Modulation of Epidermal Growth Factor Stimulated ERK Phosphorylation and Cell Motility by Inositol Trisphosphate Kinase.

Epidermal growth factor [EGF] mediated stimulation of its receptor in endothelial cell [EC] is accompanied by phosphorylation of the EGF-receptor [EGFR] and activation of phospholipase C- γ , resulting in the breakdown of phosphatidylinositol(4,5)-bisphosphate and generating inositol (1,4,5)-trisphosphate [IP3 ] and diacylglycerol. IP3 thus formed can be further converted to inositol (1,3,4,5)-tetrakisphosphate [IP4 ] by an enzyme called IP3 -kinase [IP3 K]. In this study we have investigated the effect of modulation of intracellular IP3 K activity by the use of an inhibitor, 2-trifluoromethyl [6-(4-nitrobenzyl)-purine] [IP3 KI] and siRNA against IP3 KB on EGF-induced ERK-phosphorylation and cell motility. EGF stimulated ERK-phosphorylation that has been implicated in EGF-stimulated cell migration was inhibited by both IP3 KI and siRNA against IP3 KB. Inhibition of ERK-phosphorylation was accompanied by decreased cell migration in the presence of IP3 KI.