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ABSTRACT: Arginase II has recently reported as a novel therapeutic target for the treatment of cardiovascular diseases such as atherosclerosis. In the course of screening plants used in natural medicines as arginase II inhibitory activity, a methanol extract of Scutellaria indica showed significant inhibitory effect. Further fractionation and repeated column chromatography led to the isolation of a new flavan-type (1), and seven known compounds (2-8). The chemical structures of isolated compounds were elucidated based on extensive 1D and 2D NMR spectroscopic data. The isolates 1-8 were investigated in vitro for their arginase II inhibitory activity using enzyme solution prepared from kidney of anesthetized C57BL/6 mice. Compounds 3 and 5 significantly inhibited arginase II activity with IC50 values of 25.1 and 11.6 μM, respectively, whereas the other compounds were apparently inactive.
Archives of Pharmacal Research 04/2013; · 1.59 Impact Factor
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ABSTRACT: Elevated plasma cholesterol is a hallmark of numerous cardiovascular diseases that are closely linked to endothelial dysfunction indicating decreased nitric oxide (NO) production in the endothelium. It has been previously demonstrated that piceatannol-3'-O-β-D-glucopyranoside (PG) inhibits arginase activity and reciprocally regulates NO production. Here, we aimed to ascertain whether PG ameliorates vascular function in wild-type (WT) and atherogenic model mice [apolipoprotein E-null mice (ApoE-/-)] and to investigate the possible underlying mechanism. Preincubation of aortic vessels from WT mice fed a normal diet (ND) with PG attenuated vasoconstriction response to U46619 and phenylephrine (PE), while the vasorelaxant response to acetylcholine (Ach) was markedly enhanced in an endothelium-dependent manner. However, the endothelium-independent NO donor, sodium nitroprusside (SNP), did not change vessel reactivity. In thoracic aorta from ApoE-/- mice, a high-cholesterol diet (HCD) induced an increase in arginase activity, a decrease in NO release and an increase in reactive oxygen species generation that was reversed by treatment with PG. The effect of PG was associated with enhanced stability of the eNOS dimer and was not dependent on the expression levels of arginase II and eNOS proteins, although eNOS expression was increased in ApoE-/- mice fed an HCD. Furthermore, PG treatment attenuated the PE-dependent contractile response, and significantly improved the Ach-dependent vasorelaxation response in aortic rings from ApoE-/- mice fed an HCD. On the other hand, PG incubation neither altered the contractile response to a high K+ solution nor the relaxation response to SNP. When analyzing the L-arginine content using high-performance liquid chromatography, PG incubation increased the intracellular L-arginine concentration. PG administration in the drinking water significantly reduced fatty streak formation in ApoE-/- mice fed an HCD. These data indicate that PG improves the pathophysiology of cholesterol-mediated endothelial dysfunction. Therefore, we conclude that the development of PG as a novel effective therapy for preventing atherosclerotic diseases is warranted.
International Journal of Molecular Medicine 04/2013; 31(4):803-10. · 1.98 Impact Factor
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ABSTRACT: The incidence of cardiovascular disease is predicted to increase as the population ages. There is accumulating evidence that arginase upregulation is associated with impaired endothelial function. Here, we demonstrate that arginase II (ArgII) is upregulated in aortic vessels of aged mice and contributes to decreased nitric oxide (NO) generation and increased reactive oxygen species (ROS) production via endothelial nitric oxide synthase (eNOS) uncoupling. Inhibiting ArgII with small interfering RNA technique restored eNOS coupling to that observed in young mice and increased NO generation and decreased ROS production. Furthermore, enhanced vasoconstrictor responses to U46619 and attenuated vasorelaxation responses to acetylcholine in aged vasculature were markedly improved following siRNA treatment against ArgII. These results might be associated with increased L-arginine bioavailability. Collectively, these results suggest that ArgII may be a valuable target in age-dependent vascular diseases.
