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Ryozo Nagai

Publications and source records attributed to Ryozo Nagai.

At least 73 records · Page 4Linked to original sources
PubMed2005

Analysis of double-stranded RNA-induced apoptosis pathways using interferon-response noninducible small interfering RNA expression vector library.

We have developed an original vector library that allowed us to exploit the phenomenon of RNA interference but also allowed us to avoid the confounding effects of the interferon response. In the present work, we used our library of small interfering RNA expression vectors to examine the genes involved in apoptosis that was induced by double-stranded RNA. To our surprise, screening of our library revealed two novel double-stranded RNA-induced apoptotic pathways, a JNK/SAPK-mediated mitochondrial pathway and an ERK2-related pathway, both of which appeared to be independent of the serine-threonine protein kinase-dependent caspase pathway. We also found that MST2 and protein kinase Calpha both activated the pro-apoptotic signal mediated by ERK2. The results of our screening analysis suggested the utility of large scale screenings with libraries of small interfering RNA expression vectors.

Apoptosis↗
PubMed2005

Vascular implications of the Krüppel-like family of transcription factors.

The Krüppel-like factor (KLF) family is a recently highlighted group of zinc finger transcription factors given their important biological roles which include the vasculature. KLF2, KLF4, KLF5, and KLF6 are notable factors that have been implicated in developmental as well as pathological vascular processes. In this brief review, we provide an up-to-date summary of the physiological functions and cellular effects as well as transcriptional regulatory mechanisms of the vascular KLFs. Through such, we aim to provide a working view for understanding the pathological actions of KLFs in the vasculature.

Animals↗
PubMed2005

Blockade of endogenous cytokines mitigates neointimal formation in obese Zucker rats.

BACKGROUND: It is well known that diabetes mellitus is a major risk factor for vascular diseases such as atherosclerosis and restenosis after angioplasty. It has become clear that advanced glycation end products (AGE) and their receptor (RAGE) are implicated in vascular diseases, especially in diabetes mellitus. Nevertheless, the mechanisms by which diabetes mellitus is often associated with vascular diseases remain unclear. METHODS AND RESULTS: To study the role of endogenous cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 in the development of vascular diseases and in the expression of RAGE, we used semapimod, a pharmacological inhibitor of cytokine production, and examined its effect on neointimal formation in the femoral artery of obese Zucker (OZ) rats. We also used an adenovirus construct expressing a dominant negative mutant of the receptor for TNF-alpha (AdTNFRDeltaC) to block the action of endogenous TNF-alpha. Semapimod significantly suppressed neointimal formation and RAGE expression in OZ rats compared with untreated OZ rats. This inhibitory effect of semapimod on neointimal formation was overcome by infection of an adenovirus expressing RAGE into the femoral artery of OZ rats. Furthermore, AdTNFRDeltaC infection significantly suppressed neointimal formation and RAGE expression in the femoral artery of OZ rats. CONCLUSIONS: These results suggest that endogenous cytokines, especially TNF-alpha, were implicated in neointimal formation in OZ rats and that RAGE was a mediator of the effect of these cytokines on neointimal formation.

Adenoviridae↗
PubMed2005

Carvedilol effectively blocks oxidative stress-mediated downregulation of sarcoplasmic reticulum Ca2+-ATPase 2 gene transcription through modification of Sp1 binding.

Carvedilol is a beta-adrenoceptor blocker and a potent antioxidant that improves cardiac function in patients with heart failure. The restoration of sarcoplasmic reticulum Ca2+-ATPase (SERCA2) gene expression may be an underlying mechanism of its beneficial effects on cardiac function. In primary cultured neonatal rat cardiac myocytes, treatment with either carvedilol or its beta-receptor inactive metabolite, BM910228, attenuated the hydrogen peroxide-mediated decrease in SERCA2 mRNA and protein levels, while metoprolol, a pure beta-blocker, had no effect. Moreover, carvedilol itself significantly enhanced SERCA2 gene transcription, suggesting that carvedilol specifically restores SERCA2 gene transcription. Site-directed mutagenesis revealed that two Sp1 sites in the SERCA2 gene promoter region mediated the response to carvedilol under oxidative stress. Further, electrophoretic mobility shift assays revealed that Sp1 and Sp3 transcription factors correlated with carvedilol-mediated changes in the promoter assays. These studies may provide a mechanistic explanation for the beneficial effects of carvedilol in heart failure.

