1999 Fiscal Year Final Research Report Summary
Analysis of a novel mechanism of programmed cell death regulated by calcineurin.
| Project/Area Number |
10670207
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Experimental pathology
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| Research Institution | Okayama University |
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Principal Investigator |
KONDO Eisaku Medical School, Okayama University, Assistant, 医学部, 助手 (30252951)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUSHITA Masayuki Medical School, Okayama University, Assistant, 医学部, 助手 (30273965)
MORIWAKI Akiyoshi Medical School, Okayama University, Lecturer, 医学部, 講師 (10144742)
MATSUI Hideki Medical School, Okayama University, Professor, 医学部, 教授 (30157234)
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| Project Period (FY) |
1998 – 1999
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| Keywords | calcineurin / Bcl-2 / apoptosis / dephosphorylation |
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| Research Abstract |
The serine/threonine protein phosphatase 2B, calcineurin, was revealed to be bound to anti-apoptotic protein, Bcl-2. Calcineurin specifically dephosphorylated Bcl-2 through its direct association. Dephosphorylated Bcl-2 by active calcineurin functioned as an apoptosis-suppressor, whereas phosphorylated Bcl-2 by inactivation of calcineurin (by overexpression of dominant negative type of calcineurin) lost the anti-apoptotic function.
Phosphorylation assay revealed that target regions for dephosphorylation by calcineurin were located both a BH4 domain and Loop within Bcl-2, which suggested Ser24 on BH4 and Ser70 on loop seemed to be the candidates, respectively. Cells expressing mutative Bcl-2 substituted those Serines by Alanine(A) or Aspartate(D) showed consistent biological behaviors to genetic analyses of altered function of Bcl-2 by phorylation regulation. It was clarified, as a mechanism of apoptosis regulation by Bcl-2, that the phosphorylated status of Bcl-2 affected its affinity to death-induced, Bax. Namely, dephosphorylated Bcl-2 efficiently heterodimerized to Bax, whereas phosphorylated Bcl-2 lost its association to Bax, thus excess amount of Bax accumulated at mitochondria caused apoptosis by facilitating a relase of cytochrome C. In vivo study using human leukemia/lymphoma cell lines revealed that cells carrying t(14 ; 18) chromosomal translocation predominantly overexpressed dephosphorylated form of endogenous Bcl-2.
It also revealed that apoptotic leukemia cells treated by anti-cancer drug showed mobility shift of endogenous Bcl-2 from dephosphorylated form to phosphorylated form.
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[Publications] Dobashi, Y., Shoji, M., Kondo, E., Akiyama, T., Kameya, T.: "CDK4, a possible critical regulator in rat pheochromocytoma PC12 cells"Biochem. Biophys. Res. Commun.. 253. 609-613 (1998)
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[Publications] Ueno H, Kondo E, Yamamoto-Honda R, Tobe K, Nakamoto T, Sasaki K, Mitani K, Furusaka A, Tanaka T, Tsujimoto Y, Kadowaki T, Hirai H.: "Association of insulin receptor substrate proteins with Bcl-2 and their effects on its phosphorylation and antiapoptotic function"Mol. Biol. Cell.. 11. 735-746 (2000)
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「研究成果報告書概要(欧文)」より
