Nobutaka Koibuchi

The University of Tokyo, Tōkyō, Japan

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Publications (23)121.12 Total impact

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    ABSTRACT: The γ-secretase complex (which contains presenilins, nicastrin, anterior pharynx defective-1, and presenilin enhancer-2) cleaves type I transmembrane proteins, including Notch and amyloid precursor protein. Dysregulated γ-secretase activity has been implicated in the pathogenesis of Alzheimer's disease, stroke, atherosclerosis, and cancer. Tight regulation of γ-secretase activity is required for normal physiology. Here, we isolated HIG1 (hypoxia inducible gene 1, domain member 1A) from a functional screen of γ-secretase inhibitory genes. HIG1 was highly expressed in the brain. Interestingly, HIG1 was localized to the mitochondria and was directly bound to γ-secretase components on the mitochondrial membrane in SK-N-SH neuroblastoma cells. Overexpresssion of HIG1 attenuated hypoxia-induced γ-secretase activation on the mitochondrial membrane and the accumulation of intracellular amyloid β. This accumulation was accompanied by hypoxia-induced mitochondrial dysfunction. The latter half domain of HIG1 was required for binding to the γ-secretase complex and suppression of γ-secretase activity. Moreover, depletion of HIG1 increased γ-secretase activation and enhanced hypoxia-induced mitochondrial dysfunction. In summary, HIG1 is a novel modulator of the mitochondrial γ-secretase complex, and may play a role in the maintenance of normal mitochondrial function.
    The FASEB Journal 02/2012; 26(6):2306-17. DOI:10.1096/fj.11-196063 · 5.48 Impact Factor
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    ABSTRACT: Although periostin, an extracellular matrix glycoprotein, plays pivotal roles in survival, migration, and regeneration in various cells, its expression and function in the brain are still unknown. Here, we investigated the expression and role of periostin in the ischemic brain. Expression of full-length periostin (periostin 1 [Pn1]) and its splicing variant lacking exon 17 (periostin 2 [Pn2]) was examined by real-time reverse transcription polymerase chain reaction (RT-PCR), Western blotting, and immunohistochemical staining in male C57BL6/J mice. The actions of periostin were examined in adult primary neuronal culture and in a transient middle cerebral artery occlusion (tMCAo) model. Expression of Pn2, but not of Pn1, mRNA was markedly changed after tMCAo. Pn2 mRNA was decreased in the ischemic core at 3 hours after ischemia. At 24 hours, Pn2 mRNA was significantly increased in both the peri-ischemic and ischemic regions. Periostin was mainly observed in neurons in normal brain. However, neuronal expression of periostin was decreased temporarily in the ischemic region, but increased in astrocytes and around endothelial cells at 24 hours after tMCAo. Of importance, intracerebroventricular injection of Pn2 resulted in a significant reduction in infarct volume at 24 hours after tMCAo associated with phosphorylation of Akt. Also, the Pn2-treated mice survived longer until 1 week after tMCAo. Pn2 significantly inhibited neuronal death under hypoxia and stimulated neurite outgrowth. Here, we demonstrated that periostin was expressed in the brain, and exogenous Pn2 exhibited neuroprotective effects and accelerated neurite outgrowth. Additional studies on periostin may provide new insights into the treatment of ischemic stroke.
    Stroke 02/2012; 43(4):1108-14. DOI:10.1161/STROKEAHA.111.636662 · 6.02 Impact Factor
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    ABSTRACT: Periostin (PN), a secreted adhesion-related protein expressed in the periosteum and periodontal ligaments, acts as a critical regulator of the formation and maintenance of bone and teeth, and also plays an important role in tumorigenesis. Although PN is highly expressed in various types of human cancers, its function is still unclear. In this study, we focused on the exon 17 region of PN, which is alternatively spliced out. To investigate the function of full-length PN with exon 17, we produced a neutralizing antibody (PN1-Ab) against the peptide encoded by exon 17. In vivo, administration of PN1-Ab significantly inhibited the growth of primary tumors as well as metastatic tumors, associated with prevention of bone destruction, resulting in increased survival of mice. Consistent with in vivo data, the present in vitro study demonstrated that addition of full-length PN significantly inhibited cell adhesion and detached adherent cells, while PN1-Ab inhibited the action of PN in a dose-dependent manner. In addition, PN1-Ab significantly inhibited the proliferation, migration and invasion of 4T1 mouse breast cancer cells, which produced PN. Interestingly, PN1-Ab also inhibited the differentiation of osteoclasts. Overall, the present study demonstrated that PN plays a pivotal role in the progression and metastasis of breast cancer. Since administration of PN1-Ab prolonged cell survival through inhibition of the progression and metastasis of 4T1 cells, further development of the PN1-Ab such as generation of a humanized antibody may provide a new therapeutic agent against breast cancer.