Animals↗
PubMed2005

Association between serum uric acid, metabolic syndrome, and carotid atherosclerosis in Japanese individuals.

OBJECTIVE: There are few data available on possible independent association between uric acid and carotid atherosclerosis. Here we first sought to investigate association between uric acid levels and metabolic syndrome in Japanese; second, we assessed whether there is an independent association of uric acid with prevalence of carotid atherosclerosis in individuals subdivided according to gender and metabolic syndrome status. METHODS AND RESULTS: Cross-sectional data from 8144 individuals who underwent general health screening were analyzed. After adjusting for age, total cholesterol, and smoking status, the odds ratios (95% CI) of sex-specific quartiles of serum uric acid for metabolic syndrome were 1.0, 1.06 (0.60 to 1.87), 2.18 (1.30 to 3.64), and 4.17 (2.56 to 6.79) in women, and 1.0, 0.92 (0.74 to 1.14), 1.52 (1.25 to 1.65), and 1.97 (1.61 to 2.40) in men. After adjusting for age, serum levels, total cholesterol, and smoking status, prevalence of carotid plaque was higher in subjects in the second, third, and fourth quartiles of uric acid level with odds ratios (95% CI) of 1.24 (1.01 to 1.52), 1.37 (1.11 to 1.68), and 1.31 (1.05 to 1.63), respectively, in men without metabolic syndrome but not in men with metabolic syndrome or in women with or without metabolic syndrome. CONCLUSIONS: The prevalence of metabolic syndrome showed a graded increase according to serum uric acid values in both genders. In men who did not have metabolic syndrome, uric acid was found to be an independent risk factor for incidence of carotid plaque.

Adult↗
PubMed2005

Association between cigarette smoking, metabolic syndrome, and carotid arteriosclerosis in Japanese individuals.

Cigarette smoking is associated with increased insulin resistance and other metabolic abnormalities. Here, we investigate the prevalence of metabolic syndrome (MetS) in cigarette smokers and people who never smoked by analyzing cross-sectional data of 5033 subjects aged between 35 and 65 years who underwent general health screening. Both former and current smoking was associated with an increased incidence of metabolic syndrome defined by modified-National Cholesterol Education Program (NCEP) criteria with odds ratios of 1.77 (95% CI 1.42-2.22, P < 0.0001) and 2.38 (95% CI 1.95-2.91, P < 0.0001), respectively. In both former and current smokers, prevalence of metabolic syndrome increased when the duration of cigarette smoking was > or = 10 years. The positive association between metabolic syndrome and smoking was only partially reversed even 5 years after quitting. Multivariate logistic regression analysis showed that metabolic syndrome was an independent risk factor for carotid plaque with an odds ratio of 1.72 (95% CI 1.43-2.08, P < 0.0001). On the other hand, when limited to individuals without metabolic syndrome, former and current smoking was still found to be associated with carotid plaque with odds ratios of 1.49 (95% CI 1.15-1.92, P = 0.0023) and 1.57 (95% CI 1.22-2.03, P = 0.0005), respectively, in men. Collectively, these data suggest that the atherogenic consequences of smoking may, at least in part, be explained by its association with metabolic syndrome.

Adult↗
PubMed2005

Family history.

Explore the source record for details and available documents.

Family Health↗
PubMed2005

Potent inhibitory effect of sirolimus on circulating vascular progenitor cells.

