MicroRNAs (miRNAs) regulate gene expression by repressing target genes at the post-transcriptional level. Since miRNAs have unique expression profiles in different tissues, they provide pivotal regulation of many biological processes. The current study defined miRNA expression during murine myogenic progenitor cell (MPC) proliferation and differentiation to identify miRNAs involved in muscle regeneration. Muscle related gene expression analyses revealed that the time course and expression of myosin heavy chain (MHC) and the transcription factors (Myf5, MyoD, myogenin and Pax7) were similar during in vitro MPC proliferation/differentiation and in vivo muscle regeneration. Comprehensive profiling revealed that 139 or 16 miRNAs were significantly changed >2-fold [False Discovery Rate (FDR)<0.05] during MPC differentiation or proliferation, respectively; cluster analyses revealed 5 distinct patterns of miRNA expression during the time course of MPC differentiation. Not unexpectedly, the largest miRNA changes occurred in muscle specific miRNAs (miR-1, -133a and -499) which were up-regulated greater than 10-fold during MPC differentiation (FDR<0.01). However, several previously unreported miRNA were differentially expressed including miR-10b, -335-3p, and -682. Interestingly, the temporal patterns of miR-1, -499, and -682 expression during in vitro MPC proliferation/differentiation were remarkably similar to that observed during in vivo muscle regeneration. Moreover, in vitro inhibition of miR-682, the only miRNA up-regulated in proliferating, compared to quiescent MPC, led to decreased MPC proliferation, further validating our in vitro assay system for the identification of miRNAs involved in muscle regeneration. Thus, the differentially expressed miRNAs identified in the current study could represent new regulatory elements in MPC proliferation and differentiation.

  • microRNA
  • myogenic progenitor cell
  • muscle regeneration
  • muscle differentiation
  • satellite cell