MicroRNA-106b induces mitochondrial dysfunction and insulin resistance in C2C12 myotubes by targeting mitofusin-2

Abstract

MicroRNA-106b (miR-106b) is reported to correlate closely with skeletal muscle insulin resistance and type 2 diabetes. The aim of this study was to identify an mRNA targeted by miR-106b which regulates skeletal muscle insulin sensitivity. MiR-106b was found to target the 3' untranslated region (3' UTR) of mitofusin-2 (Mfn2) through miR-106b binding sites and to downregulate Mfn2 protein abundance at the post-transcriptional level by luciferase activity assay combined with mutational analysis and immunoblotting. Overexpression of miR-106b resulted in mitochondrial dysfunction and insulin resistance in C2C12 myotubes. MiR-106b was increased in insulin-resistant cultured C2C12 myotubes induced by TNF-α, and accompanied by increasing Mfn2 level, miR-106b loss of function improved mitochondrial function and insulin sensitivity impaired by TNF-α in C2C12 myotubes. In addition, both overexpression and downregulation of miR-106b upregulated peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and estrogen-related receptor (ERR)-α expression. MiR-106b targeted Mfn2 and regulated skeletal muscle mitochondrial function and insulin sensitivity. Therefor, Inhibition of miR-106b may be a potential new strategy for treating insulin resistance and type 2 diabetes.

Keywords: 3′ UTR; 3′ untranslated region; C2C12 myotubes; DHE; DMEM; Dulbecco’s modified Eagle’s medium; ECL; ERR-α; FACS; GLUT4; IRS-1; Insulin resistance; Mfn2; MicroRNA-106b; Mitochondrial function; Mitofusin-2; PGC-1α; Peroxisome proliferator-activated receptor gamma coactivator-1α; ROS; SDS-PAGE; T2DM; TNF-α; dihydroethidium; enhanced chemiluminescence; estrogen-related receptor-α; fluorescence assisted cell sorting; glucose transporter 4; insulin receptor substrate 1; miR-106b; miRNAs; microRNA-106b; microRNAs; mitochondrial DNA; mitochondrial membrane potential; mitofusin-2; mtDNA; peroxisome proliferator-activated receptor gamma coactivator-1α; reactive oxygen species; sodium dodecyl sulfate-polyacrylamide electrophoresis; tumor necrosis factor-α; type 2 diabetes mellitus; ΔΨ.