Experimental and Molecular Medicine 08/2012; · 2.48 Impact Factor
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ABSTRACT: Peripheral benzodiazepine receptor (PBR) is a multifunctional protein mainly found on the outer mitochondrial membrane. PBR expression is increased by tumor necrosis factor-α (TNF-α) in endothelial cells. Adenoviral overexpression of PBR inhibits monocyte adhesion, VCAM-1, and ICAM-1 expression in TNF-α-activated endothelial cells. Rotenone, cyclosporine A, and bongkrekic acid suppress TNF-α-induced VCAM-1 expression. Overexpression of PBR inhibits voltage-dependent anion channel-1 (VDAC-1) expression and the silencing of PBR increases VDAC-1 expression in endothelial cells. Moreover, TNF-α-induced VCAM-1 expression is suppressed by VDAC-1 gene silencing. PBR overexpression significantly decreases TNF-α-induced mitochondrial reactive oxygen species and MnSOD expression. These results suggest that PBR can inhibit endothelial activation and this action is related to the inhibition of mitochondrial ROS and/or VDAC-1 expression in endothelial cells.
FEBS letters 05/2012; 586(9):1349-55. · 3.54 Impact Factor
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Jochen Steppan,
Huang Tran,
Alexandre M Benjo,
Laxsmi Pellakuru,
Viachaslau Barodka, Sungwoo Ryoo,
Sineád M Nyhan,
Craig Lussman,
Gaurav Gupta,
Anthony R White,
Joao P Daher,
Artin A Shoukas,
Benjamin D Levine,
Dan E Berkowitz
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ABSTRACT: Advanced glycation end-products (AGEs) initiate cellular inflammation and contribute to cardiovascular disease in the elderly. AGE can be inhibited by Alagebrium (ALT), an AGE cross-link breaker. Moreover, the beneficial effects of exercise on aging are well recognized. Thus, we investigated the effects of ALT and exercise (Ex) on cardiovascular function in a rat aging model. Compared to young (Y) rats, in sedentary old (O) rats, end-systolic elastance (Ees) decreased (0.9±0.2 vs 1.7±0.4mmHg/μL, P<0.05), dP/dt(max) was attenuated (6054±685 vs 9540±939mmHg/s, P<0.05), ventricular compliance (end-diastolic pressure-volume relationship (EDPVR)) was impaired (1.4±0.2 vs 0.5±0.4mmHg/μL, P<0.05) and diastolic relaxation time (tau) was prolonged (21±3 vs 14±2ms, P<0.05). In old rats, combined ALT+Ex (4weeks) increased dP/dt(max) and Ees (8945±665 vs 6054±685mmHg/s, and 1.5±0.2 vs 0.9±0.2 respectively, O with ALT+Ex vs O, P<0.05 for both). Diastolic function (exponential power of EDPVR and tau) was also substantially improved by treatment with Alt+Ex in old rats (0.4±0.1 vs 0.9±0.2 and 16±2 vs 21±3ms, respectively, O with ALT+EX vs O, P<0.05 for both). Pulse wave velocity (PWV) was increased in old rats (7.0±0.7 vs 3.8±0.3ms, O vs Y, P<0.01). Both ALT and Ex alone decreased PWV in old rats but the combination decreased PWV to levels observed in young (4.6±0.5 vs 3.8±0.3ms, O with ALT+Ex vs Y, NS). These results suggest that prevention of the formation of new AGEs (with exercise) and breakdown of already formed AGEs (with ALT) may represent a therapeutic strategy for age-related ventricular and vascular stiffness.
Experimental gerontology 04/2012; 47(8):565-72. · 3.34 Impact Factor
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ABSTRACT: Malabaricone C (Mal-C), isolated from nutmeg, is known to exert a variety of pharmacological activities. However, the effect of Mal-C on vascular smooth muscle cells (VSMCs) is unknown. This study examined the effect of Mal-C on proliferation and migration of primary rat aortic smooth muscle cells (RASMCs) as well as its underlying mechanisms. Treatment of RASMCs with Mal-C induced both protein and mRNA expression of heme oxygenase-1 (HO-1) in a dose- and time-dependent manner. Mal-C-mediated HO-1 induction was inhibited by treatment with actinomycin D or by cycloheximide. SB203580 (a p38 inhibitor), SP600125 (a JNK inhibitor), U0126 (a MEK inhibitor), and N-acetylcysteine (NAC, an antioxidant) did not suppress Mal-C-induced HO-1 expression. In contrast, LY294002 (a PI3K inhibitor) blocked Mal-C-induced HO-1 expression. Moreover, RASMCs treated with Mal-C exhibited activation of AKT in a dose- and time-dependent manner. Treatment of RASMCs with Mal-C increased nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2), which is a key regulator of HO-1 expression, and this translocation was also inhibited by LY294002. Consistent with the notion that HO-1 has protective effects against VSMCs, Mal-C remarkably inhibited platelet-derived growth factor (PDGF)-induced proliferation and migration of RASMCs. However, inhibition of HO-1 significantly attenuated the inhibitory effects of Mal-C on PDGF-induced proliferation and migration of RASMCs. Taken together, these findings suggest that Mal-C could suppress PDGF-induced proliferation and migration of RASMCs through Nrf2 activation and subsequent HO-1 induction via the PI3K/AKT pathway, and may be a potential HO-1 inducer for preventing or treating vascular diseases.
