17Beta-estradiol modulates endothelin-1 expression and release in human endothelial cells.
OBJECTIVE
In this study the role of 17beta-estradiol (E2) in the regulation of endothelin-1 (ET-1) mRNA expression and secretion was investigated in cultured human umbilical vein endothelial cells (HUVECs).


METHODS
Endothelial cells were either deprived of or treated with 17beta-estradiol (10(-9), 10(-7) M) for 48 h. After the incubation, the effect of E2 on ET-1 gene expression was evaluated by Northern blot analysis. ET-1 release into the media was measured by radioimmunoassay after 6 h of incubation under basal conditions and upon stimulation with thrombin (4 U/ml). In addition, the cyclic guanosine 5'-monophosphate (cGMP) content of cells was assayed by immunoassay. In order to exclude the role of nitric oxide (NO) in E2-induced effects on endothelin-1 gene expression and secretion, nitric oxide synthase (NOS) inhibitor, N-nitro L-arginine methyl ester (1 mM) (L-NAME) was added to the media of some cultures.


RESULTS
Incubation of HUVECs with 10(-9) and 10(-7) M E2 for 48 h resulted in a 30 and 47% inhibition of ET-1 mRNA expression, respectively. Incubation with E2 also decreased the basal and thrombin-stimulated ET-1 release while increasing the cGMP content of cells significantly. NOS inhibitor L-NAME increased the release of ET-1 from E2-incubated cells but did not alter the ET-1 release from hormone-deprived cells. However, ET-1 secretion of E2-treated cells were significantly less than the deprived ones. Northern blot analyses also demonstrated that inhibition of NOS only partly attenuated the effect of E2 on ET-1 gene expression. In the presence of L-NAME, treatment with 10(-7) M E2 caused a 12% decrease in ET-1 gene expression.


CONCLUSIONS
The results demonstrate that E2 may play both direct and indirect role in regulation of ET-1 gene expression and production in human endothelial cells. E2-induced increase in NO but decrease in ET-1 production may partly explain the mechanism of the protective effects of the hormone on the cardiovascular system.
Department of Biochemistry, Faculty of Medicine, Marmara University, Istanbul, Turkey. bilsele@doruk.com.tr
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Moini
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Tetik
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Aksungar
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Ozer
D000704:Analysis of Variance; D015152:Blotting, Northern; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000032:analysis; D019332:Endothelin-1 / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology*; D015870:Gene Expression; D006801:Humans; D009569:Nitric Oxide / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D013268:Stimulation, Chemical; D013917:Thrombin / Q000494:pharmacology
D019332:Endothelin-1; D012333:RNA, Messenger; D009569:Nitric Oxide; D004958:Estradiol; D013917:Thrombin; D006152:Cyclic GMP