Abstract 169: Impaired Shear Stress-induced Endothelial Nitric Oxide Production in High Glucose Condition is Restored by Inhibiton via NADPH Consumption by Polyol Pathway Activation

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Tomio Umemoto ◽  
Masatoshi Kuroki ◽  
Hiroto Ueba ◽  
Masanobu Kawakami ◽  
Hideo Fujita ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Shear Stress ◽  
Endothelial Dysfunction ◽  
High Glucose ◽  
Polyol Pathway ◽  
No Production ◽  
Pathway Activation ◽  
High Glucose Condition ◽  
Glucose Condition

Endothelial dysfunction leading to cardiovascular disease risk involves a decrease in nitric oxide (NO) production. In physiological conditions shear stress is a potent stimulation of endothelium-derived NO production and flow mediated NO production is regulated by the activation of endothelial NO synthase (eNOS). In endothelial cells, eNOS, aldose reductase (AR), a rate limiting enzyme of polyol pathway, and glutathione reductase (GR) share a NADPH as an obligate cofactor. In diabetec condition intracellular polyol pathway is activated and this may decrease shear stress-induced endothelial NO production and increase intracellular oxidative stress via inhibition of eNOS and GR by NADPH consumption. Therefore we investigated whethter AR inhibitor epalrestat improved endothelial NO production under high glucose condition to elucidate the mechanism of endothelial dysfunction in diabetes. We incubated human umbilical vein endothelial cells (HUVECs) in normal (5mM) and high (30mM) glucose condition for 72 hours, with or without epralrestat, or 100U/ml superoxide dismutase (SOD), respectively. After exchange of medium for Krebs’ buffer, HUVECs were exposed to 12dyne/cm2 steady laminar fluid shear stress for 5 minutes. NO release from HUVECs was measured as NO2 using a NOx analyzing HPLC system by Griess reaction. Next we harvested the cells in lysis buffer and analyzed phosphorylation of Akt (shear induced intracellular signal transduction) and eNOS by western blotting, and measured intracellular 8-OHdG and ratio of NADPH/NADP. In high glucose condition NO2 was decreased and 8-OHdG increased compared to low glucose. NO2 was restored and 8-OHdG was reduced by epalrestat significantly (p<0.01, p<0.05, respectively, vs. high glucose condition). In SOD-treated HUVECs, NO2 was not restored (n.s. vs. high glucose condition) despite of complete reduction of 8-OHdG (p<0.01). Both Akt and eNOS phosphorylation by shear stress was affected neither by high glucose, epalrestat nor SOD. Intracellular NADPH/NADP ratio was decreased in high glucose condition, but this reduction was restored by epalrestat. These results showed that polyol pathway activation plays a key role in endothelial NO production under high glucose condition via a cofactor NADPH.

scholarly journals High glucose-induced IKK-Hsp-90 interaction contributes to endothelial dysfunction

2009 ◽  
Vol 296 (1) ◽  
pp. C182-C192 ◽  
Author(s):  
Sumathy Mohan ◽  
Ryszard Konopinski ◽  
Bo Yan ◽  
Victoria E. Centonze ◽  
Mohan Natarajan
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Endothelial Dysfunction ◽  
High Glucose ◽  
Vascular Endothelial Cells ◽  
Heat Shock Protein 90 ◽  
No Production ◽  
Enos Activity ◽  
Hsp 90 ◽  
Endothelial Nitric Oxide

