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Nephrology Dialysis Transplantation 08/2006; 21(7):1984-7. · 3.40 Impact Factor
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ABSTRACT: Hypertension and sodium retention are features of a diminished 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2). The activity of this enzyme is reduced in various disease states with abnormal renal sodium retention and hypertension, including preeclampsia. ATP release to the extracellular compartment is observed with shear stress, inflammation, and placental ischemia. It was hypothesized that ATP downregulates 11beta-HSD2 activity. For that purpose, cell lines from different tissues that previously were used to study the regulation of 11beta-HSD2 were investigated: JEG-3, a vascular trophoblastic; LLCPK1, a renal tubular; and SW620, a colonic epithelial cell line. The 11beta-HSD2 activity, assessed by the conversion of 3H-cortisol to cortisone, was reversibly reduced during incubation with ATP or its stable analogue ATPgammaS in intact JEG-3 and LLCPK1, but not in SW620 cells. In JEG-3 cells, the purinergic antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid but not suramin reversed the inhibition. Incubation with UTP and ADP and their degradation products including adenosine and alpha,beta-methylene-ATP did not inhibit 11beta-HSD2 activity. In contrast, 11beta-HSD2 activity increased almost 2.5-fold after incubation with 2'-methylthio-ATP. This indicates a bidirectional regulation by nucleotides via purinergic receptors. In JEG-3 cells, ATP/ATPgammaS did not alter 11beta-HSD2 promoter activity but reduced 11beta-HSD2 protein and mRNA concentration and half-life, suggesting a posttranscriptional regulation. In conclusion, ATP inhibits cell type specifically via purinergic receptors the expression and activity of the 11beta-HSD2 by a posttranscriptional mechanism.
Journal of the American Society of Nephrology 01/2006; 16(12):3507-16. · 9.66 Impact Factor
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Kushiar Shojaati,
Maja Causevic,
Bert Kadereit,
Bernhard Dick,
Jeanine Imobersteg,
Henning Schneider,
Ernst Beinder,
Maki Kashiwagi,
Brigitte M Frey,
Felix J Frey,
Markus G Mohaupt
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ABSTRACT: In normal pregnancy, an increased aldosterone (Aldo) concentration coincides with volume expansion. In preeclampsia, Aldo levels are low despite intravascular volume depletion. The present investigation aimed to characterize the compromised Aldo synthesis in preeclampsia, and to identify the molecular basis hereof.
We recruited 66 pregnant women (24 uneventful, 42 preeclamptic). Genomic DNA was isolated from peripheral blood leukocytes. Urine samples were obtained for gas chromatography-mass spectroscopic measurements of steroid hormones reflecting apparent Aldo synthase (CYP11B2) and 11-hydroxylase (CYP11B1) activities. Polymerase chain reaction (PCR)-based screening for CYP11B2 mutations was performed by SSCP, restriction analysis, and sequencing.
CYP11B1 activity was unaltered, but reduction of mean tetrahydro (TH)-Aldo excretion by a factor of 3.9 indicated a diminished CYP11B2 activity in preeclampsia. Accordingly, the ratios of (TH-11-dehydrocorticosterone [A]+TH-corticosterone [B]+5alpha-THB) to (TH-cortisone +TH-cortisol [F]+5alpha-THF) and of 18-OH-THA to THAldo were increased in preeclampsia 2.6- and 15.2-fold, respectively, indicating reduced Aldo synthesis due to diminished methyl oxidase (MO) activity. A lower percentage of women with normal pregnancies had CYP11B2 mutations when compared to preeclamptic women (P < 0.05). Eight polymorphisms were detected, two of which were non-amino acid conserving. Of those, the mutation V386A, earlier found to jeopardize MO activity, was exclusively observed in preeclampsia (0% vs. 17%; P < 0.05).
Aldo deficiency due to a compromised MO step of Aldo synthesis favors extracellular volume depletion, and may account for an increased risk of placental hypoperfusion and consecutive development of preeclampsia. The sole presence of mutation V386A in preeclamptic mothers may identify a subgroup with an increased risk to develop preeclampsia during pregnancy.
Kidney International 12/2004; 66(6):2322-8. · 6.61 Impact Factor
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ABSTRACT: In preeclampsia, cortisol degradation by the enzyme 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) is compromised, which enhances intracellular cortisol availability. This leads to vasoconstriction and renal sodium retention with volume expansion, thus increasing blood pressure. An augmented availability of angiotensin II (Ang II) predisposes to preeclampsia. Some effects of Ang II are mediated by the mitogen-activated protein kinase (MAPK) cascade, which also regulates 11beta-HSD2 activity. Therefore, we hypothesized that Ang II regulates 11beta-HSD2.
The human choriocarcinoma cell line JEG-3, which expresses the 11beta-HSD2 isoenzyme, was used. 3H-cortisol/cortisone conversion assays and mRNA analyses by reverse transcription-polymerase chain reaction (RT-PCR) were performed. Cells were stimulated with Ang II and the effect was modulated by Ang II type 1 (AT1) and AT2 receptor blockers DUP753 or L-158809 and PD-123319, respectively. In order to elucidate the signaling cascade, the MAPK kinase inhibitors PD-098059 and U-0126 were probed. The impact of a modulated 11beta-HSD2 activity was assessed by determining the effect of cortisol on AT1 receptor mRNA.
Ang II reduced mRNA and activity of 11beta-HSD2 mainly by a post-transcriptional mechanism. This Ang II effect was abrogated by AT2, but not by AT1 receptor blockade. Mitogen-activated protein (MAP) kinase kinase (MAPKK) inhibitors reversed the Ang II effect. Dexamethasone augmented the mRNA expression of AT1 receptors. Cortisol enhanced AT1 receptor mRNA expression when the 11beta-HSD2 activity was reduced either by Ang II or by glycyrrhetinic acid, an 11beta-HSD2 inhibitor.
Ang II decreases the activity of 11beta-HSD2 by an AT2 receptor- and MAPK-dependent mechanism. The decreased activity of 11beta-HSD2 increases the intracellular availability of cortisol, which might be relevant for the pathogenesis of hypertension and preeclampsia.
Kidney International 10/2003; 64(3):970-7. · 6.61 Impact Factor
