Cold shock domain protein A represses angiogenesis and lymphangiogenesis via inhibition of serum response element.

Dual-targeted therapy for antiangiogenesis and antilymphangiogenesis represents a potentially effective strategy for the treatment of various malignancies. Therefore, the goal of the present study was to identify genes that encode inhibitors of both angiogenesis and lymphangiogenesis. Using a cDNA library obtained from Lewis lung carcinoma (LL/2), a candidate gene was identified by the evaluation of growth inhibition in aortic and lymphatic endothelial cells (EC) as that coding for the mouse cold shock domain protein A (mCSDA). Overexpression of mCSDA significantly repressed cell proliferation and c-fos promoter activity in aortic, venous and lymphatic ECs. CSDA is a DNA-binding protein that binds to the hypoxia response element (HRE). Furthermore, of importance, we revealed that CSDA could directly bind to the serum response element (SRE) sequence, resulting in the inhibition of SRE activity, which may lead to growth inhibition in ECs. In an LL/2-inoculated mouse model, tumor growth was significantly repressed in an mCSDA-injected group. Histopathological analysis revealed that expression of blood and lymphatic EC markers was significantly decreased in mCSDA-injected groups. In conclusion, these data suggest that expression of CSDA can repress angiogenesis and lymphangiogenesis via direct binding to SRE in addition to HRE.

NFkappaB decoy oligodeoxynucleotides ameliorates osteoporosis through inhibition of activation and differentiation of osteoclasts.

The transcription factor, nuclear factor-kappa B (NFkappaB), is believed to play a pivotal role in osteoclast formation. In this study, we focused on NFkappaB decoy oligodeoxynucleotides (ODN) as a new therapeutic strategy to attenuate osteoporosis. Tartrate-resistant acid phosphatase (TRAP)-positive multinuclear osteoclasts formed in mononuclear cells including osteoclast precursors from neonatal rabbit bone marrow were increased in the presence of 1,25-dihydroxyvitamin D3, whereas transfection of NFkappaB decoy ODN decreased the number of TRAP-positive cells and attenuated RANKL and M-CSF-induced osteoclast formation. NFkappaB decoy ODN also inhibited the activity of osteoclasts, as assessed by pit formation. In rat ovariectomized model of estrogen deficiency, continuous administration of NFkappaB decoy ODN attenuated the increase of TRAP activity, accompanied by a significant increase in calcium concentration in tibia and femur and decrease in urinary deoxypyridinoline. In additional osteoporosis model using vitamin C-deficient rat, inhibition of NFkappaB by decoy ODN dramatically improved the bone length, weight, density as assessed by dual-energy X-ray absorptiometry. Overall, inhibition of NFkappaB by decoy strategy prevented osteoporosis through the inhibition of bone resorption. Targeting of NFkappaB might be potential therapy in various bone metabolic diseases.

Production of IgA monoclonal antibody against Shiga toxin binding subunits employing nasal-associated lymphoid tissue.

We established an IgA monoclonal antibody (mAb) against Shiga toxin 1 B subunits (Stx1B) from mouse nasal-associated lymphoid tissues (NALT) of BALB/c mice. We have developed an improved protocol in which cross-linked Stx1B is intranasally administered together with cholera toxin. Surface IgA-positive NALT lymphocytes from mice immunized in this manner were enriched and then fused with mouse myeloma cells to produce hybridoma cells. Hybridoma culture supernatants were examined to see if they contain IgA against Stx1B and if they can inhibit carbohydrate recognition by Stx1B. For the latter purpose, we prepared carbohydrate ligands in which globotriose is present on the poly-lysine backbone. The established IgA mAb exhibited saturable and dose-dependent binding to the immobilized Stx1B. Inversely, the binding of the carbohydrate ligands to the immobilized Stx1B was inhibited by the mAb pretreatment. Immunoblotting and SDS-PAGE analysis revealed dimeric IgA. The IgA mAb inhibited the binding of digoxigenin-conjugated Stx1B to natural ligands displayed on a Burkitt's lymphoma cell line, Ramos. These results suggested that surface IgA-positive B cells in the inductive sites of the mucosal immune system in the upper respiratory tract are a potent source for producing IgA mAb against protein antigens with weak immunogenicity such as Stx1B.

HGF/NK4 inhibited VEGF-induced angiogenesis in in vitro cultured endothelial cells and in vivo rabbit model.