BACKGROUND: Neointimal hyperplasia is the major cause of in-stent restenosis (ISR). The sirolimus-eluting stent (SES) has emerged as a promising therapy to prevent ISR; however, the exact mechanism by which locally delivered sirolimus, an immunosuppressive agent, prevents ISR remains unknown. Recent evidence suggests that circulating progenitor cells may contribute to neointimal formation. METHODS AND RESULTS: Mononuclear cells (MNCs) were isolated from peripheral blood of healthy human volunteers. Smooth muscle (SM)-like cells outgrew from the culture of MNCs (1x10(6)) in the presence of platelet-derived growth factor-BB and basic fibroblast growth factor, whereas endothelial cell-like cells were obtained in the presence of vascular endothelial growth factor. Sirolimus potently inhibited SM-like cell outgrowth. The number of SM-like cells was significantly reduced at a concentration as low as 0.1 ng/mL (15.9+/-5.8% of control, P<0.001). Sirolimus also exerted an inhibitory effect on endothelial cell-like cells that originated from MNCs. Wire-mediated vascular injury was induced in femoral arteries of bone marrow chimeric mice. Either vehicle or sirolimus was administered locally to the perivascular area of the injured arteries. Sirolimus significantly reduced neointima hyperplasia at 4 weeks (intima/media ratio 2.0+/-0.3 versus 1.0+/-0.2, P<0.05) with a decreased number of bone marrow-derived SM-like cells and hematopoietic cells in the lesion. Reendothelialization was retarded in the arteries treated with sirolimus. CONCLUSIONS: The potent inhibitory effects of sirolimus on circulating smooth muscle progenitor cells may mediate the clinical efficacy of SES, at least in part. Sirolimus potentially may affect reendothelialization after stent implantation.

Animals↗
PubMed2005

Cimetidine inhibits angiogenesis and suppresses tumor growth.

Cimetidine, a histamine type-2 receptor antagonist, has been reported to improve survival of patients with cancers. However, the exact mechanisms by which cimetidine suppresses development of cancers remain to be elucidated. Solid tumors require neovascularization for their growth. Here, we investigated the effects of cimetidine on tumor growth and angiogenesis. Syngeneic colon cancer cells, CMT93 cells, were inoculated into the subcutaneous space of C57BL/6 mice. Mice were treated with either saline or cimetidine. Tumor size was measured everyday and angiogenesis was evaluated histologically. Cimetidine markedly suppressed tumor growth with reduced neovascularization in the tumor. Cimetidine had no effect on proliferation of CMT93 cells in vitro. Vascular endothelial growth factor production by cancer cells was not affected by cimetidine, while vascular-like tube formation by endothelial cells in vitro was significantly impaired in the presence of cimetidine. Our findings suggest that cimetidine suppresses tumor growth, at least in part, by inhibiting tumor-associated angiogenesis.

Angiogenesis Inhibitors↗
PubMed2005

The deacetylase HDAC1 negatively regulates the cardiovascular transcription factor Krüppel-like factor 5 through direct interaction.

Transcription is regulated by a network of transcription factors and related cofactors that act in concert with the general transcription machinery. Elucidating their underlying interactions is important for understanding the mechanisms regulating transcription. Recently, we have shown that Krüppel-like factor KLF5, a member of the Sp/KLF family of zinc finger factors and a key regulator of cardiovascular remodeling, is regulated positively by the acetylase p300 and negatively by the oncogenic regulator SET through coupled interaction and regulation of acetylation. Here, we have shown that the deacetylase HDAC1 can negatively regulate KLF5 through direct interaction. KLF5 interacts with HDAC1 in the cell and in vitro. Gel shift DNA binding assay showed that their interaction inhibits the DNA binding activity of KLF5, suggesting a property of HDAC1 to directly affect the DNA binding affinity of a transcription factor. Reporter assay also revealed that HDAC1 suppresses KLF5-dependent promoter activation. Additionally, overexpression of HDAC1 suppressed KLF5-dependent activation of its endogenous downstream gene, platelet-derived growth factor-A chain gene, when activated by phorbol ester. Further, HDAC1 binds to the first zinc finger of KLF5, which is the same region where p300 interacts with KLF5 and, intriguingly, HDAC1 inhibits binding of p300 to KLF5. Direct competitive interaction between acetylase and deacetylase has been hitherto unknown. Collectively, the transcription factor KLF5 is negatively regulated by the deacetylase HDAC1 through direct effects on its activities (DNA binding activity, promoter activation) and further through inhibition of interaction with p300. These findings suggest a novel role and mechanism for regulation of transcription by deacetylase.

Acetyltransferases↗
PubMed2005

Rationale and design of a randomized trial to assess the effects of beta-blocker in diastolic heart failure; Japanese Diastolic Heart Failure Study (J-DHF).