    International Journal of Molecular Medicine 08/2011; 28(2):181-6. DOI:10.3892/ijmm.2011.712 · 1.88 Impact Factor
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    ABSTRACT: Both angiotensin II (Ang II) and transforming growth factor (TGF)-β1 are thought to be involved in the progression of chronic kidney disease. In contrast, hepatocyte growth factor (HGF) counteracts the actions of Ang II and TGF-β1. Therefore, in this study, we investigated the molecular mechanisms of how HGF antagonizes the Ang II-TGF-β axis in renal cells. In cultured human mesangial cells, TGF-β1 increased angiotensin type 1 receptor (AT(1)R) mRNA, mainly dependent on the Akt/phosphatidylinositol 3-kinase signaling pathway. Furthermore, TGF-β1 decreased the expression and phosphatase activity of phosphatase and tensin homolog, deleted on chromosome 10 (PTEN), a negative regulator of the phosphatidylinositol 3-kinase/Akt pathway. These data revealed positive feedback of the Ang II-TGF-β pathway, because Ang II increased TGF-β expression. In contrast, HGF significantly attenuated the increase in AT(1)R gene expression, and inhibited the decrease in PTEN induced by TGF-β1. Of importance, a PTEN-specific inhibitor significantly attenuated the reduction in TGF-β1-induced AT(1)R expression by HGF. These data suggest that HGF attenuated TGF-β1-induced AT(1)R expression through the PTEN/Akt pathway. To investigate this hypothesis, we performed in vivo experiments in mice with increased circulating levels of HGF produced by transgenically expressing HGF under control of a cardiac-specific transgene (HGF-Tg). In HGF-Tg mice, renal injury and fibrosis were significantly decreased, associated with reduction in AT(1)R expression and increase in PTEN after Ang II infusion, as compared with control mice. Moreover, these renal protective effects were abrogated by a neutralizing antibody against HGF. Thus, the present study demonstrated that HGF counteracts the vicious cycle of Ang II-TGF-β1-AT(1)R, mediating the inhibition of PTEN.
    Hypertension 06/2011; 58(2):190-6. DOI:10.1161/HYPERTENSIONAHA.111.173013 · 7.63 Impact Factor
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    ABSTRACT: Hepatocyte growth factor (HGF) is a mesenchyme-derived pleiotropic factor which regulates cell growth, cell motility, and morphogenesis of various types of cells, and is thus considered a humoral mediator for morphogenic tissue interactions. Although HGF was originally identified as a potent mitogen for hepatocytes, it has also been identified as a member of angiogenic growth factors. Interestingly, the presence of its specific receptor, c-met, is observed in vascular cells and cardiac myocytes. On the other hand, recently, we demonstrated that HGF plasmid DNA transfer significantly improves the size of ulcer in patients with peripheral artery disease (PAD) at Phase III clinical trial, while vascular endothelial growth factor (VEGF) gene therapies for PAD at Phase III have not been succeeded yet. To further investigate this difference between HGF and VEGF, we showed that HGF but not VEGF improves the senescence EPC against oxidative stress through the inhibition of rac1. Moreover, we reported that HGF promotes SHIP-2 translocation from epithelial growth factor receptor (EGFR) to c-Met, and it would protect oxidative stress through EGFR degradation. By this anti-oxidative and anti-senescence effects of HGF would maintain the vessel so long in patients with PAD who receive much oxidative stress in real world. In this report, we discuss a potential therapeutic strategy using HGF in cardiovascular diseases.
