The miR‐696 contributes to insulin resistance by reducing mitochondrial function and antioxidant capacity in skeletal muscle cells

Abstract

Insulin resistance is associated to type II diabetes but its mechanism is not fully understood. Micro‐RNAs have been described as non‐coding molecules associated with post‐transcriptional regulation of several physiological processes including diabetes. We have observed that miR‐696 is regulated in an opposite manner compared to PGC‐1α leading to a proposition that the miR‐696 may be involved to insulin resistance. Mice mioblast cells (C2C12) were treated with palmitic acid (500μM) for 24 h. The insulin resistance was confirmed by evaluation of Akt phosphorylation after insulin incubation by western blot. Expression of mature miR‐696 was evaluated by real‐time RT‐PCR using TaqMan® MicroRNA Assay. The expression of microRNAs was normalized with the SnoR‐202. Gene expression of PGC1α was evaluated by real time RT‐PCR using Sybr Green. Analysis of oxygen consumption was performed by oxygraph (Hansatech) using CCCP and oligomycin as controls. We observed that PGC1α transcription was markedly reduced in insulin resistant cells, an effect that was reflected by a low mitochondrial respiration, reduced antioxidant capacity and elevated miR‐696 level. In contrast, the PGC1α transcription was markedly elevated after AICAR treatment as reflected by elevated mitochondrial respiration and antioxidant capacity and low miR‐696 level. Interestingly, the inhibition of miR‐696 transcription in insulin resistant cells re‐established the insulin response, PGC1α transcription and mitochondrial function indicating an association of miR‐696 and mitochondrial biogenesis. Therefore, we are suggesting that miR‐696 contributes to insulin resistance reducing mitochondrial biogenesis and mitochondrial function in skeletal muscle cells.