scholarly journals In Vivo Function of Flow-Responsive Cis -DNA Elements of the Endothelial Nitric Oxide Synthase Gene: A Role for Chromatin-Based Mechanisms

Circulation ◽  
2021 ◽  
Author(s):  
Kyung Ha Ku ◽  
Michelle K. Dubinsky ◽  
Aravin N. Sukumar ◽  
Noeline Subramaniam ◽  
Manon Y.M. Feasson ◽  
...  
Keyword(s):  
Endothelial Nitric Oxide Synthase ◽  
Proximal Promoter ◽  
Reporter Expression ◽  
Enos Expression ◽  
Disturbed Flow ◽  
Dna Elements ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

Background: Endothelial nitric oxide synthase (eNOS) is an endothelial cell (EC)-specific gene predominantly expressed in medium- to large-sized arteries where ECs experience atheroprotective laminar flow with high shear stress (SS). Disturbed flow with lower average SS decreases eNOS transcription, which leads to the development of atherosclerosis, especially at bifurcations and curvatures of arteries. This prototypic arterial EC gene contains two distinct flow-responsive cis -DNA elements in the promoter, the Shear Stress Response Element (SSRE) and the Krüppel-Like Factor (KLF) element. Previous in vitro studies suggested their positive regulatory functions on flow-induced transcription of EC genes including eNOS. However, the in vivo function of these cis -DNA elements remains unknown. Methods: Insertional transgenic mice with a mutation at each flow-responsive cis-DNA element were generated using a murine eNOS promoter-β-galactosidase reporter by linker-scanning mutagenesis and compared with episomal-based mutations in vitro . DNA methylation at the eNOS proximal promoter in mouse ECs was assessed by bisulfite sequencing or pyrosequencing. Results: Wildtype mice with a functional eNOS promoter-reporter transgene exhibited reduced endothelial reporter expression in the atheroprone regions of disturbed flow (n=5). Surprisingly, the SSRE mutation abrogated reporter expression in ECs and was associated with aberrant hypermethylation at the eNOS proximal promoter (n=7). Reporter gene silencing was independent of transgene copy number and integration position, indicating that the SSRE is a critical cis -element necessary for eNOS transcription in vivo . The KLF mutation demonstrated an integration site-specific decrease in eNOS transcription, again with marked promoter methylation (n=8), suggesting that the SSRE alone is not sufficient for eNOS transcription in vivo. In wildtype mice, the native eNOS promoter was significantly hypermethylated in ECs from the atheroprone regions where eNOS expression was markedly repressed by chronic disturbed flow, demonstrating that eNOS expression is regulated by flow-dependent DNA methylation that is region-specific in the arterial endothelium in vivo . Conclusions: We report, for the first time, that the SSRE and KLF elements are critical flow sensors necessary for a transcriptionally permissive, hypomethylated eNOS promoter in ECs under chronic SS in vivo . Moreover, eNOS expression is regulated by flow-dependent epigenetic mechanisms, which offers novel mechanistic insight on eNOS gene regulation in atherogenesis.

scholarly journals Characterization of three inhibitors of endothelial nitric oxide synthase in vitro and in vivo

1990 ◽  
Vol 101 (3) ◽  
pp. 746-752 ◽  
Author(s):  
D.D. Rees ◽  
R.M.J. Palmer ◽  
R. Schulz ◽  
H.F. Hodson ◽  
S. Moncada
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

scholarly journals Can endothelial hemoglobin-α regulate nitric oxide vasodilatory signaling?

2017 ◽  
Vol 312 (4) ◽  
pp. H854-H866 ◽  
Author(s):  
Jaimit Parikh ◽  
Adam Kapela ◽  
Nikolaos M. Tsoukias
Keyword(s):  
Mathematical Modeling ◽  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Cellular Models ◽  
No Signaling ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

We used mathematical modeling to investigate nitric oxide (NO)-dependent vasodilatory signaling in the arteriolar wall. Detailed continuum cellular models of calcium (Ca2+) dynamics and membrane electrophysiology in smooth muscle and endothelial cells (EC) were coupled with models of NO signaling and biotransport in an arteriole. We used this theoretical approach to examine the role of endothelial hemoglobin-α (Hbα) as a modulator of NO-mediated myoendothelial feedback, as previously suggested in Straub et al. ( Nature 491: 473–477, 2012). The model considers enriched expression of inositol 1,4,5-triphosphate receptors (IP3Rs), endothelial nitric oxide synthase (eNOS) enzyme, Ca2+-activated potassium (KCa) channels and Hbα in myoendothelial projections (MPs) between the two cell layers. The model suggests that NO-mediated myoendothelial feedback is plausible if a significant percentage of eNOS is localized within or near the myoendothelial projection. Model results show that the ability of Hbα to regulate the myoendothelial feedback is conditional to its colocalization with eNOS near MPs at concentrations in the high nanomolar range (>0.2 μM or 24,000 molecules). Simulations also show that the effect of Hbα observed in in vitro experimental studies may overestimate its contribution in vivo, in the presence of blood perfusion. Thus, additional experimentation is required to quantify the presence and spatial distribution of Hbα in the EC, as well as to test that the strong effect of Hbα on NO signaling seen in vitro, translates also into a physiologically relevant response in vivo. NEW & NOTEWORTHY Mathematical modeling shows that although regulation of nitric oxide signaling by hemoglobin-α (Hbα) is plausible, it is conditional to its presence in significant concentrations colocalized with endothelial nitric oxide synthase in myoendothelial projections. Additional experimentation is required to test that the strong effect of Hbα seen in vitro translates into a physiologically relevant response in vivo

