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

Abstract

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 13C6-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.

Lipids regulate the hydrolysis of membrane bound glucosylceramide by lysosomal β-glucocerebrosidase

“…4A), most especially in the presence of BMP. The stimulatory effect of cholesterol is of special interest because GBA1 has been reported to generate glucosylated cholesterol by transglucosylation of cholesterol with GlcCer as glucose donor, a reaction strongly promoted by increasing intralysosomal cholesterol levels, as observed in Niemann-Pick disease type C and pharmacologically induced by U186333A in cultured cells (66). Nevertheless, once cholesterol accumulates in Niemann-Pick disease type C, the activities of several sphingolipid activator proteins are inhibited (22,38,39) and acid sphingomyelinase activity is reduced (60,65,67) leading to a secondary accumulation of SM.…”

The crosstalk between glycosphingolipids and neural stem cells

“…Interestingly, the glucosyl cholesterol, which was firstly found in plants (Grille et al 2010) and lately in mammalian cells (Kunimoto et al 2000), has been also found in brain (Marques et al 2016). This metabolite might have a role as an intermediate in a transport pathway since is more soluble than cholesterol.…”

Distinguishing the differences in β-glycosylceramidase folds, dynamics, and actions informs therapeutic uses

“…Independently, Yildiz et al (58) and Boot et al (59) cloned the gene encoding GBA2 (locus 1p13). GBA2 shows prominent transglucosylase capacity (see section below) and is largely responsible for the (reversible) formation of -glucosylcholesterol from GlcCer in cells and tissues (47). Given its membrane-embedded pocket, GBA2 seems ideally positioned for the transfer of a glucose between membrane lipids and steroids.…”

“…The interaction of GBA2 with actin has been put forward as an explanation for the defective spermatogenesis in GBA2-deficient mice (62). On the other hand, excessive activity of the enzyme has been demonstrated to be toxic in Gaucher disease and other inherited lysosomal glycosphingolipid storage diseases (47,55).…”