Serine Phosphorylation of Insulin Receptor Substrate-1: A Novel Target for the Reversal of Insulin Resistance

Insulin resistance, the failure to respond to normal circulating concentrations of insulin, is a common state associated with obesity, aging, and a sedentary lifestyle. Compelling evidence implicates TNFalpha as the cause and link between obesity and insulin resistance. Serine phosphorylation of insulin receptor substrate-1 seems prominent among the mechanisms of TNFalpha-induced insulin resistance. Recent advances indicate that serine kinases may phosphorylate and thus inhibit the tyrosine phosphorylation of insulin receptor substrate-1, revealing an integration point of TNFalpha and insulin signaling pathways. Selective targeting of the molecular scenery whereby this key phosphorylation occurs/operates represents a rich area for the development of rationally designed new antidiabetic drugs. In relation to efficacy and side effects, this prospect should permit a more precise and perhaps individualized approach to therapeutic intervention, allowing clinicians to focus the attack where the problem lies.