Proteomics: Inactivity-induced muscle insulin resistance

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DESCRIPTION (provided by applicant): Insulin resistance and type 2 diabetes are epidemic in adults, and are now even occurring in adolescents. A decrease in physical activity has played an important role in this increase in diabetes as documented in many epidemiological and physiological papers. Of great significance are recent publications showing that increased contractile activity signals an enhanced glucose uptake through an insulin-independent signaling pathway, likely AMP kinase, but the complete pathway remains to be delineated. The importance of these observations is that they raise the probability that unexpected novel proteins linking physical inactivity to insulin resistance will be found. As the post-genome era begins with the sequencing of the human genome, tools are now available to discover the identity of proteins currently unassociated with the signaling of insulin resistance by mechanisms other than insulin modification. This proposal focuses on those proteins differentially expressed when either normal voluntary running ceases due to the removal of a running wheel from the cage, or when high fat diets are consumed. These models mimic current lifestyles of sedentary activity and/or high fat consumption. Specific aim I will use 2-D gel electrophoresis to experimentally determine differentially expressed proteins in skeletal muscle that have undergone decreased physical activity. Specific aim 2 will also employ 2-D gel electrophoresis to determine differentially expressed proteins in the skeletal muscle of rats that have undergone decreased physical activity while eating a high fat diet. One hypothesis is that both inactivity and high blood lipids will cause unique, but not identical, sets of proteins related to insulin resistance to be expressed in skeletal muscle. Many of these proteins will heretofore be unidentified as playing a role in skeletal muscle insulin resistance. Identifying the expressed proteins associated with insulin resistance in skeletal muscle will permit the development of new hypotheses, whose functions and interactions with other proteins will be the focus of future grant applications. Such new hypotheses could lead to new therapies against diabetes. Outcomes of this proposal will better establish that healthy active skeletal muscles interact with other organ systems to prevent the metabolic disorders of type 2 diabetes, atherosclerosis, and obesity.