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Expression of the 11beta-hydroxysteroid dehydrogenase 2 gene in the mouse
1Baker Medical Research Institute, Commercial Road, Prahran, Victoria, Australia.
Abstract:
Aldosterone acts via mineralocorticoid receptors (MRs) to control salt and water flux in epithelial organs such as the kidney and colon to maintain circulatory homeostasis. Inappropriate glucocorticoid-mediated activation of MRs in aldosterone-target tissues is prevented by the glucocorticoid-metabolizing enzyme 11beta-hydroxysteroid dehydrogenase type 2 (HSD2). We have studied HSD2 expression in the mouse at the level of gene transcription and further analyzed, with HSD1, its pattern of tissue-restricted gene expression. The mouse HSD2 gene, including upstream regulatory regions, has been cloned, and its transcription start site has been mapped in colon and kidney. A 2.5 kb upstream region has been sequenced, and its proximal promoter region has been analyzed. We have compared the relative expression of HSD1 and HSD2 in a variety of tissues from male mice using ribonuclease protection analysis. HSD1 was expressed in liver, kidney, adrenal, lung, spleen, thymus, fat, small intestine, stomach, heart, skin, and epididymis. HSD2 was expressed in kidney, colon, small intestine, stomach, and epididymus. No expression of either HSD1 and HSD2 was detected in bladder, testis, seminal vesicles, vas deferens, prostate, or skeletal muscle. Finally, to investigate the specific roles of HSD2 in vivo, we have created "floxed" HSD2 alleles using gene targeting in mouse embryonic stem cells with the aim to create tissue-specific ablation of HSD2 in mice via Cre recombinase mediated gene targeting.
Insights
This study characterizes the gene expression of 11beta-hydroxysteroid dehydrogenase type 2 (HSD2) in mice, revealing its specific tissue distribution. Researchers also developed genetic tools to investigate HSD2
Area of Science:
- Endocrinology
- Molecular Biology
- Genetics
Background:
- Aldosterone regulates salt and water balance via mineralocorticoid receptors (MRs).
- 11beta-hydroxysteroid dehydrogenase type 2 (HSD2) prevents inappropriate MR activation by glucocorticoids in target tissues.
- Understanding HSD2 expression is crucial for its physiological roles.
Purpose of the Study:
- To investigate the gene transcription and tissue-specific expression of HSD2 in mice.
- To analyze the regulatory regions of the mouse HSD2 gene.
- To develop genetic tools for studying HSD2 function in vivo.
Main Methods:
- Cloning of the mouse HSD2 gene and upstream regulatory regions.
- Mapping of the HSD2 transcription start site in colon and kidney.
- Ribonuclease protection analysis to compare HSD1 and HSD2 expression across various mouse tissues.
- Gene targeting in mouse embryonic stem cells to create floxed HSD2 alleles.
Main Results:
- The HSD2 gene's transcription start site was mapped in the colon and kidney.
- HSD1 expression was detected in 14 tissues, while HSD2 was found in 5 specific tissues (kidney, colon, small intestine, stomach, epididymis).
- Neither HSD1 nor HSD2 was expressed in the bladder, testis, seminal vesicles, vas deferens, prostate, or skeletal muscle.
- Floxed HSD2 alleles were generated for future tissue-specific gene ablation studies.
Conclusions:
- HSD2 exhibits a restricted tissue expression pattern in mice, primarily in organs involved in electrolyte balance.
- The study provides foundational data on HSD2 gene regulation and expression.
- The developed genetic tools will enable in-depth investigation of HSD2's in vivo functions.