Evidence of binding between diethylstilbestrol (DES) and the goldfish (Carassius auratus) membrane progesterone receptor

Background In a previous study, diethylstilbestrol (DES) was shown to induce oocyte maturation in fish. In the present study, the interaction of DES on goldfish membrane progesterone receptor alpha (GmPR alpha) was investigated using a competitive binding assay with radiolabeled steroids. The results indicate that DES exerts its effects on membrane progesterone receptor alpha (mPR alpha) and induces oocyte maturation through nongenomic steroid mechanisms. This study provides empirical data that demonstrate the binding between DES and GmPR alpha. Methods Binding of DES to GmPR alpha was achieved by using radiolabeled DES and recombinant GmPR alpha expressed in culture cells or purified GmPR alpha proteins that coupled to graphene quantum dots (GQDs). Additionally, the competitive binding of fluorescently labeled progesterone to GmPR alpha-expressing cells was evaluated. Results Although significant nonspecific binding of radiolabeled DES to the cell membrane that expresses GmPR alpha has been observed, specific binding of DES to GmPR alpha has been successfully identified in the presence of digitonin. Furthermore, the specific binding of DES to GmPR alpha was confirmed by a binding assay using GQD-GmPR alpha. The radiolabeled DES was shown to bind to GQD-GmPR alpha. Additionally, the competition for the binding of fluorescently labeled progesterone to GmPR alpha-expressing cells was achieved with the DES. Conclusions The results of the experiments revealed that DES binds to GmPR alpha. Thus, it can be concluded that DES induces goldfish oocyte maturation by binding to GmPR alpha.