A genome-wide screen identifies that PLCG2 restrains lysosomal GCase activity

Area of Science:

• Biochemistry
• Genetics
• Neuroscience

Background:

• Mutations in the GBA1 gene impair lysosomal glucocerebrosidase (GCase) activity, leading to Gaucher disease and increasing Parkinson's disease (PD) risk.
• This impairment causes substrate accumulation and drives neuroinflammation and alpha-synuclein aggregation in PD.
• Enhancing lysosomal GCase activity is a promising therapeutic strategy for these conditions.

Purpose of the Study:

• To identify novel regulators of lysosomal GCase activity using a genome-wide screen.
• To elucidate the mechanisms by which identified regulators affect GCase function and trafficking.
• To explore potential therapeutic targets for Gaucher disease and Parkinson's disease.

Main Methods:

• Conducted a genome-wide screen in primary mouse macrophages utilizing a fluorescent enzyme activity reporter for GCase.
• Validated screen hits through cellular biochemical assays and profiling.
• Investigated the mechanistic role of identified regulators in GCase transport and activity.

Main Results:

• Identified Phospholipase C Gamma 2 (PLCG2) as a novel regulator of lysosomal GCase activity.
• PLCG2 depletion leads to the accumulation of Golgi-associated phosphatidylinositols, enhancing mutant GCase transport into lysosomes.
• PLCG2 depletion boosts lysosomal GCase activity, increases glucosylceramide flux, and promotes clearance of GCase substrates.

Conclusions:

• The study uncovered genome-wide regulators of GCase abundance and lysosomal trafficking.
• PLCG2 emerges as a critical factor influencing GCase activity and substrate clearance.
• These findings highlight potential therapeutic pathways to enhance GCase activity for Gaucher and Parkinson's diseases.