Lysosomal glycosidases and glycosphingolipids: New avenues for research

This thesis describes the development of novel research tools and methods for the study of lysosomal glycosidases and glycosphingolipids. Activity-based probes are demonstrated to be valuable instruments to study the role of these enzymes in health and disease. The improved LC-MS/MS methods with internal isotope-labelled standards described assist the sensitive quantification of the substrates and products of the glycosidases deficient in different lysosomal storage disorders. The combined toolbox has furthermore allowed fundamental studies on the nature and specificity of lyso-glycosphingolipid formation, the role of GBA2 enzymatic activity in NPC neuropathology and the occurrence of glucosyl-cholesterol formed by transglucosylation. The noted induction of specific metabolite changes, as well as the over-expression of Gpnmb, in response to lysosomal glycosphingolipid stress provides new read-outs to capitalize on in future investigations. The added insight in the complex pathophysiological processes in glycosphingolipidoses provided by the employment of these novel tools will hopefully translate to the benefit of patients by rendering more accurate prognostic diagnosis and more effective interventions.