Metabolism of Ganglioside-Amides in Cultured Human Fibroblasts

Metabolism and intracellular transport of glycosphingolipids

“…Results obtained with ganglioside-amides support these findings (Klein et al, 1987a). Subcellular fractionation studies on fibroblasts fed with GM3-amide revealed that most of this derivative was internalized and directed to the lysosomes, probably by a vesicular membrane flow.…”

“…Direct glycosylation of precursor gangliosides to yield GDla has also been observed in rat liver after intravenous injection of labeled GM1, irrespective of its label position (Ghidoni et al, 1986). Moreover, when fibroblasts were fed with 10~5 M tritium-labeled GM2-amide for 48 h at 37 °C, the analysis of the lipid extract of these cells showed the formation of GD la-amide (Klein et al, 1987a). Previously, it had been shown that GM2-amide cannot be degraded beyond GM3-amide, as this derivative is resistant to the action of sialidase (Klein et al, 1987b).…”

“…Previously, it had been shown that GM2-amide cannot be degraded beyond GM3-amide, as this derivative is resistant to the action of sialidase (Klein et al, 1987b). Since GDlaamide is not produced in cells fed with GM3-amide, it can be concluded safely that GD la-amide is derived from GM2-amide by direct glycosylation (Klein et al, 1987a). However, when GM3 was incorporated in ceramidase-deficient fibroblasts from a patient suffering from Farber's disease, no products of glycosylation could be detected (Schwarzmann et al, 1986).…”