AIMS/HYPOTHESIS: As vascular endothelial growth factor (VEGF) plays a pivotal role in the development of diabetic retinopathy, inhibition of angiogenesis induced by VEGF is crucial to treat diabetic retinopathy. HGF (hepatocyte growth factor)/NK4, containing the N-terminal hairpin domain and the four subsequent kringle domains of HGF, is considered as a specific antagonist for HGF. Our aim was to explore the inhibitory effects of HGF/NK4 on angiogenesis induced by VEGF. METHODS: To analyze the in vivo angiogenesis, we used rabbit corneal micropocket assay. Proliferation and migration of human endothelial cells, expression of ets-1, an essential transcription factor for angiogenesis, and the phosphorylation of extracellular signal-regulated kinase (ERK) was examined with or without HGF/NK4. RESULTS: Using corneal micropocket assay, in vivo administration of HGF/NK4 inhibited angiogenesis induced by VEGF. HGF/NK4 inhibited proliferation and migration of human endothelial cells induced by VEGF in a dose-dependent manner. Interestingly, VEGF-mediated phosphorylation of ERK was significantly attenuated by HGF/NK4. Of importance, HGF/NK4 attenuated the increase in ets-1 protein stimulated by VEGF. Nevertheless, HGF/NK4 did not affect phosphorylation of VEGF receptor-2 [kinase domain region (KDR)/foetal liver kinase (Flk)-1]. Although tyrosine phosphatase inhibitor (Na(3)VO(4)), or okadaic acid, serine-threonin kinase inhibitor, did not prevent the inhibition of ERK phosphorylation by HGF/NK4, co-incubation of HGF/NK4 with VEGF significantly diminished mitogen-activated protein (MAP) ERK kinase (MEK) phosphorylation (p<0.01). CONCLUSIONS/INTERPRETATION: Overall, HGF/NK4 inhibited angiogenesis induced by VEGF through inhibition of phosphorylation of ERK and ets-1 expression in in vitro cultured endothelial cells and in vivo rabbit model.

Roles of angiotensin II type 2 receptor stimulation associated with selective angiotensin II type 1 receptor blockade with valsartan in the improvement of inflammation-induced vascular injury.

BACKGROUND: To investigate the effect of angiotensin (Ang) II type 1 receptor (AT(1)) blocker on vascular remodeling and explore the possibility of the involvement of Ang II type 2 receptor (AT(2)) stimulation in this process, we examined the effects of the selective AT(1) blocker valsartan on the vascular injury in wild-type (Agtr2+) and AT(2)-null (Agtr2-) mice. METHODS AND RESULTS: Neointima formation and the proliferation of vascular smooth muscle cells (VSMCs) induced by cuff placement on the femoral artery were greater in Agtr2- mice than those in Agtr2+ mice. Treatment of mice with valsartan at a dose of 1 mg. kg(-1). d(-1), which did not influence systolic blood pressure, significantly decreased neointima formation and the proliferation of VSMCs, whereas the valsartan was less effective in Agtr2- mice. Moreover, cuff placement increased the expression of monocyte chemoattractant protein-1 (MCP-1); inflammatory cytokines such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-1beta; and infiltration of CD45-positive leukocytes and macrophages in the injured arteries and further enhanced them in Agtr2- mice, suggesting the antagonistic effects of AT(1) and AT(2) for vascular inflammation. Valsartan attenuated the expression of MCP-1, TNF-alpha, IL-6, IL-1beta, and infiltration of leukocytes and macrophages in the injured arteries; however, these effects of valsartan were less prominent in Agtr2- mice. CONCLUSIONS: These results suggest that the stimulation of the AT(2) receptor after AT(1) blockade is important in the improvement of the inflammatory vascular injury.

Therapeutic angiogenesis induced by human hepatocyte growth factor gene in rat diabetic hind limb ischemia model: molecular mechanisms of delayed angiogenesis in diabetes.

