Glucose stimulation of lipogenic enzyme gene expression in cultured white adipose tissue. A role for glucose 6-phosphate.

The expression of fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) is low in the adipose tissue of suckling rats and increases markedly at weaning to a high carbohydrate diet. We have studied in vitro the factors regulating this phenomenon. Inguinal adipose tissue pieces from 19-day-old suckling rats were cultured for 6 or 24 h in minimal essential medium. Insulin (100 nM) added in the presence of lactate and pyruvate did not stimulate the expression of FAS and ACC. Glucose (20 mM) alone resulted in a 5-7-fold increase of FAS and ACC mRNA. Insulin potentiated the effect of glucose. 3-O-Methylglucose, a glucose analog that is transported into the cell but not metabolized, had no effect on FAS and ACC mRNA accumulation. However, 2-deoxyglucose (1 mM), a glucose analog which is phosphorylated to 2-deoxyglucose 6-phosphate, stimulated the expression of FAS and ACC to the same extent as 20 mM glucose. Glucose 6-phosphate concentrations in adipose tissue pieces cultured in various conditions changed in parallel with the FAS and ACC mRNA levels. We conclude that glucose 6-phosphate could be the metabolite involved in the stimulation of lipogenic enzyme gene expression in response to glucose.