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Kaori Higuchi,
Yoshikazu Nakaoka, Wataru Shioyama,
Yoh Arita,
Takahiro Hashimoto,
Taku Yasui,
Kuniyasu Ikeoka,
Tadashi Kuroda,
Takashi Minami,
Keigo Nishida,
Yasushi Fujio,
Keiko Yamauchi-Takihara,
Mikiyasu Shirai,
Naoki Mochizuki,
Issei Komuro
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ABSTRACT: Docking protein Grb2-associated binder 1 (Gab1) has critical roles in signal transduction of various growth factors, cytokines, and numerous other molecules. Our previous reports show that Gab1 is essential for postnatal angiogenesis through the analysis of endothelium-specific Gab1 knockout (Gab1ECKO) mice. However, the role of Gab1 in atherosclerosis remains unknown. The aim of the present study was to elucidate the role of endothelial Gab1 in vascular inflammation and atherosclerosis.
We intercrossed Gab1ECKO mice with apolipoprotein E (ApoE) knockout (ApoEKO) mice. Six-month-old male ApoEKO/Gab1ECKO and littermate control (ApoEKO) mice were treated with angiotensin II (AngII) via an osmotic infusion mini-pump. After AngII treatment, ApoEKO/Gab1ECKO mice showed significantly enhanced atherosclerosis and aneurysm formation compared with control mice. The production of proinflammatory cytokines in the aorta was significantly enhanced in ApoEKO/Gab1ECKO mice compared with control mice. Furthermore, the expression levels of Krüppel-like factor (KLF) 2 (KLF2) and KLF4, key transcription factors for endothelial homeostasis, were significantly reduced in the aortic endothelium of ApoEKO/Gab1ECKO mice compared with those of control mice. Consistently, both vascular cell adhesion molecule-1 expression and macrophage infiltration on the aortic walls were enhanced in ApoEKO/Gab1ECKO mice compared with control mice.
Collectively, endothelial Gab1 deletion accelerates AngII-dependent vascular inflammation and atherosclerosis on ApoE-null background presumably in association with downregulation of KLF2 and KLF4.
Circulation Journal 05/2012; 76(8):2031-40. · 3.77 Impact Factor
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ABSTRACT: The prevalence of peripheral arterial disease(PAD) is increasing with reference to the life style related disease. Up to one third of patients are not susceptible to traditional revascularization. Therefore, new strategies are needed to offer these patients a viable therapeutic option. The discovery of endothelial progenitor cells (EPCs) in human peripheral blood advanced the field of cell-based therapeutics for many pathological conditions. Bone-marrow derived stem and progenitor cells have been identified as a potential new therapeutic option to induce angiogenesis. However, the mechanism by which cell therapy improves tissue ischemia remains obscure. The present study showed that angiogenic cytokines, especially IL-1beta, were associated with the response to treatment. It is likely that muscle cells but not implanted cells are a major source of angiogenic cytokines in ischemic limbs, thereby promoting neovascularization in ischemic tissues.
Nippon rinsho. Japanese journal of clinical medicine 12/2011; 69(12):2241-5.
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Wataru Shioyama,
Yoshikazu Nakaoka,
Kaori Higuchi,
Takashi Minami,
Yoshiaki Taniyama,
Keigo Nishida,
Hiroyasu Kidoya,
Takashi Sonobe,
Hisamichi Naito,
Yoh Arita, [......],
Tadashi Kuroda,
Yasushi Fujio,
Mikiyasu Shirai,
Nobuyuki Takakura,
Ryuichi Morishita,
Keiko Yamauchi-Takihara,
Tatsuhiko Kodama,
Toshio Hirano,
Naoki Mochizuki,
Issei Komuro
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ABSTRACT: Grb2-associated binder (Gab) docking proteins, consisting of Gab1, Gab2, and Gab3, have crucial roles in growth factor-dependent signaling. Various proangiogenic growth factors regulate angiogenesis and endothelial function. However, the roles of Gab proteins in angiogenesis remain elusive.
