Transcriptional profiles of type 2 diabetes in human skeletal muscle reveal insulin resistance, metabolic defects, apoptosis, and molecular signatures of immune activation in response to infections

Skeletal muscle insulin resistance is considered to be the primary defect involved in type 2 diabetes mellitus (T2DM). Despite transcriptome studies in limited T2DM human subjects suggesting an association of T2DM with impaired oxidative phosphorylation in muscle, its molecular pathogenesis remains largely unknown. To identify dysregulated genes and gene networks that are associated with T2DM in human skeletal muscle, we examined expression patterns of 56,318 transcribed genes on 92 T2DM cases and 184 gender-, age- and race-matched non-diabetic controls from the Genotype-Tissue Expression (GTEx) database. RNA-Sequencing data suggest that diabetic skeletal muscle is characterized by decreased expression of genes that are related to insulin resistance (IRS2, MTOR, SLC2A4, and PPARA), carbohydrate, energy, and amino acid metabolism pathways (NDUFS1, NDUFA10, NDUFB4, NDUFB5, NDUFA5, NDUFB10, SDHB, SDHC, ATP5H, ATP5A, and ATP5J). Up-regulated genes in T2DM are mainly enriched in apoptosis pathways (TP53, GADD45A, TNFRSF10B, TP53AIP1, and PMAIP1), and notably include immune-related pathways suggestive of a response to various infectious diseases (C2, CFB, C4A, C4B, C1S, C1R, C3, HLA-DRA, HLA-DMA, HLA-DOA, and HLA-DPB1). These results confirm the essential regulation of impaired insulin signaling and oxidative phosphorylation in the muscle of T2DM patients, and provide novel molecular insights into the pathophysiological mechanisms of T2DM.