LRRK2 deficiency impacts ceramide metabolism in brain

Mutations in LRRK2 gene cause inherited Parkinson's disease (PD) and variations around LRRK2 act as risk factor for disease. Similar to sporadic disease, LRRK2-linked cases show late onset and, typically, the presence of proteinaceous inclusions named Lewy bodies (LBs) in neurons. Recently, defects on ceramide (Cer) metabolism have been recognized in PD. In particular, heterozygous mutations in the gene encoding for glucocerebrosidase (GBA1), a lysosomal enzyme converting glucosyl-ceramides (Glc-Cer) into Cer, increase the risk of developing PD. Although several studies have linked LRRK2 with membrane-related processes and autophagic-lysosomal pathway regulation, whether this protein impinges on the Cer pathway has not been addressed. Here, using a targeted lipidomics approach, we report an altered sphingolipid composition in Lrrk2^−/− mouse brains. In particular, we observe a significant increase of Cer levels in Lrrk2^−/− mice and direct effects on GBA1. Collectively, our results suggest a link between LRRK2 and Cer metabolism, providing new insights into the possible role of this protein in sphingolipids metabolism, with implications for PD therapeutics.