Journal of Cellular Biochemistry 04/2012; 113(9):2866-76. · 2.87 Impact Factor
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02/2012; , ISBN: 978-953-307-834-2
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ABSTRACT: Tangeretin, a natural polymethoxylated flavone concentrated in the peel of citrus fruits, is known to have antiproliferative, antiinvasive, antimetastatic and antioxidant activities. However, the effect of tangeretin on vascular smooth muscle cells (VSMCs) is unknown. This study examined the effect of tangeretin on platelet-derived growth factor (PDGF)-BB-induced proliferation and migration of rat aortic smooth muscle cells (RASMCs) as well as its underlying mechanisms. Tangeretin significantly inhibited proliferation, DNA synthesis and migration of PDGF-BB-stimulated RASMCs without inducing cell death. Treatment with tangeretin-induced cell-cycle arrest in the G₀/G₁ phase was associated with down-regulation of cyclin D1 and cyclin E in addition to up-regulation of p27(kip1). We also showed that tangeretin inhibited PDGF-BB-induced phosphorylation of AKT, while it had no effect on the phosphorylation of phospholipase Cγ (PLCγ), PDGF receptor β-chain (PDGF-Rβ) and extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases (MAPKs). An in vitro kinase assay revealed that tangeretin inhibited AKT activity in a dose-dependent manner. Moreover, treatment of LY294002, a phosphoinositide 3-kinase (PI3K) inhibitor, had similar effects than that of tangeretin on the expression of p27(kip1) and cyclin D1, as well as cell migration in PDFG-BB-stimulated RASMCs. Taken together, these findings suggest that tangeretin could suppress PDGF-BB-induced proliferation and migration of RASMCs through the suppression of PI3K/AKT signaling pathway, and may be a potential candidate for preventing or treating vascular diseases, such as atherosclerosis and restenosis.
European journal of pharmacology 12/2011; 673(1-3):56-64. · 2.59 Impact Factor
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Mehnaz Khan,
Jochen Steppan,
Karl Schuleri, Sungwoo Ryoo,
Eric Tuday,
Lukasz Bugaj,
Lakshmi Santhanam,
Tal Berkowitz,
Daniel Nyhan,
Artin A Shoukas,
Dan E Berkowitz
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ABSTRACT: Arginase-II (Arg-II) reciprocally regulates nitric oxide synthase (NOS) and offsets basal myocardial contractility. Furthermore, decreased or absent myocardial NOS activity is associated with a depression in myocardial contractile reserve. We therefore hypothesized that upregulation of Arg-II might in part be responsible for depressed myocardial contractility associated with age. We studied arginase activity/expression, NOS expression, NO production in the presence and absence of the arginase inhibitor S-(2-boronoethyl)-L: -cysteine (BEC) in old (22 months) and young (3 months) rat hearts and myocytes. The spatial confinement of Arg-II and NOS was determined with immuno-electron-miocrographic (IEM) and immuno-histochemical studies. We tested the effect of BEC on the force frequency response (FFR) in myocytes, as well as NOS abundance and activity. Arginase activity and Arg-II expression was increased in old hearts (2.27 ± 0.542 vs. 0.439 ± 0.058 nmol urea/mg protein, p = 0.02). This was associated with a decrease in NO production, which was restored with BEC (4.54 ± 0.582 vs. 12.88 ± 0.432 μmol/mg, p < 0.01). IEM illustrates increased mitochondrial density in old myocytes (51.7 ± 1.8 vs. 69 ± 2.2 × 10(6)/cm(2), p < 0.01), potentially contributing to increased Arg-II abundance and activity. Immunohistochemistry revealed an organized pattern of mitochondria and Arg-II that appears disrupted in old myocytes. The FFR was significantly depressed in old myocytes (61.42 ± 16.04 vs. -5.15 ± 5.65%), while inhibition of Arg-II restored the FFR (-5.15 ± 5.65 vs. 70.98 ± 6.10%). NOS-2 is upregulated sixfold in old hearts contributing to increased production of reactive oxygen species which is attenuated with NOS-2 inhibition by 1400 W (4,735 ± 427 vs. 4,014 ± 314 RFU/min/mg protein, p = 0.005). Arg-II upregulation in aging rat hearts contributes to age-related decreased contractile function.
