1993 Fiscal Year Final Research Report Summary
The mechanism of cell cycle G2 phase in mammalian cells
| Project/Area Number |
04671393
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
医学一般
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| Research Institution | The University of Tokyo (1993)
Osaka University (1992) |
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Principal Investigator |
NAGATA Akihisa The University of Tokyo, Faculty of Medicine, Instructor, 医学部(医), 講師 (50155933)
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| Co-Investigator(Kenkyū-buntansha) |
OKAYAMA Hiroto The University of Tokyo, Faculty of Medicine, Professor, 医学部(医), 教授 (40111950)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Cell cycle G2 phase / Cdc25 tyrosine phosphatase / Cdc2 kinase |
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| Research Abstract |
The cdc25^+ tyrosine phosphatase is a key mitotic inducer of the fission yeast Schizosaccharomyces pombe, controlling the timing of the initiation of mitosis. Mammals contain at least three cdc25^+ homologues called cdc25A, cdc25B and cdc25C.We investigate the biological function of cdc25A.Although very potent in resucuing the S.pombe cdc25 mutant, cdc25A is less structurally related to the S.pombe enzyme. Northern and Western blotting detection reveals that unlike cdc25B, cdc25C and cdc2, cdc25A is predominantly expressed in late G1. Moreover, immunodepletion of cdc25A in rat cells by microinjection of a specific antibody effectively blocks their cell cycle progression from G1 into the S phase as determined by laser scanning single cell cytometry. These results indicate that cdc25A is not a mitotic regulator but a novel phosphatase that plays an crucial role in the start of the cell cycle. In view of its strong ability to activate cdc2 kinase and its specific expression in late G1, cdc2-related kinases functioning early in the cell cycle may be targets for this phosphatase.
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