Mutations in the Myostatin gene leading to hypermuscularity in mammals: indications for a similar mechanism in fish?

The transforming growth factor beta (TGF-beta) superfamily encodes secreted factors that are important in regulating embryonic development and tissue homeostatis in adults. Myostatin (MSTN, encoded by MSTN) or 'growth and differentiation factor 8', a member of this superfamily, is a negative regulator of skeletal muscle growth and is highly conserved among animal species. In 1997, a mutation associated with the so-called double-muscling phenotype in cattle was found in the MSTN gene. During the years following the discovery of the first MSTN mutation, other mutations were found in cattle and other mammalian species, and MSTN became one of the most thoroughly studied genes in animals. The aim of this review is mainly to describe the functional mutations located in the MSTN genes of several mammalian species, leading to double muscling in these animals. Furthermore, in light of the increasing importance of fish genetics, the possibility of functional mutations in piscine MSTN with a similar effect as in mammals, and a genetic model for MSTN research in fish, will also be discussed.