Circ<i>RIMKLB</i> promotes myoblast proliferation and inhibits differentiation by sponging <i>miR-29c</i> to release <i>KCNJ12</i>

Muscle development is a complex process that was regulated by many factors, among which non-coding RNAs (ncRNAs) play a vital role in regulating multiple life activities of muscle cells. Circular RNA (circRNA), a type of non-coding RNA with closed-loop structure, has been reported to affect multiple life processes. However, the roles of circRNAs on muscle development have not been fully elucidated. The present study aimed to determine whether and how circ<i>RIMKLB</i> affects muscle development. Our study revealed that circ<i>RIMKLB</i> promoted myoblast proliferation and inhibited differentiation. Besides, <i>miR-29</i>c was proved as a downstream target of circ<i>RIMKLB</i> using dual-luciferase reporter assay and RNA-binding protein immunoprecipitation (RIP) assay. Also, potassium inwardly rectifying channel subfamily J member 12 (<i>KCNJ12</i>) was identified as a novel target of <i>miR-29c</i> via dual-luciferase reporter assay, quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), and western blot. Circ<i>RIMKLB</i> and <i>KCNJ12</i> were both proved to regulate cell cycle on muscle regeneration after injury <i>in vivo</i>. In conclusion, we demonstrated that circ<i>RIMKLB</i> sponged <i>miR-29c</i>, releasing <i>KCNJ12</i> to regulate myoblast proliferation and differentiation and regulating cell cycle during muscle regeneration after injury <i>in vivo</i>.