HOME > Members > GCOE Organizing Members > Toyoaki Murohara MD, PhD


Toyoaki Murohara MD, PhDProfessor, Department of Cardiology, Nagoya University Graduate School of Medicine


Specialized field

Cardiovascular Medicine, Vascular Biology, Regenerative Medicine

Career Summary

Education

Kumamoto University, School of Medicine, M.D. 1985 Kumamoto University, Graduate School of Medicine, Ph.D. 1992 Jefferson Medical College, Dept. of Physiology Post. Doc. 1996 Tufts University, St. Elizabeth’s Medical Center, Post. Doc. 1997

Professional Experience

1985-1987 Intern
Kumamoto University School of Medicine
Division of Cardiology, Kumamoto, Japan
1987-1988 Resident
National Kumamoto Hospital
Department of Internal medicine, Kumamoto, Japan
1992-1993 Fellow
Saiseikai Kumamoto Hospital
Division of Cardiology, Kumamoto Japan
1993-1996 Postdoctoral Fellow
Thomas Jefferson University
Department of Physiology, Philadelphia, PA
1996-1997 Postdoctoral Fellow
Tufts University School of Medicine
St Elizabeth’s Medical Center
Department of Cardiology, Boston, MA
1997-2002 Assistant Professor
Kurume University School of Medicine
The Cardiovascular Research Institute, and
Department of Internal Medicine III
2002-current Professor
Nagoya University Graduate School of Medicine
Department of Cardiology

Research Theme

The role of Girdin in regulating vascular homeostasis

Research Summary

Girdin/GIV regulates transendothelial permeability by controlling VE-cadherin trafficking through the small GTPase, R-Ras.

Background
Vascular permeability is regulated by the intercellular junction organization of endothelial cells, the dysfunction of which is implicated in numerous pathological conditions. However, the molecular mechanisms in regard to how endothelial cells regulate intercellular junctions in response to extracellular signals have so far remained elusive. Endothelial cells have at least two distinct adhesive junctional regions at intercellular junctions, which are designated adherens junctions (AJs), and tight junctions (TJs). AJs and TJs have different roles in the maintenance of vascular barrier function. It is generally accepted that AJs maintain the architectural integrity of the endothelium, whereas TJs are secondary and are enriched only in the brain microvasculature composing the blood-brain barrier. VE-cadherin is a member of the cadherin superfamily, whose expression is exclusively restricted to endothelial cells. Cis- and trans- homophilic adhesion of VE-cadherin is a crucial factor to construct AJs. The cytoplasmic domain of VE-cadherin is anchored to actin cytoskeleton by a large set of actin binding proteins, including catenins, to stabilize cell adhesion. Various stimuli such as histamine, thrombin, tumor necrosis factor, platelet activating factor, and vascular endothelial growth factor (VEGF) increase vascular permeability by inducing endothelial cell contractility and/or modulating the functions of VE-cadherin and its binding proteins. AJs are dynamic structures that undergo persistent remodeling not only in cells exposed to agents increasing permeability, but also in confluent and resting cells. One mechanism for the remodeling of AJs involves continuous trafficking, which includes endocytosis and recycling of VE-cadherin that occurs at AJs. This study identified that Girdin (girder of actin filaments; also termed GIV), an Akt substrate functioning in post-natal angiogenesis, was expressed in mature endothelial cells, where it regulated VE-cadherin trafficking to maintain vascular integrity.

