The genomic action of 17 β-estradiol accounts for altering calcium homeostasis in human endothelial cells
Our preliminary studies showed 17 ?-estradiol (E2)-regulated Ca2+ homeostasis may play a role in enhancing nitric oxide production in human endothelial cells, EA.hy926. Here, we investigated the genomic and nongenomic actions of E2 on intracellular calcium concentration ([Ca2+]i) in endothelial cells. Cells were treated with either a) E2 (1 ?M) in the presence or absence of the transcription inhibitor actinomycin D (1 ?g/mL) for 24 h or b) E2 (1 ?M) for 5 minutes prior to the analysis of [Ca2+]i. Using a spectrofluorometer, [Ca2+]i from cells loaded with the Ca2+-sensitive dye, Fura 2-AM, was monitored in the absence of extracellular Ca2+. The sarco/endoplasmic reticulum Ca2+ ATPase inhibitor, thapsigargin (TG, 1 ?M), was used to induce Ca2+ release from the endoplasmic reticulum. TG-induced [Ca2+]i increase from cells treated with actinomycin D plus E2 was not significantly different from cells treated with vehicle (ethanol). However, the extent of TG-induced [Ca2+]i increase was significantly lower in vehicle- or actinomycin D- plus E2-treated cells as compared with that observed in E2-treated cells, indicating that gene transcription is required for E2-mediated alteration in Ca2+ response. Five minutes of E2 treatment did not alter TG-induced [Ca2+]i increase as compared to vehicle-treated cells. Our results suggest that E2 regulates Ca2+ homeostasis in EA.hy926 via a genomic mechanism. Supported by NHLBI.
The genomic action of 17 β-estradiol accounts for altering calcium homeostasis in human endothelial cells.
FASEB Journal, 23(Supp 1),