BACKGROUND: Because no study has documented the angiogenic properties of hepatocyte growth factor (HGF) in a diabetes model, we examined the feasibility of gene therapy using HGF to treat peripheral arterial disease in diabetes. METHODS AND RESULTS: Because intramuscular injection of luciferase plasmid by the hemagglutinating virus of Japan (HVJ)-liposome method had much higher efficiency than injection of naked plasmid, we used the HVJ-liposome method to transfect the human HGF gene into the rat diabetic hindlimb model. As expected, transfection of human HGF vector resulted in a significant increase in blood flow as assessed by laser Doppler imaging and capillary density, even in the diabetes model, accompanied by the detection of human HGF protein. Interestingly, the degree of natural recovery of blood flow was significantly greater in nondiabetic rats than in diabetic rats. Thus, in an in vitro culture system, we further studied the molecular mechanisms of how diabetes delayed angiogenesis. Importantly, high-D-glucose treatment of endothelial cells resulted in a significant decrease in matrix metalloproteinase (MMP)-1 protein and ets-1 expression in human aortic endothelial cells. Similarly, high D-glucose significantly decreased mRNA and protein of HGF in endothelial cells. Downregulation of MMP-1 and ets-1 by high D-glucose might be due to a significant decrease in HGF, because HGF stimulated MMP-1 production and activated ets-1. CONCLUSIONS: Overall, intramuscular injection of human HGF plasmid induced therapeutic angiogenesis in a rat diabetic ischemic hindlimb model as a potential therapy for peripheral arterial disease. The delay of angiogenesis in diabetes might be due to downregulation of MMP-1 and ets-1 through a decrease in HGF by high D-glucose.

Statins as antioxidant therapy for preventing cardiac myocyte hypertrophy.

Cardiac hypertrophy is a major cause of morbidity and mortality worldwide. The hypertrophic process is mediated, in part, by small G proteins of the Rho family. We hypothesized that statins, inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase, inhibit cardiac hypertrophy by blocking Rho isoprenylation. We treated neonatal rat cardiac myocytes with angiotensin II (AngII) with and without simvastatin (Sim) and found that Sim decreased AngII-induced protein content, [3H] leucine uptake, and atrial natriuretic factor (ANF) promoter activity. These effects were associated with decreases in cell size, membrane Rho activity, superoxide anion (O2*-) production, and intracellular oxidation, and were reversed with L-mevalonate or geranylgeranylpyrophosphate, but not with farnesylpyrophosphate or cholesterol. Treatments with the Rho inhibitor C3 exotoxin and with cell-permeable superoxide dismutase also decreased AngII-induced O2*- production and myocyte hypertrophy. Overexpression of the dominant-negative Rho mutant N17Rac1 completely inhibited AngII-induced intracellular oxidation and ANF promoter activity, while N19RhoA partially inhibited it, and N17Cdc42 had no effect. Indeed, Sim inhibited cardiac hypertrophy and decreased myocardial Rac1 activity and O2*- production in rats treated with AngII infusion or subjected to transaortic constriction. These findings suggest that statins prevent the development of cardiac hypertrophy through an antioxidant mechanism involving inhibition of Rac1.

Gene therapy for preventing neuronal death using hepatocyte growth factor: in vivo gene transfer of HGF to subarachnoid space prevents delayed neuronal death in gerbil hippocampal CA1 neurons.

To develop a novel strategy to prevent delayed neuronal death (DND) following transient occlusion of arteries, the gene of hepatocyte growth factor (HGF), a novel neurotrophic factor, was transfected into the subarachnoid space of gerbils after transient forebrain ischemia. Importantly, transfection of HGF gene into the subarachnoid space prevented DND, accompanied by a significant increase in HGF in the cerebrospinal fluid. Prevention of DND by HGF is due to the inhibition of apoptosis through the blockade of bax translocation from the cytoplasm to the nucleus. HGF gene transfer into the subarachnoid space may provide a new therapeutic strategy for cerebrovascular disease.

Endothelial apoptosis induced by oxidative stress through activation of NF-kappaB: antiapoptotic effect of antioxidant agents on endothelial cells.

