CircPLXNA2 Affects the Proliferation and Apoptosis of Myoblast through circPLXNA2/gga-miR-12207-5P/MDM4 Axis.

CircRNAs are newly identified special endogenous RNA molecules that covalently close a loop by back-splicing with pre-mRNA. In the cytoplasm, circRNAs would act as molecular sponges to bind with specific miRNA to promote the expression of target genes. However, knowledge of circRNA functional alternation in skeletal myogenesis is still in its infancy. In this study, we identified a circRNA-miRNA-mRNA interaction network in which the axis may be implicated in the progression of chicken primary myoblasts' (CPMs) myogenesis by multi-omics (i.e., circRNA-seq and ribo-seq). In total, 314 circRNA-miRNA-mRNA regulatory axes containing 66 circRNAs, 70 miRNAs, and 24 mRNAs that may be relevant to myogenesis were collected. With these, the circPLXNA2-gga-miR-12207-5P-MDM4 axis aroused our research interest. The circPLXNA2 is highly differentially expressed during differentiation versus proliferation. It was demonstrated that circPLXNA2 inhibited the process of apoptosis while at the same time stimulating cell proliferation. Furthermore, we demonstrated that circPLXNA2 could inhibit the repression of gga-miR-12207-5p to MDM4 by directing binding to gga-miR-12207-5p, thereby restoring MDM4 expression. In conclusion, circPLXNA2 could function as a competing endogenous RNA (ceRNA) to recover the function of MDM4 by directing binding to gga-miR-12207-5p, thereby regulating the myogenesis.