A-to-I RNA editing impairs miR-376b-3p repression of RYBP in skeletal muscle satellite cells

Adenosine-to-inosine RNA editing can affect miRNA activity, but its role in skeletal muscle development remains unclear. Here, we investigated miR-376b-3p in goat skeletal muscle satellite cells (MuSCs), which undergo adenosine deaminase acting on RNA 1-mediated editing at the sixth nucleotide of its seed sequence. Although both isoforms were detected, the unedited miR-376b-3p (miR-WT) predominated over the edited form (miR-E) during skeletal muscle development and MuSC differentiation. Functional assays revealed that miR-WT, but not the miR-E type, enhanced MuSC proliferation and differentiation by upregulating Pax7, PCNA, MyoD, MyoG, and MyHC, and promoting myotube formation. Furthermore, we identified Ring1 and YY1 binding protein (RYBP), a repressor of myogenesis, as a direct target of miR-WT. Overexpression of RYBP inhibited MuSC differentiation, whereas miR-WT relieved this repression through direct binding to the RYBP 3'UTR. In contrast, miR-E failed to target RYBP and lacked promyogenic activity. These findings demonstrate that adenosine-to-inosine editing attenuates the function of miR-376b-3p, highlighting its role as a post-transcriptional regulator of skeletal muscle development.