[Show abstract][Hide abstract] ABSTRACT: Patients suffering from diabetes mellitus (DM) are at a severe risk of atherothrombosis. Early growth response (Egr)-1 is well characterized as a central mediator in vascular pathophysiology. We tested whether valsartan independent of Ang II type 1 receptor (AT1R) can reduce tissue factor (TF) and toll-like receptor (TLR)-2 and -4 by regulating Egr-1 in THP-1 cells and aorta in streptozotocin-induced diabetic mice. High glucose (HG, 15 mM) increased expressions of Egr-1, TF, TLR-2 and -4 which were significantly reduced by valsartan. HG increased Egr-1 expression by activation of PKC and ERK1/2 in THP-1 cells. Valsartan increased AMPK phosphorylation in a concentration and time-dependent manner via activation of LKB1. Valsartan inhibited Egr-1 without activation of PKC or ERK1/2. The reduced expression of Egr-1 by valsartan was reversed by either silencing Egr-1, or compound C, or DN-AMPK-transfected cells. Valsartan inhibited binding of NF-κB and Egr-1 to TF promoter in HG condition. Furthermore, valsartan reduced inflammatory cytokine (TNF-α, IL-6 and IL-1β) production and NF-κB activity in HG-activated THP-1 cells. Interestingly, these effects of valsartan were not affected by either silencing AT1R in THP-1 cells or CHO cells, which were devoid of AT1R. Importantly, administration of valsartan (20 mg/kg, i.p) for 8 weeks significantly reduced plasma TF activity, expression of Egr-1, TLR-2, -4 and TF in thoracic aorta and improved glucose tolerance of streptozotocin-induced diabetic mice. Taken together, we concluded that valsartan may reduce atherothrombosis in diabetic conditions through AMPK/Egr-1 regulation.
Journal of Cellular and Molecular Medicine 07/2014; · 4.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Nitric oxide synthase (NOS) gene has been partially sequenced from Hyphantria cunea and compared with those already determined from insects. Hyphantria cunea NOS possesses putative recognition sites for co-factors heme, BH4, CaM, FMN, FAD, and NADPH common to NOS. The deduced amino acid sequence of H. cunea NOS cDNA showed 70.3% identity to Manduca sexta NOS and 57.6–69.5% identity to NOS sequences from other insects. Nitric oxide synthase is expressed in all tissues of H. cunea, except in hemocytes. The NOS expression in midgut, fat body, epidermis, and Malpighian tubule strongly increased against Gram-positive and Gram-negative bacterial infection. These results suggest that NOS may play an important role in insect defense system against bacterial infection.
[Show abstract][Hide abstract] ABSTRACT: Connective tissue growth factor (CTGF) is a potent pro-fibrotic factor, which is implicated in fibrosis through extracellular matrix (ECM) induction in diabetic cardiovascular complications. It is an important downstream mediator in the fibrotic action of transforming growth factor β (TGFβ) and is potentially induced by hyperglycemia in human vascular smooth muscle cells (VSMCs). Therefore, the goal of this study is to identify the signaling pathways of CTGF effects on ECM accumulation and cell proliferation in VSMCs under hyperglycemia. We found that high glucose stimulated the levels of CTGF mRNA and protein and followed by VSMC proliferation and ECM components accumulation such as collagen type 1, collagen type 3 and fibronectin. By depleting endogenous CTGF we showed that CTGF is indispensable for the cell proliferation and ECM components accumulation in high glucose-stimulated VSMCs. In addition, pretreatment with the MEK1/2 specific inhibitors, PD98059 or U0126 potently inhibited the CTGF production and ECM components accumulation in high glucose-stimulated VSMCs. Furthermore, knockdown with ERK1/2 MAPK siRNA resulted in significantly down regulated of CTGF production, ECM components accumulation and cell proliferation in high glucose-stimulated VSMCs. Finally, ERK1/2 signaling regulated Egr-1 protein expression and treatment with recombinant CTGF reversed the Egr-1 expression in high glucose-induced VSMCs. It is conceivable that ERK1/2 MAPK signaling pathway plays an important role in regulating CTGF expression and suggests that blockade of CTGF through ERK1/2 MAPK signaling may be beneficial for therapeutic target of diabetic cardiovascular complication such as atherosclerosis.
