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Updated: May 27, 2026

A Chemical Screening Procedure for Glucocorticoid Signaling with a Zebrafish Larva Luciferase Reporter System
Published on: September 10, 2013
Discovery of a novel enzyme mediating glucocorticoid catabolism in fish: 20beta-hydroxysteroid dehydrogenase type 2
Janina Tokarz1, Rebekka Mindnich, William Norton
1Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Experimental Genetics, Genome Analysis Center, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany.
Abstract:
Hydroxysteroid dehydrogenases (HSDs) are involved in metabolism and pre-receptor regulation of steroid hormones. While 17beta-HSDs and 11beta-HSDs are extensively studied in mammals, only few orthologs are characterized in fish. We discovered a novel zebrafish HSD candidate closely related to 17beta-HSD types 3 and 12, which has orthologs in other species. The enzyme catalyzes the conversion of cortisone to 20beta-hydroxycortisone identified by LC-MS/MS. We named the new enzyme 20beta-HSD type 2. All 20beta-HSD type 2 orthologs localize in the endoplasmic reticulum. Zebrafish 20beta-HSD type 2 is expressed during embryonic development showing the same expression pattern as 11beta-HSD type 2 known to oxidize cortisol to cortisone. In adult tissues 20beta-HSD type 2 shows a ubiquitous expression pattern with some minor sex-specific differences. In contrast to other enzymes metabolizing C21-steroids and being mostly involved in reproduction we propose that novel type 2 20beta-HSDs in teleost fish are important enzymes in cortisol catabolism.
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