An inhibitory role for phosphatidylinositol 3-kinase in insulin secretion from pancreatic B cell line MIN6.

Phosphatidylinositol 3-kinase (PI3-kinase) has been implicated in the regulation of vesicular transport. We examined the roles of PI3-kinase in the glucose-induced insulin secretion from the pancreatic beta cell line MIN6 by using wortmannin, a potent inhibitor of PI3-kinase. Low concentrations of wortmannin markedly potentiated the glucose-induced insulin secretion. This effect was probably mediated by PI3-kinase inhibition. Furthermore, wortmannin completely canceled the suppressive effect of insulin-like growth factor-I on insulin secretion from MIN6 cells. On the basis of these results, we discuss a possible role of PI3-kinase in the negative feed-back regulation of insulin secretion.