A polymorphism in the porcine miR‐208b is associated with microRNA biogenesis and expressions of SOX‐6 and MYH7 with effects on muscle fibre characteristics and meat quality

Abstract

MicroRNAs (miRNAs) encoded by the myosin heavy chain (MHC) genes are muscle-specific miRNAs (myomiRs) and regulate the expression of MHC isoforms in skeletal muscle. These miRNAs have been implicated in muscle fibre types and their characteristics by affecting the heterogeneity of myosin. In pigs, miR-208b and miR-499 are embedded in introns of MYH7 and MYH7b respectively. Here, we identified a novel single nucleotide polymorphism (SNP) in intron 30 of MYH7 by which porcine miR-208b is encoded. Based on the association study using a total of 487 pigs including Berkshire (n = 164), Landrace (n = 121) and Yorkshire (n = 202), the miR-208b SNP (g.17104G>A) had significant effects on the proportions of types I and IIb fibre numbers (P < 0.010) among muscle fibre characteristics and on drip loss (P = 0.012) in meat quality traits. Moreover, the SNP affected the processing of primary miR-208b into precursor miR-208b with a marginal trend towards significance (P = 0.053), thereby leading to significant changes in the levels of mature miR-208b (P = 0.009). These SNP-dependent changes in mature miR-208b levels were negatively correlated with the expression levels of its target gene, SOX-6 (P = 0.038), and positively associated with the expression levels of its host gene, MYH7 (P = 0.046). Taken together, our data suggest that the porcine miR-208b SNP differentially represses the expression of SOX-6 by regulating miRNA biogenesis, thereby affecting the expression of MYH7 and the traits of muscle fibre characteristics and meat quality.

Differences in Circulating microRNAs between Grazing and Grain-Fed Wagyu Cattle Are Associated with Altered Expression of Intramuscular microRNA, the Potential Target PTEN, and Lipogenic Genes

“…Our previous studies revealed that skeletal muscle-specific miRNAs, namely miR-1, miR-133a/b, miR-206, miR-208a/b, miR-496, and miR-499, were abundant in the muscles of JB cattle [4], whereas none of them was detected in the plasma profiles except for a modest miR-486 content [24]. In contrast, the plasma samples were enriched with moderate concentrations of miRNAs associated with adipose tissue, such as miR-15a, miR-19a/b, miR-21, miR-27b, miR-92a/b, miR-103, miR-106a/b, miR-107, miR-125b, and miR-150 [11,12]. It is especially notable that the bovine-specific miR-1584-5p, miR-2305, miR-2412, and miR-2478, most of which are associated with energy metabolism [32], were highly enriched in the plasma samples of both groups in the present study.…”

“…In addition, skeletal muscle miR-206 and miR-208b expression is temporally upregulated, accompanying the downregulation of myosin heavy chain 2x expression, in grazing Japanese Shorthorn (JSH) cattle whereas the expression did not change in housed [7]. Since muscle physiological property determined by the muscle type have impacts on meat quality [8–10], potential association of miRNAs with muscle gene expression and mat quality have been focused recently [11–13]. Besides skeletal muscle, transcriptomic miRNA analyses in mammalian adipose tissue have unveiled their roles in fat accumulation.…”

An analysis of <i>MYH7</i> single nucleotide polymorphism (g.7:75667956G>A) in relation to growth and carcass traits in pigs

“…This finding is in contrast to the results of our and Kim et al (2015) studies and may be associated with the different age of pig used in the experiments. In our study, as well as in the experiment of Kim et al (2015) pigs were at the slaughter age, however in the study of Komatsu et al (2016) animals aged 23 days. Moreover growth rate groups were selected based on the expected breeding value not direct phenotypic data.…”

“…Highest values for these traits were noticed in GG genotypes (P ≤ 0.05 or P ≤ 0.01). Kim et al (2015) in previous study showed that AA genotype is associated with highest expression of MYH7 gene in the longissimus dorsi muscle tissue of Berkshire pigs. Komatsu et al (2016), however, stated that high expression of MYH7 gene in longissimus dorsi is associated with extremely low growth rate in Landrace pigs.…”

“…miR-208b locus is situated, however, in intron 30 (Luo et al, 2012;Aken et al, 2016). Kim et al (2015) identified in this intron single nucleotide polymorphism (SNP) -g.17104G>A (updated location: g.7:75667956G>A) that is located 105 bp downstream of pre-miR-208b. The study showed that G to A allele substitution may induce a considerable change in the secondary structure of primary miR-208b, leading to differential expression of precursor and mature miR-208b between genotypes.…”