Result and Discussion
Girdin depletion abrogated VEGF-induced VE-cadherin endocytosis and the disassembly of adherens junctions in a monolayer of endothelial cells, thus leading to a significant decrease in the permeability (A, B, and C). Moreover, we found that Girdin forms a complex with VE-cadherin and clathrin heavy chain in VEGF stimulated HUVECs (data not shown). R-Ras, a member of the Ras family GTPase, is a master regulator of transendothelial permeability, which is activated downstream of VEGF stimulation. Activated R-Ras formed a complex with Girdin and regulates the interaction of Girdin with VE-cadherin in endothelial cells (D, E, F, and G). In addition, Girdin was colocalized at the peripheral actin fibers in the cell-cell contact sites in a static monolayer of HUVECs, which was abrogated in R-Ras depleted cells (H). These results suggest that R-Ras regulates the interaction between Girdin and VE-cadherin-containing vesicles upon VEGF stimulation, which may be important for determining their subcellular localization and intracellular trafficking of VE-cadherin containing vesicles. The increased permeability mediated by the loss of R-Ras was rescued by Girdin depletion (I), thus suggesting that Girdin may function in VE-cadherin endocytosis partially independent of R-Ras. These results show that Girdin regulates transendothelial permeability in synergy with R-Ras and VE-cadherin in mature endothelial cells.
Figure J shows the working model how R-Ras and Girdin regulate the intracellular trafficking of VE-cadherin. VEGF stimulation activates R-Ras, which binds to Girdin and mediates the interaction of Girdin with VE-cadherin on intracellular vesicles such as endosomes around the cell-cell contact sites. Although speculative, given the previous study on R-Ras function in the membrane trafficking system, the R-Ras/Girdin complex may promote the recycling of VE-cadherin-containing vesicles to the plasma membrane. The current data also indicate the role of Girdin in endocytosis of VE-cadherin, which seems to be independent of its interaction with R-Ras, leading to the disassembly of AJs and the increase of transendothelial permeability. However, it remains unknown precisely how R-Ras binding to Girdin modulates its function and how Girdin is released from VE-cadherin containing vesicles when R-Ras is inactivated by some GTPase-activating proteins.
Finally, it is important to note that R-Ras and Girdin may be candidate proteins useful for the development and effective treatment for pathological conditions with vascular hyperpermeability such as brain edema after cerebral infarction and diabetic retinopathy. A recent study revealed that the dysregulation of VE-cadherin and disruption of AJs are important initial events in the pathogenesis of the atheroma formed in hyperlipidemia model mice. Therefore, the development of antagonists for R-Ras and Girdin may lead to the development of useful therapeutic modalities for a variety of vascular diseases including atherosclerosis.

