The fate of glucosylceramide (glucocerebroside) in genetically impaired (lysosomal beta-glucosidase deficient) Gaucher disease diploid human fibroblasts.
Diploid human infant skin fibroblasts cultured from normal infants and Gaucher disease infants, with genetically defective lysosomal glucosylceramide:beta-glucohydrolase activity, had a full range of homologous glycosphingolipids from the simplest (glucosylceramide) to higher neutral derivatives (lactosyl-, trihexosyl- and tetrahexosylceramide) and anionic sialo derivatives (gangliosides) (sialosyllactosyl-, disialosyllactosyl-, sialosylgangliotriaosyl-, and mono- and disialosylgangliotetraosylceramide). Although excessive storage of glucosylceramide in histiocytes is pathognomonic for Gaucher disease, we found that Gaucher disease fibroblasts contained 1.23 +/- 0.08 nmol of glucosylceramide/mg cell protein; normal infant cells, 1.11 +/- 0.48. When we aged infantile Gaucher disease fibroblasts for 20 days beyond their confluency state, we found no increased accumulation of glucosylceramide, but a 1.5-2-fold increase in trihexosylceramide, sialosylgangliotetraosylceramide, and disialosyllactosylceramide. Gaucher disease fibroblasts took up and could not degrade but, instead, effectively converted pulse-chase 3-O-[3H]glucosylceramide supplied in the growth medium in liposomes into higher glycosphingolipids, especially the plasma membrane ganglioside, sialosyllactosylceramide. When grown with extracellular particulate [3H]glucosylceramide, infantile Gaucher fibroblasts localized it and higher labeled homologues in the plasma membrane; glucosylceramide did not accumulate in the lysosomes. These findings indicate that fibroblasts that are genetically deficient in lysosomal glucosylceramide:beta-glucosidase avoid pathological lysosomal accumulation by relegating undegradable glucosylceramide to an anabolic compartment where glucosylceramide is converted into more highly glycosylated glycosphingolipids.
D002458:Cell Fractionation; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002554:Cerebrosides / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism* / Q000648:ultrastructure; D005776:Gaucher Disease / Q000378:metabolism*; D005963:Glucosylceramides / Q000378:metabolism*; D006028:Glycosphingolipids / Q000378:metabolism; D006801:Humans; D007223:Infant; D008081:Liposomes / Q000378:metabolism; D008247:Lysosomes / Q000201:enzymology; D010743:Phospholipids / Q000378:metabolism; D014316:Tritium; D001617:beta-Glucosidase / Q000172:deficiency
D002554:Cerebrosides; D005963:Glucosylceramides; D006028:Glycosphingolipids; D008081:Liposomes; D010743:Phospholipids; D014316:Tritium; D001617:beta-Glucosidase