    Current Signal Transduction Therapy 04/2011; 6(2):221-227. DOI:10.2174/157436211795660016 · 0.45 Impact Factor
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    ABSTRACT: The progression of chronic kidney disease (CKD) is characterized by the persistent accumulation of extracellular matrix. Especially, α-SMA-positive myofibroblasts producing large amounts of TGF-β1 are considered to play a key role in interstitial fibrosis. Although hepatocyte growth factor (HGF) improved renal fibrosis in various models, the molecular mechanisms involved are not yet fully understood. In this study, the molecular mechanisms of the inhibition of fibrosis by HGF was examined using HGF transgenic mice (HGF-Tg) with angiotensin II (Ang II) infusion in 4 weeks models. HGF-Tg mice showed significantly decreased Ang II-induced renal fibrosis and lesser numbers of interstitial myofibroblasts, whereas the antifibrotic effect of HGF was abrogated using HGF-neutralizing antibody. The antifibrotic action in HGF-Tg mice was concordant with a decrease in TGF- β1, collagen type I and IV mRNA expression and an increase in MMP-2 and MMP-9 expression. Furthermore, HGF-Tg mice treated with Ang II showed apoptosis of myofibroblasts. To further investigate the antifibrotic effect of HGF, cultured human mesangial cells were used. HGF induced apoptosis of myofibroblast. Inhibition of the FAK-ERK-MMP signaling cascade by specific inhibitor or siRNA significantly decreased HGF-induced myofibroblast apoptosis. The present study demonstrates that the increase in metalloproteinases through FAK-ERK signaling by HGF promotes myofibroblast apoptosis. Activation of metalloproteinases by HGF in the fibrotic kidney might be considered to attenuate the progression of CKD.
    Journal of Hypertension 12/2010; 28(12):2454-61. DOI:10.1097/HJH.0b013e32833e4149 · 4.22 Impact Factor
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    ABSTRACT: To clarify the impact of breast cancer resistance protein 1 (BCRP1)/ATP-binding cassette transporter subfamily G member 2 (ABCG2) expression on cardiac repair after myocardial infarction (MI). The ATP-binding cassette transporter BCRP1/ABCG2 is expressed in various organs, including the heart, and may regulate several tissue defense mechanisms. BCRP1/ABCG2 was mainly expressed in endothelial cells of microvessels in the heart. MI was induced in 8- to 12-week-old wild-type (WT) and Bcrp1/Abcg2 knockout (KO) mice by ligating the left anterior descending artery. At 28 days after MI, the survival rate was significantly lower in KO mice than in WT mice because of cardiac rupture. Echocardiographic, hemodynamic, and histological assessments showed that ventricular remodeling was more deteriorated in KO than in WT mice. Capillary, myofibroblast, and macrophage densities in the peri-infarction area at 5 days after MI were significantly reduced in KO compared with WT mice. In vitro experiments demonstrated that inhibition of BCRP1/ABCG2 resulted in accumulation of intracellular protoporphyrin IX and impaired survival of microvascular endothelial cells under oxidative stress. Moreover, BCRP1/ABCG2 inhibition impaired migration and tube formation of endothelial cells. BCRP1/ABCG2 plays a pivotal role in cardiac repair after MI via modulation of microvascular endothelial cell survival and function.
    Arteriosclerosis Thrombosis and Vascular Biology 11/2010; 30(11):2128-35. DOI:10.1161/ATVBAHA.110.211755 · 5.53 Impact Factor
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    Tokumitsu Watanabe, Nobutaka Koibuchi, Michael T Chin
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    ABSTRACT: The transcription factor CHF1/Hey2 has been implicated in a variety of cardiovascular developmental abnormalities including ventricular septal defect, deformed valves and cardiomyopathy. To date, its role in coronary vascular development remains unknown. We have found that KO mice developed coronary vascular abnormalities accompanied by a thin compact ventricular myocardium but grossly normal epicardial and subepicardial layers. The coronary vascular anomalies included dysmorphic large vessels and abnormal vascular structures at E15.5 and reduced recruitment of vascular smooth muscle cells into the coronary arteries at E18.5. In E18.5 KO hearts, the abnormal coronary veins demonstrated reduced expression of markers for vein identity. Whole-mount PECAM staining of the E18.5 KO hearts indicated that EphB4 negative vein networks were increased in the surface layers of the myocardium compared to those of the controls. CHF1/Hey2 was not expressed in the epicardium in vivo, and cultured epicardium-derived cells isolated from E12.5 wild-type mice showed no CHF1/Hey2 expression. KO mice with a myocardially expressed CHF1/Hey2 transgene partially rescued the vascular phenotypes. Quantitative RT-PCR analysis demonstrated that PDGF and Angiopoietin/Tie2 signaling pathways are altered in E12.5 KO hearts. Taken together, global CHF1/Hey2 deficiency caused impaired vascular formation, the reduced recruitment of vascular smooth muscle cells into coronary arteries and abnormally remodeled vein networks. These findings suggest that CHF1/Hey2 regulates the later steps of coronary vascular development in both a myocardial-dependent, non-cell autonomous fashion and likely a vascular cell-specific effect as well.
