Comparative Analysis of miRNA Expression Profiles in Skeletal Muscle of Bian Chickens at Different Embryonic Ages.

MicroRNAs (miRNAs) are widely involved in the growth and development of skeletal muscle through the negative regulation of target genes. In order to screen out the differentially expressed miRNAs (DEMs) associated with skeletal muscle development of Bian chickens at different embryonic ages, we used the leg muscles of fast-growing and slow-growing Bian chickens at the 14th and 20th embryonic ages (F14, F20, S14 and S20) for RNA-seq. A total of 836 known miRNAs were identified, and 121 novel miRNAs were predicted. In the F14 vs. F20 comparison group, 127 DEMs were screened, targeting a total of 2871 genes, with 61 miRNAs significantly upregulated and 66 miRNAs significantly downregulated. In the S14 vs. S20 comparison group, 131 DEMs were screened, targeting a total of 3236 genes, with 60 miRNAs significantly upregulated and 71 miRNAs significantly downregulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the predicted target genes were significantly enriched in 706 GO terms and 6 KEGG pathways in the F14 vs. F20 group and 677 GO terms and 5 KEGG pathways in the S14 vs. S20 group. According to the interaction network analysis, we screened five coexpressed DEMs (gga-miR-146a-3p, gga-miR-2954, gga-miR-34a-5p, gga-miR-1625-5p and gga-miR-18b-3p) with the highest connectivity degree with predicted target genes between the two comparison groups, and five hub genes (HSPA5, PKM2, Notch1, Notch2 and RBPJ) related to muscle development were obtained as well. Subsequently, we further identified nine DEMs (gga-let-7g-3p, gga-miR-490-3p, gga-miR-6660-3p, gga-miR-12223-5p, novel-miR-327, gga-miR-18a-5p, gga-miR-18b-5p, gga-miR-34a-5p and gga-miR-1677-3p) with a targeting relationship to the hub genes, suggesting that they may play important roles in the muscle development of Bian chickens. This study reveals the miRNA differences in skeletal muscle development between 14- and 20-day embryos of Bian chickens from fast- and slow-growing groups and provides a miRNA database for further studies on the molecular mechanisms of the skeletal muscle development in Bian chickens.