Circular RNA screening identifies circMYLK4 as a regulator of fast/slow myofibers in porcine skeletal muscles
Abstract Background: The myofiber type is related to the quality of meat; specifically, slow-oxidized myofiber helps to increase the tenderness and juiciness of meat. An increasing number of studies have shown that circRNAs play a key role in skeletal muscle development. However, the key circRNAs that regulate myofiber types and their roles are still poorly understood.Results: A total of 40757 circRNAs were identified from the longissimus dorsi (LD) and the soleus (Sol) muscles, of which 10388 were co-expressed in the two muscles. Further analysis found 181 differentially expressed circRNAs in the LD compared with Sol. Functional enrichment analysis showed that target genes of differentially expressed circRNA-sponge miRNAs were enriched in the AMPK, FoxO and PI3K-Akt signaling pathways. In addition, we focused on a novel circRNA—circMYLK4. CircMYLK4 significantly increased the mRNA and protein levels of slow muscle marker genes and caused the flesh to turn red.Conclusion: Our study laid an essential foundation for further research on circRNAs in myofiber type conversion and the achievement of higher meat quality.