    Mechanisms of development 09/2010; 127(9-12):418-27. DOI:10.1016/j.mod.2010.07.001 · 2.24 Impact Factor
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    ABSTRACT: Arterial calcification and osteoporosis are associated in postmenopausal women. RANK (the receptor activator of nuclear factor kappaB), RANKL (RANK ligand), and osteoprotegerin are key proteins in bone metabolism and have been found at the site of aortic calcification. The role of these proteins in vasculature, as well as the contribution of estrogen to vascular calcification, is poorly understood. To clarify the mechanism of RANKL system to vascular calcification in the context of estrogen deficiency. RANKL induced the calcification inducer bone morphogenetic protein-2 by human aortic endothelial cells (HAECs) and decreased the calcification inhibitor matrix Gla protein (MGP) in human aortic smooth muscle cells (HASMCs), as quantified by real-time PCR and Western blot analysis. RANKL also induced bone-related gene mRNA expression and calcium deposition (Alizarin red staining) followed by the osteogenic differentiation of HASMCs. Estrogen inhibited RANKL signaling in HAECs and HASMCs mainly through estrogen receptor alpha. Apolipoprotein E-deficient mice fed with Western high-fat diet for 3 months presented atherosclerotic calcification (Oil red and Alizarin red staining) and osteoporosis (microcomputed tomographic analysis) after ovariectomy and increased expression of RANKL, RANK, and osteopontin in atherosclerotic lesion, as detected by in situ hybridization. Estrogen replacement inhibited osteoporosis and the bone morphogenetic protein osteogenic pathway in aorta by decreasing phosphorylation of smad-1/5/8 and increasing MGP mRNA expression. RANKL contributes to vascular calcification by regulating bone morphogenetic protein-2 and MGP expression, as well as bone-related proteins, and is counteracted by estrogen in a receptor-dependent manner.
    Circulation Research 08/2010; 107(4):466-75. DOI:10.1161/CIRCRESAHA.110.216846 · 11.09 Impact Factor
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    ABSTRACT: Neointimal hyperplasia contributes to atherosclerosis and restenosis after percutaneous coronary intervention. Vascular injury in each of these conditions results in the release of mitogenic growth factors and hormones that contribute to pathological vascular smooth muscle cell growth and inflammation. Hepatocyte growth factor (HGF) is known as an antiinflammatory growth factor, although it is downregulated in injured tissue. However, the precise mechanism how HGF reduces inflammation is unclear. To elucidate the mechanism how HGF and its receptor c-Met reduces angiotensin II (Ang II)-induced inflammation. HGF reduced Ang II-induced vascular smooth muscle cell growth and inflammation by controlling translocation of SHIP2 (Src homology domain 2-containing inositol 5'-phosphatase 2), which led to Ang II-dependent degradation of epithelial growth factor receptor. Moreover, the present study also revealed a preventive effect of HGF on atherosclerotic change in an Ang II infusion and cuff HGF transgenic mouse model. These data suggest that the HGF/c-Met system might regulate extrinsic factor signaling that maintains the homeostasis of organs.
