| Project/Area Number |
21580345
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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 |
Applied animal science
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| Research Institution | The University of Tokyo |
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Principal Investigator |
HAKUNO Fumihiko 東京大学, 大学院・農学生命科学研究科, 助教 (30282700)
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| Project Period (FY) |
2009 – 2011
|
| Project Status |
Completed (Fiscal Year 2011)
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| Budget Amount *help |
¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
Fiscal Year 2011: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2010: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2009: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Keywords | IGF-I / PI 3-kinase / PI3KAP / 細胞増殖 / PITKAP / PI3-kinase |
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| Research Abstract |
We previously demonstrated that long-term pretreatment of rat FRTL-5 thyroid cells with TSH or cAMP-generating reagents potentiated IGF-I-dependent DNA synthesis. Under this condition, cAMP treatment increased tyrosine phosphorylation of a 125 kDa protein(p125) and its association with a p85 regulatory subunit of phosphatidylinositol 3-kinase(p85 PI3K), which were suggested to be important for potentiation of DNA synthesis. This study was undertaken to identify p125 and to elucidate its roles in potentiation of DNA synthesis induced by IGF-I. Immunoprecipitated phosphotyrosyl p125 in cAMP-stimulated FRTL-5 cells, was shown by MALDI-TOF MS analysis, to be a rat orthologue of human XB130, which we named phosphatidylinositol 3-kinase-associated protein(PI3KAP). cAMP treatment elevated PI3KAP/XB130 mRNA and protein levels as well as tyrosine phosphorylation and PI3KAP/XB130 interaction with p85 PI3K, leading to increased PI3K activities. Importantly, PI3KAP/XB130 knockdown in FRTL-5 cells attenuated cAMP-dependent potentiation of IGF-I-induced DNA synthesis. Addition of Src family kinase inhibitors, PP1 or PP2, during cAMP treatment abolished tyrosine phosphorylation of PI3KAP/XB130 and its interaction with p85 PI3K. In addition, c-Src was associated with PI3KAP/XB130 and was activated in response to cAMP. Together, these data indicate that cAMP-dependent induction of PI3KAP/XB130 and its association with PI3K are required for enhancement of IGF mitogenic activities.
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