Identification of circulating miRNA involved in meat yield of Korean cattle. Bos taurus

Cattle plays an important role in providing essential nutrients through meat production. Thus, we focused on epigenetic factors associated with meat yield. To investigating circulating miRNAs that are involved with meat yield and connect biofluids and longissimus dorsi (LD) muscle in Korean cattle, we performed analyses of the carcass characteristics, miRNA array, qPCR, and bioinformatics. Carcass characteristics relative to the yield grade (YG) showed that the yield index and rib eye area were the highest, whereas the backfat thickness was the lowest for YG A (equal to high yield grade) cattle among the three YGs. miRNA array sorted the circulating miRNAs that connect biofluids and LD muscle. miRNA qPCR showed that miR-15a (r = 0.84), miR-26b (r = 0.91), and miR-29c (r = 0.92) had positive relationships with biofluids and LD muscle. In YG A cattle, miR-26b was considered to be a circulating miRNA connecting biofluids and LD muscle because the target genes of miR-26b was more involved with myogenesis. Then, miR-26b targeted genes, DIAPH3 and YOD1 were downregulated in YG A cattle. Our results suggest that miR-15a, miR-26b, and miR-29c are upregulated in biofluids and LD muscle whereas, downregulation of DIAPH3 and YOD1 in the LD muscle of finishing cattle steers. Overall design: 29 or 30 month Korean cattle steers were classified by yield grade(YG) A, B, and C. miRNA expression patterns for exosome and LD muscle were compared among YGs.