Effect of glucagon on insulin receptor substrate-1 (IRS-1) phosphorylation and association with phosphatidylinositol 3-kinase (PI 3-kinase)
Saad, M.J.; Hartmann, L.G.; de Carvalho, D.S.; Galoro, C.A.; Brenelli, S.L.; Carvalho, C.R.
FEBS Letters 370(1-2): 131-134
ISSN/ISBN: 0014-5793 PMID: 7544300 DOI: 10.1016/0014-5793(95)00809-n
In the present study we have examined the levels and phosphorylation state of the insulin receptor and insulin receptor substrate 1 (IRS-1) as well as the association between IRS-1 and phosphatidylinositol 3-kinase (PI 3-kinase) in the liver and muscle of rats treated with glucagon. There was a decrease in the insulin-stimulated receptor and IRS-1 phosphorylation levels which was paralleled by a reduced association between IRS-1 and PI 3-kinase in vivo in the liver and muscle of glucagon-treated rats. These observations suggest that glucagon, probably acting through cAMP, may impair insulin signaling in the three early steps in insulin action after binding.