The mechanism of transcriptional regulation of Mullerian inhibiting substance in Japanese flounder (Paralichthys olivaceus)

Mullerian inhibiting substance (MI S), also known as anti-Mullerian hormone (AMH ), is a glycoprotein belonging to the transforming growth factor b superfamily. In Japanese flounder (Paralichthys olivaceus), a teleost fish that has XX(female)/XY(male) sex determination system, mis mRNA is expressed in the somatic cells of the gonads during gonadal sex differentiation. However, the mechanism of transcriptional regulation of mis gene in the flounder has yet to be clarified. To elucidate the mechanism of transcriptional regulation of mis gene in Japanese flounder, we first isolated 5'-flanking region of mis gene in the flounder. Next, we investigated whether the mis gene expression was regulated by the steroidogenic factor 1 (SF1) and the liver receptor homologue 1 (LRH1), orphan receptors that are involved in the expression of MIS gene in mammals. As a result, electrophoretic mobility shift assay showed that both SF1 and LRH1 bound to a potential Ad4 site of the mis promoter region in Japanese flounder. Therefore, we suggest that SF1 and LRH1 are directly involved in transcriptional regulation of mis gene in Japanese flounder.