Quantitative determination and tissue distribution of human 11β-hydroxysteroid dehydrogenase, hexose-6-phosphate dehydrogenase, glucose-6-phosphate transporter, glucocorticoid receptor and mineralocorticoid receptor mRNAs

Abstract

Background: Glucocorticoid (GC) concentrations in peripheral tissues are precisely regulated by 11β-hydroxysteroid dehydrogenase (HSD) isozymes. When considering the physiological effects of GC in various tissues, quantitative determination of these isozymes and other components involved in corticosteroid signaling is important and informative. We thus performed comprehensive determination of the expression of these mRNAs in a wide range of human tissues.

Methods: An absolute comparison of mRNA expression of human 11β-HSD isozymes, hexose-6-phosphate dehydrogenase (H6PDH), glucose-6-phosphate transporter (G6PT), glucocorticoid receptors (GRs), and mineralocorticoid receptor (MR) was performed by real-time RT-PCR.

Results: Human 11β-HSD type 1 mRNA was strongly expressed in the liver and placenta at comparatively high levels. H6PDH was expressed at low copy number, and comparatively high expression was observed in the kidney, testis, and ovary. G6PT expression was ubiquitous, but marked expression was observed in the liver, kidney, small intestine, and colon. GRα was also ubiquitously expressed at relatively high levels, which were approximately 10-fold higher than those of MR, whereas GRβ levels were below the detection limit in all tissues. 11β-HSD type 2 was predominantly expressed in the kidney, small intestine and colon; however, copy numbers of these transcripts showed a nearly identical pattern to type 1. MR was observed in various tissues examined, but was not fully correlated to the distribution of 11β-HSD type 2.

Conclusions: The present quantitative results were partially consistent with previous studies. This quantification method can thus provide valuable information for understanding the physiological effects and physiological roles of glucocorticoid in humans.