A decline in the bioavailability of nitric oxide (NO) that causes endothelial dysfunction is a hallmark of diabetes. The availability of NO to the vasculature is regulated by endothelial nitric oxide synthase (eNOS) activity and the involvement of heat shock protein-90 (Hsp-90) in the regulation of eNOS activity has been demonstrated. Hsp-90 has been shown to interact with upstream kinases [inhibitor κB kinases (IKK)α, β, and γ] in nonvascular cells. In this study, we have investigated the interaction of Hsp-90-IKKβ in endothelial cells under conditions of high glucose (HG) as a possible mechanism that diminishes Hsp-90-eNOS interaction, which could contribute to reduced bioavailability of NO. We report for the first time that IKKβ interacts with Hsp-90, and this interaction is augmented by HG in vascular endothelial cells. HG also augments transcriptional (3.5 ± 0.65-fold) and translational (1.97 ± 0.17-fold) expression as well as the catalytic activity of IKKβ (2.45 ± 0.4-fold). Both IKKβ and eNOS could be coimmunoprecipitated with Hsp-90. Inhibition of Hsp-90 with geldanamycin (2 μM) or Radicicol (20 μM) mitigated (0.45 ± 0.04-fold and 0.93 ± 0.16-fold, respectively) HG induced-IKKβ activity (2.5 ± 0.42-fold). Blocking of IKKβ expression by IKK inhibitor II (15 μM wedelolactone) or small interferring RNA (siRNA) improved Hsp-90-eNOS interaction and NO production under conditions of HG. These results illuminate a possible mechanism for the declining eNOS activity reported under conditions of HG.

Effects of simulated hyperglycemia, insulin, and glucagon on endothelial nitric oxide synthase expression

2000 ◽  
Vol 279 (1) ◽  
pp. E11-E17 ◽  
Author(s):  
Yaoxian Ding ◽  
Nosratola D. Vaziri ◽  
Richard Coulson ◽  
Vaijinath S. Kamanna ◽  
Daeyoung D. Roh
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Endothelial Dysfunction ◽  
High Glucose ◽  
Glucose Concentration ◽  
No Production ◽  
High Glucose Concentration ◽  
Enos Expression ◽  
Cultured Endothelial Cells ◽  
Increased Risk

Diabetes is associated with endothelial dysfunction and increased risk of hypertension, cardiovascular disease, and renal complications. Earlier studies have revealed that hyperglycemia impairs nitric oxide (NO) production and diabetes causes endothelial dysfunction in humans and experimental animals. This study was designed to test the effects of altered concentrations of glucose, insulin, and glucagon, the principal variables in types I and II diabetes, on NO production and endothelial NO synthase (eNOS) expression in cultured human coronary endothelial cells. Cultured endothelial cells were incubated in the presence of glucose at either normal (5.6 mM) or high (25 mM) concentrations for 7 days. The rates of basal and bradykinin-stimulated NO production (nitrate + nitrite) and eNOS protein expression (Western blot) were then determined at the basal condition and in the presence of insulin (10−8 and 10−7 M), glucagon (10−8 and 10−7 M), or both. Incubation with a high-glucose concentration for 7 days significantly downregulated, whereas insulin significantly upregulated, basal and bradykinin-stimulated NO production and eNOS expression in cultured endothelial cells. The stimulatory action of insulin was mitigated by high-glucose concentration and abolished by cotreatment of cells with glucagon. Thus hyperglycemia, insulinopenia, and hyperglucagonemia, which frequently coexist in diabetes, can work in concert to suppress NO production by human coronary artery endothelial cells.

Laminar Flow on Endothelial Cells Suppresses eNOS O-GlcNAcylation to Promote eNOS Activity

2021 ◽  
Author(s):  
Sarah Basehore ◽  
Samantha Bohlman ◽  
Callie Weber ◽  
Swathi Swaminathan ◽  
Yuji Zhang ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Shear Stress ◽  
Laminar Flow ◽  
No Production ◽  
Disturbed Flow ◽  
Enos Activity ◽  
Enos Phosphorylation ◽  
Steady Laminar ◽  
In Cells

