title: Uridine diphosphate N-acetylglucosamine stimulates uptake of nutrients by quiescent BALB/C3T3 cells.
abstract: Preincubation of quiescent BALB/C3T3 cells with uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) in conditioned medium resulted in a time- and concentration-dependent stimulation of uptake of 2-deoxyglucose, uridine, and alpha-aminoisobutyric acid over that seen in conditioned medium alone. The apparent Km values for 2-deoxyglucose and uridine uptake were the same for cells incubated with or without UDP-GlcNAc, whereas the Vmax values were higher for cells pretreated with the nucleotide sugar. The stimulation of uptake was specific for UDP-GlcNAc, and the other nucleotide sugars tested were ineffective; incubation of UDP-GlcNAc-pretreated cells with N-acetylglucosaminidase abolished the stimulatory effect. In all cases, the extent of stimulation of nutrient uptake was comparable to that seen with serum-stimulated cells. Incubation of quiescent cells in situ with UDP-[3H]GlcNAc led to incorporation of radioactive N-acetylglucosamine into the acid-precipitable fraction; a large fraction of the labeled amino sugar was found on the cell surface acceptors. We interpret these data to mean that the cellular acceptors of quiescent cells are "under-glycosylated," at least in terms of N-acetylglucosamine, and that stimulation of uptake of nutrients may be a consequence of restoration of the amino sugar residues on the oligosaccharide chains of acceptors on the cell surface.
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism; D000621:Aminoisobutyric Acids / Q000378:metabolism*; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D003837:Deoxy Sugars / Q000378:metabolism*; D003847:Deoxyglucose / Q000378:metabolism*; D014529:Uridine / Q000378:metabolism*; D014537:Uridine Diphosphate N-Acetylglucosamine / Q000494:pharmacology*; D014539:Uridine Diphosphate Sugars / Q000494:pharmacology*
chemical_list: D000621:Aminoisobutyric Acids; D003837:Deoxy Sugars; D014539:Uridine Diphosphate Sugars; D014537:Uridine Diphosphate N-Acetylglucosamine; D003847:Deoxyglucose; D000117:Acetylglucosamine; D014529:Uridine