Epidermal growth factor stimulates the incorporation of phosphate into phosphatidic acid and phosphoinositides but does not affect phosphoinositide breakdown by phospholipase C in renal cortical slices

Abstract

The effects of epidermal growth factor (EGF) on the metabolism of phosphatidic acid and phosphoinositides were examined using renal cortical slices labelled with either sodium [32P]orthophosphate or myo-[3H]inositol. EGF was found to increase the incorporation of phosphate into phosphatidic acid and phosphoinositides. This effect is not dependent on external calcium and is inhibited by 12-O-tetradecanoylphorbol 13-acetate (TPA). When phospholipids were prelabelled, EGF did not decrease the level of 32P in phosphatidic acid and phosphoinositides, and EGF did not affect the formation of inositol phosphates or the concentration of cAMP and cGMP in renal tissue. The results show that EGF stimulates the incorporation of phosphate into phosphatidic acid and phosphoinositides, but does not affect breakdown of phosphoinositides by phospholipase C in renal cortical slices.