The impact of polymorphisms in the gene encoding aldosterone synthase (CYP11B2) on steroid synthesis and blood pressure regulation

Connell, J. M.C., Fraser, R., MacKenzie, S. M. , Friel, E. C., Ingram, M. C., Holloway, C. D. and Davies, E. (2004) The impact of polymorphisms in the gene encoding aldosterone synthase (CYP11B2) on steroid synthesis and blood pressure regulation. Molecular and Cellular Endocrinology, 217(1-2), pp. 243-247. (doi: 10.1016/j.mce.2003.10.025) (PMID:15134824)

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Abstract

The terminal stages in the synthesis of aldosterone and cortisol are catalysed by the enzymes aldosterone synthase and 11β-hydroxylase respectively. We have previously reported that polymorphic variation in the 5′ promoter region (-344C/T) of the gene encoding aldosterone synthase (CYP11B2) is associated with increased aldosterone metabolite excretion and with hypertension associated with a raised aldosterone to renin ratio (ARR). Additionally, basal and ACTH-stimulated plasma levels of 11-deoxycortisol, the precursor of cortisol, are higher in subjects carrying the T-allelic variant. We have now identified in a family study (573 individuals from 105 extended families ascertained through a hypertensive proband) that excretion of the main metabolite of this steroid (tetrahydro-11-deoxycortisol, THS) is heritable (19.4%) and that the T-allele of CYP11B2 is more strongly associated with higher THS levels than the C-allele. Raised plasma and urinary levels of 11-deoxycortisol suggest that there is relative inefficiency of 11β-hydroxylation in the zona fasciculata; the P450 enzyme responsible for this step is encoded by the gene CYP11B1, which is highly homologous with and adjacent to CYP11B2. The association of genetic variation in the promoter of CYP11B2 which, in the adrenal cortex, is only expressed in zona glomerulosa, and zona fasciculata 11β-hydroxylation function is paradoxical. There may be linkage dys-equilibrium between this polymorphism and a quantitative trait locus (QTL) in CYP11B1. Chronic alteration of 11β-hydroxylase activity may increase ACTH drive to the adrenal cortex, altering the regulation of aldosterone synthesis. This may explain, at least partly, the association between CYP11B2 polymorphisms and hypertension.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Friel, Mrs Elaine and Davies, Professor Eleanor and Connell, Professor John and MacKenzie, Dr Scott
Authors: Connell, J. M.C., Fraser, R., MacKenzie, S. M., Friel, E. C., Ingram, M. C., Holloway, C. D., and Davies, E.
College/School:College of Medical Veterinary and Life Sciences
College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
Journal Name:Molecular and Cellular Endocrinology
Publisher:Elsevier
ISSN:0303-7207
ISSN (Online):1872-8057
Published Online:21 November 2003

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