Korean Journal of Physiology and Pharmacology 08/2013; 17(4):307-14. · 1.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Insulin-like growth factor binding proteins (IGFBPs) are important components of insulin growth factor (IGF) signaling pathways. One of the binding proteins, IGFBP-5, enhances the actions of IGF-1, which include the enhanced proliferation of smooth muscle cells. In the present study, we examined the expression and the biological effects of IGFBP-5 in vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). The levels of IGFBP-5 mRNA and protein were found to be higher in the VSMC from SHR than in those from WKY. Treatment with recombinant IGFBP-5-stimulated VSMC proliferation in WKY to the levels observed in SHR. In the VSMCs of WKY, incubation with angiotensin (Ang) II or IGF-1 dose dependently increased IGFBP-5 protein levels. Transfection with IGFBP-5 siRNA reduced VSMC proliferation in SHR to the levels exhibited in WKY. In addition, recombinant IGFBP-5 significantly up-regulated ERK1/2 phosphorylation in the VSMCs of WKY as much as those of SHR. Concurrent treatment with the MEK1/2 inhibitors, PD98059 or U0126 completely inhibited recombinant IGFBP-5-induced VSMC proliferation in WKY, while concurrent treatment with the phosphatidylinositol-3 kinase inhibitor, LY294002, had no effect. Furthermore, knockdown with IGFBP-5 siRNA inhibited ERK1/2 phosphorylation in VSMC of SHR. These results suggest that IGFBP-5 plays a role in the regulation of VSMC proliferation via ERK1/2 MAPK signaling in hypertensive rats.
Korean Journal of Physiology and Pharmacology 04/2013; 17(2):157-62. · 1.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Methionine sulfoxide reductase A (MsrA) functions as a protein repair enzyme by catalyzing the stereospecific reduction of methionine-S-sulfoxide to methionine. We previously identified that MsrA deficiency inhibits normal cell growth via activation of the p53-p21 pathway. In this study, we report a critical role of MsrA in expression of heme oxygenase-1 (HO-1), a highly inducible enzyme that has an anti-proliferative effect mediated by up-regulation of p21. Down-regulation of MsrA induced HO-1 expression in mammalian cells with increased p21 levels, but MsrA overexpression did not affect HO-1 expression. MsrA depletion activated Nrf2 by increasing its expression and nuclear translocation. Nrf2 activation was associated with increased reactive oxygen species production. MsrA overexpression in MsrA-depleted cells led to the reduction of increased HO-1 expression, and suppressed nuclear accumulation of Nrf2. Taken together, the data suggest that MsrA attenuates HO-1 induction by inhibiting Nrf2 activation.
Archives of Biochemistry and Biophysics 10/2012; 528(2):134-140. · 3.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Vascular cells have a limited lifespan with limited cell proliferation and undergo cellular senescence. The functional changes associated with cellular senescence are thought to contribute to age-related vascular disorders. AMP-activated protein kinase (AMPK) has been discussed in terms of beneficial or harmful effects for aging-related diseases. However, the detailed functional mechanisms of AMPK are largely unclear. An aging model was established by stimulating vascular smooth muscle cell (VSMC) with adriamycin. Adriamycin progressively increased the mRNA and protein expressions of AMPK. The phosphorylation levels of LKB1 and acetyl-CoA carboxylase (ACC), the upstream and downstream of AMPK, were dramatically increased by adriamycin stimulation. The expressions of p53 and p21, which contribute to vascular senescence, were also increased. Inhibition of AMPK diminished senescence-associated β-galactosidase (SA-β-gal) staining, and restored VSMC proliferation. Cytosolic translocation of LKB1 by adriamycin could be a mechanism for AMPK activation in senescence. Furthermore, p53 siRNA and p21 siRNA transfection attenuated adriamycin-induced SA-β-gal staining. These results suggest that LKB1 dependent AMPK activation elicits VSMC senescence and p53-p21 pathway is a mediator of LKB1/AMPK-induced senescence.