scholarly journals Aortic valve sclerosis in mice deficient in endothelial nitric oxide synthase

2014 ◽  
Vol 306 (9) ◽  
pp. H1302-H1313 ◽  
Author(s):  
Ramzi N. El Accaoui ◽  
Sarah T. Gould ◽  
Georges P. Hajj ◽  
Yi Chu ◽  
Melissa K. Davis ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Aortic Valve ◽  
Endothelial Nitric Oxide Synthase ◽  
Wild Type ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide ◽  
Metalloproteinase 9

Risk factors for fibrocalcific aortic valve disease (FCAVD) are associated with systemic decreases in bioavailability of endothelium-derived nitric oxide (EDNO). In patients with bicuspid aortic valve (BAV), vascular expression of endothelial nitric oxide synthase (eNOS) is decreased, and eNOS−/− mice have increased prevalence of BAV. The goal of this study was to test the hypotheses that EDNO attenuates profibrotic actions of valve interstitial cells (VICs) in vitro and that EDNO deficiency accelerates development of FCAVD in vivo. As a result of the study, coculture of VICs with aortic valve endothelial cells (vlvECs) significantly decreased VIC activation, a critical early phase of FCAVD. Inhibition of VIC activation by vlvECs was attenuated by NG-nitro-l-arginine methyl ester or indomethacin. Coculture with vlvECs attenuated VIC expression of matrix metalloproteinase-9, which depended on stiffness of the culture matrix. Coculture with vlvECs preferentially inhibited collagen-3, compared with collagen-1, gene expression. BAV occurred in 30% of eNOS−/− mice. At age 6 mo, collagen was increased in both bicuspid and trileaflet eNOS−/− aortic valves, compared with wild-type valves. At 18 mo, total collagen was similar in eNOS−/− and wild-type mice, but collagen-3 was preferentially increased in eNOS−/− mice. Calcification and apoptosis were significantly increased in BAV of eNOS−/− mice at ages 6 and 18 mo. Remarkably, these histological changes were not accompanied by physiologically significant valve stenosis or regurgitation. In conclusion, coculture with vlvECs inhibits specific profibrotic VIC processes. In vivo, eNOS deficiency produces fibrosis in both trileaflet and BAVs but produces calcification only in BAVs.

scholarly journals Endothelial nitric oxide synthase is central to skeletal muscle metabolic regulation and enzymatic signaling during exercise in vivo

2010 ◽  
Vol 298 (5) ◽  
pp. R1399-R1408 ◽  
Author(s):  
Robert S. Lee-Young ◽  
Julio E. Ayala ◽  
Charles F. Hunley ◽  
Freyja D. James ◽  
Deanna P. Bracy ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Skeletal Muscle ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Metabolic Regulation ◽  
Acid Uptake ◽  
Enos Expression ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

Endothelial nitric oxide synthase (eNOS) is associated with a number of physiological functions involved in the regulation of metabolism; however, the functional role of eNOS is poorly understood. We tested the hypothesis that eNOS is critical to muscle cell signaling and fuel usage during exercise in vivo, using 16-wk-old catheterized (carotid artery and jugular vein) C57BL/6J mice with wild-type (WT), partial (+/−), or no expression (−/−) of eNOS. Quantitative reductions in eNOS expression (∼40%) elicited many of the phenotypic effects observed in enos−/− mice under fasted, sedentary conditions, with expression of oxidative phosphorylation complexes I to V and ATP levels being decreased, and total NOS activity and Ca2+/CaM kinase II Thr286 phosphorylation being increased in skeletal muscle. Despite these alterations, exercise tolerance was markedly impaired in enos−/− mice during an acute 30-min bout of exercise. An eNOS-dependent effect was observed with regard to AMP-activated protein kinase signaling and muscle perfusion. Muscle glucose and long-chain fatty acid uptake, and hepatic and skeletal muscle glycogenolysis during the exercise bout was markedly accelerated in enos−/− mice compared with enos+/− and WT mice. Correspondingly, enos−/− mice exhibited hypoglycemia during exercise. Thus, the ablation of eNOS alters a number of physiological processes that result in impaired exercise capacity in vivo. The finding that a partial reduction in eNOS expression is sufficient to induce many of the changes associated with ablation of eNOS has implications for chronic metabolic diseases, such as obesity and insulin resistance, which are associated with reduced eNOS expression.