Rationale: In diabetic animals as well as high glucose cell culture conditions, endothelial nitric oxide synthase (eNOS) is heavily O-GlcNAcylated, which inhibits its phosphorylation and nitric oxide (NO) production. It is unknown, however, whether varied blood flow conditions, which affect eNOS phosphorylation, modulate eNOS activity via O-GlcNAcylation-dependent mechanisms. Objective: The goal of this study was to test if steady laminar flow, but not oscillating disturbed flow, decreases eNOS O-GlcNAcylation, thereby elevating eNOS phosphorylation and NO production. Methods and Results: Human umbilical vein endothelial cells (HUVEC) were exposed to either laminar flow (20 dynes/cm2 shear stress) or oscillating disturbed flow (4{plus minus}6 dynes/cm2 shear stress) for 24 hours in a cone-and-plate device. eNOS O-GlcNAcylation was almost completely abolished in cells exposed to steady laminar but not oscillating disturbed flow. Interestingly, there was no change in protein level or activity of key O-GlcNAcylation enzymes (OGT, OGA, or GFAT). Instead, metabolomics data suggest that steady laminar flow decreases glycolysis and hexosamine biosynthetic pathway (HBP) activity, thereby reducing UDP-GlcNAc pool size and consequent O-GlcNAcylation. Inhibition of glycolysis via 2-deoxy-2-glucose (2-DG) in cells exposed to disturbed flow efficiently decreased eNOS O-GlcNAcylation, thereby increasing eNOS phosphorylation and NO production. Finally, we detected significantly higher O-GlcNAcylated proteins in endothelium of the inner aortic arch in mice, suggesting that disturbed flow increases protein O-GlcNAcylation in vivo. Conclusions: Our data demonstrate that steady laminar but not oscillating disturbed flow decreases eNOS O-GlcNAcylation by limiting glycolysis and UDP-GlcNAc substrate availability, thus enhancing eNOS phosphorylation and NO production. This research shows for the first time that O-GlcNAcylation is regulated by mechanical stimuli, relates flow-induced glycolytic reductions to macrovascular disease, and highlights targeting HBP metabolic enzymes in endothelial cells as a novel therapeutic strategy to restore eNOS activity and prevent EC dysfunction in cardiovascular disease.

scholarly journals (−)-Epicatechin induces calcium and translocation independent eNOS activation in arterial endothelial cells

2011 ◽  
Vol 300 (4) ◽  
pp. C880-C887 ◽  
Author(s):  
Israel Ramirez-Sanchez ◽  
Lisandro Maya ◽  
Guillermo Ceballos ◽  
Francisco Villarreal
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Cardiovascular Effects ◽  
Mesenteric Arteries ◽  
No Production ◽  
Human Coronary Artery ◽  
Calmodulin Binding ◽  
Pathway Activation ◽  
Functional Relevance ◽  
Endothelial Nitric Oxide

The consumption of cacao-derived (i.e., cocoa) products provides beneficial cardiovascular effects in healthy subjects as well as individuals with endothelial dysfunction such as smokers, diabetics, and postmenopausal women. The vascular actions of cocoa are related to enhanced nitric oxide (NO) production. These actions can be reproduced by the administration of the cacao flavanol (−)-epicatechin (EPI). To further understand the mechanisms behind the vascular action of EPI, we investigated the effects of Ca2+ depletion on endothelial nitric oxide (NO) synthase (eNOS) activation/phosphorylation and translocation. Human coronary artery endothelial cells were treated with EPI or with bradykinin (BK), a well-known Ca2+-dependent eNOS activator. Results demonstrate that both EPI and BK induce increases in intracellular calcium and NO levels. However, under Ca2+-free conditions, EPI (but not BK) is still capable of inducing NO production through eNOS phosphorylation at serine 615, 633, and 1177. Interestingly, EPI-induced translocation of eNOS from the plasmalemma was abolished upon Ca2+ depletion. Thus, under Ca2+-free conditions, EPI can stimulate NO synthesis independent of calmodulin binding to eNOS and of its translocation into the cytoplasm. We also examined the effect of EPI on the NO/cGMP/vasodilator-stimulated phosphoprotein (VASP) pathway activation in isolated Ca2+-deprived canine mesenteric arteries. Results demonstrate that under these conditions, EPI induces the activation of this vasorelaxation-related pathway and that this effect is inhibited by pretreatment with nitro-l-arginine methyl ester, suggesting a functional relevance for this phenomenon.