Injury of endothelial cells has been assumed to be an initial trigger of the development of atherosclerosis. In this study, we investigated the molecular mechanisms of endothelial cell death induced by hypoxia, which leads to oxidative stress. To study the relation between hypoxia-induced cell death and activation of nuclear factor-kappaB (NF-kappaB) in a hypoxic state, we evaluated the effect of 2 antioxidant drugs, probucol and pyrrolidine dithiocarbamate (PDTC), on human endothelial apoptosis. Although hypoxic treatment of human aortic endothelial cells resulted in a significant decrease in cell number and a significant increase in apoptotic cells compared with that of cells under normoxia (P<0.01), treatment with probucol (50 micromol/L) or PDTC (100 micromol/L) significantly attenuated the decrease in cell number (P<0.01) and was accompanied by inhibition of NF-kappaB activation. Furthermore, downregulation of bcl-2 caused by hypoxia was inhibited by these drugs. We further investigated the translocation of bax protein from the cytoplasm to the mitochondrial heavy fraction membrane, as translocation of bax protein is considered to be a determinant of apoptosis. Interestingly, we found that antioxidant treatment inhibited the translocation of bax protein caused by hypoxia. Moreover, upregulation of p53, a proapoptotic molecule, was observed in hypoxia, whereas treatment with probucol attenuated the expression of p53 accompanied by suppression of NF-kappaB activation. These data suggest functional links between p53 and endothelial apoptosis through the activation of NF-kappaB. Overall, the current study demonstrated that oxidative stress induced apoptosis in human aortic endothelial cells through the downregulation of bcl-2, translocation of bax, and upregulation of p53, probably through NF-kappaB activation. Oxidative stress may play an important role in endothelial apoptosis mediated by hypoxia, through the activation of NF-kappaB.

Cell cycle regulation of cyclin-dependent kinases in tobacco cultivar Bright Yellow-2 cells.

Plants possess two major classes of cyclin-dependent kinases (CDK) with cyclin-binding motifs PSTAIRE (CDK-a) and PPTA/TLRE (CDK-b). Tobacco (Nicotiana tabacum L. cv Bright Yellow-2) cells are the most highly synchronizable plant culture, but no detailed analysis of CDK activities has been reported in this system. Here we describe isolation of new PPTALRE CDKs (Nicta;CdkB1) from Bright Yellow-2 cells and present detailed analysis of the mRNA, protein and kinase activity levels of CdkB1, and the PSTAIRE CDKA during the growth and cell cycles. CdkA and CdkB1 transcripts are more abundant in exponential than in stationary phase cells, but the two genes show strikingly different regulation during the cell cycle. CdkA mRNA and protein accumulate during G1 in cells re-entering the cell cycle, and immunoprecipitated histone H1 kinase activity increases at the G1/S boundary. Aphidicolin synchronized cells show the highest CDKA-associated histone H1 kinase activity during S-G2 phases, although CdkA mRNA and protein levels are not significantly regulated. In contrast, CdkB1 transcripts are present at very low levels until S phase and CDKB1 protein and kinase activity is almost undetectable in G1. CdkB1 mRNA accumulates through S until M phase and its associated kinase activity peaks at the G2/M boundary, confirming that transcription of PPTALRE CDKs is cell cycle regulated. We suggest that CDKA kinase activity likely plays roles at the G1/S phase boundary, during S phase, and at the G2/M phase transition, and that CDKB1 kinase activity is present only at G2/M.

Contribution of Bcl-2, but not Bcl-xL and Bax, to antiapoptotic actions of hepatocyte growth factor in hypoxia-conditioned human endothelial cells.

Angiogenic growth factors play important roles in angiogenic responses, such as vasculogenesis and angiogenesis in response to hypoxia. A novel angiogenic growth factor, hepatocyte growth factor (HGF), has been reported to inhibit endothelial cell death. However, its molecular mechanisms are largely unknown. Thus, we studied (1) the effects of HGF on hypoxia-induced endothelial apoptosis and (2) the molecular mechanisms of the antiapoptotic actions of HGF in endothelial cells. Severe hypoxia increased the cell death rate in human aortic endothelial cells, whereas HGF significantly attenuated cell death. In addition, hypoxic treatment resulted in a significant increase in apoptotic cells, whereas HGF could attenuate apoptosis, accompanied by attenuation of the increase in caspase-3-like activity (P<0.01). Of importance, HGF significantly increased Bcl-2, an inhibitor of apoptosis, in a dose-dependent manner under normoxic and hypoxic conditions (P<0.01), whereas hypoxic conditions resulted in a significant decrease in Bcl-2. In contrast, HGF failed to affect Bcl-xL, which is also well known as an inhibitor of apoptosis under both normoxic and hypoxic conditions, whereas Bcl-xL was significantly decreased in endothelial cells exposed to hypoxia (P<0.01). No significant change in Bax, a promoter of apoptosis, was also observed in endothelial cells under hypoxia, whereas HGF did not affect BAX: Overall, this study demonstrated that HGF prevented endothelial cell death induced by hypoxia through its antiapoptotic action. The antiapoptotic mechanisms of HGF in hypoxia-induced endothelial cell death largely depend on Bcl-2, but not Bcl-xL and BAX:

Phosphorylation of p38 mitogen-activated protein kinase downstream of bax-caspase-3 pathway leads to cell death induced by high D-glucose in human endothelial cells.

