Higher lipid turnover and oxidation in cultured human myotubes from athletic versus sedentary young male subjects

Abstract

In this study we compared fatty acid (FA) metabolism in myotubes established from athletic and sedentary young subjects. Six healthy sedentary (maximal oxygen uptake (VO2max) ≤ 46 ml/kg/min) and six healthy athletic (VO2max > 60 ml/kg/min) young men were included. Myoblasts were cultured and differentiated to myotubes from satellite cells isolated from biopsy of musculus vastus lateralis. FA metabolism was studied in myotubes using [14C]oleic acid. Lipid distribution was assessed by thin layer chromatography, and FA accumulation, lipolysis and re-esterification were measured by scintillation proximity assay. Gene and protein expressions were studied. Myotubes from athletic subjects showed lower FA accumulation, lower incorporation of FA into total lipids, triacylglycerol (TAG), diacylglycerol and cholesteryl ester, higher TAG-related lipolysis and re-esterification, and higher complete oxidation and incomplete β-oxidation of FA compared to myotubes from sedentary subjects. mRNA expression of the mitochondrial electron transport chain complex III gene UQCRB was higher in cells from athletic compared to sedentary. Myotubes established from athletic subjects have higher lipid turnover and oxidation compared to myotubes from sedentary subjects. Our findings suggest that cultured myotubes retain some of the phenotypic traits of their donors.

Growth and differentiation factor 15 is secreted by skeletal muscle during exercise and promotes lipolysis in humans

“…As we hypothesized that skeletal muscle contraction can release a cellular stress signal able to induce lipolysis, we developed an experimental model of exercise in cultured human myotubes. Human primary culture of skeletal muscle cells has been widely used by several investigators (22)(23)(24)(25)(26) and provides a powerful tool for mechanistic studies of skeletal muscle and study muscle autonomous adaptations in the absence of the systemic milieu (27). EPS of human myotubes can be used to induce forced contraction and mimic exercise in vitro (28).…”

Altered dynamics of lipid metabolism in muscle cells from patients with idiopathic inflammatory myopathy is ameliorated by 6 months of training

“…Lund et al . (2018) described lower lipid accumulation and higher fat oxidation in myotubes from young athletes as compared to age‐matched sedentary individuals. The in vitro metabolic or secretory profiles of muscle cells, which mirror the donor's clinical phenotype, are paralleled by specific changes in DNA methylation (Lund et al .…”

“…2011) and lipases have also been shown to be regulated by metabolic disease and saturated fatty acids (Lund et al . 2018). The majority of fatty acids that enter myocytes are first esterified into triglycerides before being oxidized (Meex et al .…”

Treatment of human skeletal muscle cells with inhibitors of diacylglycerol acyltransferases 1 and 2 to explore isozyme-specific roles on lipid metabolism

“…For most experiments, the cells were cultured on multiwell plates in DMEM-Glutamax (5.5 mM glucose) supplemented with 2% FBS, 25 IU penicillin, 25 µg/ml streptomycin, 1.25 µg/ml amphotericin B, 50 ng/ml gentamycin, and 2% Ultroser G. At approximately 80% confluency, the growth medium was replaced by DMEM-Glutamax (5.5 mM glucose) supplemented with 2% FBS, 25 IU penicillin, 25 µg/ml streptomycin, 1.25 µg/ml amphotericin B, 50 ng/ ml gentamycin, and 25 pM insulin. During culturing, the cells were incubated in a humidified 5% CO 2 atmosphere at 37 °C, and the medium was changed every 2-3 days as previously described 29 . Experiments were performed on myotubes after 6-7 days of differentiation.…”