To elucidate the role of Gab proteins in postnatal angiogenesis.
Endothelium-specific Gab1 knockout (Gab1ECKO) mice were viable and showed no obvious defects in vascular development. Therefore, we analyzed a hindlimb ischemia (HLI) model of control, Gab1ECKO, or conventional Gab2 knockout (Gab2KO) mice. Intriguingly, impaired blood flow recovery and necrosis in the operated limb was observed in all of Gab1ECKO, but not in control or Gab2KO mice. Among several proangiogenic growth factors, hepatocyte growth factor (HGF) induced the most prominent tyrosine phosphorylation of Gab1 and subsequent complex formation of Gab1 with SHP2 (Src homology-2-containing protein tyrosine phosphatase 2) and phosphatidylinositol 3-kinase subunit p85 in human endothelial cells (ECs). Gab1-SHP2 complex was required for HGF-induced migration and proliferation of ECs via extracellular signal-regulated kinase (ERK)1/2 pathway and for HGF-induced stabilization of ECs via ERK5. In contrast, Gab1-p85 complex regulated activation of AKT and contributed partially to migration of ECs after HGF stimulation. Microarray analysis demonstrated that HGF upregulated angiogenesis-related genes such as KLF2 (Krüppel-like factor 2) and Egr1 (early growth response 1) via Gab1-SHP2 complex in human ECs. In Gab1ECKO mice, gene transfer of vascular endothelial growth factor, but not HGF, improved blood flow recovery and ameliorated limb necrosis after HLI.
Gab1 is essential for postnatal angiogenesis after ischemia via HGF/c-Met signaling.
Circulation Research 02/2011; 108(6):664-75. · 9.49 Impact Factor
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Takahiro Hashimoto,
Yasushi Sakata,
Kentaro Fukushima,
Tetsuo Maeda,
Yoh Arita, Wataru Shioyama,
Yoshikazu Nakaoka,
Yumiko Hori,
Eiichi Morii,
Katsuyuki Aozasa,
Yuzuru Kanakura,
Keiko Yamauchi-Takihara,
Issei Komuro
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ABSTRACT: A 45-year-old man with chronic active Epstein-Barr virus (EBV) infection (CAEBV) with natural killer cell type developed pulmonary arterial hypertension (PAH). After chemotherapy, he showed marked depression of the EBV DNA genome in the peripheral blood, but PAH sustained. He died of heart failure due to PAH, and the histo-pathological examination revealed pulmonary vascular abnormalities without lung disease on autopsy. Although the EBV DNA genome and the infiltrating lymphocytes were not detected in the lung, his clinical course suggested that his PAH might be caused by CAEBV. This is the first reported case of PAH associated CAEBV in an adult.
Internal Medicine 01/2011; 50(2):119-24. · 0.94 Impact Factor
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Yoh Arita,
Yasushi Sakata,
Takao Sudo,
Tetsuo Maeda,
Ken Matsuoka,
Keito Tamai,
Kaori Higuchi, Wataru Shioyama,
Yoshikazu Nakaoka,
Yuzuru Kanakura,
Keiko Yamauchi-Takihara
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ABSTRACT: Castleman's disease is a highly heterogeneous clinical-pathological entity that belongs to the lymphoproliferative disorders and is associated with pulmonary arterial hypertension (PAH) in some patients. It is linked to excessive immune stimulation by interleukin-6 (IL-6), which is also involved in the pathogenesis of PAH. A 31-year-old woman with Castleman's disease demonstrated PAH characterized by severe right heart failure. Since she was resistant to various conventional therapies including steroids, prostacyclins, bosentan, and sildenafil, tocilizumab (anti-IL-6 receptor antibody) therapy was started. Her clinical course was followed for 6 months, with significant improvement without any adverse effect. This is the first reported case of use of tocilizumab in addition to steroids and conventional PAH therapy in a patient with PAH associated with Castleman's disease.
