miR-208b modulating skeletal muscle development and energy homeostasis through targeting distinct targets

Embryonic and neonatal skeletal muscles grow via the proliferation and fusion of myogenic cells, whereas adult skeletal muscle adapts largely by remodeling pre-existing myofibers and optimizing metabolic balance. It has been reported that miRNAs played key roles during skeletal muscle development through targeting different genes at post-transcriptional level. In this study, we show that a single miRNA (miR-208b) can modulate both the myogenesis and homeostasis of skeletal muscle by distinct targets. As results, miR-208b accelerates the proliferation and inhibits the differentiation of myogenic cells by targeting the E-protein family member transcription factor 12 (TCF12). Also, miR-208b can stimulate fast-to-slow fiber conversion and oxidative metabolism program through targeting folliculin interacting protein 1 (FNIP1) but notTCF12 gene. Further, miR-208b could active the AMPK/PGC-1a signaling and mitochondrial biogenesis through targeting FNIP1. Thus, miR-208b could mediate skeletal muscle development and homeostasis through specifically targeting of TCF12 and FNIP1.