Transition from physical activity to inactivity increases skeletal muscle miR-148b content and triggers insulin resistance.

This study investigated miR-148b as a potential physiological actor of physical inactivity-induced effects in skeletal muscle. By using animal and human protocols, we demonstrated that the early phase of transition toward inactivity was associated with an increase in muscle miR-148b content, which triggered the downregulation of NRAS and ROCK1 target genes. Using human myotubes, we demonstrated that overexpression of miR-148b decreased NRAS and ROCK1 protein levels, and PKB phosphorylation and glucose uptake in response to insulin. Increase in muscle miR-148b content might thus participate in the decrease in insulin sensitivity at the whole body level during the transition toward physical inactivity.