title: Identification of Differential ER-Alpha Versus ER-Beta Mediated Activation of eNOS in Ovine Uterine Artery Endothelial Cells.
abstract: Endothelial nitric oxide (NO) production is partly responsible for maintenance of uterine vasodilatation during physiologic states of high circulating estrogen levels, e.g., pregnancy. Although 3%-5% of estrogen receptors (ER-alpha/beta) localize to the endothelial plasmalemma, these receptors are responsible for the nongenomic vasodilator responses. Estradiol induces endothelial NO synthase (eNOS) activation to increase NO production; however, it is unknown if eNOS regulation is dependent on both ERs. We hypothesize that ER-alpha and/or ER-beta are capable of changing eNOS phosphorylation and increasing NO production in uterine artery endothelial cells (UAECs). UAECs were 1) treated with vehicle or increasing concentrations (0.1-100 nM) or timed treatments (0-30 min) of estradiol and 2) pretreated with the inhibitors ICI 182,780 (nonspecific ER), 1,3-Bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1H-pyrazole dihydrochloride (MPP; ER-alpha specific), or 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-a]pyrimidin-3-yl]phenol (PHTPP; ER-beta specific) followed by estradiol to analyze the changes in eNOS stimulatory (Ser1177)eNOS and (Ser635)eNOS versus inhibitory (Thr495)eNOS via Western blot analysis. UAECs were also pretreated with MPP, PHTPP, or MPP + PHTTP followed by estradiol or treated with the agonists estradiol, 4,4',4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol, 2,3-bis(4-hydroxyphenyl)-propionitrile, or ATP to quantify total NOx levels (NO2+NO3). Estrogen and ER-alpha activation induced an increase in (Ser1177)eNOS and (Ser635)eNOS, a decrease in (Thr495)eNOS, and an increase in NOx levels. In contrast, ER-beta activation only reduced (Thr495)eNOS without changes in (Ser1177)eNOS or (Ser635)eNOS. However, ER-beta activation increased NOx levels. Lastly, the antagonism of both receptors induced a reduction in basal and stimulated NOx levels in UAECs. These data demonstrate that 1) eNOS phosphorylation changes occur via ER-alpha- and ER-beta-dependent mechanisms and 2) ER-alpha and ER-beta can both increase NO levels independently from each other.
authors.affiliation: Department of Obstetrics & Gynecology Perinatal Research Labs, University of Wisconsin-Madison, Madison, Wisconsin.
authors.forename: Mayra B
authors.initials: MB
authors.lastname: Pastore
authors.affiliation: Department of Obstetrics & Gynecology Perinatal Research Labs, University of Wisconsin-Madison, Madison, Wisconsin.
authors.forename: Saira
authors.initials: S
authors.lastname: Talwar
authors.affiliation: Department of Obstetrics & Gynecology Perinatal Research Labs, University of Wisconsin-Madison, Madison, Wisconsin.
authors.forename: Meghan R
authors.initials: MR
authors.lastname: Conley
authors.affiliation: Department of Obstetrics & Gynecology Perinatal Research Labs, University of Wisconsin-Madison, Madison, Wisconsin Department of Animal Sciences, University of Wisconsin-Madison, Madison, Wisconsin Department of Pediatrics, University of Wisconsin-Madison, Madison, Wisconsin University of South Florida Perinatal Research Center, Tampa, Florida rmagness@health.usf.edu.
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Magness
mesh_terms: D000818:Animals; D042783:Endothelial Cells / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism*; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D047629:Estrogen Receptor beta / Q000378:metabolism*; D005260:Female; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010766:Phosphorylation; D011247:Pregnancy; D012756:Sheep; D055988:Uterine Artery / Q000166:cytology / Q000378:metabolism*
chemical_list: D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D009569:Nitric Oxide; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III
keywords: ERα; ERβ; NO; eNOS; endothelial cells; estradiol; estrogen; estrogen receptor; nitric oxide; pregnancy; uterine vasculature