Type II Diabetes Mellitus is one of the most common diseases in the Western world, with prevalence ranging from 10-50% in older populations. An integral component of Type II diabetes mellitus is insulin resistance, i.e. an inability of maximal concentrations of the hormone to stimulate appropriate muscle glucose transport and other physiological response. A plausible strategy leading to the development of novel in insulin-sensitizing drugs begins with the systematic analysis of the insulin signaling. After over 20 years of intensive research in the pursuit of relevant serine/threonine protein kinases, Akt/PKB has emerged as a major candidate mediator of insulin's regulation of important metabolic targets. Akt/PKB has emerged as a major candidate mediator of insulin's regulation of important metabolic targets. Akt/PKB is a fairly ubiquitous serine/threonine protein kinase, whose activity depends on the lipid products of phosphatidylinositol 3'-kinase, an enzyme known to be required for virtually all of the metabolic actions of insulin. Though this a rapidly evolving field, at the present time the bulk of evidence suggests that Akt/PKB almost certainly mediates insulin's and IGF1's effects to time the bok of evidence suggests that Akt/PKB almost certainly mediates insulin's and IGF1's effects to antagonize apoptosis, probably contribute to insulin's stimulation of protein, glycogen and triglyceride synthesis, and possibly is involved in insulin's activation of glucose transport. Moreover, there is definitive data demonstrating that Akt/PKB represents an obligate intermediate in an insulin receptor-initiated pathway in the nematode, C. elegans. The primary goals of the studies describes in this grant proposal are to more carefully define the role of Akt/PKB in physiologically relevant insulin signaling, and to understand in more detail the intermediates both between the insulin receptor and Akt/PKB, as well as intervening between the latter kinase and biological outputs. These goals will be accomplished via two distinct strategies: 1) the evaluation of candidate proteins suspected or implicated in the Akt/PKB pathway, and several genetic and biochemical screens for new intermediates, and 2) a careful analysis of the phenomenon of """"""""insulin specificity"""""""" in cultured murine adipocytes, in which activation of Akt/PKB parallels that of glucose transport . Insulin specificity, in the context employed here, refers to the observation that only insulin, but not other growth factors such as PDGF, stimulates glucose transport, in spite of both sets of agonists activating the same early steps in signaling with equal efficacy. It is anticipated that, through these studies, a much deeper understanding will be obtained concerned the critical intracellular events which mediate insulin's regulation of essential metabolic functions.
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