Effects of sex steroids on expression of myostatin in rare minnow, Gobiocypris rarus

Abstract

Myostatin (MSTN), belonging to transforming growth factor (TGF) β superfamily, is a negative regulator of muscular development in mammals and fish. The expression of MSTN can be regulated by hormone and environmental factors. Sex steroids, androgen and estrogen can affect sex differentiation and also can affect muscle development. However, few documents are concerned about the effects of sex steroids on MSTN expression in fish. Here, we report the cloning and expressional analyses of MSTN in rare minnow (Gobiocypris rarus), an emerging model fish in China. The MSTN cDNA of rare minnow that has an open reading frame of 1128 base pairs (bp) encodes a protein of 375 amino acids belonging to fish MSTN1 with typical structures like a prodomain, a mature MSTN domain, a conservative hydrolytic site (RIRR) and 9 conservative cysteine residues in mature MSTN. MSTN was detectable in all the examined tissues by RT-PCR that indicated the ubiquitous expression of MSTN in adult tissues. MSTN was detectable from zygote till hatching showed the maternal deposition of MSTN mRNA from oocytes and continuous expression during embryogenesis. Treatment of rare minnow with 1μg/L 17α-methyl testosterone (MT) or 17α-ethynyl estradiol (EE2) significantly impaired the body growth and increased the expression of MSTN mRNA detected by quantitative real time PCR. However, low dosage of MT (10ng/L) had no significant effects on body growth and MSTN expression. The results suggest that the effects of exogenous sex steroids on growth can be mediated through MSTN. It is also suggested that low concentration of sex steroid (less than10ng/L) may have little effect on MSTN expression.