scholarly journals VE-PTP inhibition elicits eNOS phosphorylation to blunt endothelial dysfunction and hypertension in diabetes

2020 ◽  
Author(s):  
Mauro Siragusa ◽  
Alberto Fernando Oliveira Justo ◽  
Pedro Felipe Malacarne ◽  
Anna Strano ◽  
Akshay Buch ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Endothelial Cells ◽  
Shear Stress ◽  
Endothelial Dysfunction ◽  
Vascular Reactivity ◽  
Therapeutic Option ◽  
Diabetic Patients ◽  
No Production ◽  
Vascular Endothelial ◽  
Enos Activity

Abstract Aims Receptor-type vascular endothelial protein tyrosine phosphatase (VE-PTP) dephosphorylates Tie-2 as well as CD31, VE-cadherin, and vascular endothelial growth factor receptor 2 (VEGFR2). The latter form a signal transduction complex that mediates the endothelial cell response to shear stress, including the activation of the endothelial nitric oxide (NO) synthase (eNOS). As VE-PTP expression is increased in diabetes, we investigated the consequences of VE-PTP inhibition (using AKB-9778) on blood pressure in diabetic patients and the role of VE-PTP in the regulation of eNOS activity and vascular reactivity. Methods and results In diabetic patients AKB-9778 significantly lowered systolic and diastolic blood pressure. This could be linked to elevated NO production, as AKB increased NO generation by cultured endothelial cells and elicited the NOS inhibitor-sensitive relaxation of endothelium-intact rings of mouse aorta. At the molecular level, VE-PTP inhibition increased the phosphorylation of eNOS on Tyr81 and Ser1177 (human sequence). The PIEZO1 activator Yoda1, which was used to mimic the response to shear stress, also increased eNOS Tyr81 phosphorylation, an effect that was enhanced by VE-PTP inhibition. Two kinases, i.e. abelson-tyrosine protein kinase (ABL)1 and Src were identified as eNOS Tyr81 kinases as their inhibition and down-regulation significantly reduced the basal and Yoda1-induced tyrosine phosphorylation and activity of eNOS. VE-PTP, on the other hand, formed a complex with eNOS in endothelial cells and directly dephosphorylated eNOS Tyr81 in vitro. Finally, phosphorylation of eNOS on Tyr80 (murine sequence) was found to be reduced in diabetic mice and diabetes-induced endothelial dysfunction (isolated aortic rings) was blunted by VE-PTP inhibition. Conclusions VE-PTP inhibition enhances eNOS activity to improve endothelial function and decrease blood pressure indirectly, through the activation of Tie-2 and the CD31/VE-cadherin/VEGFR2 complex, and directly by dephosphorylating eNOS Tyr81. VE-PTP inhibition, therefore, represents an attractive novel therapeutic option for diabetes-induced endothelial dysfunction and hypertension.

scholarly journals Salidroside Stimulates Mitochondrial Biogenesis and Protects against H2O2-Induced Endothelial Dysfunction

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Shasha Xing ◽  
Xiaoyan Yang ◽  
Wenjing Li ◽  
Fang Bian ◽  
Dan Wu ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Transcription Factor ◽  
Endothelial Dysfunction ◽  
Mitochondrial Biogenesis ◽  
Umbilical Vein ◽  
Adenosine Monophosphate ◽  
No Production ◽  
Peroxisome Proliferator ◽  
Atp Production