Principal Research Achievement

  1. Uchida Y, Takeshita K, Yamamoto K, Kikuchi R, Nakayama T, Nomura M, Cheng XW, Egashira K, Matsushita T, Nakamura H, Murohara T: Stress Augments Insulin Resistance and Prothrombotic State: Role of Visceral Adipose-Derived Monocyte Chemoattractant Protein-1. Diabetes, in press (2012)
  2. Ishii H, Kumada Y, Takahashi H, Toriyama T, Aoyama T, Tanaka M, Yoshikawa D, Hayashi M, Kasuga H, Yasuda Y, Maruyama S, Matsubara T, Matsuo S, Murohara T: Impact of diabetes and glycaemic control on peripheral artery disease in Japanese patients with end-stage renal disease: long-term follow-up study from the beginning of haemodialysis. Diabetologia, in press (2012)
  3. Cheng XW, Shi GP, Kuzuya M, Sasaki T, Okumura K, Murohara T: Role for cysteine protease cathepsins in heart disease: focus on biology and mechanisms with clinical implication. Circulation, 125, 1551-1562 (2012)
  4. Murase T, Hattori T, Ohtake M, Nakashima C, Takatsu M, Murohara T, Nagata K: Effects of Estrogen on Cardiovascular Injury in Ovariectomized Female DahlS.Z-Leprfa/Leprfa Rats as a New Animal Model of Metabolic Syndrome. Hypertension, 59, 694-704 (2012)
  5. Maruyama S, Shibata R, Kikuchi R, Izumiya Y, Rokutanda T, Araki S, Kataoka Y, Ohashi K, Daida H, Kihara S, Ogawa H, Murohara T, Ouchi N: Fat-derived factor omentin stimulates endothelial cell function and ischemia-induced revascularization via endothelial nitric oxide synthase-dependent mechanism. J Biol Chem, 287, 408-417 (2012)
  6. Shimano M, Ouchi N, Nakamura K, van Wijk B, Ohashi K, Asaumi Y, Higuchi A, Pimentel DR, Sam F, Murohara T, van den Hoff MJ, Walsh K: Cardiac myocyte follistatin-like 1 functions to attenuate hypertrophy following pressure overload. Proc Natl Acad Sci U S A, 108, E899-906 (2011)
  7. Cheng XW, Huang Z, Kuzuya M, Okumura K, Murohara T: Cysteine protease cathepsins in atherosclerosis-based vascular disease and its complications. Hypertension, 58, 978-986 (2011)
  8. Enomoto T, Ohashi K, Shibata R, Higuchi A, Maruyama S, Izumiya Y, Walsh K, Murohara T, Ouchi N: Adipolin/C1qdc2/CTRP12 protein functions as an adipokine that improves glucose metabolism. J Biol Chem, 286, 34552-34558 (2011)
  9. Maruyama S, Shibata R, Ohashi K, Ohashi T, Daida H, Walsh K, Murohara T, Ouchi N: Adiponectin ameliorates doxorubicin-induced cardiotoxicity through Akt protein-dependent mechanism. J Biol Chem, 286, 32790-32800 (2011)
  10. Ishii M, Shibata R, Numaguchi Y, Kito T, Suzuki H, Shimizu K, Ito A, Honda H, Murohara T: Enhanced angiogenesis by transplantation of mesenchymal stem cell sheet created by a novel magnetic tissue engineering method. Arterioscler Thromb Vasc Biol, 31, 2210-2215 (2011)
  11. Tsuji Y, Hojo M, Voigt N, El-Armouche A, Inden Y, Murohara T, Dobrev D, Nattel S, Kodama I, Kamiya K: Ca(2+)-related signaling and protein phosphorylation abnormalities play central roles in a new experimental model of electrical storm. Circulation, 123, 2192-2203 (2011)
  12. Cheng XW, Song H, Sasaki T, Hu L, Inoue A, Bando YK, Shi GP, Kuzuya M, Okumura K, Murohara T: Angiotensin type 1 receptor blocker reduces intimal neovascularization and plaque growth in apolipoprotein E-deficient mice. Hypertension, 57, 981-989 (2011)
  13. Miyake H, Maeda K, Asai N, Shibata R, Ichimiya H, Isotani-Sakakibara M, Yamamura Y, Kato K, Enomoto A, Takahashi M, Murohara T: The actin-binding protein Girdin and its Akt-mediated phosphorylation regulate neointima formation after vascular injury. Circ Res, 108, 1170-1179 (2011)
