Saori Kakehi1,2, Yoshifumi Tamura1,2, Kageumi Takeno1,2, Shin-Ichi Ikeda1,2, Yuji Ogura3,4, Norio Saga3,4, Takeshi Miyatsuka1,5,6, Hisashi Naito3,4, Ryuzo Kawamori1,2, Hirotaka Watada1,2,5,6. 1. Department of Metabolism and Endocrinology Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan. 2. Sportology Center, Juntendo University, Tokyo 113-8421, Japan. 3. Institute of Health and Sports Science & Medicine, Juntendo University, Chiba 270-1695, Japan. 4. Department of Exercise Physiology, Graduate School of Health and Sports Science, Juntendo University, Chiba 270-1695, Japan. 5. Center for Therapeutic Innovations in Diabetes, Juntendo University, Tokyo 113-8421, Japan. 6. Center for Identification of Diabetic Therapeutic Targets, Graduate School of Medicine, Juntendo University, Tokyo 113-8421, Japan.
Abstract
CONTEXT: Endurance-trained athletes have high oxidative capacities, enhanced insulin sensitivities, and high intracellular lipid accumulation in muscle. These characteristics are likely due to altered gene expression levels in muscle. DESIGN AND SETTING: We compared intramyocellular lipid (IMCL), insulin sensitivity, and gene expression levels of the muscle in eight nonobese healthy men (control group) and seven male endurance athletes (athlete group). Their IMCL levels were measured by proton-magnetic resonance spectroscopy, and their insulin sensitivity was evaluated by glucose infusion rate (GIR) during a euglycemic-hyperinsulinemic clamp. Gene expression levels in the vastus lateralis were evaluated by quantitative RT-PCR (qRT-PCR) and microarray analysis. RESULTS: IMCL levels in the tibialis anterior muscle were approximately 2.5 times higher in the athlete group compared to the control group, while the IMCL levels in the soleus muscle and GIR were comparable. In the microarray hierarchical clustering analysis, gene expression patterns were not clearly divided into control and athlete groups. In a gene set enrichment analysis with Gene Ontology gene sets, "RESPONSE TO LIPID" was significantly upregulated in the athlete group compared with the control group. Indeed, qRT-PCR analysis revealed that, compared to the control group, the athlete group had 2-3 times higher expressions of proliferator-activated receptor gamma coactivator-1 alpha (PGC1A), adiponectin receptors (AdipoRs), and fatty acid transporters including fatty acid transporter-1, plasma membrane-associated fatty acid binding protein, and lipoprotein lipase. CONCLUSIONS: Endurance runners with higher IMCL levels have higher expression levels of genes related to lipid metabolism such as PGC1A, AdipoRs, and fatty acid transporters in muscle.
CONTEXT: Endurance-trained athletes have high oxidative capacities, enhanced insulin sensitivities, and high intracellular lipid accumulation in muscle. These characteristics are likely due to altered gene expression levels in muscle. DESIGN AND SETTING: We compared intramyocellular lipid (IMCL), insulin sensitivity, and gene expression levels of the muscle in eight nonobese healthy men (control group) and seven male endurance athletes (athlete group). Their IMCL levels were measured by proton-magnetic resonance spectroscopy, and their insulin sensitivity was evaluated by glucose infusion rate (GIR) during a euglycemic-hyperinsulinemic clamp. Gene expression levels in the vastus lateralis were evaluated by quantitative RT-PCR (qRT-PCR) and microarray analysis. RESULTS:IMCL levels in the tibialis anterior muscle were approximately 2.5 times higher in the athlete group compared to the control group, while the IMCL levels in the soleus muscle and GIR were comparable. In the microarray hierarchical clustering analysis, gene expression patterns were not clearly divided into control and athlete groups. In a gene set enrichment analysis with Gene Ontology gene sets, "RESPONSE TO LIPID" was significantly upregulated in the athlete group compared with the control group. Indeed, qRT-PCR analysis revealed that, compared to the control group, the athlete group had 2-3 times higher expressions of proliferator-activated receptor gamma coactivator-1 alpha (PGC1A), adiponectin receptors (AdipoRs), and fatty acid transporters including fatty acid transporter-1, plasma membrane-associated fatty acid binding protein, and lipoprotein lipase. CONCLUSIONS: Endurance runners with higher IMCL levels have higher expression levels of genes related to lipid metabolism such as PGC1A, AdipoRs, and fatty acid transporters in muscle.
Authors: Margarita Teran-Garcia; Tuomo Rankinen; Robert A Koza; D C Rao; Claude Bouchard Journal: Am J Physiol Endocrinol Metab Date: 2005-02-01 Impact factor: 4.310
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Authors: Luc J C van Loon; René Koopman; Ralph Manders; Walter van der Weegen; Gerrit P van Kranenburg; Hans A Keizer Journal: Am J Physiol Endocrinol Metab Date: 2004-05-27 Impact factor: 4.310