Original articleExpression and functional consequences of 11β-hydroxysteroid dehydrogenase activity in human bone
Introduction
Glucocorticoids have an essential role in normal skeletal development and function but are detrimental in excess. The effects of glucocorticoids in vitro depend upon corticosteroid concentration and receptor expression, timing of exposure, and stage of cellular differentiation, although little is known about the mechanisms underlying changes in cellular sensitivity to these agents. These mechanisms are particularly important in bone where glucocorticoid excess in vivo is associated with decreased bone formation and rapid decreases in bone formation markers17, 21 due to direct effects on cells of the osteoblast lineage.9, 16 Glucocorticoids may additionally cause a transient increase in bone resorption due to inappropriately increased osteoclastic activity. Despite this, susceptibility to the bone-specific effects of endogenous or exogenous glucocorticoids in individuals correlates only weakly with circulating levels of glucocorticoids7, 10 or variation in the affinity or concentration of the glucocorticoid receptor (GR).12 This suggests that there are intrinsic tissue-specific factors that modulate individual sensitivity to the effects of glucocorticoids. Recently, the functional importance of intracellular glucocorticoid metabolism in several tissues, such as kidney,27 liver,15 and omental fat,3, 4 has been demonstrated, but little is known about glucocorticoid metabolism in skeletal cells.
By catalyzing the interconversion of hormonally active cortisol (F) to inactive cortisone (E), 11β-hydroxysteroid dehydrogenase (11β-HSD) has been established as an important prereceptor signaling pathway in corticosteroid hormone action.31 Two isozymes of 11β-HSD, 11β-HSD1 and 11β-HSD2, have been shown to regulate glucocorticoid and mineralocorticoid hormone action.26 11β-HSD1 is a low-affinity bidirectional nicotinamide adenine dinucleotide phosphate (NADP[H])-dependent enzyme that can interconvert F and E,30 but, in intact tissues studied to date, acts predominantly as a reductase converting E to F. By contrast, 11β-HSD2 is a high-affinity nicotinamide adenine dinucleotine (NAD)-dependent dehydrogenase inactivating F to E28; reductase activity for physiological glucocorticoids has not been seen for 11β-HSD2. Both 11β-HSD isoenzymes are inhibited by liquorice and its derivatives, carbenoxolone and glycyrrhetinic acid. These inhibitors have been used in vivo to examine the functional role of 11β-HSD expression and activity.29 We have previously demonstrated the expression and activity of the 11β-HSD2 isozyme in rat and human osteosarcoma cell lines1 and expression in osteoblasts of normal human fetal bone,8 whereas the 11β-HSD1 isozyme is expressed in human osteoblast cultures generated from trabecular bone samples.1 A full and detailed analysis of the expression of 11β-HSD isozymes within human bone is required. In addition, by measuring well-established markers of bone formation (C- and N-terminal propeptides of type I collagen [PICP and PINP]) and resorption (pyridinoline and deoxypyridinoline) we investigated whether short-term inhibition of 11β-HSDs with the liquorice derivative, carbenoxolone,29 can affect bone metabolism in vivo.
Section snippets
Tissue preparation
Fresh human bone tissue was obtained from surgical resections with the approval of the local ethics committee. For enzyme activity and reverse transcription-polymerase chain reaction (RT-PCR) studies, specimens were obtained from four individuals (ages between 5 and 30 years) who were having lower limb amputation for localized malignancy. Normal tissue was obtained at least 10 cm distant from the site of pathology. For immunohistochemistry and in situ hybridization studies, tissue was obtained
Enzyme assays for glucocorticoid metabolism in normal human bone
Data shown in Figure 1 indicate the presence of intrinsic 11β-HSD activity in intact bone chips. For conversion of F to E, activity was considerably greater at 1 μmol/L F than at 50 nmol/L F, suggesting predominant 11β-HSD1 activity. Conversion of E to F was also evident again suggesting the presence of 11β-HSD1. Between individuals there was considerable variation in dehydrogenase activities, but the reductase activity was relatively constant. In bone homogenates, dehydrogenase activity was
Discussion
11β-HSD expression has been shown to be important in mediating glucocorticoid hormone action in several tissues.26 However, the extent to which this occurs in bone in vivo, and its functional role, is not yet clear. We have recently demonstrated the presence of 11β-HSD1 in primary cultures of human osteoblasts,1 and 11β-HSD2 in fetal human bone8 and human osteosarcoma cells.1 In this study, using primary human bone samples, we have shown that 11β-HSD1 is the predominant isozyme expressed in
Acknowledgements
The authors are grateful to Dr. D. C. Mangham, Maurice Adkins, and the staff at the Department of Musculoskeletal Pathology, Birmingham, UK, for the technical assistance in tissue sectioning and immunohistochemistry. We also thank Cedric Shackleton, Children’s Hospital, Oakland Research Institute, Oakland, CA, for performing the GC/MS on urine samples. Technical assistance for bone marker assays was provided by Brian Durham and Geoff Birkinshaw, Department of Clinical Chemistry, Royal Liverpool
References (32)
A rapid and sensitive method for the utilization of microgram quantities of protein utilizing the principle of protein-dye binding
Anal Biochem
(1976)- et al.