Because high D-glucose significantly stimulates endothelial cell death, we examined the molecular mechanisms of high D-glucose-induced endothelial apoptosis. Treatment of human aortic endothelial cells with high D-glucose (25 mmol/l), but not mannitol and L-glucose, resulted in a significant decrease in cell number and a significant increase in apoptotic cells as compared with a physiological concentration (5 mmol/l). Interestingly, high D-glucose treatment significantly increased bax protein, accompanied by translocation of bax protein from cytosol to mitochondria-enriched heavy membrane fraction. In contrast, the expression and distribution of bcl-2 protein were not altered by high D-glucose. In addition, the activity of caspase-3 proteases was increased after exposure to high glucose, whereas caspase inhibitors prevented endothelial cell death induced by high D-glucose. On the other hand, p38 mitogen-activated protein kinase (MAPK) was markedly phosphorylated and showed sustained phosphorylation after stimulation. A specific inhibitor of p38 MAPK, SB 203580, and the overexpression of kinase-inactive p38 MAPK significantly attenuated cell death induced by high D-glucose in human aortic endothelial cells, whereas at 6 h after high D-glucose treatment, SB 203580 and overexpression of kinase-inactive p38 MAPK did not attenuate caspase-3 activation induced by high D-glucose. Importantly, caspase inhibitors significantly attenuated the sustained phosphorylation of p38 MAPK induced by high D-glucose. Thus, we finally focused the MAPK kinase (MEK) kinase 1 (MEKK1) to further examine the cross-talk between p38 MAPK and the bax-caspase proteases pathway. High D-glucose treatment induced MEKK1 cleavage, whereas caspase inhibitors significantly attenuated the cleavage. Importantly, kinase-inactive MEKK1 also blocked the phosphorylation of p38 MAPK induced by high D-glucose. Here, we demonstrated that high D-glucose induced apoptosis in human endothelial cells through activation of the bax-caspase proteases pathway and through phosphorylation of p38 MAPK mediated by MEKK1. Phosphorylation of p38 MAPK downstream of the bax-caspase pathway may play a pivotal role in endothelial apoptosis mediated by high D-glucose.

Therapeutic angiogenesis induced by human hepatocyte growth factor gene in rat and rabbit hindlimb ischemia models: preclinical study for treatment of peripheral arterial disease.

Hepatocyte growth factor (HGF) exclusively stimulates the growth of endothelial cells without replication of vascular smooth muscle cells, and acts as a survival factor against endothelial cell death. Recently, a novel therapeutic strategy for ischemic diseases using angiogenic growth factors to expedite and/or augment collateral artery development has been proposed. We have previously reported that intra-arterial administration of recombinant HGF induced angiogenesis in a rabbit hindlimb ischemia model. In this study, we examined the feasibility of gene therapy using HGF to treat peripheral arterial disease rather than recombinant therapy, due to its disadvantages. Initially, we examined the transfection of 'naked' human HGF plasmid into a rat hindlimb ischemia model. Intramuscular injection of human HGF plasmid resulted in a significant increase in blood flow as assessed by laser Doppler imaging, accompanied by the detection of human HGF protein. A significant increase in capillary density was found in rats transfected with human HGF as compared with control vector, in a dose-dependent manner (P < 0.01). Importantly, at 5 weeks after transfection, the degree of angiogenesis induced by transfection of HGF plasmid was significantly greater than that caused by a single injection of recombinant HGF. As an approach to human gene therapy, we also employed a rabbit hindlimb ischemia model as a preclinical study. Naked HGF plasmid was intramuscularly injected in the ischemic hindlimb of rabbits, to evaluate its angiogenic activity. Intramuscular injection of HGF plasmid once on day 10 after surgery produced significant augmentation of collateral vessel development on day 30 in the ischemia model, as assessed by angiography (P < 0.01). Serial angiograms revealed progressive linear extension of collateral arteries from the origin stem artery to the distal point of the reconstituted parent vessel in HGF-transfected animals. In addition, a significant increase in blood flow was assessed by a Doppler flow wire and the ratio in blood pressure of the ischemic limb to the normal limb was observed in rabbits transfected with HGF plasmid as compared with rabbits transfected with control vector (P < 0.01). Overall, intramuscular injection of naked human HGF plasmid induced therapeutic angiogenesis in rat and rabbit ischemic hindlimb models, as potential therapy for peripheral arterial disease.

