The role of microRNAs in skeletal muscle health and disease

Abstract

Over the last decade non-coding RNAs have emerged as importance regulators of gene expression. In particular, microRNAs are a class of small RNAs of ∼ 22 nucleotides that repress gene expression through a post-transcriptional mechanism. MicroRNAs have been shown to be involved in a broader range of biological processes, both physiological and pathological, including myogenesis, adaptation to exercise and various myopathies. The purpose of this review is to provide a comprehensive summary of what is currently known about the role of microRNAs in skeletal muscle health and disease.

Figure 1

The microRNA network that is involved in regulating myogenesis. Major myogenic regulatory factors (MFRs) and muscle-enriched miRNAs are indicated by a box. Signaling pathways that promote myogenesis (either proliferation or differentiation) are denoted by green text. Signaling pathways that inhibit myogenesis are denoted by red text. Green arrows (←) indicate direct upregulation of a gene or miRNA. Blunt red arrows (┴) indicate direct down-regulation of a gene or miRNA. Black arrows indicate general stimulation of a biological process or pathway.

Figure 2

Temporal changes of microRNA levels in either skeletal muscle or circulation in response to aerobic exercise. The model is based on published data examining the temporal response of the myomiRs in human participants. Generally, miR-1 and −133 demonstrate an increase in both skeletal muscle and the circulation in response to an acute endurance exercise bout, however the increase in circulation may only occur following intense bouts. Conversely, following training these miRNAs, along with miR-206, appear to be down-regulated. In the circulation, training results in minimal change in these miRNAs, however miR-133 may become down-regulated.