| Project/Area Number |
12470201
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Hematology
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| Research Institution | Osaka University |
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Principal Investigator |
TOMIYAMA Yoshiaki Osaka University, Graduate School of Medicine, Assistant Professor, 医学系研究科, 助手 (80252667)
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| Co-Investigator(Kenkyū-buntansha) |
KASHIWAGI Hirokazu Osaka University Hospital, Medical Staff, 医学部・附属病院, 医員
ORITANI Kenji Osaka University, Graduate School of Medicine, Assistant Professor, 医学系研究科, 助手 (70324762)
HONDA Shigenori Osaka University, Graduate School of Medicine, Assistant Professor, 医学系研究科, 助手 (00303959)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥12,100,000 (Direct Cost: ¥12,100,000)
Fiscal Year 2001: ¥4,700,000 (Direct Cost: ¥4,700,000)
Fiscal Year 2000: ¥7,400,000 (Direct Cost: ¥7,400,000)
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| Keywords | β_3 integrin / Megakaryocyte / Inside-out signaling / NCX / 活性化シグナル / インテグリン / 機能活性化機構 / リガンド結合能 / 機能欠失変異 / IAP / CD47 |
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| Research Abstract |
β_3 integrins, which contain α_<IIb>β_3 and α_vβ_3, play critical roles in atherosclerosis as well as thrombosis. Therefore, the elucidation of the regulatory mechanisms for integrin function is a critical issue to control these vascular events. In this research project, we have tried to establish a new experimental model other than platelets to examine the regulation of β_3 integrin function.
Firstly, we have analyzed structural and functional analyses of αvβ_3 integrin. Based on the β-propeller model we have examined ligand-binding sites in the αv subunit employing alanine-scanning mutagenesis. We demonstrated that 178Tyr in the W3 2-3 loop is one of the critical residues for ligand-binding. Secondly, we have examined early megakaryocytes derived from umbilical cord blood mononuclear cells and certain megakaryocytic cell lines and demonstrated that CD42b(GPIb)-positive cells could activate α_<IIb>β_3 within several minutes after TRAP and/or PMA stimulation. We have been searching molecules responsible for integrin activation employing differential display method between CD42b-positive and CD42b-negative cells in a certain megakaryocytic cell line. Thirdly, we have examined Na^+/Ca^<2+> exchanger in platelets which we have firstly demonstrated as an important signaling molecule for integrin activation. We demonstrated a new 70 kD isoform in platelets instead of 110-kD form. The functional significance of the 70 kD NCX is under investigation.
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