Salidroside (SAL) is an active component ofRhodiola roseawith documented antioxidative properties. The purpose of this study is to explore the mechanism of the protective effect of SAL on hydrogen peroxide- (H2O2-) induced endothelial dysfunction. Pretreatment of the human umbilical vein endothelial cells (HUVECs) with SAL significantly reduced the cytotoxicity brought by H2O2. Functional studies on the rat aortas found that SAL rescued the endothelium-dependent relaxation and reduced superoxide anion (O2∙-) production induced by H2O2. Meanwhile, SAL pretreatment inhibited H2O2-induced nitric oxide (NO) production. The underlying mechanisms involve the inhibition of H2O2-induced activation of endothelial nitric oxide synthase (eNOS), adenosine monophosphate-activated protein kinase (AMPK), and Akt, as well as the redox sensitive transcription factor, NF-kappa B (NF-κB). SAL also increased mitochondrial mass and upregulated the mitochondrial biogenesis factors, peroxisome proliferator-activated receptor gamma-coactivator-1alpha (PGC-1α), and mitochondrial transcription factor A (TFAM) in the endothelial cells. H2O2-induced mitochondrial dysfunction, as demonstrated by reduced mitochondrial membrane potential (Δψm) and ATP production, was rescued by SAL pretreatment. Taken together, these findings implicate that SAL could protect endothelium against H2O2-induced injury via promoting mitochondrial biogenesis and function, thus preventing the overactivation of oxidative stress-related downstream signaling pathways.

Role of G proteins in shear stress-mediated nitric oxide production by endothelial cells

1994 ◽  
Vol 267 (3) ◽  
pp. C753-C758 ◽  
Author(s):  
M. J. Kuchan ◽  
H. Jo ◽  
J. A. Frangos
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Shear Stress ◽  
G Protein ◽  
G Proteins ◽  
No Production ◽  
Dependent Manner ◽  
Protein Activation ◽  
Synthase Inhibitor

Exposure of cultured endothelial cells to shear stress resulting from well-defined fluid flow stimulates the production of nitric oxide (NO). We have established that an initial burst in production is followed by sustained steady-state NO production. The signal transduction events leading to this stimulation are not well understood. In the present study, we examined the role of regulatory guanine nucleotide binding proteins (G proteins) in shear stress-mediated NO production. In endothelial cells not exposed to shear stress, AIF4-, a general activator of G proteins, markedly elevated the production of guanosine 3',5'-cyclic monophosphate (cGMP). Pretreatment with NO synthase inhibitor N omega-nitro-L-arginine completely blocked this stimulation. Incubation with guanosine 5'-O-(2-thiodiphosphate) (GDP beta S), a general G protein inhibitor, blocked the flow-mediated burst in cGMP production in a dose-dependent manner. Likewise, GDP beta S inhibited NOx (NO2 + NO3) production for the 1st h. However, inhibition was not detectable between 1 and 3 h. Pertussis toxin (PTx) had no effect on the shear response at any time point. The burst in NO production caused by a change in shear stress appears to be dependent on a PTx-refractory G protein. Sustained shear-mediated production is independent of G protein activation.

Abstract 141: Histone Deacetylase 1 Regulates Nitric Oxide Production and Nitric Oxide Synthase-3 Acetylation in Endothelial Cells

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Kelly A Hyndman ◽  
Dao H Ho ◽  
Jennifer S Pollock
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Endothelial Dysfunction ◽  
Histone Deacetylase ◽  
Life Stress ◽  
Trichostatin A ◽  
Early Life Stress ◽  
No Production ◽  
Histone Deacetylase 1 ◽  
Nitrite Production

