Expression of 3 β-hydroxysteroid/dehydrogenase/Δ 5 -Δ 4 /isomerase in the tracheal cartilage of the rat

Abstract

The enzyme complex 3beta-hydroxysteroid dehydrogenase isomerase/delta5-delta4 (3beta-HSD) is involved in the biosynthesis of all classes of active steroids. In this study, the presence of 3beta-HSD was defined in rat tracheal cartilage. The expression of the 3beta-HSD gene was examined by Northern blot analysis from 30-day-old rats. Western blot and immunohistochemical localization were also performed with antibodies raised against purified human placental 3beta-HSD to obtain further information on the expression of 3beta-HSD protein during fetal and postnatal periods of development in rat cartilage. Northern blot analysis using an oligonucleotide common to the 4 known 3beta-HSD isoforms showed 3beta-HSD mRNA corresponding to a transcript of 1.7 kb. Furthermore, a 42 KDa protein band was detected in the tracheal cartilage extracts by Western blot analysis. Immunostaining for 3beta-SD was observed in chondrocytes. The first expression was detected on the 17th day of fetal life by Western blot and immunohistochemistry. Immunoreactivity of 3beta-HSD showed a significant increase at 7 and 15 days after birth, and then remained unchanged through adulthood, in agreement with the data of the Western blot. Our results demonstrated the expression for 3beta-HSD in the tracheal cartilage at both the mRNA and protein levels during fetal life and postnatal development of the rat. These results suggest that 3beta-HSD may synthesize certain steroids which play major roles in differentiation and maintenance of function during development of rat cartilage.