Mitogenic and antiapoptotic actions of hepatocyte growth factor through ERK, STAT3, and AKT in endothelial cells.

Hepatocyte growth factor (HGF), a member of the angiogenic growth factors, may play a pivotal role in the regulation of endothelial cells, inasmuch as HGF shows mitogenic and antiapoptotic actions in endothelial cells. Because the mechanism of these actions is still unclear, we examined the signal transduction system of HGF in human aortic endothelial cells. Treatment of endothelial cells with recombinant HGF (rHGF) resulted in a significant increase in DNA synthesis as assessed by thymidine incorporation. Importantly, phosphorylation of extracellular signal-related kinase (ERK) and Akt by rHGF was clearly observed. Thus, we further examined the effects of specific inhibitors of ERK or Akt on cell proliferation. Pretreatment with PD98059, a mitogen-activated protein kinase kinase inhibitor, significantly attenuated cell proliferation induced by rHGF, whereas inhibitors of phosphatidylinositol-3-OH kinase, wortmannin, and LY-294002, did not. Interestingly, treatment with rHGF significantly increased the phosphorylation of the signal transducers and activators of transcription (STAT)3 (Ser727), whereas PD98059 attenuated the phosphorylation of Ser727 induced by rHGF. In addition, treatment with rHGF significantly increased the promoter activity of c-fos, which includes the sis-inducible element and serum response element, whereas PD98059 completely attenuated the activation of the c-fos promoter induced by rHGF. In contrast, inhibition of Akt by wortmannin and LY-294002 failed to inhibit the phosphorylation of STAT3 and c-fos activation. On the other hand, treatment with rHGF attenuated the increase in LDH release and caspase-3 activity induced by tumor necrosis factor-alpha stimulation. In contrast to DNA synthesis, wortmannin and LY-294002 markedly attenuated the decrease in caspase-3 activity mediated by rHGF, whereas PD98059 did not. Overall, the present study demonstrated that HGF stimulated cell proliferation through the ERK-STAT3 (Ser727) pathway and had an antiapoptotic action through the phosphatidylinositol-3-OH kinase-Akt pathway in human aortic endothelial cells. These findings provide new perspectives in the role of HGF in cardiovascular disease.

Pivotal role of tyrosine phosphatase SHP-1 in AT2 receptor-mediated apoptosis in rat fetal vascular smooth muscle cell.

OBJECTIVE: To examine the possible crosstalk and the roles of angiotensin (Ang) II type 1 (AT1) and type 2 (AT2) receptors in the control of apoptosis in fetal vascular smooth muscle cells (VSMCs). METHODS: Fetal VSMCs were prepared from rat fetal aorta at embryonic day 20. Expression of Ang II receptors was measured by a radioligand binding assay. Apoptotic changes were assessed by caspase 3 activity and chromatin dye staining. Regulation of extracellular signal-regulated kinase (ERK) activity via Ang II receptors was analysed by determining phosphorylated ERK with Western blot. Ang II receptor-mediated activation of tyrosine phosphatase SHP-1 was assessed by protein tyrosine phosphatase assay. RESULTS: The expression of AT1 and AT2 receptors was approximately 70%: 30% per cell. Serum depletion induced apoptosis in fetal VSMCs and selective AT1 receptor stimulation attenuated the apoptotic changes, whereas selective AT2 receptor activation enhanced apoptosis. Ang II increased ERK phosphorylation, which was inhibited by addition of the AT1 receptor-specific antagonist CV11974, but enhanced by addition of the AT2 receptor-specific antagonist PD123319, suggesting that activation of AT2 receptor attenuated the AT1 receptor-mediated ERK phosphorylation. Moreover, we demonstrated that AT2 receptor stimulation activated SHP-1 in fetal VSMCs, whereas AT1 receptor stimulation did not. Transient transfection of a dominant-negative SHP-1 mutant into rat fetal VSMCs resulted in a significant decrease of the AT2 receptor-mediated inhibition of ERK phosphorylation and attenuated the proapoptotic effect of AT2 receptor. CONCLUSION: These results indicate that a crosstalk between AT1 and AT2 receptors regulates the survival of fetal VSMCs and substantiate SHP-1 as a key molecule in AT2 receptor signaling.

Involvement of bradykinin and nitric oxide in leptin-mediated glucose uptake in skeletal muscle.

