Tyrosine phosphorylation of insulin receptor substrate-1 and activation of the PI-3-kinase pathway by glycine-extended gastrin precursors

A Kowalski-Chauvel, L Pradayrol, N Vaysse… - … and biophysical research …, 1997 - Elsevier
A Kowalski-Chauvel, L Pradayrol, N Vaysse, C Seva
Biochemical and biophysical research communications, 1997Elsevier
Glycine-extended gastrin precursors (G-Gly) were considered as processing intermediates
devoid of biological activity. However, we have recently identified selective receptors for G-
Gly which mediate the proliferative effects of this precursor. Little is known about the
signaling pathways activated by G-Gly. In the present study, we demonstrate that PI-3-kinase
is rapidly and transiently activated by G-Gly. We also observed a rapid increase in the
tyrosine phosphorylation of IRS-1 and an activation of the PI-3-kinase in anti-IRS-1 …
Glycine-extended gastrin precursors (G-Gly) were considered as processing intermediates devoid of biological activity. However, we have recently identified selective receptors for G-Gly which mediate the proliferative effects of this precursor. Little is known about the signaling pathways activated by G-Gly. In the present study, we demonstrate that PI-3-kinase is rapidly and transiently activated by G-Gly. We also observed a rapid increase in the tyrosine phosphorylation of IRS-1 and an activation of the PI-3-kinase in anti-IRS-1 immunoprecipitates, suggesting that PI-3-kinase may be activated by association with tyrosine phosphorylated IRS-1. We also demonstrated that gastrin precursors activate the serine/threonine kinase, p70 kDa S6 kinase (p70S6K), through a wortmannin sensitive pathway.
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