Active site variability of type 1 11β-hydroxysteroid dehydrogenase revealed by selective inhibitors and cross-species comparisons

详细信息    查看全文

• 作者：Malin Hult ; Naeem Shafqat ; Bjö ; rn Elleby ; Doreen Mitschke ; Stefan Svensson ; Margareta Forsgren ; Tjeerd Barf ; Jerk Vallgå ; rda ; Lars Abrahmsen and Udo Oppermann
• 关键词：11β ; -Hydroxysteroid dehydrogenase ; Pre-receptor control ; Glucocorticoid metabolism ; Metabolic disease ; Insulin resistance ; Short-chain dehydrogenases/reductases
• 刊名：Molecular and Cellular Endocrinology
• 出版年：2006
• 出版时间：27 March 2006
• 年：2006
• 卷：248
• 期：1-2
• 页码：26-33
• 全文大小：568 K

文摘

The NADPH-dependent enzyme type 1 11β-hydroxysteroid dehydrogenase (11β-HSD1) activates in a tissue-specific manner circulating pro-glucocorticoid hormones (cortisone in humans) to the 11β-OH ligand (cortisol in humans), which is able to bind to its cognate receptor and regulate gene transcription. Modulation of this pre-receptor activation mechanism by selective enzyme inhibitors is a desirable goal in the treatment of insulin resistance and related metabolic disorders. Like most other hydroxysteroid dehydrogenases 11β-HSD1 belongs to the evolutionarily conserved enzyme superfamily of short-chain dehydrogenases/reductases (SDR). The enzyme is anchored within the endoplasmic reticulum through an N-terminal transmembrane domain.

In this study we aimed to characterize the active site of mammalian 11β-HSD1 by determining primary structures from several mammalian lines (cat, hamster, cynomolgus, chimpanzee, dog) thus increasing substantially available sequence information, and allowing us to determine highly variable and constant parts within the primary structure. These regions were mapped to the recently determined three-dimensional structure and are mostly found around the substrate binding site. Furthermore we performed inhibition studies by using different series of inhibitors, comprising 11β-HSD1 selective arylsulfonamidothiazoles and the unselective steroid-based compound carbenoxolone. The different arylsulfonamidothiazoles display distinct inhibition profiles versus the mammalian species tested, with several tight binding inhibitors for the human enzyme (K_i 50 nM), intermediate for mouse, and weak or not binding inhibitors for rat and guinea pig (K_i > 3 μM). Analysis of the inhibition mode reveals that the tight binding inhibitor BVT.528 is a competitive inhibitor for the human form, whereas the related compound BVT.2733 displays a mixed-type inhibition pattern versus the mouse enzyme.

Taken together, this structure–activity study provides increased insight into active site complexity and catalytic mechanism of 11β-HSD1, useful for further inhibitor design.