Glucosylated cholesterol in mammalian cells and tissues: formation and degradation by multiple cellular β-glucosidases.

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Marques, André RA 
Mirzaian, Mina 
Akiyama, Hisako 
Wisse, Patrick 
Ferraz, Maria J 

The membrane lipid glucosylceramide (GlcCer) is continuously formed and degraded. Cells express two GlcCer-degrading β-glucosidases, glucocerebrosidase (GBA) and GBA2, located in and outside the lysosome, respectively. Here we demonstrate that through transglucosylation both GBA and GBA2 are able to catalyze in vitro the transfer of glucosyl-moieties from GlcCer to cholesterol, and vice versa. Furthermore, the natural occurrence of 1-O-cholesteryl-β-D-glucopyranoside (GlcChol) in mouse tissues and human plasma is demonstrated using LC-MS/MS and (13)C6-labeled GlcChol as internal standard. In cells, the inhibition of GBA increases GlcChol, whereas inhibition of GBA2 decreases glucosylated sterol. Similarly, in GBA2-deficient mice, GlcChol is reduced. Depletion of GlcCer by inhibition of GlcCer synthase decreases GlcChol in cells and likewise in plasma of inhibitor-treated Gaucher disease patients. In tissues of mice with Niemann-Pick type C disease, a condition characterized by intralysosomal accumulation of cholesterol, marked elevations in GlcChol occur as well. When lysosomal accumulation of cholesterol is induced in cultured cells, GlcChol is formed via lysosomal GBA. This illustrates that reversible transglucosylation reactions are highly dependent on local availability of suitable acceptors. In conclusion, mammalian tissues contain GlcChol formed by transglucosylation through β-glucosidases using GlcCer as donor. Our findings reveal a novel metabolic function for GlcCer.

Gaucher disease, Niemann-Pick type C disease, glucocerebrosidase, glucosyl-β-D-cholesterol, glucosylceramide, Animals, COS Cells, Cercopithecus aethiops, Cholesterol, Female, Gaucher Disease, Glycosylation, Humans, Male, Mice, Niemann-Pick Diseases, RAW 264.7 Cells, beta-Glucosidase
Journal Title
Journal of Lipid Research
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Lipid Research, Inc.
Medical Research Council (MR/K015338/1)
Medical Research Council (MR/K025570/1)
This study was made possible by the ERC AdG CHEMBIOSPHIN. The authors declare no financial conflicts of interest relevant to this study.