Regular physical exercise can prevent and/or ameliorate many diseases including type 2 diabetes and heart disease. These beneficial effects are partially the consequence of improved glucose and lipid homeostasis in peripheral tissues, especially skeletal muscle. The overall goal of this project is to determine the underlying molecular signaling mechanisms through which physical exercise regulates skeletal muscle glucose metabolism. In people with type 2 diabetes, skeletal muscles are typically insulin resistant, whereas the effects of exercise on glucose transport are preserved, perhaps due to distinct proximal signaling events leading to insulin- and contraction-stimulated glucose transport. At present, the precise nature of the contraction-stimulated signals remains obscure. However, the current hypothesis is that multiple signaling mechanisms mediate contraction-stimulated glucose transport.
Specific Aim 1 will determine the effects of members of the Ca2????dependent protein kinase (CaMK) family on contraction-stimulated glucose uptake.
Specific Aim 2 is designed to explore the role of atypical isoforms of protein kinase C (aPKC) on skeletal muscle glucose uptake. For both Aims 1 and 2, members of these signaling networks will be selectively activated and inhibited by using a powerful in vivo gene transfer model and muscle specific knockout mice, and their resultant effects on glucose transport will then be evaluated.
Specific Aim 3 proposes to look downstream of these signals to study whether multiple contraction-stimulated pathways converge at the Akt substrate of 160 kDa (AS160) and TBC1D1, leading to increased glucose transport.
This aim will employ site directed mutagenesis and in vivo gene transfer to pinpoint novel mechanisms for AS160 and TBC1D1 regulation of glucose transport. Collectively, these studies will significantly enhance the understanding of contraction-induced alterations in skeletal muscle glucose metabolism.
Studies designed to understand how exercise alleviates the insulin resistance associated with type 2 diabetes is relevant to public health because type 2 diabetes is pervading virtually every demographic subset, with conspicuous and alarming affinity for younger individuals. Fortunately, physical exercise represents a cornerstone therapy to prevent or improve diabetes and its related pathologies. The goal of this proposal is to determine the molecular basis for these beneficial effects in exercising muscles, which may then be used to develop breakthrough drugs designed to treat diabetes.
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