Different effects of progesterone and estradiol on chimeric and wild type aldosterone synthase in vitro

Reproductive Biology and Endocrinology

Research

Kuniaki Mukai¹  Tadashi Ogishima²  Sandra Solari³  Fidel Allende³  Gareth Owen⁴  Andrea Vecchiola⁵  Carolina Valdivia⁵  Alejandra Tapia-Castillo⁵  Cristóbal A Fuentes⁵  Carlos F Lagos⁶  Cristian A Carvajal⁷  Carlos E Fardella⁷  Carmen Campino⁷ 

[1] Department of Biochemistry, School of Medicine, Keio University, 35 Shinanomachi, 160-8582, Shinjuku-ku, Tokyo, Japan;Department of Chemistry, Faculty of Sciences, Kyushu University, 6-10-1 Hakozaki, 812-8581, Higashi-ku, Fukuoka, Japan;Department of Clinical Laboratories, School of Medicine, Pontificia Universidad Catolica de Chile, Av. Vicuña Mackenna, 4860, Macul, Santiago, Chile;Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Catolica de Chile, Portugal 45, Santiago, Chile;Molecular Endocrinology Laboratory, Department of Endocrinology, School of Medicine, Pontificia Universidad Catolica de Chile, Lira 85, 5th Floor, Santiago, Chile;Molecular Endocrinology Laboratory, Department of Endocrinology, School of Medicine, Pontificia Universidad Catolica de Chile, Lira 85, 5th Floor, Santiago, Chile;Department of Pharmacy, Faculty of Chemistry, Pontificia Universidad Catolica de Chile, Av. Vicuña Mackenna, 4860, Macul, Santiago, Chile;Molecular Endocrinology Laboratory, Department of Endocrinology, School of Medicine, Pontificia Universidad Catolica de Chile, Lira 85, 5th Floor, Santiago, Chile;Millennium Institute of Immunology and Immunotherapy, Santiago, Chile;

关键词: Familial hyperaldosteronism type I;    Aldosterone synthase;    Chimeric CYP11B1/B2 gene;    In vitro;    Molecular modelling;   

DOI  :  10.1186/1477-7827-11-76

 received in 2013-03-06, accepted in 2013-08-08,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundFamilial hyperaldosteronism type I (FH-I) is caused by the unequal recombination between the 11beta-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) genes, resulting in the generation of a CYP11B1/B2 chimeric gene and abnormal adrenal aldosterone production. Affected patients usually show severe hypertension and an elevated frequency of stroke at a young age. Aldosterone levels rise during pregnancy, yet in pregnant women with FH-1, their hypertensive condition either remains unchanged or may even improve. The purpose of this study was to investigate in vitro whether female sex steroids modulate the activity of chimeric (ASCE) or wild type (ASWT) aldosterone synthase enzymes.MethodsWe designed an in vitro assay using HEK-293 cell line transiently transfected with vectors containing the full ASCE or ASWT cDNAs. Progesterone or estradiol effects on AS enzyme activities were evaluated in transfected cells incubated with deoxycorticosterone (DOC) alone or DOC plus increasing doses of these steroids.ResultsIn our in vitro model, both enzymes showed similar apparent kinetic parameters (Km = 1.191 microM and Vmax = 27.08 microM/24 h for ASCE and Km = 1.163 microM and Vmax = 36.98 microM/24 h for ASWT; p = ns, Mann–Whitney test). Progesterone inhibited aldosterone production by ASCE- and ASWT-transfected cells, while estradiol demonstrated no effect. Progesterone acted as a competitive inhibitor for both enzymes. Molecular modelling studies and binding affinity estimations indicate that progesterone might bind to the substrate site in both ASCE and ASWT, supporting the idea that this steroid could regulate these enzymatic activities and contribute to the decay of aldosterone synthase activity in chimeric gene-positive patients.ConclusionsOur results show an inhibitory action of progesterone in the aldosterone synthesis by chimeric or wild type aldosterone synthase enzymes. This is a novel regulatory mechanism of progesterone action, which could be involved in protecting pregnant women with FH-1 against hypertension. In vitro, both enzymes showed comparable kinetic parameters, but ASWT was more strongly inhibited than ASCE. This study implicates a new role for progesterone in the regulation of aldosterone levels that could contribute, along with other factors, to the maintenance of an adequate aldosterone-progesterone balance in pregnancy.

【 授权许可】

Unknown   
© Vecchiola et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.