    Circulation Research 09/2009; 105(7):667-75, 13 p following 675. DOI:10.1161/CIRCRESAHA.109.202713 · 11.09 Impact Factor
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    ABSTRACT: Epithelial-mesenchymal transition (EMT) confers destabilization of cell-cell adhesion and cell motility required for morphogenesis or cancer metastasis. Here we report that zyxin, a focal adhesion-associated LIM protein, is essential for actin reorganization for cell migration in TGF-beta1-induced EMT in normal murine mammary gland (NMuMG) cells. TGF-beta1 induced the relocation of zyxin from focal adhesions to actin fibers. In addition, TGF-beta1 up-regulated zyxin via a transcription factor, Twist1. Depletion of either zyxin or Twist1 abrogated the TGF-beta1-dependent EMT, including enhanced cell motility and actin reorganization, indicating the TGF-beta1-Twist1-zyxin signal for EMT. Both zyxin and Twist1 were predominantly expressed in the cardiac atrioventricular canal (AVC) that undergoes EMT during heart development. We further performed ex vivo AVC explant assay and revealed that zyxin was required for the reorganization of actin fibers and migration of the endocardial cells. Thus, zyxin reorganizes actin fibers and enhances cell motility in response to TGF-beta1, thereby regulating EMT.
    Molecular biology of the cell 06/2009; 20(13):3115-24. DOI:10.1091/mbc.E09-01-0046 · 5.98 Impact Factor
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    ABSTRACT: Although both hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) are potent angiogenic growth factors in animal models of ischemia, their characteristics are not the same in animal experiments and clinical trials. To elucidate the discrepancy between HGF and VEGF, we compared the effects of HGF and VEGF on endothelial progenitor cells under angiotensin II stimulation, which is a well-known risk factor for atherosclerosis. Here, we demonstrated that HGF, but not VEGF, attenuated angiotensin II-induced senescence of endothelial progenitor cells through a reduction of oxidative stress by inhibition of the phosphatidylinositol-3,4,5-triphosphate/rac1 pathway. Potent induction of neovascularization of endothelial progenitor cells by HGF, but not VEGF, under angiotensin II was also confirmed by in vivo experiments using several models, including HGF transgenic mice.
    Hypertension 01/2009; 53(1):77-82. DOI:10.1161/HYPERTENSIONAHA.108.120725 · 7.63 Impact Factor
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    ABSTRACT: The renin-angiotensin (Ang) system plays a critical role in the regulation of blood pressure, body fluid, electrolyte homeostasis, and organ remodeling under physiological and pathological conditions. The carboxypeptidase ACE2 is a homologue of angiotensin-converting enzyme (ACE). It has been reported that ACE2-deficient mice develop cardiac dysfunction with increased plasma levels of Ang II. However, the molecular mechanism by which genetic disruption of ACE2 results in heart dysfunction is not fully understood. Here, we generated mice with targeted disruption of the Ace2 gene and compared the cardiovascular function of ACE2(-/y) mice with that of their wild-type littermates. ACE2-deficient mice were viable and fertile and lacked any gross structural abnormalities. Echocardiographic study detected no functional difference between ACE2(-/y) and wild-type mice at 12 weeks of age. Twenty-four-week-old ACE2(-/y) mice displayed significantly enlarged hearts with impaired systolic and diastolic function. The Ang II level was elevated in the plasma and heart of ACE2(-/y) mice. Pharmacological blockade of Ang II type 1 receptor (AT1) with candesartan attenuated the development of cardiac dysfunction in ACE2(-/y) mice. These results suggest that enhanced stimulation of AT1 may play a role in the development of cardiac dysfunction observed in ACE2-deficient mice.
    Hypertension Research 11/2008; 31(10):1953-61. DOI:10.1291/hypres.31.1953 · 2.94 Impact Factor
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    ABSTRACT: Although the pathophysiology of post-angioplasty restenosis has been extensively studied in extracranial arteries using transluminal vascular injury model in rodents, it is still not well known in the intracranial arteries, which have quite different structures from extracranial arteries. Here, we examined whether 1-min placement of modified intraluminal suture could induce an injury in the internal carotid artery (ICA) in rats and observed temporal profile of histological change after the injury. HE staining showed that the injured intracranial ICA was dilated, while the media was markedly thinned at 1 day after injury. The internal elastic lamina was not observed, and the media contained few cells. At 1 week after injury, a thin layer of neointimal hyperplasia was observed on the luminal side of the internal elastic lamina. Neointimal hyperplasia developed until at least 4 weeks after injury. Morphometric analysis demonstrated that the healing process of the injury was related to arterial remodeling. Immunohistochemical staining for alpha-smooth muscle actin and electron microscopic analysis showed that the neointima was composed of smooth muscle cells. Re-endothelialization was observed from 1 to 4 weeks after injury by immunohistochemical staining for von Willebrand's factor and electron microscopic analysis. Vascular endothelial growth factor was expressed in neointima on days 7 and 14. Interestingly, superoxide anion was not increased in injured arteries on day 3, when the infiltration of macrophages was intensive, but increased on day 7, when infiltrating macrophages almost disappeared. These findings might shed new light on pathophysiology of post-angioplasty restenosis in intracranial arteries.
