Effect of transforming growth factor-alpha on inositol phospholipid metabolism in human epidermoid carcinoma cells.
Transforming growth factor-alpha (TGF-alpha) stimulates (in a dose-dependent manner) the incorporation of [32P]Pi into phosphatidylinositol (PI), phosphatidylinositol 4-phosphate (PIP), phosphatidylinositol 4,5-bisphosphate (PIP2), and phosphatidic acid (PA) in the human epidermoid carcinoma cell line (A431). The effect of TGF-alpha on the incorporation was found to be similar to that of EGF. On the other hand, a striking difference in the activation of diacylglycerol (DG) kinase activity was seen between TGF-alpha and EGF. At least 100 times more TGF-alpha was required to achieve maximal stimulation of DG kinase activity relative to EGF. These results suggest that the activation of DG kinase by TGF-alpha may involve a mechanism independent from or subsequent to activation of the EGF receptor.
Kato
M
M
Department of Pharmacology, Tokyo Metropolitan Institute of Gerontology, Japan.
Takenawa
T
T
Twardzik
D R
DR
D002294:Carcinoma, Squamous Cell / Q000378:metabolism*; D002460:Cell Line; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D010455:Peptides / Q000494:pharmacology*; D010710:Phosphates / Q000378:metabolism; D010712:Phosphatidic Acids / Q000096:biosynthesis*; D010716:Phosphatidylinositols / Q000096:biosynthesis*; D010761:Phosphorus Radioisotopes; D015291:Transforming Growth Factors
D006133:Growth Substances; D010455:Peptides; D010710:Phosphates; D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; D010761:Phosphorus Radioisotopes; D015291:Transforming Growth Factors