Studies on the Cell Association of Exogenously Added Sialo-Glycolipids

Abstract

The mode of uptake of exogenous sialoglycolipids by a permanent mouse fibroblast cell line (Clone-1D) was studied. The cell association of ganglioside II3NeuAc-Gg4 Cer was compared with that of a synthetic C18-hydrocarbon-chain ganglioside analog (desphingo-G1-stearamide). In contrast to monolayer cultures, Clone-1D cells in suspension bind both sialo-glycolipids rapidly and independently of time and temperature (4.degree./37.degree. C) of incubation. Three modes of cell association were distinguished: a serum- and serum albumin-sensitive association; a trypsin-sensitive association and a serum- and trypsin-insensitive association. Inhibition of pinocytosis by deoxyglucose/sodium azide did not significantly influence cellular uptake or release of exogenous ganglioside. In monolayer culture, Clone 1D cells in M-phase associate more ganglioside than randomly growing cells. This may explain in part the inhomogeneous cellular distribution of ganglioside binding. In contrast, uptake of desphingo-G1-stearamide by cells in mitosis equalled that bound by control cells.