Study:

• To investigate the pathogenic mechanisms of CLN4-associated neurodegeneration.
• To identify cellular pathways that protect against lysosomal damage.
• To explore therapeutic targets for lysosome-related neurodegenerative diseases.

Main Methods:

• Generation and characterization of induced pluripotent stem cell (iPSC)-derived neurons (i3Neuron) with CLN4 mutations.
• In vitro membrane-damaging experiments to assess lysosomal damage.
• Genome-wide CRISPR screens to identify regulators of microautophagy.
• Testing CHIP's therapeutic potential in a Drosophila CLN4 disease model.

Main Results:

• CLN4 mutant aggregates cause critical lysosomal damage in neurons.
• A ubiquitin-dependent microautophagy mechanism downregulates CLN4 aggregates in non-neuronal cells.
• Genome-wide CRISPR screens identified CHIP as a key regulator of this protective microautophagy.
• Ectopic CHIP expression improved lysosomal function and reduced pathology in CLN4 i3Neurons and a Drosophila model.

Conclusions:

• CHIP-mediated microautophagy is a crucial mechanism for lysosome protection.
• This pathway effectively counteracts CLN4-associated lysotoxicity and neurodegeneration.
• CHIP represents a promising therapeutic target for lysosome-related neurodegenerative diseases.