The estrogen effects on endothelial repair and mitogen-activated protein kinase activation are abolished in endothelial nitric-oxide (NO) synthase knockout mice, but not by NO synthase inhibition by N-nitro-L-arginine methyl ester.
We have previously shown that estrogen exerts a vasoprotective effect by accelerating reendothelialization after perivascular artery injury through activation of the estrogen receptor alpha. Because 17beta-estradiol (E2) is known to increase the bioavailability of nitric oxide, in this study, we used the same perivascular model to characterize the role of the endothelial nitric oxide synthase (eNOS) pathway in reendothelialization. Surprisingly, we found that the stimulatory effect of E2 on reendothelialization was not altered following pharmacological inhibition of nitric-oxide synthase enzymatic activity by N-nitro-L-arginine methyl ester, whereas it was abolished in eNOS-deficient (eNOS-/-) mice. This discrepancy between eNOS gene inactivation and the pharmacological inhibition of eNOS was confirmed in a classical model of endovascular injury. When assessing the involvement of eNOS in short-term membrane-associated signaling events induced by E2, we found that E2 stimulated phosphorylation of extracellular signal-regulated kinase 1/2 in isolated perfused carotid arteries from wild-type mice in the absence or presence of N-nitro-l-arginine methyl ester, whereas this stimulation was abolished in carotid arteries from eNOS-/- mice. Similar results were obtained in primary cultures of mouse aortic endothelial cells. These data reveal an original and unexpected role of eNOS, in which its presence but not its enzymatic activity appears to be a determinant for estrogen signaling in the endothelium. The consequences of this novel function of eNOS with respect to vascular diseases should be explored.
Billon
Audrey
A
INSERM U858, Toulouse Cedex, France.
Lehoux
Stéphanie
S
Lam Shang Leen
Laetitia
L
Laurell
Henrik
H
Filipe
Cédric
C
Benouaich
Vincent
V
Brouchet
Laurent
L
Dessy
Chantal
C
Gourdy
Pierre
P
Gadeau
Alain-Pierre
AP
Tedgui
Alain
A
Balligand
Jean-Luc
JL
Arnal
Jean-François
JF
D000818:Animals; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha / Q000235:genetics; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D012038:Regeneration / Q000187:drug effects* / Q000235:genetics; D017539:Tunica Intima / Q000201:enzymology / Q000378:metabolism
D004791:Enzyme Inhibitors; D047628:Estrogen Receptor alpha; D009569:Nitric Oxide; D004958:Estradiol; D052250:Nitric Oxide Synthase Type III; D020929:Mitogen-Activated Protein Kinase Kinases; D019331:NG-Nitroarginine Methyl Ester