Arbeitsphysiologie 12/2011; 112(8):2933-41. · 2.15 Impact Factor
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Ji Eun Park,
To Dao Cuong,
Tran Manh Hung,
IkSoo Lee,
MinKyun Na,
Jin Cheol Kim, SungWoo Ryoo,
Jeong Hyung Lee,
Jae Sue Choi,
Mi Hee Woo,
Byung Sun Min
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ABSTRACT: A new alkaloid, methyl 2'-(7,8-dihydrosanguinarine-8-yl)acetate (1), together with six known alkaloids, stylopine (2), protopine (3), norchelidonine (4), chelidonine (5), berberine (6), and 8-hydroxydihydrosanguinarine (7), were isolated from Chelidonium majus. Their chemical structures were primarily established using 1D and 2D NMR techniques and mass spectrometry. The anti-inflammatory activity of the isolates was examined for their inhibitory effects on LPS-induced NO production in macrophage RAW264.7 cells. Among them, compounds 5 and 7 showed strong inhibitory activities toward the LPS-induced NO production in macrophage RAW264.7 cells with IC(50) values of 7.3 and 4.5 μM, respectively. In addition, compounds 5 and 7 inhibited the inductions of COX-2 and iNOS mRNA in dose-dependent manners, indicating that these compounds attenuated the syntheses of these transcripts at the transcriptional level.
Bioorganic & medicinal chemistry letters 12/2011; 21(23):6960-3. · 2.65 Impact Factor
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ABSTRACT: Three new phenolics: ((7S)-8'-(benzo[3',4']dioxol-1'-yl)-7-hydroxypropyl)benzene-2,4-diol (1), ((7S)-8'-(4'-hydroxy-3'-methoxyphenyl)-7-hydroxypropyl)benzene-2,4-diol (2) and ((8R,8'S)-7-(4-hydroxy-3-methoxyphenyl)-8'-methylbutan-8-yl)-3'-methoxybenzene-4',5'-diol (3), along with four known compounds (4-7) were isolated from the seeds of Myristica fragrans. Their chemical structures were established mainly by 1D and 2D NMR techniques and mass spectrometry. Their anti-inflammatory activity was evaluated against LPS-induced NO production in macrophage RAW264.7 cells.
Bioorganic & medicinal chemistry letters 11/2011; 21(22):6884-7. · 2.65 Impact Factor
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ABSTRACT: Atherosclerotic vascular disease is the leading cause of morbidity and mortality in developed countries. While it is a complex condition resulting from numerous genetic and environmental factors, it is well recognized that oxidized low-density lipoprotein produces pro-atherogenic effects in endothelial cells (ECs) by inducing the expression of adhesion molecules, stimulating EC apoptosis, inducing superoxide anion formation and impairing protective endothelial nitric oxide (NO) formation. Emerging evidence suggests that the enzyme arginase reciprocally regulates NO synthase and NO production by competing for the common substrate L-arginine. As oxidized LDL (OxLDL) results in arginase activation/upregulation, it appears to be an important contributor to endothelial dysfunction by a mechanism that involves substrate limitation for endothelial NO synthase (eNOS) and NO synthesis. Additionally, arginase enhances production of reactive oxygen species by eNOS. Arginase inhibition in hypercholesterolemic (ApoE(-/-)) mice or arginase II deletion (ArgII(-/-)) mice restores endothelial vasorelaxant function, reduces vascular stiffness and markedly reduces atherosclerotic plaque burden. Furthermore, arginase activation contributes to vascular changes including polyamine-dependent vascular smooth muscle cell proliferation and collagen synthesis. Collectively, arginase may play a key role in the prevention and treatment of atherosclerotic vascular disease.
Korean journal of anesthesiology 07/2011; 61(1):3-11.
