Disease relevance of eNOS

• We conclude that chronic intrauterine pulmonary hypertension decreases eNOS in the fetal lung [1].
• Chronic hypertension reduced lung eNOS mRNA content by 30% (P < 0.05) [1].
• This suggests that chronic hypoxemia has an opposing effect on eNOS and nNOS gene regulation [2].
• On the other hand, downregulation of eNOS activity and expression may compromise the neuroprotective effect of eNOS and, therefore, further exacerbate brain injury [2].
• Upregulation of eNOS in pregnant ovine uterine arteries by chronic hypoxia [3].

High impact information on eNOS

• In studies of intact ovine endothelial cells, 17beta-estradiol (E2) caused acute (five-minute) activation of eNOS that was unaffected by actinomycin D but was fully inhibited by concomitant acute treatment with specific estrogen receptor (ER) antagonists [4].
• These findings demonstrate that the short-term effects of estrogen central to cardiovascular physiology are mediated by ERalpha functioning in a novel, nongenomic manner to activate eNOS via MAP kinase-dependent mechanisms [4].
• In addition, the acute response of eNOS to E2 was reconstituted in COS-7 cells cotransfected with wild-type ERalpha and eNOS, but not by transfection with eNOS alone [4].
• Furthermore, the inhibition of tyrosine kinases or mitogen-activated protein (MAP) kinase kinase prevented the activation of eNOS by E2, and E2 caused rapid ER-dependent activation of MAP kinase [4].
• Estrogen is an important vasoprotective molecule that causes the rapid dilation of blood vessels by activating endothelial nitric oxide synthase (eNOS) through an unknown mechanism [4].

Chemical compound and disease context of eNOS

• However, endothelial nitric oxide synthase protein expression was similar in both groups, whereas endothelium-independent relaxation to sodium nitroprusside was greater in the fistula group compared with controls [5].

Biological context of eNOS

• We investigated signaling mechanisms underlying pulsatile shear stress-induced increases in eNOS phosphorylation and protein expression by OFPAE cells [6].
• The ovine eNOS cDNA has high homology to published human and bovine sequences and shares identity with the bovine amino acid sequence [7].
• To determine the effects of intrauterine hypertension on lung eNOS content, fetal lung tissue was harvested 8-12 days after intrauterine closure of the ductus arteriosus (DA) performed at 125-128 days of gestation (term = 147 days) [1].
• Thus, acylation targets eNOS to plasmalemmal caveolae [8].
• We designed studies to determine whether eNOS is localized to plasmalemmal microdomains implicated in signal transduction called caveolae [8].

Anatomical context of eNOS

• The sheep, however, is widely used as a model for cardiovascular adaptation to pregnancy and ovine uterine artery endothelial cell (UAEC) eNOS undergoes pregnancy-specific (P) enhancement of activity associated with increased Ca(2+) and protein kinase signaling in response to a number of agonists, including adenosine triphosphate (ATP) [7].
• When ovine eNOS was transiently expressed in COS-7 cells (COS-7/oeNOS), A23187 increased specific catalytic activity in a dose- and time-dependent manner [7].
• Although positive immunostaining for eNOS persisted in lung vascular endothelium, eNOS protein content was reduced by 48%, as measured by Western analysis (P < 0.001) [1].
• Immunoelectron microscopy showed that eNOS heavily decorated endothelial caveolae, whereas coated pits and smooth plasma membrane were devoid of gold particles [8].
• In newborn lambs, PTHrP-induced relaxation was not affected by endothelium removal, inhibition of eNOS, or inhibition of adenylyl cyclases by SQ-22536 [9].

Associations of eNOS with chemical compounds

• Phosphorylation of eNOS Ser1177 under shear stress was elevated by 20 min, a response that was blocked by the phosphatidyl inositol-3-kinase (PI-3K)-inhibitors wortmannin and LY294002 but not by the mitogen activated protein kinase kinase (MEK)-inhibitor UO126 [6].
• Given this information we can now begin to dissect the relationship between Ca(2+) elevation and specific phosphorylation events in eNOS activation in the ovine model, and thereby gain insight into the possible basis for pregnancy-related dysfunction [7].
• We concluded that endothelium-derived placental artery eNOS levels, AF NO (nitrates plus nitrites), and AF cGMP were markedly increased during the third trimester, thus supporting a role for NO-mediated elevations in cGMP in the control of fetoplacental blood flow [10].
• We hypothesized that the expression of endothelial nitric oxide synthase (eNOS) in fetoplacental artery endothelium and the concentrations of nitric oxide (NO) and cyclic GMP (cGMP) in amniotic fluid (AF) are increased during the third trimester of ovine gestation [10].
• Estrogen selectively up-regulates eNOS and nNOS in reproductive arteries by transcriptional mechanisms [11].

Regulatory relationships of eNOS

• We evaluated eNOS activation by E2 in cultured endothelial cells that express endogenous ERbeta to determine whether the ERbeta isoform has nongenomic action and to reveal the subcellular locale of that function [12].

Other interactions of eNOS

• Neuronal (nNOS), inducible (iNOS), and endothelial (eNOS) mRNA was measured using real-time PCR methodology specific for ovine NOS isoforms [13].
• Vascular endothelial growth factor (VEGF) has been reported to increase eNOS expression and NO production in endothelial cell cultures [14].
• While ERalpha and eNOS were not elevated in any other reproductive or non-reproductive endothelia tested, ERbeta was augmented by pregnancy in uterine, mammary, placenta, and coronary artery endothelia [15].
• Through dual immunostaining we further identified for the first time a zona intermedia without strong staining for 17 alpha-hydroxylase/C(17/20)-lyase P450 or angiotensin II type 1 receptor, but positive for eNOS [16].
• Caveolin-1, 90-kDa heat shock protein, ERK-1/2, and Akt, all known and proposed regulators of eNOS activity, were detected throughout the ovine adrenal cortex [16].

Analytical, diagnostic and therapeutic context of eNOS

• We measured eNOS mRNA and protein content by Northern and Western blot analyses, respectively [1].
• Expression of eNOS protein was measured in intact and denuded placental arteries and in endothelium-derived protein by Western analysis and confirmed by immunohistochemistry [10].
• Persistent eNOS in lung hypoplasia caused by left pulmonary artery ligation in the ovine fetus [17].
• To investigate the effects of decreased blood flow and the potential role of altered eNOS content in lung hypoplasia, we studied an animal model of lung hypoplasia after left pulmonary artery (LPA) ligation in nine fetal lambs (114-124 days gestation; term = 147 days) [17].
• Molecular cloning of ovine endothelial nitric oxide synthase and expression in COS-7 cells [7].

References