Hepatic expression profiles of three subtypes of vitellogenin and estrogen receptor during vitellogenesis in cultured female yellowtail

•Three vitellogenin and estrogen receptor subtypes were cloned from female liver.•All vitellogenins and estrogen receptor α were predicted to be estrogen-responsive.•All estrogen receptors are potentially involved in vitellogenin transcription.•Estrogen receptor α is considered a bottleneck in vitellogenesis. Estradiol-17β (E2) promotes the transcription of vitellogenin (Vtg) via nuclear estrogen receptor (ER). Three Vtg (VtgAa, VtgAb, and VtgC) and ER subtypes (ERα, ERβ1, and ERβ2) have been reported in perciform fish; however, the relationship between the transcriptional regulation of Vtg and ER subtypes remains unclear. Molecular characterization was performed and the expression profiles of vtg and er subtypes were investigated to elucidate mechanisms of synthesis of vtg subtypes in yellowtail, Seriola quinqueradiata. Primary structures and promoter regions were revealed in three subtypes of vtg and er, and all the vtg subtypes and erα were presumed to be estrogen-responsive genes. When all vtg subtypes were expressed significantly in the liver, hepatic expression levels of all the er subtypes also increased. Conversely, although plasma E2 concentrations did not change significantly, the concentrations were high at the same time. Hepatic expression levels of all the vtg subtypes were highly correlated with hepatic erα, rather than with hepatic erβ subtypes and plasma E2. A high positive correlation was also observed between erβ1 and β2, which seemed to be highly expressed at the pre- and late-vitellogenic stages. The results of the present study suggest that the transcription of the three vtg subtypes are regulated by three ER subtypes jointly, and ERα is the key transcription factor regulating the three vtg subtypes in yellowtail.