Cytosolic Glucosylceramide regulates endolysosomal function in Niemann-Pick type C disease

A new paradigm for Niemann-Pick C disease is presented where lysosomal storage leads to a deficit in cytoplasmic glucosylceramide (GlcCer) where it performs important functions. Previously it had been reported that Gaucher cells have defective endolysosomal pH. GlcCer also accumulates in Niemann-Pick C disease and also shows this defect. Niemann-Pick C cells were found to have reduced cytoplasmic glucosylceramide (GlcCer) transport. Inhibiting cytoplasmic glucocerebrosidase (GBA2), increased GlcCer, decreased endolysosomal pH in normal cells, reversed increases in endolysosomal pH and restored disrupted BODIPY-LacCer trafficking and increased expression of vATPase a subunit in Niemann-Pick C fibroblasts. The results are consistent with a model where both endolysosomal pH and Golgi targeting of BODIPY-LacCer are dependent on adequate levels of cytosolic GlcCer which are reduced in NPC disease. This work consequently suggests GBA2 and vATPase as new therapeutic targets in Niemann-Pick C and related neurodegenerative diseases. The work was in collaboration with colleagues in the Netherlands and Leicester University. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.