Kim J M, Lim K S, Hong J S, Kang J H, Lee Y S, Hong K C
College of Life Sciences and Biotechnology, Korea University, Seoul, 136-713, South Korea; Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, University of Queensland, Brisbane, Qld, 4072, Australia.
Anim Genet. 2015 Feb;46(1):73-7. doi: 10.1111/age.12255. Epub 2014 Dec 22.
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.
由肌球蛋白重链（MHC）基因编码的微小RNA（miRNA）是肌肉特异性miRNA（肌miR），可调节骨骼肌中MHC亚型的表达。这些miRNA通过影响肌球蛋白的异质性，与肌纤维类型及其特性有关。在猪中，miR-208b和miR-499分别嵌入MYH7和MYH7b的内含子中。在此，我们在MYH7的第30内含子中鉴定出一个新的单核苷酸多态性（SNP），猪miR-208b由此编码。基于对总共487头猪的关联研究，包括伯克夏猪（n = 164）、长白猪（n = 121）和约克夏猪（n = 202），miR-208b SNP（g.17104G>A）对肌肉纤维特征中I型和IIb型纤维数量的比例（P < 0.010）以及肉质性状中的滴水损失（P = 0.012）有显著影响。此外，该SNP影响初级miR-208b加工成前体miR-208b，具有边缘显著趋势（P = 0.053），从而导致成熟miR-208b水平发生显著变化（P = 0.009）。成熟miR-208b水平的这些SNP依赖性变化与其靶基因SOX-6的表达水平呈负相关（P = 0.038），与其宿主基因MYH7的表达水平呈正相关（P = 0.046）。综上所述，我们的数据表明，猪miR-208b SNP通过调节miRNA生物合成差异抑制SOX-6的表达，从而影响MYH7的表达以及肌纤维特征和肉质性状。