Biochemical and Biophysical Research Communications 08/2011; 413(1):143-8. · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Cilostazol is a selective inhibitor of phosphodiesterase 3 that increases intracellular cAMP levels and activates protein kinase A, thereby inhibiting vascular smooth muscle cell (VSMC) proliferation. We investigated whether AMP-activated protein kinase (AMPK) activation induced by heme oxygenase-1 (HO-1) is a mediator of the beneficial effects of cilostazol and whether cilostazol may prevent cell proliferation and reactive oxygen species (ROS) production by activating AMPK in VSMC. In the present study, we investigated VSMC with various concentrations of cilostazol. Treatment with cilostazol increased HO-1 expression and phosphorylation of AMPK in a dose- and time-dependent manner. Cilostazol also significantly decreased platelet-derived growth factor (PDGF)-induced VSMC proliferation and ROS production by activating AMPK induced by HO-1. Pharmacological and genetic inhibition of HO-1 and AMPK blocked the cilostazol-induced inhibition of cell proliferation and ROS production.These data suggest that cilostazol-induced HO-1 expression and AMPK activation might attenuate PDGF-induced VSMC proliferation and ROS production.
Korean Journal of Physiology and Pharmacology 08/2011; 15(4):203-10. · 1.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Apolipophorin-III (apoLp-III), a hemolymph protein that facilitates lipid transport in aqueous media in insects was recently shown to play a role in insect immune activation. Here, we report another novel possible function of apoLp-III in insects. To identify genes affected by apoLp-III expression in larvae, we decreased endogenous apoLp-III mRNA in Hyphantria cunea (Hc) through RNA interference; subsequently, we observed lower levels of antioxidant enzymes, including manganese superoxide dismutase (MnSOD), glutathione S-transferase, and immune proteins. Knockdown of Hc apoLp-III led to decreased MnSOD expression in fat body tissues and elevated superoxide anion levels in Hc fat body cells, suggesting that Hc apoLp-III is involved in the action and/or expression of antioxidant enzymes, especially MnSOD.
Comparative biochemistry and physiology. Part A, Molecular & integrative physiology 03/2011; 159(3):303-12. · 2.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Reparixin, an inhibitor of CXCL8 receptor CXCR1 and CXCR2 activation, has been shown to attenuate inflammatory responses in various injury models. In the present study, the hypertension-related functional roles of reparixin were examined in hypertensive animals. Spontaneously hypertensive rats (SHR) at the age of 18 weeks were administered a subcutaneous injection of reparixin (5 mg/kg) daily for 3 weeks (SHR-R, n=5). Control groups consisted of normal saline-treated SHR (SHR-N, n=5) and normotensive Wistar-Kyoto rats (WKY-N, n=5). Reparixin effectively decreased systolic blood pressure and increased the blood flow. The thoracic aorta wall thickness was significantly decreased in SHR-R compared to SHR-N. Expressions of CXCL8, CCL2, 12-lipoxygenase (LO) and endothelin (ET)-1 were significantly decreased in SHR-R thoracic aorta tissues compared to SHR-N. Furthermore, expression of angiotensin II subtype I receptor (AT(1)R) protein was decreased in SHR-R thoracic aorta tissues compared to SHR-N. In addition, the plasma levels of nitric oxide were slightly elevated in SHR-R compared to the levels in SHR-N. These findings indicate that inhibition of hypertension-related mediators by reparixin results in the reduction of blood pressure in SHR. Therefore, these results suggest that reparixin-mediated blockade of CXCL8 receptor activation attenuates vascular hypertension in SHR.
[Show abstract][Hide abstract] ABSTRACT: Two kinds of Ce0.8Gd0.2O2−δ pellets were synthesized by a solid-state reaction using two types of commercial CeO2 and Gd2O3. In contrast to previous reports, pellets with a sintered density of 99% at 1300°C were obtained regardless the powder used. Mechanochemical activation of the starting materials by 7h of high energy milling, which resulted in particles several tens of nanometer in size, was effective in reducing the sintering temperature. Ce0.8Gd0.2O2−δ pellets could be synthesized by direct sintering without calcination due to the homogeneous distribution of fine starting materials. The final phase was confirmed by the ionic conductivity, X-ray diffraction patterns and lattice parameters.
Ceramics International 01/2010; 36(1):371-374. · 2.09 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Metal-supported solid oxide fuel cells (SOFCs) have the advantage of the thermal shock resistance and higher mechanical strength compared with anode-supported SOFCs. In this study, Ni-Fe metal was used as supporting metal. The supporting metal was initially prepared in oxide form of NiO-Fe2O3, and co-sintered with Gd-doped ceria electrolyte at 1350ºC for 3h in air and later reduced to Ni-Fe metal. Two different cells were prepared and compared to see the effect of the thickness of the electrolyte and the role of the electrode on the performance of the cell.
