The microRNA miR-696 regulates PGC-1α in mouse skeletal muscle in response to physical activity

Aoi W, Naito Y, Mizushima K, Takanami Y, Kawai Y, Ichikawa H, Yoshikawa T. The microRNA miR-696 regulates PGC-1 alpha in mouse skeletal muscle in response to physical activity. Am J Physiol Endocrinol Metab 298: E799-E806, 2010. First published January 19, 2010; doi:10.1152/ajpendo.00448.2009.-MicroRNAs (miRNAs) are small noncoding RNAs involved in posttranscriptional gene regulation that have been shown to be involved in growth, development, function, and stress responses of various organs. The purpose of this study was to identify the miRNA response to physical activity, which was related to functions such as nutrient metabolism, although the miRNAs involved are currently unknown. C57BL/6 mice were divided into exercise and control groups. The exercise group performed running exercise, with a gradual increase of the load over 4 wk. On the other hand, to examine the effect of muscle inactivity, the unilateral hindlimbs of other mice were fixed in a cast for 5 days. Microarray analysis for miRNA in gastrocnemius revealed that miR-696 was markedly affected by both exercise and immobilization, showing opposite responses to these two interventions. Peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1 alpha), which was increased by exercise and decreased by immobilization in the protein level, was predicted as a target regulated by miR-696. In cultured myocytes, intracellular miR- 696 variation led to negative regulation of PGC-1 alpha protein along with the expression of mRNAs for downstream genes. In addition, we found decreases in the biogenesis of mitochondria and fatty acid oxidation in miR-696-overexpressing myocytes compared with normal control myocytes. These observations demonstrate that miR- 696 is a physical activity-dependent miRNA involved in the translational regulation of PGC-1 alpha and skeletal muscle metabolism in mice.