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ABSTRACT: Caesalpinia sappan (C. sappan) is a medicinal plant used for promoting blood circulation and removing stasis. During a screening procedure on medicinal plants, the ethylacetate extract of the lignum of C. sappan (CLE) showed inhibitory activity on arginase which has recently been reported as a novel therapeutic target for the treatment of cardiovascular diseases such as atherosclerosis. CLE inhibited arginase II activity prepared from kidney lysate in a dose-dependent manner. In HUVECs, inhibition of arginase activity by CLE reciprocally increased NOx production through enhancement of eNOS dimer stability without any significant changes in the protein levels of eNOS and arginase II expression. Furthermore, CLE-dependent arginase inhibition resulted in increase of NO generation and decrease of superoxide production on endothelium of isolated mice aorta. These results indicate that CLE augments NO production on endothelium through inhibition of arginase activity, and may imply their usefulness for the treatment of cardiovascular diseases associated with endothelial dysfunction.
Korean Journal of Physiology and Pharmacology 06/2011; 15(3):123-8. · 0.96 Impact Factor
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ABSTRACT: Inhibition of cell-cycle progression is a target for the treatment of cancer. 3-Oxoolean-12-en-27-oic acid (3-OOLA) has shown significant anticancer activity towards diverse cancer cells, but has not been investigated for non-small cell lung carcinoma (NSCLC) cells. In this study, we investigated the antiproliferative effect of 3-OOLA in NSCLC cell lines and its underlying mechanism.
The MTT assay, bromodeoxyuridine (BrdU) incorporation assay, and flow cytometry were used for cell proliferation studies, and annexin V staining for apoptotic effects. Western blot analysis was used to evaluate expression of cell-cycle regulatory proteins, such as cyclins and cyclin-dependent kinases (CDKs).
3-OOLA caused G0/G1 phase cell-cycle arrest without inducing apoptosis in NSCLC cells, and Western blot analyses demonstrated down-regulation of cyclin D1, cyclin E and phosphorylated Rb.
3-OOLA inhibits cell proliferation of NSCLC cells by inducing cell-cycle arrest at G0/G1 through down-regulation of cyclin D1 and cyclin E.
Anticancer research 06/2011; 31(6):2179-85. · 1.73 Impact Factor
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ABSTRACT: Stimulation of human aortic smooth muscle cells (hAoSMCs) with native low-density lipoprotein (nLDL) induced the production of interleukin-8 (IL-8) that is involved in the pathogenesis of cardiovascular diseases. However, the process of signal transduction of nLDL was currently uncharacterized. Therefore, the aim of this study was to investigate the signal transduction pathway of nLDL-dependent IL-8 production and the effect of IL-8 on hAoSMCs migration.
nLDL was prepared by ultracentrifugation with density-adjusted human serum of normocholesterolemia. In hAoSMCs, IL-8 secreted to medium was measured using ELISA assay, and Western blot analysis was performed to detect p38 MAPK activation as a key regulator of IL-8 production. nLDL-dependent H₂O₂ generation was determined by microscopic analysis using 2',7'-dichlorofluoroscein diacetate (DCF-DA). IL-8-induced migration of hAoSMCs was evaluated by counting the cell numbers moved to lower chamber using Transwell plates.
nLDL-induced IL-8 production was completely blocked by preincubation of hAoSMCs with pertussis toxin (PTX), which inhibited nLDL-dependent p38 MAPK phosphorylation. PTX-sensitive G-protein coupled receptor was responsible for nLDL-dependent H₂O₂ generation that was abrogated with preincubation of the cells with of polyethylene glycol-conjugated catalase (PEG-Cat). Pretreatment of PEG-Cat prevented nLDL-induced p38 MAPK phosphorylation and IL-8 production, which was partly mimicked by treatment with exogenous H₂O₂2. Finally, IL-8 increased hAoSMCs migration that was completely blocked by incubation with IL-8 neutralizing antibody.
PTX-sensitive G-protein coupled receptor-dependent H₂O₂ generation by nLDL plays a critical role in IL-8 production in hAoSMC, and IL-8 may contribute to atherogenesis through increased migration of hAoSMCs.
Yonsei medical journal 05/2011; 52(3):413-9. · 0.77 Impact Factor
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ABSTRACT: Phosphorylation of the adaptor protein p66shc is essential for p66shc-mediated oxidative stress. We investigated the role of the reducing protein/DNA repair enzyme apurinic/apyrimidinic endonuclease1 (APE1) in modulating protein kinase CβII (PKCβII)-mediated p66shc phosphorylation in cultured endothelial cells and PKC-mediated vasoconstriction of arteries.
