The G protein‐coupled receptor (GPER/GPR30) activates endothelial nitric oxide synthase (1075.5)

Abstract

Endogenous estrogens mediate protective effects in the cardiovascular system in part due to rapid activation of endothelial nitric oxide synthase (eNOS), which involves the classical estrogen receptor (ER) α. In intact blood vessels, nitric oxide (NO) bioactivity is also regulated by the G protein‐coupled estrogen receptor (GPER/GPR30), suggesting an alternative pathway of estrogen‐dependent eNOS activation. We have further investigated this mechanism by analyzing GPER signaling in telomerase‐immortalized human umbilical vein endothelial (TIVE) cells. Using an antibody recognizing the second extracellular loop of GPER, immunofluorescence microscopy revealed that GPER is expressed predominantly in intracellular membranes as determined by permeabilizing vs. non‐permeabilizing conditions. Similar to the non‐selective ER agonist 17β‐estradiol, the GPER‐selective agonist G‐1 stimulated phosphorylation of Akt (ser437) and eNOS (ser1171) in a dose‐dependent manner. Additional studies have examined the roles of EGFR and ERK in G‐1‐mediated eNOS activation. Pharmacological inhibition of GPER was used to assess its contribution to estrogen‐mediated NO production. Our results further characterize the signaling pathway of GPER‐mediated eNOS activation, suggesting that the beneficial NO‐dependent effects of endogenous estrogens in the cardiovascular system may partly be mediated by GPER.