Heart and Vessels 09/2010; 25(5):444-7. · 2.05 Impact Factor
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Yoshikazu Nakaoka, Wataru Shioyama,
Satoshi Kunimoto,
Yoh Arita,
Kaori Higuchi,
Kaori Yamamoto,
Yasushi Fujio,
Keigo Nishida,
Tadashi Kuroda,
Hisao Hirota,
Keiko Yamauchi-Takihara,
Toshio Hirano,
Issei Komuro,
Naoki Mochizuki
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ABSTRACT: Morphological and biochemical phenotypes of cardiomyocyte hypertrophy are determined by neurohumoral factors. Stimulation of G protein-coupled receptor (GPCR) results in uniform cell enlargement in all directions with an increase in skeletal alpha-actin (alpha-SKA) gene expression, while stimulation of gp130 receptor by interleukin-6 (IL-6)-related cytokines induces longitudinal elongation with no increase in alpha-SKA gene expression. Thus, alpha-SKA is a discriminating marker for hypertrophic phenotypes; however, regulatory mechanisms of alpha-SKA gene expression remain unknown. Here, we clarified the role of SH2-containing protein tyrosine phosphatase 2 (SHP2) in alpha-SKA gene expression. In neonatal rat cardiomyocytes, endothelin-1 (ET-1), a GPCR agonist, but not leukemia inhibitory factor (LIF), an IL-6-related cytokine, induced RhoA activation and promotes alpha-SKA gene expression via RhoA. In contrast, LIF, but not ET-1, induced activation of SHP2 in cardiomyocytes, suggesting that SHP2 might negatively regulate alpha-SKA gene expression downstream of gp130. Therefore, we examined the effect of adenovirus-mediated overexpression of wild-type SHP2 (SHP2(WT)), dominant-negative SHP2 (SHP2(C/S)), or beta-galactosidase (beta-gal), on alpha-SKA gene expression. LIF did not upregulate alpha-SKA mRNA in cardiomyocytes overexpressing either beta-gal or SHP2(WT). In cardiomyocytes overexpressing SHP2(C/S), LIF induced upregulation of alpha-SKA mRNA, which was abrogated by concomitant overexpression of either C3-toxin or dominant-negative RhoA. RhoA was activated after LIF stimulation in the cardiomyocytes overexpressing SHP2(C/S), but not in myocytes overexpressing beta-gal. Furthermore, SHP2 mediates LIF-induced longitudinal elongation of cardiomyocytes via ERK5 activation. Collectively, these findings indicate that SHP2 negatively regulates alpha-SKA expression via RhoA inactivation and suggest that SHP2 implicates ERK5 in cardiomyocyte elongation downstream of gp130.
Journal of Molecular and Cellular Cardiology 03/2010; 49(2):157-64. · 5.17 Impact Factor
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ABSTRACT: Endothelin (ET)-1 has been shown to play a significant pathogenic role in pulmonary arterial hypertension (PAH). However, the pathobiological significance of increased ET-1 concentration after administration of ET receptor antagonist in patients with PAH has not yet been fully examined.
In 16 PAH patients, plasma ET-1 concentration was measured at 0, 1, 3, 6, and 24h after a single 62.5mg dose of bosentan, a dual ET receptor antagonist, and the peak and 24-h change in ET-1 concentration from baseline were examined. The severity of PAH was evaluated by hemodynamic parameters, 6-min walk distance, New York Heart Association (NYHA) functional class, and brain natriuretic peptide (BNP).
Plasma ET-1 concentration significantly increased from 1.93+/-0.12 to 3.36+/-0.18 pg/ml after bosentan administration in PAH patients (p<0.01). The peak-to-baseline ratio of ET-1 concentration after bosentan administration showed a significant positive correlation with baseline ET-1 concentration (p<0.05). After 4-week bosentan administration, NYHA functional class improved in 7 patients but was not changed in 9 patients. The optimal cut-off point of % change of ET-1 concentration at 24h for discriminating the two groups was 30%. According to this cut-off point, patients were divided into the higher (n=7) and the lower (n=9) groups. NYHA functional class did not change in the lower group, but significantly improved (p<0.01) in the higher group after 4-week bosentan administration. In addition, plasma BNP levels significantly decreased from baseline in the higher group compared with those in the lower group after 12-week bosentan administration (-44+/-11% vs. 7+/-20%, p<0.05).
