Abstract
We studied the intracellular signaling pathway of insulin in primary cultured rat Sertoli cells. When the cells were incubated with insulin for 5 to 30 minutes some cellular proteins were detected to be tyrosine phosphorylated. Immunoblot analysis showed the masses of two of these proteins to be 97 kDa and 170kDa, which correspond to the insulin receptor β-subunit and insulin receptor substrate-1 (IRS-1), respectively. Insulin stimulated glucose uptake by the cells for 50 minutes and incorporation of thymidine into DNA 15 hours after its addition to culture. Pretreatment of cells with wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI 3-kinase), prevented the insulin-dependent increase in glucose uptake and DNA synthesis. These results suggest the existence of an intracellular signaling system for insulin through insulin receptor, IRS-l, and PI 3-kinase in primary cultured Sertoli cells.