Oxidized low-density lipoprotein (oxLDL)induced p66shc phosphorylation at serine 36 residue and PKCβII phosphorylation in mouse endothelial cells. Adenoviral overexpression of APE1 resulted in reduction of oxLDL-induced p66shc and PKCβII phosphorylation. Phorbol 12-myristate 13-acetate (PMA), which stimulates PKCs, induced p66shc phosphorylation and this was inhibited by a selective PKCβII inhibitor. Adenoviral overexpression of PKCβII also increased p66shc phosphorylation. Overexpression of APE1 suppressed PMA-induced p66shc phosphorylation. Moreover, PMA-induced p66shc phosphorylation was augmented in cells in which APE1 was knocked down. PMA increased cytoplasmic APE1 expression, compared with the basal condition, suggesting the role of cytoplasmic APE1 against p66shc phosphorylation. Finally, vasoconstriction induced by phorbol-12,13, dibutylrate, another PKC agonist, was partially inhibited by transduction of Tat-APE1 into arteries.
APE1 suppresses oxLDL-induced p66shc activation in endothelial cells by inhibiting PKCβII-mediated serine phosphorylation of p66shc, and mitigates vasoconstriction induced by activation of PKC.
Cardiovascular research 04/2011; 91(3):502-9. · 5.80 Impact Factor
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ABSTRACT: Arginase II regulates NOS activity by competing for the substrate l-arginine. Oxidized LDL (OxLDL) is a proatherogenic molecule that activates arginase II. We tested the hypotheses that OxLDL-dependent arginase II activation occurs through a specific receptor, and via a Rho GTPase effector mechanism that is inhibited by statins.
Arginase II activation by OxLDL was attenuated following preincubation with the LOX-1 receptor-blocking antibody JTX92. This also prevented the dissociation of arginase II from microtubules. LOX-1(-/-) mice failed to exhibit the increased arginase II activity seen in WT mice fed a high cholesterol diet. Furthermore, endothelium from LOX-1(-/-) mice failed to demonstrate the diet-dependent reduction in NO and increase in ROS that were observed in WT mice. OxLDL induced Rho translocation to the membrane and Rho activation, and these effects were inhibited by pretreatment with JTX92 or statins. Transfection with siRNA for RhoA, or inhibition of ROCK both decreased OxLDL-stimulated arginase II activation. Preincubation with simvastatin or lovastatin blocked OxLDL-induced dissociation of arginase II from microtubules and prevented microtubule depolymerization.
This study provides a new focus for preventive therapy for atherosclerotic disease by delineating a clearer path from OxLDL through the endothelial cell LOX-1 receptor, RhoA, and ROCK, to the activation of arginase II, downregulation of NO, and vascular dysfunction.
Atherosclerosis 02/2011; 214(2):279-87. · 3.79 Impact Factor
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Anthony R White, Sungwoo Ryoo,
Lukasz Bugaj,
David O Attarzadeh,
Srikanth Thiyagarajan,
Kexun Chen,
Sarah Attwater,
Bryce Abbot,
Dechun Li,
Hunter C Champion,
Artin A Shoukas,
Daniel Nyhan,
Joshua M Hare,
Dan E Berkowitz,
Eric C Tuday
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ABSTRACT: Emerging evidence suggests that nitric oxide (NO) plays a pivotal role in the mechanism of vascular hyporesponsiveness contributing to microgravity-induced orthostatic intolerance. The cellular and enzymatic source of the NO, however, remains controversial. In addition, the time course of the endothelial-dependent contribution remains unstudied. We tested the hypotheses that the change in vasoresponsiveness seen in acute (3-day) hindlimb unweighted (HLU) animals is due to an endothelium-dependent mechanism and that endothelial-dependent attenuation in vasoreactivity is due to endothelial nitric oxide synthase (NOS-3) dependent activation. Vasoreactivity was investigated in rat aortic rings following acute HLU treatment. Dose responsiveness to norepinepherine (NE) was depressed after 3-day HLU [1,338 +/- 54 vs. 2,325 +/- 58 mg at max (NE), HLU vs. C, P < 0.001]. However, removal of the endothelium restored the vascular contractility to that of C. In addition, 1H-oxadiazole quinoxalin-1-one (ODQ), a soluble guanylyl cyclase inhibitor, restored the reduced vasoconstrictor responses to phenylephrine (PE) seen in 3-day HLU rings (1.30 +/- 0.10 vs. 0.53 +/- 0.07 g, HLU + ODQ vs. HLU, P = 0.0001). Ca(+) dependent nitric oxide synthase (NOS) activity was increased, as was vascular NO products as a result of HLU. While NOS-3 expression was not increased in HLU rats, phosphorylation of NOS-3 at serine-1177 (an activator of NOS-3) was increased while phosphorylation of serine-495 (an inactivator of NOS-3) was decreased. These findings demonstrate that changes in vasoresponsiveness in the acute HLU model of microgravity are due to an upregulation of the endothelial-dependent NO/cGMP pathway through NOS phosphorylation.