[Show abstract][Hide abstract] ABSTRACT: Spontaneous hypertensive rats (SHR) are an established model of genetic hypertension. Vascular smooth muscle cells (VSMC) from SHR proliferate faster than those of control rats (Wistar-Kyoto rats; WKY). We tested the hypothesis that induction of heme oxygenase (HO)-1 induced by aprotinin inhibits VSMC proliferation through cell cycle arrest in hypertensive rats. Aprotinin treatment inhibited VSMC proliferation in SHR more than in normotensive rats. These inhibitory effects were associated with cell cycle arrest in the G1 phase. Tin protoporphyrin IX (SnPPIX) reversed the anti-proliferative effect of aprotinin in VSMC from SHR. The level of cyclin D was higher in VSMC of SHR than those of WKY. Aprotinin treatment downregulated the cell cycle regulator, cyclin D, but upregulated the cyclin-dependent kinase inhibitor, p21, in VSMC of SHR. Aprotinin induced HO-1 in VSMC of SHR, but not in those of control rats. Furthermore, aprotinin-induced HO-1 inhibited VSMC proliferation of SHR. Consistently, VSMC proliferation in SHR was significantly inhibited by transfection with the HO-1 gene. These results indicate that induction of HO-1 by aprotinin inhibits VSMC proliferation through cell cycle arrest in hypertensive rats.
Korean Journal of Physiology and Pharmacology 08/2009; 13(4):309-13. · 1.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Heme oxygenase (HO)-1 is a well-known cytoprotectant against oxidative stress and exhibits an antiproliferative effect in vascular smooth muscle cells (VSMCs). The purpose of the present study was to test whether isoproterenol, one of the synthetic catecholamines having beta-adrenergic activity, affected angiotensin II (Ang II)-induced cell proliferation and reactive oxygen species (ROS) production. Also, the presumptive underlying signaling pathways in VSMCs were studied. Aortic VSMCs from 11-week-old male Sprague-Dawley rats were used. Isoproterenol dose-dependently increased HO-1 expression through beta(2)-adrenoceptor (AR) and protein kinase A (PKA) pathway, and isoproterenol concentration-dependently increased beta(2)-AR mRNA expression. Isoproterenol attenuated Ang II-induced cell proliferation, as evidenced by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay. This effect of isoproterenol was inhibited by pretreatment of the cells with beta(2)-AR antagonist butoxamine, PKA inhibitor H-89 and HO inhibitor Tin Protoporphyrin IX (SnPP IX), respectively. Isoproterenol inhibited phosphorylation level of Ang II-induced extracellular signal-regulated kinase (ERK1/2). Isoproterenol significantly inhibited Ang II-induced ROS production through the ERK1/2 pathway. These findings suggest that isoproterenol, via induction of HO-1, inhibits Ang II-stimulated proliferation and ROS production in cultured VSMCs.
[Show abstract][Hide abstract] ABSTRACT: Alumina and transition metals were added to Gd-doped ceria and the electrical properties of doped ceria were studied. For 10 mol% Gd-doped ceria (GDC), 1 at.% transition metals (Fe, Co, Ni, Cu, or Ga) were added as a sintering aid and 1, 2, 5, 10, and 20 at.% alumina was added as a possible strengthening media. The electrical conductivity was measured as a function of temperature (250–700 °C) in air. The open circuit voltage (OCV) and the impedance spectra of the cell in dual atmosphere (air on one side, hydrogen on another side) were measured as a function of time. Samples added with both 1 at.% Cu and 2 at.% alumina showed good sinterability without much loss of electrical conductivity. The time-dependence of the OCV value and the impedance spectra showed that either the alumina-added or the Cu and alumina co-added sample exhibited the slower degradation of OCV and the less electrode polarization than GDC. The results indicate that Cu and alumina addition improved the stability of the cell.
Solid State Ionics 06/2009; 180(11):886-890. · 2.05 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We previously demonstrated remarkable differences in the expression of IL-8/CXCL8 in aortic tissues and vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) compared to VSMC from normotensive Wistar-Kyoto rats (WKY). In the present study, we investigated the direct effect of IL-8/CXCL8 on expression of 12-lipoxygenase (LO), a hypertensive modulator, in SHR VSMC.