Does central obesity reflect “Cushing’s disease of the omentum”?
Lancet
(1997) - et al.
Human 11 beta-hydroxysteroid dehydrogenaseStudies on the stably transfected isoforms and localization of the type 2 isozyme within renal tissue
Steroids
(1997) - et al.
The science and therapy of glucocorticoid-induced bone loss
Endocrinol Metab Clin N Am
(1998) - et al.
Hypertension in the syndrome of apparent mineralocorticoid excess due to mutation of the 11β-hydroxysteroid dehydrogenase type 2 gene
Lancet
(1996) - et al.
The human gene for 11β-hydroxysteroid dehydrogenase. Structure, tissue distribution and chromosomal localization
J Biol Chem
(1991) - et al.
Detection of human 11β-hydroxysteroid dehydrogenase isoforms using reverse transcription-polymerase chain reaction and localization of the type 2 isoform to renal collecting ducts
Mol Cell Endocrinol
(1995) - et al.
Characterization of 11β-hydroxysteroid dehydrogenase activity and corticosteroid receptor expression in human osteosarcoma cell lines
J Endocrinol
(1999) - et al.
Differentiation of adipose stromal cellsThe role of glucocorticoids and 11β-hydroxysteroid dehydrogenase
Endocrinology
(1999) - et al.
Glucocorticoid receptors and inhibition of bone cell growth in primary cultures
Endocrinology
(1997)
Alterations of bone turnover and bone mass at different skeletal sites due to pure glucocorticoid excessStudy in eumenorrheic patients with Cushing’s syndrome
J Clin Endocrinol Metab
Expression of type 2 11β-hydroxysteroid dehydrogenase and corticosteroid hormone receptors in early fetal life
J Clin Endocrinol Metab
Glucocorticoid activity, inactivity and the osteoblast
J Endocrinol
Profiles of endogenous circulating cortisol and bone mineral density in healthy elderly men
J Clin Endocrinol Metab
Regulation of 11β-hydroxysteroid dehydrogenase activity in human skin fibroblastsEnzymatic modulation of glucocorticoid action
J Clin Endocrinol Metab
A polymorphism in the glucocorticoid receptor gene may be associated with an increased sensitivity to glucocorticoids in vivo
J Clin Endocrinol Metab
Cited by (147)
11β-Hydroxysteroid dehydrogenase 2: A key mediator of high susceptibility to osteoporosis in offspring after prenatal dexamethasone exposure
2022, Pharmacological ResearchCitation Excerpt :Meanwhile, the bone local corticosterone concentration and bone/serum corticosterone ratio in the PDE male and female offspring were increased significantly over the control, while the bone local corticosterone (rather than bone/serum corticosterone ratio) was increased more significantly after chronic stress (P < 0.05, P < 0.01, Fig. 3A, E). As 11β-HSD2 is a key enzyme for the oxidative metabolism of active glucocorticoids in local tissues [19,20], we detected its expression in the bone, and found that the expression of bone 11β-HSD2 in the PDE male and female offspring were significantly reduced before chronic stress when compared with the control, while the expression levels of 11β-HSD2 did not further decrease after chronic stress (P < 0.05, P < 0.01, Fig. 3B-D, 3F-H). Taken together, these results suggested that PDE induced a continuous inhibition of bone 11β-HSD2 expression in the adult offspring, which in turn led to the accumulation of bone local corticosterone in the adult offspring.
The rise in expression and activity of 11β-HSD1 in human mesenchymal progenitor cells induces adipogenesis through increased local cortisol synthesis
2021, Journal of Steroid Biochemistry and Molecular BiologyBasic and clinical aspects of glucocorticoid action in bone
2019, Principles of Bone BiologyDesign, synthesis, and biological evaluation of novel selective peptide inhibitors of 11β-hydroxysteroid dehydrogenase 1
2018, Bioorganic and Medicinal Chemistry