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Estrogen mediated intracellular calcium increase in human endothelial cells is estrogen receptor alpha dependent
Author(s) -
Thor Der,
Cereghino Geoff Lin,
Rahimian Roshanak
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1164-b
Subject(s) - thapsigargin , gene knockdown , estrogen receptor , homeostasis , extracellular , endoplasmic reticulum , chemistry , intracellular , estrogen , microbiology and biotechnology , calcium , endocrinology , medicine , biology , biochemistry , apoptosis , organic chemistry , cancer , breast cancer
Our preliminary studies showed 17 β‐estradiol (E2)‐regulated Ca 2+ homeostasis may play a role in enhancing nitric oxide (NO) production in endothelial cells. Here, we investigated whether the effect of E2 on intracellular calcium concentration ([Ca 2+ ] i ) regulation in human endothelial cells (EA.hy926) was estrogen receptor (ER) dependent. Using PCR, we showed ERα but not ERβ was expressed in EA.hy926. To establish the role of ERα in E2‐regulated Ca 2+ homeostasis, ERα was down‐regulated in EA.hy926 using siRNA (90 pmol) as determined by real time RT‐PCR and Western blotting. [Ca 2+ ] i in Fura 2 loaded ERα knockdown cells and negative control knockdown cells was measured using spectrofluorometry. In the absence of extracellular Ca 2+ , inhibition of endoplasmic reticulum Ca 2+ ‐ATPase with thapsigargin (1 μM) caused a single Ca 2+ transient response, indicating Ca 2+ release from the store. Cells subjected to siRNA‐mediated ERα knockdown treated with E2 (1 μM, 24 h) exhibited reduced TG‐induced Ca 2+ release compared to E2 treated negative control knockdown cells. Furthermore, a subsequent increase in extracellular Ca 2+ concentration led to a robust increase in [Ca 2+ ] i which was significantly reduced in E2 treated ERα knockdown compared to E2 treated control cells. Our results indicated that ERα may contribute to E2‐regulated Ca 2+ homeostasis and subsequently NO production in endothelial cells. Supported by NHLBI.