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RNA-sequencing of human skeletal myocytes from healthy, obese, and type 2 diabetic subjects

ABSTRACT: Skeletal muscle is one of the primary tissues involved in the development of type 2 diabetes (T2D). Obesity is tightly associated with T2D, making it challenging to isolate specific effects attributed to the disease alone. By using an in vitro myocyte model system we were able to isolate the inherent properties retained in myocytes originating from donor muscle precursor cells, without being confounded by varying extracellular factors present in the in vivo environment of the donor. We generated and characterized transcriptional profiles of myocytes from 24 human subjects, using a factorial design with two levels each of the factors T2D (healthy or diseased) and obesity (non-obese or obese), and determined the influence of each specific factor on genome-wide transcription. We identified a striking similarity of the transcriptional profiles associated independently with T2D or obesity. Obesity thus presents an inherent phenotype in skeletal myocytes, similar to that induced by T2D. Through bioinformatics analysis we found a candidate epigenetic mechanism, H3K27me3 histone methylation, mediating the observed transcriptional signatures. Functional characterization of the expression profiles revealed dysregulated myogenesis and down-regulated muscle function in connection with T2D and obesity, as well as up-regulation of genes involved in inflammation and the extracellular matrix. Further on, we identified a metabolite subnetwork involved in sphingolipid metabolism and affected by transcriptional up-regulation in T2D. Collectively, these findings pinpoint transcriptional changes that are hard-wired in skeletal myocytes in connection with both obesity and T2D.

ORGANISM(S): Homo sapiens

PROVIDER: GSE81965 | GEO | 2017/04/22

SECONDARY ACCESSION(S): PRJNA323538

REPOSITORIES: GEO

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Project description:Physical inactivity and western diet are the main factors leading to skeletal muscle (and whole-body) insulin resistance – a defect in insulin-mediated glucose uptake and metabolism – and associated metabolic diseases, such as obesity and type 2 diabetes mellitus (T2D). The study of the response to a mixed meal (normalized for body mass and/or basal metabolic rate) is of particular interest, as it simulates the physiological response to a typical (daily) single meal that depends on both the secretory function of the beta cells (insulin response) and the sensitivity of skeletal muscle signaling to insulin – variables, which markedly changing during development of insulin resistance and T2D. We aimed to compare the early transcriptomic response to a mixed meal normalized to body mass in skeletal muscle of healthy subjects and obese patients without (Ob) and with T2D (Ob+T2D). To investigate the early transcriptomic response we took biopsy samples from the vastus lateralis muscle prior to and 1 h after a meal. In the Ob+T2D group the average level and increase in C-peptide and insulin in the blood were comparable with healthy subjects that, apparently, is explained by dysfunction of the beta-cells induced by chronic T2D. At the same time, the Ob+T2D group demonstrated dysregulation of mixed meal-induced gene expression in skeletal muscle: morу than two times lower number of DEGs and a small overlapping with the gene response in the control group. On the contrary, the postprandial level of C-peptide and insulin in the Ob group was significantly greater than in healthy control that is related to insulin oversecretion associated with insulin resistance. Despite this, the gene response in skeletal muscle was also significantly dysregulated; moreover, it differed from the response in the Ob+T2D group. It means that defect in regulation of insulin-induced gene expression (insulin resistance in terms of gene expression) appears at the first stage of the development of metabolic disorders.

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RNA-sequencing of human skeletal myocytes from healthy, obese, and type 2 diabetic subjects

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