Single nucleotide polymorphisms in the upstream regulatory region alter the expression of myostatin.

The expression of the gene encoding myostatin (MSTN), the product of which is a negative regulator of skeletal muscle growth and development in mammals, is regulated by many cis-regulatory elements, including enhancer box (E-box) motifs. While E-box motif mutants of MSTN exhibit altered expression of myostatin in many animal models, the phenotypes of these mutations in chicken are not investigated. In this study, we cloned and sequenced the full encoded DNA sequence of MSTN gene and its upstream promoter region in Wenshang Luhua chicken breed. After analysis of the sequence, 13 E-box motifs were identified in the MSTN promoter region, which were denoted by E1 to E13 according to their positions in the region. Although many single nucleotide polymorphisms (SNPs) were revealed in the MSTN promoter region, only two SNPs were in the E-boxes, i.e., the first nucleotide of the E3 and the fifth nucleotide of E4. The effects of these two polymorphisms on the expression of MSTN gene were explored both with MSTN-GFP reporter constructs in vitro and real-time PCR in vivo. The results suggested that the E-boxes in the chicken MSTN promoter region are involved in the regulation of myostatin expression and the polymorphisms in E3 and E4 altered the expression of myostatin.