    Journal of Neuroscience Methods 09/2008; 175(2):187-95. DOI:10.1016/j.jneumeth.2008.08.018 · 1.96 Impact Factor
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    ABSTRACT: During heart development, various signaling cascades are tightly regulated in a stage- and region-dependent manner. Vascular endothelial growth factor (VEGF) is one of the important molecules required for both vascular development and cardiac morphogenesis. VEGF receptors are present in the embryonic heart, so we focused on heart formation in VEGF-over-expressing Xenopus embryos. Over-expression of VEGF(170) caused disorganized vessels, while the expression of an endothelial marker, Tie-2, was increased. The embryo's heart was distinctly larger than that of control, and showed abnormal morphology. Histological analysis of these embryos showed failure of heart looping. In situ hybridization with Hand-1, which controls intrinsic morphogenetic pathways, revealed that the expression level of Hand-1 was decreased in the heart region. These results suggest that increased VEGF(170) levels disturb Hand-1 expression in the region required for normal heart morphogenesis. VEGF expression level may be important in heart morphology during embryonic development.
    Biochemical and Biophysical Research Communications 09/2007; 359(3):431-7. DOI:10.1016/j.bbrc.2007.05.140 · 2.28 Impact Factor
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    ABSTRACT: Our previous study demonstrated that periostin, an extracellular matrix protein, plays an important role in left ventricular remodeling through the inhibition of cell-cell interactions. Because the gene regulation of periostin has not yet been examined, we focused on the effects of angiotensin (Ang) II and mechanical stretch, because Ang II and mechanical stretch are related to cardiac remodeling after myocardial infarction. First, we examined the effects of Ang II on periostin in myocytes and fibroblasts in vitro. Ang II significantly increased periostin through phosphatidylinositol 3-kinase, c-Jun N-terminal kinase, p38, and extracellular signal-regulated kinase 1/2 pathways in myocytes and fibroblasts (P<0.05). On the other hand, mechanical stretch also significantly increased periostin expression (P<0.05). This increase was inhibited partially, but significantly, by an Ang II receptor blocker, valsartan, and inhibited almost completely by valsartan with the neutralization antibodies for transforming growth factor-beta and platelet-derived growth factor-BB (P<0.05). Therefore, we further examined periostin expression in vivo. Periostin expression was significantly increased in infarcted myocardium (P<0.05), and treatment with valsartan significantly attenuated it at 4 weeks after myocardial infarction (P<0.05), accompanied by a significant improvement in cardiac dysfunction (P<0.05). Overall, the present study demonstrated that Ang II, as well as mechanical stretch, stimulated periostin expression in both cardiac myocytes and fibroblasts, whereas valsartan significantly attenuated the increase in periostin expression. The inhibition of periostin by valsartan might especially contribute to its beneficial effects on cardiac remodeling after myocardial infarction.