Abstract 1283: Endothelial Nitric Oxide Synthase Promotes Mesenchymal Stem Cell Migration Towards the Ischemic Myocardium

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Na Li ◽  
Fuli Xiang ◽  
Xiangru Lu ◽  
Morris Karmazyn ◽  
Qingping Feng
Keyword(s):  
Nitric Oxide ◽  
Bone Marrow ◽  
Nitric Oxide Synthase ◽  
Conditioned Medium ◽  
Endothelial Nitric Oxide Synthase ◽  
Ischemic Myocardium ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

Background: Bone marrow mesenchymal stem cells (MSCs) migrate from bone marrow towards the heart and contribute to cardiac repair post myocardial infarction. However, mechanisms by which MSCs migrate to the ischemic heart remain unclear. The present study investigated the role of endothelial nitric oxide synthase (eNOS) on MSC migration towards the ischemic myocardium and whether stromal cell derived factor-1 (SDF-1) contributes to the eNOS-mediated MSC migration. Methods and Results: MSCs were isolated from wild-type (WT) bone marrow and cultured in vitro for 3 generations. Coronary microvascular endothelial cells were isolated from adult mouse hearts and seeded on inserts for transendothelial migration assay. Neonatal cardiomyocytes were isolated from WT, eNOS −/− and eNOS transgenic (Tg) mice, cultured to subconfluence and subjected to 30 min of anoxia followed by 6 hours of reoxygenation (A/R). The conditioned medium was collected and served as a chemoattractant. MSC migration was significantly decreased in eNOS −/− compared to WT conditioned medium (9.8± 1.8% vs. 14.7±2.3%), but increased in eNOS-Tg conditioned medium (38.0±4.5%, P <0.05). SDF-1 protein secretion was significantly decreased in eNOS −/− but increased in eNOS-Tg conditioned medium. To examine MSC migration in vivo, WT, eNOS −/− or eNOS-Tg mice were subjected to myocardial ischemia for 45 min followed by 24 hrs of reperfusion (I/R). Immediately after reperfusion, GFP + MSCs were administered via a tail vein. GFP + cells in the ischemic region were significantly decreased in eNOS −/− compared to WT hearts (3.4±0.3 vs. 5.6±0.4 cell per mm 2 , P<0.05) but significantly increased in eNOS-Tg compared to WT (10.2±1.6 vs. 5.6±0.4 cell per mm 2 , P<0.05). Furthermore, SDF-1 mRNA and protein expression was increased in eNOS-Tg as compared to WT and eNOS −/− after myocardial I/R. Conclusions: eNOS promotes MSC migration towards the ischemic myocardium. This is likely due to an upregulation of SDF-1.

In vivo Function of Flow-Responsive cis-DNA Elements of the Endothelial Nitric Oxide Synthase Gene: a Role for Chromatin-based Mechanisms

2018 ◽  
Vol 32 ◽  
pp. 109
Author(s):  
Kyung Ha Ku ◽  
Britta J. Knight ◽  
Michelle K. Dubinsky ◽  
Aravin N. Sukumar ◽  
Eileen Tran ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Dna Elements ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

scholarly journals Gene transfer of recombinant endothelial nitric oxide synthase to liver in vivo and in vitro

2000 ◽  
Vol 279 (5) ◽  
pp. G1023-G1030 ◽  
Author(s):  
Vijay Shah ◽  
Alex F. Chen ◽  
Sheng Cao ◽  
Helen Hendrickson ◽  
Deb Weiler ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Enos Gene ◽  
No Production ◽  
Vasomotor Function ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

Endothelial nitric oxide synthase (eNOS)-derived nitric oxide (NO) contributes to hepatic vascular homeostasis. The aim of this study was to examine whether delivery of an adenoviral vector encoding eNOS gene to liver affects vasomotor function in vivo and the mechanism of NO production in vitro. Rats were administered adenoviruses encoding β-galactosidase (AdCMVLacZ) or eNOS (AdCMVeNOS) via tail vein injection and studied 1 wk later. In animals transduced with AdCMVLacZ, β-galactosidase activity was increased in the liver, most prominently in hepatocytes. In AdCMVeNOS-transduced animals, eNOS protein levels and catalytic activity were significantly increased. Overexpression of eNOS diminished baseline perfusion pressure and constriction in response to the α1-agonist methoxamine in the perfused liver. Transduction of cultured hepatocytes with AdCMVeNOS resulted in the targeting of recombinant eNOS to a perinuclear distribution and binding with the NOS-activating protein heat shock protein 90. These events were associated with increased ionomycin-stimulated NO release. In summary, this is the first study to demonstrate successful delivery of the recombinant eNOS gene to liver in vivo and in vitro with ensuing NO production.

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