Previous reports showed that NOS3 is regulated by acetylation through transcriptional mechanisms via histone acetylation or through direct lysine acetylation. Histone deacetylase (HDAC) enzymes and histone acetyltransferases (HATs) modulate acetylation processes. Recent work by our lab, demonstrated increased expression of aortic HDAC1 and HDAC6 while HATs were unchanged in a mouse model of early life stress with endothelial dysfunction. These data suggest a negative correlation between endothelial dysfunction and HDAC expression. The purpose of this study was to test the hypothesis that HDAC1 and 6 regulate endothelial NO production and/or NOS3 acetylation. Initial immunoprecipitation studies with anti-acetyl lysine and anti-NOS3 antibodies demonstrated that NOS3 is basally acetylated in primary bovine aortic endothelial cells (BAECs). Treatment with the HDAC inhibitor, trichostatin A (500 nM) for 1 hr, significantly increased NOS3 acetylation. BAECs were transfected with HDAC1, HDAC6, vector expression plasmids, or untransfected, with nitrite production determined by HPLC and NOS3 acetylation and expression probed by immunoprecipitation and Western blotting. Untransfected and vector transfected control BAECs had similar NO production (357 ± 10 and 344 ± 30 pmol/mg pr/h, respectively, N=6) as well as NOS3 acetylation (7.8 ± 1.6 and 6.8 ±0.3 AU, N=3). HDAC6 transfected BAECs had similar NO production to the control BAECs (272 ± 93 pmol/mg pr/h, N=3) with an increase in NOS3 acetylation (17.4 ± 1.7 AU, N=3). In contrast, HDAC1 overexpression significantly decreased NO production (89 ± 50 pmol/mg pr/h, P< 0.05, N=3) and reduced NOS3 acetylation (3.8 ± 0.5 A.U, N=3), P <0.05). Control transfections, HDAC6, and HDAC1 transfected BAECS all had similar NOS3 expression (10.14 ± 1.8; 9.8 ±1.6; 8.9 ± 1.5; 10.6 ± 1.0 AU, respectively, N=3). Thus, we conclude that HDAC1 regulates NO production via direct lysine deacetylation of NOS3.

scholarly journals Activation of Endothelial Nitric Oxide Synthase by the Angiotensin II Type 1 Receptor

Endocrinology ◽  
2006 ◽  
Vol 147 (12) ◽  
pp. 5914-5920 ◽  
Author(s):  
Hiroyuki Suzuki ◽  
Kunie Eguchi ◽  
Haruhiko Ohtsu ◽  
Sadaharu Higuchi ◽  
Sudhir Dhobale ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Angiotensin Ii ◽  
Endothelial Dysfunction ◽  
Enos Gene ◽  
No Production ◽  
Hypertrophic Response ◽  
Cgmp Production ◽  
At1 Antagonist

Enhanced angiotensin II (AngII) action has been implicated in endothelial dysfunction that is characterized as decreased nitric oxide availability. Although endothelial cells have been reported to express AngII type 1 (AT1) receptors, the exact role of AT1 in regulating endothelial NO synthase (eNOS) activity remains unclear. We investigated the possible regulation of eNOS through AT1 in bovine aortic endothelial cells (BAECs) and its functional significance in rat aortic vascular smooth muscle cells (VSMCs). In BAECs infected with adenovirus encoding AT1 and in VSMCs infected with adenovirus encoding eNOS, AngII rapidly stimulated phosphorylation of eNOS at Ser1179. This was accompanied with increased cGMP production. These effects were blocked by an AT1 antagonist. The cGMP production was abolished by a NOS inhibitor as well. To explore the importance of eNOS phosphorylation, VSMCs were also infected with adenovirus encoding S1179A-eNOS. AngII did not stimulate cGMP production in VSMCs expressing S1179A. However, S1179A was able to enhance basal NO production as confirmed with cGMP production and enhanced vasodilator-stimulated phosphoprotein phosphorylation. Interestingly, S1179A prevented the hypertrophic response similar to wild type in VSMCs. From these data, we conclude that the AngII/AT1 system positively couples to eNOS via Ser1179 phosphorylation in ECs and VSMCs if eNOS and AT1 coexist. However, basal level NO production may be sufficient for prevention of AngII-induced hypertrophy by eNOS expression. These data demonstrate a novel molecular mechanism of eNOS regulation and function and thus provide useful information for eNOS gene therapy under endothelial dysfunction.

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