Porcine methionine sulfoxide reductase B3：molecular cloning, tissue-specific expression profiles, and polymorphisms associated with ear size in Sus scrofa

Background: In Sus scrofa, methionine sulfoxide reductase B3(MSRB3) is a crucial candidate gene for ear size, and an important conformational trait of pig breeds. However, challenges in MSRB3 c DNA amplification have prevented further identification of MSRB3 allelic variants influencing pig ear size.Results: We cloned a full-length c DNA sequence of porcine MSRB3 by rapid-amplification of c DNA ends. The3,765-bp gene contained a 5’-untranslated region(UTR)(190 bp), a coding region(552 bp), and a 3’-UTR(3,016 bp) and shared 84 %, 84 %, 87 %, 86 %, and 70 % sequence identities with human, orangutan, mouse, chicken, and zebrafish,respectively. The gene encoded a 183-amino acid protein, which shared 88 %, 91 %, 89 %, 86 %, and 67 % identities with human, orangutan, mouse, chicken, and zebrafish, respectively. Tissue expression analysis using q RT-PCR revealed that MSRB3 was expressed in the heart, liver, lung, kidney, spleen, ear, muscle, fat, lymph, skeletal, and hypothalamic tissues. Three single nucleotide polymorphisms(SNPs) were identified in MSRB3: c.-735 C > T in the 5’ flanking region,c.2571 T > C in the 3’-UTR, and a synonymous mutation of c.484 T > C in the coding region. The SNPs c.-735 C > T and c.2571 T > C were significantly associated with ear size in a Large White × Minzhu F2 population other than in Beijing Black pigs. Subsequently, at SNP c.-735 C > T, the m RNA of MSRB3 was significantly higher expressed in ears of individuals with the TT genotype(Minzhu) than those with CC(Large White).Conclusions: The porcine MSRB3 owned a 3,765-bp full-length c DNA sequence and was detected to express in ear tissue. Two SNPs of this gene were shown to be significantly associated with ear size in a Large White × Minzhu intercross population instead of Beijing Black pig population. What’s more, the individuals with higher m RNA expression of MSRB3 have larger ear sizes. These results provide useful information for further functional analyses of MSRB3 influencing ear size in pigs.