Polymorphic microRNA-target interactions: a novel source of phenotypic variation
Texel sheep are renowned for their exceptional meatiness. To identify the genes underlying this economically important racial feature we have performed a whole genome scan in a Romanov x Texel F2 population. A quantitative trait locus (QTL) with major effect on muscle mass was mapped to chromosome 2 and subsequently fine-mapped to a chromosome interval encompassing the myostatin (MSTN) gene. We herein demonstrate that the MSTN allele of Texel sheep is characterized by a G to A transition in the 3’UTR that creates a target site for mir1 and mir206, miRNAs which are highly expressed in skeletal muscle. This causes translational inhibition of the myostatin gene and hence contributes to the muscular hypertrophy of Texel sheep. Analysis of SNPs databases for human and mice, demonstrates that mutations creating or destroying putative miRNA target sites are abundant and might be important effectors of phenotypic variation.