MicroRNA-494 plays a role in fiber type-specific skeletal myogenesis by targeting transcriptional coactivator p300 in human induced pluripotent stem cells

Human skeletal muscle fibers are classified into three types; Type I (slow muscle) rich in mitochondria and highly aerobic metabolism, Type IIx (fast muscle) highly dependent on glycolysis system, and Type IIa (medium type muscle). It is important to investigate the mechanisms of fiber type-specific skeletal myogenesis in a reliable human system, because of that the muscle fiber composition is closely related to the diseases, such as type 2 diabetes and sarcopenia. We and others have reported that, with the endurance exercise load, miR-494 downregulated in mouse gastrocnemius muscle and in human vastus lateralis. Transcriptional coactivator p300 has been reported to play a role in skeletal myogenesis via the activation of MyoD. We have established human skeletal myogenesis system using human induced pluripotent stem cells (hiPSCs) transefected with muscle-specific transcription factor (MyoD/Tet-ON), as we previously reported. In this study, we investigated the role of miR-494 and p300 in fiber type-specific skeletal myogenesis in hiPS-MyoD cells.