Expression of 3 beta-hydroxysteroid/dehydrogenase/Delta 5-Delta 4/isomerase in the tracheal cartilage of the rat

The enzyme complex 3 beta-hydroxysteroid dehydrogenase isomerase/Delta(5)-D elta(4) (3 beta-HSD) is involved in the biosynthesis of all classes of acti ve steroids. In this study, the presence of 3 beta-HSD was defined in rat t racheal cartilage. The expression of the 3 beta-HSD gene was examined by No rthern blot analysis from 30-day-old rats. Western blot and immunohistochem ical localization were also performed with antibodies raised against purifi ed human placental 3 beta-HSD to obtain further information on the expressi on of 3 beta-HSD protein during fetal and postnatal periods of development in rat cartilage. Northern blot analysis using an oligonucleotide common to the 4 known 3 beta-HSD isoforms showed 3 beta-HSD mRNA corresponding to a transcript of 1.7 kb. Furthermore, a 42 KDa protein band was detected in th e tracheal cartilage extracts by Western blot analysis. Immunostaining for 3 beta-SD was observed in chondrocytes. The first expression was detected o n the 17th day of fetal life by Western blot and immunohistochemistry. Immu noreactivity of 3 beta-HSD showed a significant increase at 7 and 15 days a fter birth, and then remained unchanged through adulthood, in agreement wit h the data of the Western blot. Our results demonstrated the expression for 3 beta-HSD in the tracheal cart ilage at both the mRNA and protein levels during fetal life and postnatal d evelopment of the rat. These results suggest that 3 beta-HSD may synthesize certain steroids which play major roles in differentiation and maintenance of function during development of rat cartilage.