Cultured aortic VSMC from SHR and WKY were used. Expression of 12-LO mRNA was determined by real-time polymerase chain reaction. Phosphorlyation of ERK1/2 and production of 12-LO and angiotensin II subtype 1 (AT(1)) receptor were assessed by Western blots. IL-8/CXCL8-stimulated DNA synthesis was determined by measuring incorporation of [(3)H]-thymidine. And effect of IL-8/CXCL8 on vascular tone was determined by phenylephrine-induced contraction of thoracic aortic rings.
Treatment with IL-8/CXCL8 greatly increased 12-LO mRNA expression and protein production compared to treatment with angiotensin II. IL-8/CXCL8 also increased the expression of the AT(1) receptor. The increase in 12-LO induced by IL-8/CXCL8 was inhibited by treatment with an AT(1) receptor antagonist. The induction of 12-LO mRNA production and the proliferation of SHR VSMC by IL-8/CXCL8 was mediated by the ERK pathway. The proliferation of SHR VSMC and the vascular contraction in the thoracic aortic ring, both of which were induced by IL-8/CXCL8, were inhibited by baicalein, a 12-LO inhibitor.
These results suggest that the potential role of IL-8/CXCL8 in hypertensive processes is likely mediated through the 12-LO pathway.
[Show abstract][Hide abstract] ABSTRACT: Direct functionalization of 4,5-dichloropyridazin-6-one with some nucleophiles in seven solvents gave regioselectively 5-halo-4-substituted-pyridazin-6-ones as main product. Reaction of 4,5-dichloropyridazin-6-one with 2-mercaptopyrimidine (2 equivalents) also afforded 4,5-di(pyrimidin-2-ylsulfanyl)pyridazin-6-one as the main product.
[Show abstract][Hide abstract] ABSTRACT: Aprotinin is used clinically in cardiopulmonary bypass surgery to reduce transfusion requirements and the inflammatory response. The mechanism of action for the anti-inflammatory effects of aprotinin is still unclear. We examined our hypothesis whether inhibitory effects of aprotinin on cytokine-induced inducible nitric oxide synthase (iNOS) expression (IL-1beta plus TNF-alpha), reactive oxygen species (ROS) generation, and vascular smooth muscle cell (VSMC) proliferation were due to HO-1 induction in rat VSMCs. Aprotinin induced HO-1 protein expression in a dose-dependent manner, which was potentiated during inflammatory condition. Aprotinin reduced cytokine mixture (CM)-induced iNOS expression in a dose dependent manner. Furthermore, aprotinin reduced CM-induced ROS generation, cell proliferation, and phosphorylation of JNK but not of P38 and ERK1/2 kinases. Aprotinin effects were reversed by pre-treatment with the HO-1 inhibitor, tin protoporphyrin IX (SnPPIX). HO-1 is therefore closely involved in inflammatory-stimulated VSMC proliferation through the regulation of ROS generation and JNK phosphorylation. Our results suggest a new molecular basis for aprotinin anti-inflammatory properties.
Korean Journal of Physiology and Pharmacology 04/2009; 13(2):123-9. · 1.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Reaction of 1-chloromethyl-4,5-dichloropyridazin-6-one with some nucleophiles such as sodium methoxide, sodium azide, 2-mercaptopyrimidine and phenol gave 2, 3, 4, 7, 8 and 10. 5-Chloro-4-phenoxypyridazin-6-one (10) was also synthesized from 8 through 9.
[Show abstract][Hide abstract] ABSTRACT: Functionalization of 1-acetyloxymethyl-4,5-dihalopyridazin-6-ones via retro-ene reaction with some nucleophiles gave regioselectively only 5-halo-4-substitutedpyridazin-6-ones.
[Show abstract][Hide abstract] ABSTRACT: In order to confirm the regiochemistry for the functionalization of 1-(1,1-dibromo-2-oxopropyl)-4,5-dihalopyridazin-6-ones, the dehalogenation of 1-methyl-5-halo-4-substituted-pyridazin-6-ones using Pd/C and hydrogen was carried out. The results of the title reaction are reported.