    Hypertension 07/2007; 49(6):1409-14. DOI:10.1161/HYPERTENSIONAHA.106.080994 · 7.63 Impact Factor
  • Nobutaka Koibuchi, Michael T Chin
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    ABSTRACT: We previously reported that mice lacking the hairy-related basic helix-loop-helix (bHLH) transcription factor CHF1/Hey2 develop a thin-walled left ventricle. To explore the basis for this phenotype, we examined regional gene expression patterns in the developing myocardium. We found that atrial natriuretic factor (ANF), which is normally expressed in the atria and trabeculae and is restricted from the developing compact myocardium beginning at embryonic day 13.5, is persistently expressed in the left ventricular compact myocardium of the knockout animals. We also examined the expression pattern of the T-box transcription factor Tbx5, a known regulator of ANF, and an additional Tbx5-dependent gene, connexin 40 (Cx40), both of which share a similar expression pattern to ANF during development. Tbx5 and Cx40 were similarly expressed ectopically in the compact myocardium of the CHF1/Hey2 knockout mouse. The atrial contractile genes mlc1a and mlc2a were also expressed ectopically in the left ventricular compact myocardium, providing evidence for a general dysregulation of atrial gene expression. Crossing of a myocardial-specific CHF1/Hey2 transgenic mouse with the knockouts led to rescue of the thin-walled myocardial phenotype and restoration of the normal patterns of gene expression. Myocardial cell proliferation, which has been shown previously to be suppressed by Tbx5, was also decreased in the knockout mice and rescued by the transgene. Our findings suggest that CHF1/Hey2 suppresses atrial identity in the left ventricular compact myocardium, facilitates myocardial proliferation by suppressing Tbx5, and thereby promotes proper ventricular myocardial maturation.
    Circulation Research 04/2007; 100(6):850-5. DOI:10.1161/ · 11.09 Impact Factor
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    ABSTRACT: Vascular endothelial growth factor (VEGF) is known to play an essential role in vascular development. We have overexpressed VEGF122 or VEGF170, which are equivalent to mouse VEGF120 and VEGF164, in developing Xenopus embryos. Overexpression of VEGF170 but not VEGF122 demonstrated an absence of expression of hematopoietic markers alpha-globin and GATA-1 but only in the posterior portion of the blood island. Interestingly, strong signals of endothelial markers, msr, fli-1, and tie-2, were detectable in those regions, instead of hematopoietic markers. These results suggested both that injection of VEGF170 resulted in disturbance of vasculogenesis in the posterior portion of the blood island, with excessive production of endothelial cells at the expense of blood cells, and that the anterior and posterior portions of the VBI may have distinct characteristics.
    Biochemical and Biophysical Research Communications 06/2006; 344(1):339-45. DOI:10.1016/j.bbrc.2006.03.140 · 2.28 Impact Factor
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    ABSTRACT: CHF1/Hey2 null mice generated in different laboratories have discrepant cardiovascular phenotypes. To determine the effect of genetic background on phenotype, we backcrossed our knockout strain more than eight generations to the inbred strains BALB/c and C57BL/6. Knockout mice on these backgrounds showed disparate phenotypes. Mice on both backgrounds demonstrated ventricular septal defects (VSDs), tricuspid stenosis and mitral valve thickening, but at varying frequencies, suggesting a general defect in endocardial cushion remodeling. Additional defects seen exclusively on the C57BL/6 background included biventricular wall thinning and left ventricular enlargement, implying a more severe myocardial defect than previously observed. In addition, aortas and pulmonary arteries from these null mice had thinner walls. Intercrossing of the CHF1/Hey2 null mice on a C57BL/6 background with a C57BL/6 MLC2v-CHF1/Hey2 transgenic line overexpressing CHF1/Hey2 in the atrial and ventricular myocardium also rescued the VSD and myocardial phenotypes, but did not affect vascular wall thickness. Our results indicate that CHF1/Hey2 provides an important myocardial signal to the endocardial cushion for proper septation and valve formation and also plays an important role in maturation of the myocardium and vasculature.
    Journal of Molecular and Cellular Cardiology 03/2006; 40(2):267-73. DOI:10.1016/j.yjmcc.2005.09.006 · 5.22 Impact Factor

Publication Stats

414 Citations
121.12 Total Impact Points


  • 2008–2012
    • The University of Tokyo
      • Faculty & Graduate School of Medicine
      Tōkyō, Japan
  • 2011
    • Kumamoto University
      • Department of Pharmacology and Molecular Therapeutics
      Kumamoto, Kumamoto, Japan
  • 2007
    • Harvard University
      Cambridge, Massachusetts, United States
  • 2006–2007
    • Osaka University
      • Department of Clinical Gene Therapy
      Suika, Ōsaka, Japan
    • Harvard Medical School
      • Department of Medicine
      Boston, Massachusetts, United States