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Abstract

Expression of 11β-hydroxylase in rat Leydig cells 
Wang,Gui-Min; Ge,Renshan; Latif,Syed A.; Morris,David J.; Hardy,Matthew P.
Endocrinology 143(2): 621-626
Publication date: 2002


11ß-Hydroxy (11ß-OH) derivatives of certainsteroids function as inhibitors of 11ß-hydroxysteroiddehydrogenase isoform 1 (11ßHSD1), an enzyme expressedin Leydig cells that catalyzes the reversible oxidation of biologicallyactive glucocorticoids to inactive 11-dehydro metabolites. 11ß-Hydroxylaseis an adrenal enzyme responsible for glucocorticoid biosynthesis,catalyzing 11ß-hydroxylation of steroids and thusproducing 11ß-OH-steroid derivatives. The aims ofthe present study were 1) to examine whether 11ß-hydroxylaseis expressed in testis, 2) to define the biochemical characteristicsof the testicular form of this enzyme, and 3) to establish whether11ß-hydroxylated steroids inhibit Leydig cell 11ßHSD1activities. 11ß-Hydroxylase mRNA was detected in purifiedrat Leydig cells by RT-PCR. Sequencing confirmed that the PCRproducts had 100% identity with the published rat adrenal enzymecDNA sequence. Immunohistochemistry and Western blot analysisusing a mouse monoclonal antibody confirmed the expression of11ß-hydroxylase protein in Leydig cells. Moreover,11ß-hydroxylase activity, synthesis of corticosteronefrom 11-deoxycorticosterone, was measurable in Leydig cells,and the K and maximum velocity values were 7.28 ± 0.92 µM and 1.13 ± 0.04 µmol/10 cell·h,respectively. When assayed in Leydig cells, several 11ß-hydroxylatedsteroids were efficient inhibitors of 11ßHSD1 dehydrogenaseactivity, whereas other 11-keto compounds were effective asinhibitors of oxidoreductase activity. These results providethe first direct evidence that rat Leydig cells express 11ß-hydroxylase,which may be involved in the regulation of glucocorticoid metabolismwithin the testis through local biosynthesis of endogenous inhibitorsof 11ßHSD1.