Insulin stimulation of glucose uptake can be mediated by diacylglycerol in adipocytes

An early effect of insulin in adipocytes is to stimulate glucose uptake. The increased uptake appears to be due to mobilization of glucose transporters from an intracellular location to the plasma membrane and to enhanced intrinsic activity of the transporters. Little is known about the insulin-generated signals causing these changes. Phorbol esters have been shown to mimic the insulin effect, but phosphorylation of the transporter does not seem to be involved. A phospho-oligosaccharide was recently shown to mimic the effects of insulin on protein phosphorylation, suggesting that it could be a mediator for some intracellular metabolic effects of the hormone, but it did not affect glucose uptake. A diacyglycerol is produced in the plasma membrane in conjunction with the generation of the phospho-oligosaccharide. Here I show that added 1,2-diacylglycerols potently increase glucose transporter-mediated uptake of glucose in rat adipocytes, but without activation of protein kinase C.