In vivo role of Rho-kinase in glucose metabolism

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DESCRIPTION (provided by applicant): Insulin's ability to acutely stimulate glucose uptake and metabolism in peripheral tissues is essential for normal glucose homeostasis. Resistance to this effect of insulin is a major pathogenic feature of type 2 diabetes and obesity. Although many of the proximal steps in insulin signaling have been identified, the molecular mechanism(s) for insulin action to maintain glucose homeostasis are still unclear. Our recent study suggests that Rho-kinase is an important mediator of insulin action and glucose homeostasis. We found that Rho-kinase regulates insulin-stimulated glucose transport and signaling via IRS-1 serine phosphorylation in cultured adipocytes and muscle cells, establishing a novel mechanism for the regulation of glucose transport and insulin signaling. In this application, we will further define the physiological role of Rho-kinase in the regulation of glucose transport and insulin sensitivity in vivo, using genetic approaches. In Aim 1, we will develop transgenic mice in which Rho-kinase overexpression is conditionally regulated tissue specifically by Cre recombinase co-expression. We will generate adipose-specific Rho-kinase transgenic mice by breeding with the adiponectin Cre recombinase transgenic mice. In Aim 2, we will examine the effects of Rho-kinase expression selectively in adipocytes on whole-body insulin sensitivity, glucose homeostasis, and leanness in vivo. These studies will provide a better understanding of the mechanisms for regulation of glucose homeostasis, and may offer a novel target for the treatment of diabetes and obesity. Insulin resistance is a major risk factor for type 2 diabetes, and the cause of this is not fully understood. Preliminary data show that inhibition of Rho-kinase function results in a decreased insulin response, leading to insulin resistance. The goal of the study is to determine the physiological significance of Rho-kinase in the regulation of glucose homeostasis and insulin sensitivity. These experiments could lead to the identification of a potential target for new diabetes drugs.