Expression and localization of the 20α-hydroxysteroid dehydrogenase (HSD) enzyme in the reproductive tissues of the cynomolgus monkey Macaca fascicularis.

This study was conducted to characterize and functionally analyze the monkey 20α-hydroxysteroid dehydrogenase (20α-HSD) in the ovary, placenta, and oviduct. We focused on 20α-HSD mRNA expression and protein localization in monkey reproductive tissues and the molecular characterization of the promoter region. Reverse transcription-polymerase chain reaction (RT-PCR) monkey 20α-HSD mRNA was more strongly detected in the ovary at pre-ovulation than in the placenta and oviduct at pre-parturition. The mRNA was approximately 1.2kb in size and the expression was high in the ovary, which was the same as the RT-PCR result. We also produced His tagged 20α-HSD proteins by using an Escherichia coli expression system. In a western blot for the 20α-HSD protein, only 1 band of approximately 37-kDa was detected in the ovary, oviduct tissue, and recombinant protein produced in the Chinese hamster ovary (CHO) cell line. However, in the placenta, additional 2 bands (35 and 39 kDa) were detected. Immunohistochemical analyses suggested that the monkey 20α-HSD protein was localized mainly in the syncytiotrophoblast of the placenta and the isthmus cells of the oviduct. According to promoter analyses with the enhanced green fluorescent protein (EGFP) gene, the monkey 20α-HSD promoter was efficiently expressed in the CHO-K1 cell line; however, the promoter was not expressed in bovine fetal fibroblast (bFF) cell. Taken together, our study showed that the 20α-HSD mRNA and protein are coordinately expressed in the ovary at pre-ovulation and in the placenta and oviduct at pre-parturition. Therefore, monkey 20α-HSD in the placenta, ovary and oviduct plays an important role in the estrous cycle, pregnancy, and parturition.