The MyomiR network in skeletal muscle plasticity

Abstract

MicroRNA (miRNA) are a class of noncoding RNA involved in regulating gene expression by a posttranscriptional mechanism. Based on work from our laboratory, this review explores the hypothesis that a recently described muscle-specific miRNA, myomiR, network has a central role in the regulation of skeletal muscle plasticity by coordinating changes in fiber type and muscle mass in response to altered contractile activity.

Figure

The muscle-specific microRNA (myomiR) network in skeletal muscle. A schematic diagram of the myomiR network in skeletal muscle. MiRNA-208b and miR-499 are each encoded by an intron (31 and 19, respectively) within myosin heavy-chain (MHC) (Myh) genes 7 and 7b, respectively. Myh7 encodes the β-MHC protein that is expressed highly in slow-twitch skeletal muscle. Both miR-208b and miR-499 have been shown experimentally to regulate the expression of transcriptional repressors (Sox6, Purβ, and Sp3) of β-MHC expression. Multiple lines of evidence indicate that Sox6 is a major repressor of β-MHC expression in skeletal muscle. In addition to regulating fiber type, miR-208b and miR- 499 have been shown to regulate myostatin (Mstn) expression, suggesting that the myomiR network may coordinate changes in fiber type and muscle mass.