2000 Fiscal Year Final Research Report Summary
ANALYSIS FOR MECHANISM OF SELF-RENEWAL SIGNAL TRANSDUCTION IN EMBRYONIC STEM CELLS
| Project/Area Number |
11480176
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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 |
Functional biochemistry
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| Research Institution | The University of Tokyo |
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Principal Investigator |
YOKOTA Takashi The University of Tokyo, The Institute of Medical Science, VISITING PROFESSOR, 医科学研究所, 客員教授 (50134622)
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| Co-Investigator(Kenkyū-buntansha) |
KOIDE Hiroshi The University of Tokyo, The Institute of Medical Science, VISITING RESEARCH ASSOCIATE, 医科学研究所, 寄付研究部門教員 (70260536)
NISHINAKAMURA Ryuichi The University of Tokyo, The Institute of Medical Science, VISITING ASSOCIATE PROFESSOR, 医科学研究所, 客員助教授 (70291309)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Cytokine / gp130 / LIF / Embryonic stem cell / chimeric cytokine receptor / self-renewal mechanism / transgenic mice / STAT3 |
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| Research Abstract |
The pluripotent phenotype of ES cells is maintained in the presence of LIF.LIF binds to a cell surface receptor complex composed of LIF receptor β and gp130, through which several signaling molecules including MAP kinase and STAT3 are activated. We reported that the intracellular domain of gp130 plays an important role in self-renewal of ES cells. In the present study, we examined the signaling pathway through which gp130 contributes to the self-renewal of ES cells. Mutational analysis of the cytoplasmic domain of gp130 responsible for STAT3 activation is necessary for self-renewal of ES cells, while that required for SHP2 and MAP kinase activation was dispensable. Next, we have constructed a fusion protein composed of the entire region of STAT3 and the ligand binding domain of estrogen receptor. This fusion protein(STAT3ER)was dimerized and activated in the presence of a synthetic ligand 4-hydroxytamoxifen(4HT). When ES cells stably expressing STAT3ER were cultured in the presence of 4HT without LIF and feeder cells, they maintained a morphologically undifferentiated state and expressed undifferentiated state-specific markers(SSEA-1 and alkaline phosphatase). Moreover, ES cells maintained by STAT3ER and 4HT contributed to chimeric mice production when they were injected into blastocysts. These results indicate that STAT3 activation is sufficient to maintain the pluripotency of ES cells. Oct-3/4 transcription factor is expressed in ES cells and EG cells specifically. It is known to be essential for the formation of inner cell mass and for the maintenance of undifferentiated state of ES cells. It is likely that LIF or STAT3 signals inhibit differentiation of ES cells through yet unidentified factor by cooperating with Oct-3/4.
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