Regulation of glucose metabolism in peripheral tissues by leptin has been highlighted recently, although its mechanism is unclear. In this study, we postulated that bradykinin and nitric oxide (NO) are involved in the effect of leptin-mediated glucose uptake in peripheral tissues and examined these possibilities. Injection of leptin (200 pg/mouse) into the ventromedial hypothalamus-enhanced glucose uptake in skeletal muscle and brown adipose tissue, but not in white adipose tissue. Treatment with Hoe140 (0.1 mg/kg), bradykinin B2 receptor antagonist, or L-NAME (N:(G)-nitro-L-arginine methyl ester) (30 mg/kg), nitric oxide synthase inhibitor, did not influence the basal level of glucose uptake in skeletal muscle and the adipose tissue, whereas Hoe140 and L-NAME inhibited leptin-mediated glucose uptake in skeletal muscles, but had no effect in adipose tissue. However, Hoe140 and L-NAME did not inhibit insulin (1.0 U/kg)-mediated glucose uptake in all tissues examined. Taken together, these results suggest that leptin enhances bradykinin and/or the NO system, which contributes at least partially to the enhanced glucose uptake in skeletal muscles.

Inhibition of intimal hyperplasia after balloon injury in rat carotid artery model using cis-element 'decoy' of nuclear factor-kappaB binding site as a novel molecular strategy.

The transcription factor, NFkB, plays a pivotal role in the coordinated transactivation of cytokine and adhesion molecule genes involved in atherosclerosis and lesion formation after vascular injury. We hypothesized that synthetic double-stranded DNA with high affinity for NFkB may be introduced as a 'decoy' cis element to bind the transcription factor, and block gene activation, resulting in an effective therapeutic agent for treating intimal hyperplasia. In vivo transfection of NFkB decoy oligodeoxynucleotides (ODN) into balloon-injured rat carotid artery resulted in the inhibition of neointimal formation at 14 days after injury as compared with vessels transfected with scrambled ODN (P < 0.01). It is of importance to note that in the vessels transfected with NFkB decoy ODN, the expression of p53, a pro-apoptotic gene, was upregulated in neointimal area, followed by increased apoptosis at 14 days. In addition, gene expression of ICAM-1 and VCAM-1 was markedly decreased in blood vessels transfected with NFkB decoy ODN compared with scrambled ODN, whereas balloon injury induced ICAM and VCAM expression in the neointimal area. More importantly, the migration of macrophages and T-lymphocytes into the neointima and media was significantly inhibited by NFkB decoy ODN as compared with scrambled ODN. Here, we demonstrated that in vivo transfer of NFkB decoy ODN successfully inhibited neointimal formation after balloon injury, accompanied by (1) induction of apoptosis through p53 upregulation, and (2) inhibition of local inflammatory actions through the downregulation of adhesion molecules. These results suggest that decoy treatment against NFkB provides a new therapeutic strategy to inhibit neointimal hyperplasia after angioplasty.

Anti-apoptotic action of hepatocyte growth factor through mitogen-activated protein kinase on human aortic endothelial cells.

OBJECTIVE: To investigate the molecular mechanisms of the anti-apoptotic action of hepatocyte growth factor (HGF), a novel angiogenic growth factor that may have a pivotal role in the regulation of endothelial cells, on human aortic endothelial cells. METHODS: An index of cell number and death was determined using a water-soluble tetrazolium salt dye assay, DNA fragmentation enzyme-linked immunosorbent assay, and non-confocal fluorescence microscopy of nuclear staining with Hoechst 33258 and propidium iodide. Extracellular-signal-regulated protein kinase (ERK) and the p38 mitogen-activated protein kinase (p38MAPK) were analysed by Western blotting using a phospho-specific antibody. RESULTS: Treatment of quiescent endothelial cells with HGF resulted in significant dose-dependent increases in cell numbers and decreases in lactate dehydrogenase (LDH) release. Moreover, HGF significantly attenuated endothelial cell death induced by culture in serum-free conditions. We therefore focused on the signal transduction system, and in particular on ERK and p38MAPK. ERK was markedly phosphorylated by HGF. The contribution of ERK to cell growth was supported by the observation that addition of PD98059, a specific inhibitor of MAPK kinase, significantly attenuated the increase in endothelial cell numbers induced by HGF, in a dose-dependent manner. Similarly, PD98059 also attenuated the decrease in LDH release and DNA fragmentation by HGF under serum-free conditions. Interestingly, ERK was re-phosphorylated at 12 h after stimulation. Re-phosphorylation of ERK was the result of induction of endogenous HGF by exogenously added HGF, as addition of neutralizing anti-HGF antibody to the conditioned medium attenuated re-phosphorylation of ERK at 12 h. In contrast, although p38MAPK was also phosphorylated by HGF, SB203580, a specific inhibitor of p38MAPK, failed to change the endothelial cell growth induced by HGF. CONCLUSION: We have demonstrated that the anti-apoptotic action of HGF against endothelial cell death was mainly through phosphorylation of ERK on human endothelial cells.

