Modulation of IR/PTP1B interaction and downstream signaling in insulin sensitive tissues of MSG-rats

PTP1B has been shown to be a negative regulator of the Insulin signal transduction in Insulin resistant states. Herein we investigated IR/PTP1B interaction and downstream signaling in Insulin sensitive tissues of 10 and 28-week-old MSG-insulin resistant rats which represent different stages of Insulin resistance. Our results demonstrated that the increase in PTP1B expression and/or association with IR in MSG Animals may contribute to the impaired Insulin signaling mainly in liver and muscle. Although, adipose tissue of 10-week-old MSG rats showed higher PTP1B expression and IR/PTP1B interaction, they were not sufficient to impair all Insulin signaling since IRS-2 phosphorylation and association with PI3-kinase and Akt serine phosphorylation were increased, which may contribute for the increased adiposity of these Animals. In 28-week-old-MSG rats there was an increase in IR/PTP1B interaction and reduced Insulin signaling in liver, muscle and adipocytes, and a more pronounced Insulin resistance.