Ovarian and placental expression of 20α-hydroxysteroid dehydrogenase during pregnancy in deer

The enzyme 20α-hydroxysteroid dehydrogenase (20α-HSD) catalyzes the conversion of progesterone to its inactive form, 20α-hydroxyprogesterone. This enzyme has been shown to play a critical role in the regulation of luteal function in experimental animals. In this study, we cloned and expressed the gene encoding elk deer 20α-HSD from reproductive placental and ovarian tissues. PCR, 3'- and 5'-RACE, and northern blot analysis were performed for the cloning and characterization of deer 20α-HSD gene. We expressed recombinant deer 20α-HSD protein and used western blot analysis to determine protein expression levels in the placenta and ovary during pregnancy. The full cDNA sequence of 20α-HSD was used to clone an open reading frame encoding 323 amino acids and consisting of 1142 bp. The nucleotide sequence of deer 20α-HSD showed high homology with the sequences of the bovine (96%), goat (96%), and human (83%) 20α-HSD genes. 20α-HSD mRNA was strongly expressed in the placenta on days 30, 60, and 70 of pregnancy. A high level of the protein was also detected in the placenta but not in fetal skin tissue. The recombinant 20α-HSD protein produced in mammalian cells and bacterial systems had a molecular weight of approximately 37-kDa. The deer 20α-HSD protein signal was specifically localized in the basal part of the primary chorionic villi and chorionic stem villus of the placenta during early pregnancy. The 20α-HSD protein was also intensively localized in the larger luteal cells of the corpus luteum during pregnancy.