Ribozyme oligonucleotides against transforming growth factor-beta inhibited neointimal formation after vascular injury in rat model: potential application of ribozyme strategy to treat cardiovascular disease.

BACKGROUND: Because the mechanisms of atherosclerosis or restenosis after angioplasty have been postulated to involve an increase in transforming growth factor (TGF)-beta, a selective decrease in TGF-beta may have therapeutic value. Thus, we used the ribozyme strategy to actively cleave the targeted gene to selectively inhibit TGF-beta expression. METHODS AND RESULTS: We constructed ribozyme oligonucleotides (ONs) targeted to the sequence of the TGF-beta gene that shows 100% homology among the human, rat, and mouse species. The specificity of ribozyme against TGF-beta gene was confirmed by selective inhibition of TGF-beta mRNA in cultured vascular smooth muscle cells as well as balloon-injured blood vessels in vivo. Importantly, the marked decrease in TGF-beta resulted in significant inhibition of neointimal formation after vascular injury in a rat carotid artery model (P:<0.01), whereas DNA-based control ONs and mismatched ribozyme ONs did not have any inhibitory effect on neointimal formation. Inhibition of neointimal formation was accompanied by (1) a reduction in collagen synthesis and mRNA expression of collagen I and III and (2) a significant decrease in DNA synthesis as assessed by proliferating cell nuclear antigen staining. Moreover, we modified ribozyme ONs containing phosphorothioate DNA and RNA targeted to the TGF-beta gene. Of importance, modified ribozyme ONs showed a further reduction in TGF-beta expression. CONCLUSIONS: Overall, this study provides the first evidence that selective blockade of TGF-beta resulted in inhibition of neointimal formation, accompanied by a reduction in collagen synthesis and DNA synthesis in a rat model. We anticipate that modification of ribozyme ON pharmacokinetics will facilitate the potential clinical utility of the ribozyme strategy.

Potential contribution of a novel antifibrotic factor, hepatocyte growth factor, to prevention of myocardial fibrosis by angiotensin II blockade in cardiomyopathic hamsters.

BACKGROUND: Because hepatocyte growth factor (HGF) prevented and/or regressed fibrosis in liver and pulmonary injury models, HGF may play an important role in the pathogenesis of fibrotic cardiovascular disease. Because angiotensin (Ang) II significantly decreased local HGF production, we performed (1) in vitro experiments using fibroblasts and (2) administration of an ACE inhibitor (temocapril) and an Ang II type 1 receptor antagonist (CS-866) to cardiomyopathic hamsters. METHODS AND RESULTS: In human fibroblasts, HGF significantly increased the production of matrix metalloprotease-1 (MMP-1) and urokinase plasminogen activator, whereas HGF also significantly attenuated the reduction of MMP-1 activity induced by Ang II. In contrast, HGF significantly decreased transforming growth factor (TGF)-beta mRNA stimulated by Ang II, whereas HGF also decreased basal TGF-beta protein level without affecting growth. Similarly, in rat cardiac fibroblasts, HGF inhibited the expression and production of TGF-beta, whereas HGF upregulated its specific receptor, c-met. Conversely, in vivo experiments revealed that administration of temocapril and CS-866 to cardiomyopathic hamsters resulted in a significant decrease in fibrotic area and increase in cardiac HGF concentration and mRNA (P<0.01), whereas cardiac concentration and mRNA of HGF were significantly decreased in cardiomyopathic hamsters. In contrast, mRNA expression of collagen III was markedly decreased by treatment with temocapril and CS-866. CONCLUSIONS: Here, we demonstrated that Ang II blockade prevented myocardial fibrosis in the cardiomyopathic hamster, accompanied by a significant increase in cardiac HGF. Overall, increase in local HGF expression may participate in the prevention of myocardial injury by Ang II blockade through its antifibrotic action.