Abstract:

The study aimed to clarify the expression of miRNA in bovine skeletal muscle tissues at different developmental stages and screen the key miRNAs affecting bovine skeletal muscle development. The present study conducted RNA sequencing analysis on muscle tissues from 3-month-old and 6-month-old embryos, as well as 9-month-old fetal muscle tissues obtained through embryo splitting and embryo transfer techniques, all originating from the same source with highly consistent genetic backgrounds. Bioinformatics approaches were applied to screen for differentially expressed miRNAs, followed by target gene prediction and functional enrichment analysis. Compared with muscle tissue at 3 months old, 262 differentially expressed miRNAs (130 up-regulated and 132 down-regulated) were screened in muscle tissue at 6 months old; Compared with muscle tissue at 6 months old, 397 differentially expressed miRNAs (199 up-regulated and 198 down-regulated) were screened in muscle tissue at 9 months old; And compared with muscle tissue at 3 months old, 448 differentially expressed miRNAs (224 up-regulated and 224 down-regulated) were screened in muscle tissue at 9 months old. Meanwhile, 3 854, 7 434 and 8 167 target genes were predicted, respectively. Functional annotation and pathway analysis of the target genes revealed that the differentially expressed miRNAs between the 6-month and 3-month stages were predominantly involved in 5 muscle development-related pathways, including cytoskeleton in muscle cells, focal adhesion, autophagy-animal, etc. Similarly, the differentially expressed miRNAs between the 9-month and 6-month stages were primarily associated with 4 muscle development-related pathways, such as cytoskeleton in muscle cells, focal adhesion and growth hormone synthesis, secretion and action, etc. Furthermore, the differentially expressed miRNAs between the 9-month and 3-month stages were significantly enriched in 6 muscle development-related pathways, including cytoskeleton in muscle cells, focal adhesion, regulation of the actin cytoskeleton, etc. A regulatory network of differentially expressed miRNAs and functional target genes associated with skeletal muscle development was constructed, identifying 38 miRNAs, including bta-miR-139, bta-miR-499, bta-miR-7, bta-miR-148a and bta-miR-204, which might play regulatory roles in the growth and development of bovine skeletal muscle at different stages. The results of this study provide an important theoretical basis for in depth understanding of the molecular mechanism of bovine skeletal muscle development, and also provide basic data for subsequent miRNA research on bovine skeletal muscle.

Key words: cattle, skeletal muscle development, miRNA sequencing, target gene prediction