Regulation of Store‐Operated Ca2+ Entry in the Vascular Endothelium by the G Protein‐coupled Estrogen Receptor 1 (LB570)

Abstract

The novel G protein‐coupled estrogen receptor 1 (GPER/GPR30) has been found to participate in numerous cardiovascular functions. Store‐operated Ca2+ entry (SOCE) is an essential mechanism that is required for many endothelial cell functions. We found that activation of GPER using the GPER specific agonist G1 causes a dose‐dependent inhibition of SOCE in primary vascular endothelial cells. Heterologous of GPER in HEK 293 cells is associated with substantial decreases in the total Ca2+ signal triggered by thapsigargin, and a 40% decrease in the rate of SOCE. Knockdown of GPER in endothelial cells using antisense directed against GPER increases SOCE by approximately 50% compared to cells transfected scrambled oligo. Interestingly, GPER specific antagonist G15 triggers total Ca2+ signals via SOCE by releasing the same internal Ca2+ stores as does thapsigargin. In primary endothelial cells, GPER forms a complex with the stromal interaction molecule 1 (Stim1), an essential molecular switcher of SOCE. In addition, Stim1‐ECFP colocalizes with GPER‐tetracysteine when heterologously expressed in HEK 293 cells. Heterologous expression of GPER‐DsRed2 fusion substantially decreases total Ca2+ signal stimulated by thapsigargin. Interestingly, SOCE measured in cells stably expressing fusions between EYFP and individual sub‐membrane domains (SMDs) 1 ‐ 4 of GPER does not differ from internal controls. These data indicate that GPER may be an important regulatory input of store‐operated Ca2+ entry via its interaction with Stim1. Since the EYFP‐SMD fusions are all cytoplasmically expressed, the data may also suggest that proper membrane docking (PM or ER) of full‐length GPER is required for it to exert its effect on SOCE.Grant Funding Source: National Institutes of Health