Lysosomal phospholipase A2 contributes to the biosynthesis of the atypical late endosome lipid bis(monoacylglycero)phosphate

Lysosomal phospholipase A2 (LPLA2) is the PG to LPG converting enzyme in the BMP biosynthetic pathway, and changes in LPLA2 levels in cells affect cholesterol levels and late endosome/lysosome morphology. The late endosome/lysosome (LE/Lys) lipid bis(monoacylglycero)phosphate (BMP) plays major roles in cargo sorting and degradation, regulation of cholesterol and intercellular communication and has been linked to viral infection and neurodegeneration. Although BMP was initially described over fifty years ago, the enzymes regulating its synthesis remain unknown. The first step in the BMP biosynthetic pathway is the conversion of phosphatidylglycerol (PG) into lysophosphatidylglycerol (LPG) by a phospholipase A2 (PLA2) enzyme. Here we report that this enzyme is lysosomal PLA2 (LPLA2). We show that LPLA2 is sufficient to convert PG into LPG in vitro. We show that modulating LPLA2 levels regulates BMP levels in HeLa cells, and affects downstream pathways such as LE/Lys morphology and cholesterol levels. Finally, we show that in a model of Niemann-Pick disease type C, overexpressing LPLA2 alleviates the LE/Lys cholesterol accumulation phenotype. Altogether, we shed new light on BMP biosynthesis and contribute tools to regulate BMP-dependent pathways.

Automated summary

This study identifies lysosomal phospholipase A2 (LPLA2) as the enzyme responsible for converting phosphatidylglycerol (PG) into lysophosphatidylglycerol (LPG) in the BMP biosynthetic pathway. Modulating LPLA2 levels affects cholesterol levels and late endosome/lysosome morphology.