Human vascular endothelial cells contain membrane binding sites for estradiol, which mediate rapid intracellular signaling.
Estrogen induces both rapid and delayed effects on the cardiovascular system. The early effects take place within minutes (e.g., changes in vasomotor tone) and are mediated through rapid intracellular signaling pathways; whereas the delayed effects (e.g., remodeling or lipid alterations) require hours to days to occur and require transcriptional effects with subsequent modulation of protein expression. To study the acute effects of 17beta-estradiol (E2) treatment on vascular function, we have investigated the rapid (on the order of minutes) effects of E2 treatment on intracellular signaling in human endothelial cells (EC). Our previous data have shown that E2 induces rapid release of NO from and activation of guanylate cyclase in human EC. In this study, we demonstrate that E2 also activates mitogen-activated protein kinase (extracellular signal-related kinase) signaling within minutes in EC. We hypothesized that this effect might be mediated by estrogen receptors (ER) localized to the cell surface. Our data show that membrane-impermeant forms of E2 also activate EC mitogen-activated protein kinase as well as stimulate cGMP production and NO release. The ER antagonist ICI 182,780 blocks this effect. Using confocal microscopy and flow cytometric analysis, we demonstrate that EC contain surface binding sites for E2, detectable by cell-impermeant ligand binding and equally with an anti-ERalpha antibody. Immunoreactive bands of 66 and 45 kDa are detectable with an anti-ERalpha mAb in human EC, and their individual presence correlates functionally with E2-stimulated genomic and rapid nongenomic responses, respectively. Membrane ERs may provide key molecular switches in these novel, rapid signaling pathways induced by E2 in EC.
Russell
K S
KS
Division of Cardiovascular Medicine and Molecular Cardiobiology, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, CT 06536-0812, USA.
Haynes
M P
MP
Sinha
D
D
Clerisme
E
E
Bender
J R
JR
D000911:Antibodies, Monoclonal / Q000276:immunology; D002460:Cell Line; D002463:Cell Membrane Permeability; D002478:Cells, Cultured / Q000187:drug effects; D006152:Cyclic GMP / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D005434:Flow Cytometry; D006801:Humans; D020935:MAP Kinase Signaling System; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D011960:Receptors, Estrogen / Q000187:drug effects* / Q000276:immunology / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors; D014162:Transfection
D000911:Antibodies, Monoclonal; D011960:Receptors, Estrogen; D011993:Recombinant Fusion Proteins; C043090:estradiol-bovine serum albumin; D012710:Serum Albumin, Bovine; D009569:Nitric Oxide; D004958:Estradiol; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D006152:Cyclic GMP