Circ-06958 Is Involved in Meat Quality by Regulating Cell Proliferation Through miR-31-5p/AK4 Axis in Pigs

Circular RNA (CircRNA) can regulate gene expression through acting as a competitive endogenous RNA (ceRNA), thus becoming involved in various biological processes. However, little was known about the role of circRNA in the formation of meat quality in pigs. Here, circRNAs were first characterized in muscles with differential meat quality and myofiber composition, longissimus thoracis, and semitendinosus muscles, with RNA-sequencing (RNA-seq). A total of 1126 differentially expressed circRNAs were identified. Among them, Circ-06958 is highly expressed in both muscles. Circ-06958 originated from Long-chain acyl-CoA synthetase 1 (<i>ACSL1</i>), a gene involved in muscle development. Circ-06958 was then characterized experimentally for the first time. Next, it was revealed that Circ-06958 increased proliferation of muscle cells, including porcine skeletal muscle satellite cells (PMSCs) and C2C12 myoblasts, by promoting cell cycle progression. Circ-06958 was mainly localized in cytoplasm, indicating it can function as a ceRNA. A regulatory axis Circ-06958/miR-31-5p/Adenylate Kinase 4 (<i>AK4</i>) axis was constructed with molecular biology techniques. Afterward, it was shown that miR-31-5p inhibited cell proliferation by affecting cell cycle progression in the two cells, while <i>AK4</i> increased it. We made it clear that Circ-06958 promoted muscle cell proliferation via the miR-31-5p/<i>AK4</i> axis. The results will contribute to further revealing the mechanisms through which meat quality generates.