  14. Kikuchi R, Takeshita K, Uchida Y, Kondo M, Cheng XW, Nakayama T, Yamamoto K, Matsushita T, Liao JK, Murohara T: Pitavastatin-induced angiogenesis and arteriogenesis is mediated by Notch1 in a murine hindlimb ischemia model without induction of VEGF. Lab Invest, 91, 691-703 (2011)
  15. Matsushita E, Asai N, Enomoto A, Kawamoto Y, Kato T, Mii S, Maeda K, Shibata R, Hattori S, Hagikura M, Takahashi K, Sokabe M, Murakumo Y, Murohara T, Takahashi M: Protective role of Gipie, a Girdin family protein, in endoplasmic reticulum stress responses in endothelial cells. Mol Biol Cell, 22, 736-747 (2011)
  16. Morimoto Y, Kureishi Bando Y, Shigeta T, Monji A, Murohara T: Atorvastatin Prevents Ischemic Limb Loss in Type 2 Diabetes: Role of p53. J Atheroscler Thromb, 18, 200-208 (2011)
  17. Cheng XW, Kuzuya M, Sasaki T, Inoue A, Hu L, Song H, Huang Z, Li P, Takeshita K, Hirashiki A, Sato K, Shi GP, Okumura K, Murohara T: Inhibition of mineralocorticoid receptor is a renoprotective effect of the 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor pitavastatin. J Hypertens, 29, 542-552 (2011)
  18. Kubota R, Numaguchi Y, Ishii M, Niwa M, Okumura K, Naruse K, Murohara T: Ischemia-induced angiogenesis is impaired in aminopeptidase A deficient mice via down-regulation of HIF-1α. Biochem Biophys Res Commun, 402, 396-401 (2010)
  19. Suzuki H, Shibata R, Kito T, Ishii M, Li P, Yoshikai T, Nishio N, Ito S, Numaguchi Y, Yamashita JK, Murohara T, Isobe K: Therapeutic angiogenesis by transplantation of induced pluripotent stem cell-derived Flk-1 positive cells. BMC Cell Biol, 11, 72 (2010)
  20. Murakami R, Murakami H, Kataoka H, Cheng XW, Takahashi R, Numaguchi Y, Murohara T, Okumura K: Unmetabolized fenofibrate, but not fenofibric acid, activates AMPK and inhibits the expression of phosphoenolpyruvate carboxykinase in hepatocytes. Life Sci, 87, 495-500 (2010)
  21. Cheng XW, Kuzuya M, Kim W, Song H, Hu L, Inoue A, Nakamura K, Di Q, Sasaki T, Tsuzuki M, Shi GP, Okumura K, Murohara T: Exercise training stimulates ischemia-induced neovascularization via phosphatidylinositol 3-kinase/Akt-dependent hypoxia-induced factor-1 alpha reactivation in mice of advanced age. Circulation, 122, 707-16 (2010)
  22. Li P, Shibata R, Maruyama S, Kondo M, Ohashi K, Ouchi N, Murohara T: Fenofibrate promotes ischemia-induced revascularization through the adiponectin-dependent pathway. Am J Physiol Endocrinol Metab, 299, E560-6 (2010)
  23. Nishizawa T, Cheng XW, Jin Z, Obata K, Nagata K, Hirashiki A, Sasaki T, Noda A, Takeshita K, Izawa H, Shi GP, Kuzuya M, Okumura K, Murohara T: Ca(2+) channel blocker benidipine promotes coronary angiogenesis and reduces both left-ventricular diastolic stiffness and mortality in hypertensive rats. J Hypertens, 28, 1515-1526 (2010)
  24. Kataoka H, Murakami R, Numaguchi Y, Okumura K, Murohara T: Angiotensin II type 1 receptor blockers prevent tumor necrosis factor-alpha-mediated endothelial nitric oxide synthase reduction and superoxide production in human umbilical vein endothelial cells. Eur J Pharmacol, 636, 36-41(2010)
  25. Asano Y, Kishida S, Mu P, Sakamoto K, Murohara T, Kadomatsu K: DRR1 is expressed in the developing nervous system and downregulated during neuroblastoma carcinogenesis. Biochem Biophys Res Commun, 394, 829-35 (2010)
  26. Kondo K, Shibata R, Unno K, Shimano M, Ishii M, Tetsutaro K, Shintani S, Walsh K, Ouchi N, Murohara T. Impact of a Single Intracoronary Administration of Adiponectin on Myocardial Ischemia/Reperfusion Injury in a Pig Model. Circ Cardiovasc Interv, 3, 166-173 (2010)
  27. Uetani T, Amano T, Kunimura A, Kumagai S, Ando H, Yokoi K, Yoshida T, Kato B, Kato M, Marui N, Nanki M, Matsubara T, Ishii H, Izawa H, Murohara T. The Association Between Plaque Characterization by CT Angiography and Post-Procedural Myocardial Infarction in Patients With Elective Stent Implantation. J Am Coll Cardiol Cardiovasc Imaging, 3, 19-28 (2010)
