Glucocerebrosidase and glycolipids: In and beyond the lysosome
The lysosomal β-glucosidase named glucocerebrosidase (GCase) is a retaining β-glucosidase that hydrolyzes the glycosphingolipid glucosylceramide (GlcCer) to ceramide and glucose at acid pH.
- Boer, D.E.C.
- 07 January 2021
- Thesis in Leiden Repository
The lysosomal β-glucosidase named glucocerebrosidase (GCase) is a retaining β-glucosidase that hydrolyzes the glycosphingolipid glucosylceramide (GlcCer) to ceramide and glucose at acid pH. Inherited deficiency of GCase causes Gaucher disease (GD), a relatively common lysosomal storage disorder. GCase fulfills another crucial function beyond lysosomes. The enzyme generates ceramides from GlcCer molecules in the outer part of the skin, the stratum corneum. This is essential for skin barrier properties compatible with terrestrial life. GCase is catalytically versatile and can hydrolyze as well as catalyze transglycosylation.In this thesis a novel sensitive in situ method for the detection of active GCase in skin sections is described. Followed by a study of skin sections of patiens with atopic dermatitis revealing that the localization and activity of GCase and acid sphingomyelinase (ASM) was abnormal in skin of AD patients, particularly at lesional skin sites.It is demonstrated that GCase not only cleaves 4-methylumbelliferyl-β-D-glucose, but also 4-methylumbelliferyl-β-D-xylose. It is reported for the first time that GCase is able to transxylosylate cholesterol to render xylosyl-β-cholesterol (XylChol). The formed XylChol can act as a subsequent acceptor for further transxylosylation, rendering di-xylosyl-cholesterol. And finally the discovery of of GlcChol as novel component of human epidermis is reported.