Myostatin promoter analysis and expression pattern in pigs

Myostatin, a member of the transforming growth factor β superfamily, is expressed in skeletal muscle both pre- and postnatally. Myostatin prevents excessive differentiation of myoblasts during muscular development. Loss of function mutations to Myostatin can produce supernumerary muscle fibers, resulting in muscle hyperplasia. Despite the large effects of Myostatin mutations in different cattle breeds, no mutations with major effects have been described in pigs. In this study, we identified single nucleotide polymorphisms (SNPs) in the promoter region of the Myostatin gene, investigated allele frequencies, analyzed gene expression pattern in the longissimus dorsi muscle and performed statistical associations with performance, carcass composition and meat quality traits in pigs. Pigs from different breeds and commercial lines were included in these analysis. Two SNPs, G-847A and A-835G, in complete linkage disequilibrium were identified. Their allele and genotypic frequencies were analyzed and an association study conducted. Determination of Myostatin gene expression was obtained by semi-quantitative real-time PCR and correlated to phenotypic traits. The SNPs were associated (P < 0.1) to growth and meat quality traits in two commercial populations. The expression of Myostatin mRNA in muscle was also correlated (P < 0.1) to growth and meat quality traits, despite the fact that the SNPs were not significantly associated with the expression levels. Despite the importance of Myostatin in muscle development, little is known about its regulation and role in the myogenic process. The data presented here demonstrate the importance of this information to commercial pig production.