  28. Kondo K, Shintani S, Shibata R, Murakami H, Murakami R, Imaizumi T, Kitagawa S, Murohara T. Implantation of adipose-derived regenerative cells enhances ischemia-induced angiogenesis. Arterioscler Thromb Vasc Biol, 29, 61-66 (2009)
  29. Kondo M, Shibata R, Miura R, Shimano M, Kondo K, Li P, Ohashi T, Kihara S, Maeda N, Walsh K, Ouchi N, Murohara T. Caloric restriction stimulates revascularization in response to ischemia via adiponectin-mediated activation of eNOS. J Biol Chem, 284, 1718-1724 (2009)
  30. Mori K, Amano M, Takefuji M, Kato K, Morita Y, Nishioka T, Matsuura Y, Murohara T, Kaibuchi K. Rho-kinase contributes to sustained RhoA activation through phosphorylation of p190A RhoGAP. J Biol Chem, 284, 5067-5076 (2009)
  31. Morikawa S, Sone T, Tsuboi H, Mukawa H, Morishima I, Uesugi M, Morita Y, Numaguchi Y, Okumura K, Murohara T. Renal protective effects and the prevention of contrast-induced nephropathy by atrial natriuretic peptide. J Am Coll Cardiol, 53, 1040-1046 (2009)
  32. Uetani T, Amano T, Kumagai S, Ando H, Yokoi K, Yoshida T, Kato B, Kato M, Marui N, Nanki M, Matsubara T, Ishii H, Izawa H, Murohara T. Intracoronary electrocardiogram recording with a bare-wire system: perioperative ST-segment elevation in the intracoronary electrocardiogram Is associated with myocardial injury after elective coronary stent implantation. JACC Cardiovasc Interv, 2, 127-135 (2009)
  33. Numaguchi Y, Ishii M, Kubota R, Morita Y, Yamamoto K, Matsushita T, Okumura K, Murohara T. Ablation of Angiotensin IV Receptor Attenuates Hypofibrinolysis via PAI-1 Downregulation and Reduces Occlusive Arterial Thrombosis. Arterioscler Thromb Vasc Biol, 29, 2102-2108 (2009)
  34. Li P, Shibata R, Unno K, Shimano M, Furukawa M, Ohashi T, Cheng X, Nagata K, Ouchi N, Murohara T. Evidence for the importance of adiponectin in the cardioprotective effects of pioglitazone. Hypertension, 55, 69-75 (2009)
  35. Ishii H, Toriyama T, Aoyama T, Takahashi H, Amano T, Hayashi M, Tanaka M, Kawamura Y, Yasuda Y, Yuzawa Y, Maruyama S, Matsuo S, Matsubara T, Murohara T. Prognostic values of C-reactive protein levels on clinical outcome after implantation of sirolimus-eluting stents in patients on hemodialysis. Circ Cardiovasc Interv, 2, 513-518 (2009)
  36. Li P, Kondo T, Numaguchi Y, Kobayashi K, Aoki M, Inoue N, Murohara T. Role of bradykinin, nitric oxide and angiotensin II type 2 receptor in imidapril-induced angiogenesis. Hypertension, 51, 252-258 (2008)
  37. Amano T, Matsubara T, Uetani T, Nanki M, Marui N, Kato M, Yoshida T, Arai K, Yokoi K, Ando H, Kumagai S, Ishii H, Izawa H, Hotta N, Murohara T. Abnormal glucose regulation is associated with lipid rich coronary plaque: relationship to insulin resistance JACC Cardiovasc Imaging, 1, 39-45 (2008)
  38. Kitamura T, Asai N, Enomoto A, Maeda K, Kato T, Ishida M, Jiang P, Watanabe T, Usukura J, Kondo T, Costantini F, Murohara T, Takahashi M. Regulation of VEGF-mediated angiogenesis by the Akt/PKB substrate Girdin. Nat Cell Biol, 10, 329-337 (2008)
  39. Sugiura T, Kondo T, Kureishi-Bando Y, Numaguchi Y, Yoshida O, Dohi Y, Kimura G, Ueda R, Rabelink TJ, Murohara T. Nifedipine improves endothelial function: role of endothelial progenitor cell. Hypertension, 52, 491-498 (2008)
  40. Ishii H, Amano T, Matsubara T, Murohara T. Pharmacological intervention for prevention of left ventricular remodeling and improving prognosis in myocardial infarction. Circulation, 118, 2710-2718 (2008)
