2009 Fiscal Year Final Research Report
mechanistic analysis of cardiac functions by building G protein signal network
| Project/Area Number |
17079007
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Biological Sciences
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| Research Institution | Kyushu University |
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Principal Investigator |
KUROSE Hitoshi Kyushu University, 大学院・薬学研究院, 教授 (10183039)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIDA Motohiro 九州大学, 大学院・薬学研究院, 准教授 (90342641)
NAKAYA Michio 九州大学, 大学院・薬学研究院, 助教 (80464387)
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| Project Period (FY) |
2005 – 2009
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| Keywords | G蛋白質 / 心肥大 / 心不全 / 線維化 / 受容体 / 圧負荷 / ATP / 百日咳毒素 / アンジオテンシンII受容体 |
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| Research Abstract |
The heart is hypertrophied when it is exposed to stresses such as hypertension. When the stress is not removed, the heart develops heart failure that does not properly provide the blood to peripheral tissues. Cardiac fibrosis is characterized by excessive deposition of extracellular matrix proteins, and is one of the causes of heart failure that contributes to the impairment of cardiac function, especially relaxation ability. So far, it is believed that fibrosis of various tissues including the heart is a secondary event following hypertrophy, and is regulated by the signaling pathway of angiotensin II (Ang II) and transforming growth factor-β (TGF-β). In order to examine the roles of heterotrimeric G12 family G protein (G_<α12>/G_<α13> : Gα12/13) in the heart, we used RGS domain of p115RhoGEF (p115-RGS) to selectively block G_<α12/13>. Transgenic mice (p115-Tg mice) expressing inhibitory p115-RGS only in cardiac myocytes shows pressure overload-induced fibrosis without affecting hyper
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trophy. As p115-RGS is selectively expressed in cardiac myocytes, p115RGS is selective inhibitor of heterotrimeric G_<α12/13> protein, and G protein is generally activated by G protein-coupled receptors (GPCRs), there should be a GPCR that triggers cardiac fibrosis when the heart is exposed to pressure overload. To identify a GPCR that regulates fibrosis, we used stretch treatment of neonatal cardiomyocytes, as it is thought that stretch treatment of cells in vitro mimics in vivo pressure overload. The activation of Rho downstream of G_<α12/13> by stretch treatment is initiated by ATP and UDP released from cardiac myocytes, as enzymes involved in ATP degradation or blockers of purine receptor inhibit stretch-induced Rho activation. Purine receptor-selective blockers reveal that the receptor is P2Y6. Furthermore, inhibition of G-protein-coupled P2Y_6 receptors in vivo inhibits pressure overload-induced cardiac fibrosis. These results suggest that activation of G_<α12/13> in cardiomyocytes by ATP and/or UDP-stimulated P2Y_6 receptor triggers fibrosis in pressure overload-induced cardiac fibrosis.
Pertussis toxin (PTX) is widely used as a specific tool that ADP-ribosylates Gi and Go (Gi/Go) and uncouples receptors from Gi/Go. To examine signaling pathways of angiotensin II receptor (AT1R) stimulation in cardiac fibroblasts, we found that PTX increases the expression of AT1R and enhances AT1R-mediated response. Microarray analysis shows that PTX increases the expression of interleukin (IL)-1β. Decreased expression of IL-1β by knockdown or antibody inhibits the PTX-treatment-stimulated enhancement of AT1R-mediated response. PTX increased the expression of IL-1β and AT1R through activation of a small GTP-binding protein Rac that stimulates NADPH oxidase-dependent production of reactive oxygen species. PTX-induced late but not an early phase of Rac activation is blocked by inhibition of IL-1β. It is known that PYX binds to Toll-like receptor 4 (TLR4). Knockdown of TLR4 inhibits PTX-induced Rac activation and enhancement of AT1R-mediated responses. However, inhibition of TLR4 does not affect PTX-mediated ADP-ribosylation of Gi/Go. Thus, PTX binds to at least two receptors: one is TLR4 that activates Rac and enhances AT1R responses, and another is the binding site that mediates entry of PTX into cells ADP-ribosylation of Gi/Go. Less
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Research Products
(16 results)
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[Journal Article] Phosphorylation of TRPC6 channels at Thr69 is required for anti-hypertrophic effects of phosphodiesterase 5 inhibition2010
Author(s)
Nishida, M., Watanabe, K., Sato, Y., Nakaya, M., Kitajima, N., Ide, T., Inoue, R., Kurose, H.