Arbeitsphysiologie 09/2010; 110(2):395-404. · 2.15 Impact Factor
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ABSTRACT: Arginase competitively inhibits nitric oxide synthase (NOS) via use of the common substrate L-arginine. Arginase II has recently reported as a novel therapeutic target for the treatment of cardiovascular diseases such as atherosclerosis. Here, we demonstrate that piceatannol-3'-O-beta-D-glucopyranoside (PG), a potent component of stilbenes, inhibits the activity of arginase I and II prepared from mouse liver and kidney lysates, respectively, in a dose-dependent manner. In human umbilical vein endothelial cells, incubation of PG markedly blocked arginase activity and increased NOx production, as measured by Griess assay. The PG effect was associated with increase of eNOS dimer ratio, although the protein levels of arginase II or eNOS were not changed. Furthermore, isolated mice aortic rings treated with PG showed inhibited arginase activity that resulted in increased nitric oxide (NO) production upto 78%, as measured using 4-amino-5-methylamino-2',7'-difluorescein (DAF-FM) and a decreased superoxide anions up to 63%, as measured using dihydroethidine (DHE) in the intact endothelium. PG showed IC((50)) value of 11.22 microM and 11.06 microM against arginase I and II, respectively. PG as an arginase inhibitor, therefore, represents a novel molecule for the therapy of cardiovascular diseases derived from endothelial dysfunction and may be used for the design of pharmaceutical compounds.
Experimental and Molecular Medicine 07/2010; 42(7):524-32. · 2.48 Impact Factor
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Kevin G Soucy,
Hyun Kyo Lim,
David O Attarzadeh,
Lakshmi Santhanam,
Jae Hyung Kim,
Anil K Bhunia,
Baris Sevinc, Sungwoo Ryoo,
Marcelo E Vazquez,
Daniel Nyhan,
Artin A Shoukas,
Dan E Berkowitz
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ABSTRACT: Radiation exposure is associated with the development of various cardiovascular diseases. Although irradiation is known to cause elevated oxidant stress and chronic inflammation, both of which are detrimental to vascular function, the molecular mechanisms remain incompletely understood. We previously demonstrated that radiation causes endothelial dysfunction and increased vascular stiffness by xanthine oxidase (XO) activation. In this study, we investigated whether dietary inhibition of XO protects against radiation-induced vascular injury. We exposed 4-mo-old rats to a single dose of 0 or 5 Gy gamma radiation. These rats received normal drinking water or water containing 1 mM oxypurinol, an XO inhibitor. We measured XO activity and superoxide production in rat aorta and demonstrated that both were significantly elevated 2 wk after radiation exposure. However, oxypurinol treatment in irradiated rats prevented aortic XO activation and superoxide elevation. We next investigated endothelial function through fluorescent measurement of nitric oxide (NO) and vascular tension dose responses. Radiation reduced endothelium-dependent NO production in rat aorta. Similarly, endothelium-dependent vasorelaxation in the aorta of irradiated rats was significantly attenuated compared with the control group. Dietary XO inhibition maintained NO production at control levels and prevented the development of endothelial dysfunction. Furthermore, pulse wave velocity, a measure of vascular stiffness, increased by 1 day postirradiation and remained elevated 2 wk after irradiation, despite unchanged blood pressures. In oxypurinol-treated rats, pulse wave velocities remained unchanged from baseline throughout the experiment, signifying preserved vascular health. These findings demonstrate that XO inhibition can offer protection from radiation-induced endothelial dysfunction and cardiovascular complications.
Journal of Applied Physiology 02/2010; 108(5):1250-8. · 3.75 Impact Factor
