Phosphoprotein Phosphatase PP2A Regulation of Insulin Receptor Substrate 1 and Insulin Metabolic Signaling

Insulin (INS) metabolic signaling is important for normal cardiovascular and renal function as well as for exerting the classic actions of INS, such as glucose uptake in skeletal muscle tissue. There is emerging evidence that tyrosine phosphatases as well as protein kinases have important modulating roles in INS metabolic signaling in both cardiovascular and classically INS- sensitive tissues. For example, increases in phosphatase activity may partially explain how angiotensin II and aldosterone attenuate activation of the INS receptor substrate protein 1 (IRS-1)-phosphatidylinositol 3 kinase-protein kinase B pathway, thereby promoting INS resistance. On the other hand, phosphatase activation may also exert beneficial and cardiovascular protective effects in conditions such as overnutrition by blocking serine phosphorylation of IRS-1, thereby improving downstream INS metabolic signaling. Both the beneficial and the detrimental effects exerted by the activation of phosphatases will be covered in this report.