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Journal Title
J Biol Chem. 286(17)
Pages: 13244-13253
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[Journal Article] Pertussis toxin up-regulates angiotensin type 1 receptors through Toll-like receptor 4-mediated Rac activation.2010
Author(s)
Nishida, M., Suda, R., Nagamatsu, Y., Tanabe, S., Onohara, N., Nakaya, M., Kanaho, Y., Shibata, T., Uchida, K., Sumimoto, H., Sato, Y., Kurose, H.
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Journal Title
J Biol Chem. 285(20)
Pages: 15268-15277
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[Journal Article] P2Y6 receptor-Gα12/13 signaling in cardiomyocytes triggers pressure overload-induced cardiac fibrosis2008
Author(s)
Nishida, M., Sato, Y., Uemura, A., Narita, Y., Tozaki-Saitoh, H., Nakaya, M., Ide, T., Suzuki, K., Inoue, K., Nagao, T., Kurose, H.
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Journal Title
EMBO J. 27(23)
Pages: 3104-3115
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[Journal Article] Gα12/13-mediated upregulation of TRPC6 negatively regulates endothelin-1-induced cardiac myofibroblast formation and collagen synthesis through NFAT activation2007
Author(s)
Nishida, M., Onohara, N., Sato, Y., Suda, R., Ogushi, M., Tanabe, S., Inoue, R., Mori, Y., Kurose, H.
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Journal Title
J. Biol. Chem. 282(32)
Pages: 23117-23128
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[Journal Article] Heterotrimeric G protein Gα13-induced induction of cytokine mRNAs through two distinct pathways in cardiac fibroblasts.2006
Author(s)
Nagamatsu, Y., Nishida, M., Onohara, N., Fukutomi, M., Maruyama, Y., Kobayashi, H., Sato, Y., Kurose, H.
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Journal Title
J. Pharmacol. Sci. 101
Pages: 144-150
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[Journal Article] TRPC3 and TRPC6 are essential for angiotensin II-induced cardiac hypertrophy.2006
Author(s)
Onohara, N., Nishida, N., Inoue, R., Kobayashi, H., Sumimoto, H., Sato, Y., Mori, Y., Nagao, T., Kurose, H.
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Journal Title
EMBO J. 25(22)
Pages: 5305-5316
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[Journal Article] Gα12/13-mediated production of reactive oxygen species is critical for angiotensin receptor-induced NFAT activation in cardiac fibroblasts2005
Author(s)
Fujii, T., Onohara, N., Maruyama, Y., Tanabe, S., Kobayashi, H., Fukutomi, M., Nagamatsu, Y., Nishihara, N., Inoue, R., Sumimoto, H., Shibasaki, F., Nagao, T., Nishida, M., Kurose, H.
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Journal Title
J. Biol. Chem. 280(24)
Pages: 23041-23047
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[Journal Article] Gα12/13- and reactive oxygen species-dependent activation of c-Jun NH2-terminal kinase and p38 MAPK by angiotensin receptor stimulation in rat neonatal cardiomyocytes.2005
Author(s)
Nishida, M., Tanabe, S., Maruyama, Y., Mangmool S., Urayama K., Nagamatsu, Y., Takagahara, S., Turner, J.H., Kozasa, T., Kobayashi, H., Sato, Y., Kawanishi, T., Inoue, R., Nagao, T., Kurose, H.
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Journal Title
J. Biol. Chem. 280(18)
Pages: 18434-18441
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