Adipose tissue 11beta-hydroxysteroid dehydrogenase type 1 expression in obesity and Cushing's syndrome

Cell-type specific regulation of the human 11beta-hydroxysteroid dehydrogenase type 1 promoter

The intracellular enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts cortisone into the more active metabolite cortisol. Overexpression of 11beta-HSD1 was associated with features of the metabolic syndrome such as obesity or impaired glucose tolerance. Despite this considerable impact of 11beta-HSD1, the human 11beta-HSD1 promoter has not been described in detail yet. We therefore cloned eight different promoter fragments of the 5'-upstream region of the known transcription/translation-start up to -3034 bp into the luciferase-reporter vector pGL3. A low-cost in-house assay was developed and validated to detect firefly and renilla luciferase activity. Promoter fragments were analysed in human HepG2 and undifferentiated and differentiated murine 3T3-L1 cells. A differential regulation of the human 11beta-HSD1 promoter depending upon the cell type was observed. Specifically, a strong repressor of the basal promoter activity was found between -85 and -172 bp in HepG2 cells only, while an additional repressor appeared to be active between -342 and -823 bp in both, the hepatic and the adipose cell line. The presented data suggest a cell-type specific regulation of the 11beta-HSD1 promoter, which is in agreement with existing expression data from animal and human studies. The described promoter constructs will allow subsequent studies about the role of specific hormonal, metabolic and transcription factors to finally characterise the regulation of the human 11beta-HSD1-promoter in more detail.