Elevated fat levels within skeletal muscle cells (intramyocellular lipids) are highly correlated with muscle and whole-body insulin resistance, and more prevalent in obesity. The molecular links and metabolic shifts driving this association remain open to debate, but notably, reduced muscle mitochondrial fatty acid (FA) beta-oxidation is more prevalent among insulin-resistant/diabetic persons. Therefore, discovery of biomarkers reflective of the status of an individual's muscle FA beta-oxidation activity or capacity would have tremendous prognostic and diagnostic value in terms of diabetes. Furthermore, characterization of metabolites associated with muscle mitochondrial fat metabolism should uncover candidate signaling factors which tie FA beta-oxidation to insulin signaling. We propose to identify, for the first time, specific biomarkers of muscle FA beta- oxidation using multiple metabolomic analytical platforms to compare metabolite profiles in samples derived from biological systems displaying disparate muscle fat combustion, including: isolated mitochondrial organelles and muscle cells catabolizing FA at different rates, a UCP3 transgenic animal model, and human subjects harboring a UCP3 truncation polymorphism (Aims 1 &2). Pilot validation studies in Aim 3 will test whether plasma metabolites and/or metabolite signatures that track muscular FA beta-oxidation (as identified in Aims 1 and 2) can be experimentally increased in obese, insulin-resistant subjects via a diet-exercise regimen designed to improve muscle fitness and FA combustion.
Aim 1 --Identify Metabolite Biomarkers of Muscle Fat Combustion in Organelle, Cell, and Animal Models Displaying Significantly Altered Fatty Acid beta-Oxidation. We will determine how metabolite profiles shift in models displaying increased muscle beta-oxidation (uncoupling protein 3-overexpressing muscle cell line and muscle UCP3-transgenic mice), and hypothesize that profiles in UCP3-overexpressing systems will reflect increased FA beta-oxidation. Complementary studies will identify tissue-specific metabolites generated by mitochondria in the course of palmitate catabolism in vitro, comparing muscle to liver and kidney preparations.
Aim 2 --Identify Metabolite Biomarkers of Muscle Fat Combustion in Humans Harboring a UCP3 Missense Polymorphic Allele. We predict that subjects with this polymorphism (which yields a truncated UCP3 and 50% decreased whole-body fat combustion) will display a distinctive plasma metabolite profile indicative of reduced muscle FA oxidation, when compared to subjects without the polymorphism.
Aim 3 --Determine Whether Metabolomic Profiles Reflective of Muscle Fat Combustion Predict Metabolic Health Changes Following Diet &Exercise Intervention in Obese Subjects. We hypothesize that biomarkers reflective of normal to increased muscle beta-oxidation will be increased, and markers indicative of poor muscle fat combustion reduced, in a cohort of sedentary obese subjects undergoing a 4 month diet- exercise protocol which will increase muscle fitness and improve insulin action.

Public Health Relevance

A reduced ability of the pancreatic hormone insulin to trigger tissue uptake of blood sugar is an early event in the course of development of type 2 diabetes mellitus (T2DM), and the muscle beds are important sites for this phenomenon in many people. Relatively poor fat combustion by fasting muscle is often correlated with insulin resistance, even in the pre-diabetic state. Thus, the overarching aim of our research-- identification of clinically-relevant biomarkers of muscle fat metabolism--is critical to help identify at-risk persons, determine etiology of disease, and ultimately thwart development of T2DM through nutritional, physical activity, and pharmacological interventions.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
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Clinical and Integrative Diabetes and Obesity Study Section (CIDO)
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Castle, Arthur
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U.S. Agricultural Research Service
United States
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Hirahatake, Kristin M; Slavin, Joanne L; Maki, Kevin C et al. (2014) Associations between dairy foods, diabetes, and metabolic health: potential mechanisms and future directions. Metabolism 63:618-27
Campbell, Caitlin; Grapov, Dmitry; Fiehn, Oliver et al. (2014) Improved metabolic health alters host metabolism in parallel with changes in systemic xeno-metabolites of gut origin. PLoS One 9:e84260
Rutkowsky, Jennifer M; Knotts, Trina A; Ono-Moore, Kikumi D et al. (2014) Acylcarnitines activate proinflammatory signaling pathways. Am J Physiol Endocrinol Metab 306:E1378-87
Aguer, Celine; Fiehn, Oliver; Seifert, Erin L et al. (2013) Muscle uncoupling protein 3 overexpression mimics endurance training and reduces circulating biomarkers of incomplete *-oxidation. FASEB J 27:4213-25
Lackey, Denise E; Lynch, Christopher J; Olson, Kristine C et al. (2013) Regulation of adipose branched-chain amino acid catabolism enzyme expression and cross-adipose amino acid flux in human obesity. Am J Physiol Endocrinol Metab 304:E1175-87
She, Pengxiang; Olson, Kristine C; Kadota, Yoshihiro et al. (2013) Leucine and protein metabolism in obese Zucker rats. PLoS One 8:e59443
Seifert, Erin L; Fiehn, Oliver; Bezaire, Veronic et al. (2010) Long-chain fatty acid combustion rate is associated with unique metabolite profiles in skeletal muscle mitochondria. PLoS One 5:e9834
Fiehn, Oliver; Garvey, W Timothy; Newman, John W et al. (2010) Plasma metabolomic profiles reflective of glucose homeostasis in non-diabetic and type 2 diabetic obese African-American women. PLoS One 5:e15234
Adams, Sean H; Hoppel, Charles L; Lok, Kerry H et al. (2009) Plasma acylcarnitine profiles suggest incomplete long-chain fatty acid beta-oxidation and altered tricarboxylic acid cycle activity in type 2 diabetic African-American women. J Nutr 139:1073-81