BACKGROUND: Heart failure consists of two phenotypes: systolic heart failure and diastolic heart failure (DHF). A growing body of evidence demonstrated benefits of beta-blocker, angiotensin-converting enzyme inhibitor, and angiotensin II receptor blocker in systolic heart failure; however, evidence leading to therapeutic strategy of DHF is lacking. METHODS AND RESULTS: The Japanese Diastolic Heart Failure Study (J-DHF) is a multicenter, prospective, randomized trial designed to assess effects of beta-blocker in patients with DHF. A total of 800 patients (400 patients in each group) will be enrolled. The primary outcome is a composite of cardiovascular death and unplanned admission to hospital for congestive heart failure. Other outcomes include all-cause mortality, worsening of the symptoms of heart failure, or a need for modification of the treatment for heart failure. Serial assessment of echocardiographic and neurohumoral parameters and cost analysis of the treatment regimen will be conducted. The follow-up period is a minimum of 2 years. CONCLUSION: This study will provide important evidences for the treatment of DHF.

Adrenergic beta-Antagonists↗
PubMed2005

Krüppel-like transcription factor KLF5 is a key regulator of adipocyte differentiation.

Krüppel-like factor 5 (KLF5) is a zinc-finger transcription factor known to play a pivotal role in the pathogenesis of cardiovascular disease. Here, we show that neonatal heterozygous KLF5 knockout mice exhibit a marked deficiency in white adipose tissue development, suggesting that KLF5 is also required for adipogenesis. In 3T3-L1 preadipocytes, KLF5 expression was induced at an early stage of differentiation, and this was followed by expression of PPARgamma2. Constitutive overexpression of dominant-negative KLF5 inhibited adipocyte differentiation, whereas overexpression of wild-type KLF5 induced differentiation even without hormonal stimulation. Moreover, embryonic fibroblasts obtained from KLF5+/- mice showed much attenuated adipocyte differentiation, confirming the key role played by KLF5 in adipocyte differentiation. KLF5 expression is induced by C/EBPbeta and delta. KLF5, in turn, acts in concert with C/EBPbeta/delta to activate the PPARgamma2 promoter. This study establishes KLF5 as a key component of the transcription factor network controlling adipocyte differentiation.

3T3-L1 Cells↗
PubMed2005

Co-ordinate activation of lipogenic enzymes in hepatocellular carcinoma.

Hepatocellular carcinoma is a very common neoplastic disease in countries where hepatitis viruses B and/or C are prevalent. Small hepatocellular carcinoma lesions detected by ultrasonography at an early stage are often hyperechoic because they are composed of well-differentiated cancer cells that are rich in triglyceride droplets. The triglyceride content of hepatocytes depends in part on the rate of lipogenesis. Key lipogenic enzymes, such as fatty acid synthase, are co-ordinately regulated at the transcriptional level. We therefore examined the mRNA expression of lipogenic enzymes in human hepatocellular carcinoma samples from 10 patients who had undergone surgical resection. All of the samples exhibited marked elevation of expression of mRNA for lipogenic enzymes, such as fatty acid synthase, acetyl-CoA carboxylase and ATP citrate lyase, compared with surrounding non-cancerous liver tissue. In contrast, the changes in mRNA expression of SREBP-1, a transcription factor that regulates a battery of lipogenic enzymes, did not show a consistent trend. In some cases where SREBP-1 was elevated, the main contributing isoform was SREBP-1c rather than SREBP-1a. Thus, lipogenic enzymes are markedly induced in hepatocellular carcinomas, and in some cases SREBP-1c is involved in this activation.

Adult↗
PubMed2005

Transcriptional regulation at the chromatin level in the cardiovasculature through protein-protein interactions and chemical modifications.

Transcriptional regulation in eukaryotes requires an understanding of the regulation of the chromatin structure. Chromatin is the eukaryotic-specific packaging/compaction of DNA with nucleosomal histones. This present review discusses recent advancements made in the field of chromatin-associated transcriptional regulation and their implications to the cardiovasculature.

Cardiovascular Physiological Phenomena↗
PubMed2005

Contractile dysfunction of cardiomyopathic hamster myocytes is pronounced under high load conditions.

