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dc.contributor.authorSparks, Lauren M.
dc.contributor.authorMoro, Cedric
dc.contributor.authorUkropcova, Barbara
dc.contributor.authorBajpeyi, Sudip
dc.contributor.authorCivitarese, Anthony E.
dc.contributor.authorHulver, Matthew W.
dc.contributor.authorThoresen, G. Hege
dc.contributor.authorRustan, Arild C.
dc.contributor.authorSmith, Steven R.
dc.description.abstractObjective: Disturbances in lipid metabolism are strongly associated with insulin resistance and type 2 diabetes (T2D). We hypothesized that activation of cAMP/PKA and calcium signaling pathways in cultured human myotubes would provide further insight into regulation of lipid storage, lipolysis, lipid oxidation and insulin responsiveness. Methods: Human myoblasts were isolated from vastus lateralis, purified, cultured and differentiated into myotubes. All cells were incubated with palmitate during differentiation. Treatment cells were pulsed 1 hour each day with forskolin and ionomycin (PFI) during the final 3 days of differentiation to activate the cAMP/PKA and calcium signaling pathways. Control cells were not pulsed (control). Mitochondrial content, ¹⁴C lipid oxidation and storage were measured, as well as lipolysis and insulin-stimulated glycogen storage. Myotubes were stained for lipids and gene expression measured. Results: PFI increased oxidation of oleate and palmitate to CO₂ (p,0.001), isoproterenol-stimulated lipolysis (p = 0.01), triacylglycerol (TAG) storage (p,0.05) and mitochondrial DNA copy number (p = 0.01) and related enzyme activities. Candidate gene and microarray analysis revealed increased expression of genes involved in lipolysis, TAG synthesis and mitochondrial biogenesis. PFI increased the organization of lipid droplets along the myofibrillar apparatus. These changes in lipid metabolism were associated with an increase in insulin-mediated glycogen storage (p,0.001). Conclusions: Activation of cAMP/PKA and calcium signaling pathways in myotubes induces a remodeling of lipid droplets and functional changes in lipid metabolism. These results provide a novel pharmacological approach to promote lipid metabolism and improve insulin responsiveness in myotubes, which may be of therapeutic importance for obesity and type 2 diabetes.en
dc.description.sponsorshipThe study was supported in part by a pilot and feasibility grant (BU) from the Health and Performance Enhancement Division of the Pennington Biomedical Research Center PBRC 011-61-0114, and by grants from PBRC CNRU P30-DK072476, USDA 2003-34323-14010 and R01AG030226 (SRS). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.en
dc.rightsCreative Commons Attribution 3.0 United Statesen
dc.titleRemodeling Lipid Metabolism and Improving Insulin Responsiveness in Human Primary Myotubesen
dc.typeArticle - Refereed
dc.title.serialPLOS One

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Creative Commons Attribution 3.0 United States
License: Creative Commons Attribution 3.0 United States