  41. Nakamura T et al. Significance and Therapeutic Potential of Endothelial Progenitor Cell Transplantation in a Cirrhotic Liver Rat Model. Gastroenterology 133: 91-107 (2007)
  42. Cheng XW et al. Mechanisms underlying the impairment of ischemia-induced neovascularization in MMP-2-deficient mice. Circ. Res. 100: 904-913 (2007)
  43. Numaguchi Y et al. The impact of the capability of circulating progenitor cell to differentiate on myocardial salvage in patients with primary acute myocardial infarction. Circulation 114: I114-I119 (2006)
  44. Shintani S et al. Synergistic effect of combined intramyocardial CD34 cells and VEGF-2 gene therapy post-myocardial infarction. Nature Clin. Pract. Cardiovasc. Med. 3: S123-S128 (2006)
  45. Egami K et al. Role of host angiotensin II type 1 receptor in tumor angiogenesis and growth. J. Clin. Invest. 112: 67-75 (2003)
  46. Tateishi-Yuyama E et al. for the Therapeutic Angiogenesis using Cell Transplantation (TACT) Study Investigators. Therapeutic angiogenesis for patients with limb ischaemia by autologous transplantation of bone-marrow cells: a pilot study and a randomised controlled trial. Lancet 360: 427-435 (2002)
  47. Sasaki K et al. Evidence for the importance of angiotensin II type 1 receptor in ischemia-induced angiogenesis. J Clin Invest. 109: 603-611 (2002)
  48. Kamihata H et al. Implantation of bone marrow mononuclear cells into ischemic myocardium enhances collateral perfusion and regional function via side supply of angioblasts, angiogenic ligands, and cytokines. Circulation 104: 1046-1052 (2001)
  49. Shintani S et al. Mobilization of endothelial progenitor cells in patients with acute myocardial infarction. Circulation 103: 2776-2779 (2001)
  50. Shintani S et al. Augmentation of postnatal neovascularization with autologous bone marrow transplantation. Circulation 103: 897-903 (2001)
  51. Murohara T et al. Transplanted cord blood-derived endothelial precursor cells augment postnatal neovascularization. J Clin Invest. 105: 1527-1536 (2000)
  52. Murohara T et al. Nitric oxide synthase modulates angiogenesis in response to tissue ischemia. J Clin Invest. 101: 2567-2578 (1998)
  53. Murohara T et al. Vascular endothelial growth factor/vascular permeability factor enhances vascular permeability via nitric oxide and prostacyclin. Circulation 97: 99-107 (1998)
  54. Murohara T et al. Reciprocal relation between VEGF and NO in the regulation of endothelial integrity. Nature Med. 3: 879-886 (1997)
  55. Asahara T et al. Isolation of putative progenitor endothelial cells for angiogenesis. Science 275: 964-967 (1997)
  56. Buerke M et al. Cardioprotective effect of insulin-like growth factor I in myocardial ischemia and reperfusion. Proc. Natl. Acad. Sci. USA. 92: 8031-8035 (1995)

Award

Irvine H. Page Award. American Heart Association (AHA), Annual Scientific Sessions 1997, November 9-12,1997, Orlando, Florida. Title: Reciprocal relationship between vascular endothelial growth factor and nitric oxide in the regulation of endothelial integrity.

Young Investigators Award, American College of Cardiology, The 49th Annual Scientific Sessions. March 12-15, 2000, Anaheim, CA. Title: Augmentation of postnatal neovascularization by transplantation of cord blood-derived endothelial progenitor cells.

Press Conference

American Heart Association (AHA), Scientific Sessions 1999, November 7-10, 1999. Atlanta, GA. Murohara T. Heterologous transplantation of human cord blood-derived endothelial progenitor cells participate in postnatal angiogenesis in vivo. CNN, BBC On line. http://news.bbc.co.uk/1/hi/health/510072.stm

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