To understand the pathophysiology of hereditary cardiomyopathy, the contractile function of cardiomyopathic hamsters has been studied at the cellular level. However, most of the studies to date have described the cell shortening under the unloaded condition. Using a novel force-length measurement system for single cardiomyocytes, we studied the contractile function of cardiomyopathic hamster myocytes over a wide range of loading conditions. Cardiomyocytes were isolated from the ventricles of eight- to 10-week-old cardiomyopathic (CMP) hamsters (Bio TO-2 strain), as well as control (CTRL) Syrian hamsters. A pair of carbon fibers was attached to both ends of single cardiomyocytes and their contractile characteristics were recorded while changing the after-load by controlling the fiber motion. Under the unloaded condition, the shortening fraction (CMP 9.2+/-0.5% vs. CTRL 10.7+/-0.8%, P=0.06) and maximum shortening velocity (CMP 98.2+/-7.3 microm/s vs. CTRL 147.2+/-6.5 microm/s, P<0.05) were decreased in CMP hamster myocytes. The peak force under the isometric condition (CMP 35.8+/-2.2 mN/mm2 vs. CTRL 69.0+/-8.4 mN/mm2, P<0.05) and external work (CMP 898+/-130 J/m3 vs. CTRL 3058+/-576 J/m3, P<0.05) under physiologically loaded conditions were also decreased, but the differences were more pronounced under the loaded conditions. Calcium transients measured by Indo-1 revealed elevated diastolic level, decreased peak level, and slower diastolic decay in CMP myocytes thus being consistent with the observed contractile dysfunction. These results clearly indicate the importance of the loading conditions in evaluating the contractile function of CMP hamster myocytes, and may provide insights into the mechanism of contractile dysfunction in this disease.

Animals↗
PubMed2005

Molecular and pharmacological characteristics of transient voltage-dependent K+ currents in cultured human pulmonary arterial smooth muscle cells.

The A-type voltage-dependent K(+) current (I(A)) has been identified in several types of smooth muscle cells including the pulmonary artery (PA), but little is known about the pharmacological and molecular characteristics of I(A) in human pulmonary arterial smooth muscle cells (hPASMCs). We investigated I(A) expressed in cultured PASMCs isolated from the human main pulmonary artery, using patch-clamp techniques, reverse transcriptase-polymerase chain reaction (RT-PCR), quantitative real-time RT-PCR and immunocytochemical studies. With high EGTA and ATP in the pipette, the outward currents were dominated by a transient K(+) current (I(A)), followed by a relatively small sustained outward current (I(K)). I(A) was inhibited by 4-aminopyridine (4-AP) concentration-dependently, and could be separated pharmacologically into two components by tetraethylammonium (TEA) sensitivity. A component was sensitive to TEA, and the second component was insensitive to TEA. I(A) was inhibited by blood depressing substrate (BDS)-II, a specific blocker of K(V)3.4 subunit, and phrixotoxin-II, a specific blocker of K(V)4.2 and 4.3. Flecainide inhibited I(A) concentration-dependently, but it inhibited it preferentially in the presence of TEA (TEA-insensitive I(A)). Systematic screening of expression of K(V) genes using RT-PCR showed the definite presence of transcripts of the I(A)-encoding genes for K(V)3.4, K(V)4.1, K(V)4.2 and K(V)4.3 as well as the I(K)-encoding genes for K(V)1.1, K(V)1.5 and K(V)2.1. The real-time RT-PCR analysis showed that the relative abundance of the encoding genes of I(A) alpha-subunit and K(V) channel-interacting proteins (KChIPs) was K(V)4.2 > K(V)3.4 > K(V)4.3 (long) > K(V)4.1, and KChIP3 >> KChIP2, respectively. The presence of K(V)3.4, K(V)4.2 and K(V)4.3 proteins was also demonstrated by immunocytochemical studies, and confirmed by immunohistochemical staining using intact human PA sections. These results suggest that I(A) in cultured hPASMCs consists of two kinetically and pharmacologically distinct components, probably K(V)3.4 and K(V)4 channels.

Calcium-Binding Proteins↗