1999 Volume 45 Issue 5 Pages 321-329
20α-Hydroxysteroid dehydrogenase (20α-HSD) converts progesterone to a biologically inactive steroid, 20α-dihydroprogesterone. To examine a potential role of 20α-HSD in tissues other than corpus luteum (CL) during pregnancy, mouse 20α-HSD cDNA was cloned and was used for the examination of its mRNA localization in the conceptus and uterus at different stages of gestation. Using probes based on the rat sequence, mouse 20α-HSD cDNA clone was isolated from a cDNA library prepared from ovaries of day 12 pseudopregnant mice. The mouse 20α-HSD cDNA was 1193 bp in length and encoded 323 amino acids with an estimated molecular weight of 37 kD. The mouse 20α-HSD was homologous to the rat 20α-HSD in nucleotide and amino acid sequences (both in 93% homology), and to other members of aldo-keto reductase superfamily at the cofactor (NADP(H)) binding site. By in situ hybridization, 20α-HSD mRNA was localized in endometrial epithelial cells on days 10, 15 and 18 of pregnancy, maternal placental endothelial cells on day 10, and fetal epidermal cells on day 15. During pseudopregnancy as well as early pregnancy, however, 20α-HSD mRNA was not detected in endometrial cells. Together, 20α-HSD mRNA was localized in cells that surround fetuses during the mid and late stages of gestation.