Although the population in this study is small and heterogeneous, measurement of plasma ET-1 concentration after bosentan administration might predict the responsiveness to bosentan treatment, and be useful in the determination of effective therapy in treatment of PAH patients.
Journal of Cardiology 06/2009; 53(3):374-80. · 1.28 Impact Factor
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ABSTRACT: Prostacyclin (PGI2) and its analogues exert cardioprotective effects via the rhodopsin type membrane PGI2 receptor, IP. Peroxisome proliferator-activated receptor (PPAR) delta is a nuclear receptor abundantly expressed in cardiomyocytes and plays a pivotal role in maintaining constitutive mitochondrial fatty acid beta-oxidation (FAO). Recently, a novel signaling pathway of PGI2 via PPARdelta has been demonstrated in non-cardiac tissues. We therefore examined whether carbacyclin (cPGI2), a PGI2 analogue, up-regulates transcriptional expression of carnitine palmitoyltransferase-1 (CPT-1), the rate-limiting enzyme in mitochondrial FAO, via PPARdelta in cardiomyocytes. Intraperitoneal injection of cPGI2 increased CPT-1 mRNA expression in murine hearts. Transcriptional activity was evaluated by PPAR responsive element (PPRE)-luciferase reporter gene assay in cultured neonatal rat cardiomyocytes. CPT-1 mRNA expression and PPRE promoter activity were significantly increased by cPGI2 in a concentration-dependent manner, where PPRE has been mapped to the promoter region of the CPT-1 gene. Moreover, the elevation of CPT-1 mRNA expression and PPRE promoter activity by cPGI2 was not abolished by H-89, a potent protein kinase A inhibitor, but was significantly inhibited in cardiomyocytes over-expressing a dominant-negative type of PPARdelta. Furthermore, electrophoretic mobility shift assays demonstrated that binding of PPARdelta to PPRE in the CPT-1 gene promoter is enhanced in response to cPGI2 stimulation. In addition, down-regulation of CPT-1 mRNA expression in cardiomyocytes subjected to hypoxia was attenuated by cPGI2. These results indicate that cPGI2 induces CPT-1 mRNA expression through PPARdelta, independent of the IP receptor signaling pathway, suggesting a possibility that cPGI2 modulates cardiac energy metabolism by activating FAO via PPARdelta.
Journal of Molecular and Cellular Cardiology 08/2007; 43(1):54-62. · 5.17 Impact Factor
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ABSTRACT: Pulmonary arterial hypertension (PAH) is a progressive disease with high mortality. An orally active dual endothelin (ET) receptor antagonist, bosentan, has been reported to improve exercise capacity and survival in patients with PAH. Plasma ET-1 concentration is known to be increased in PAH patients; however, the effect of bosentan on ET-1 concentration has not yet been investigated.
The concentration of ET-1 after bosentan administration was examined in 7 PAH patients, including 2 primary and 5 secondary cases. They were clinically assessed by pulmonary artery pressure (PAP), 6-min walk distance (6MWD) and plasma brain natriuretic peptide (BNP) concentration. Baseline ET-1 concentration was significantly higher in patients with PAH than in normal individuals (2.19+/-0.71 pg/ml vs 1.45+/-0.10 pg/ml, p<0.05) and was significantly correlated with 6MWD and BNP. A single dose of 62.5 mg bosentan in patients with PAH significantly increased plasma ET-1 concentration to 2.04 times the basal concentration (p<0.01) with a peak at 8.1 h. The peak to base ratio of ET-1 after bosentan administration correlated negatively with severity of PAH as assessed by PAP.
The present study is the first study to show that bosentan administration increases plasma ET-1 in patients with PAH. The response of plasma ET-1 to bosentan administration might be useful for determining the severity of PAH.
Circulation Journal 03/2007; 71(3):367-9. · 3.77 Impact Factor
