1992 Fiscal Year Final Research Report Summary
The interaction between IGF-I-dependent and other hormones-dependent signal pathways in cell growth and differentiation
| Project/Area Number |
03660078
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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 |
応用生物化学・栄養化学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TAKAHASHI Shin-ichiro The University of Tokyo,Faculty of Agriculture Associate Professor, 農学部, 助教授 (00197146)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Insulin-like growth factor-I / Tyrosine phosphorylation / Thyroid stimulating hormone / FRTL-5 cells / DNA synthesis / Protein synthesis / Insulin / Primary cultures of rat hepatocytes |
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| Research Abstract |
Studies were undertaken to determine the mechanism(s) by which thyroid stimulating hormone (TSH) and insulin-like growth factor-I (IGF-I) act synergistically to stimulate protein synthesis and DNA synthesis in FRTL-5 cells. The response of these cells to TSH and IGF-I greatly surpass the sum of the effects of the individual hormones when acting alone. Preincubation with IGF-I potentiates the effect of TSH on protein synthesis. On the contrary,after preincubation with TSH,FRTL-5 cells exhibited greatly increased response to the mitogenic activity of IGF-I.
Furthermore,pretreatment of the cells for 24h with either TSH or other agents that elevate intracellular cAMP potentiated the IGF-I-dependent tyrosine phosphorylation (pp175 and pp95),and increased IGF-I-independent tyrosine phosphorylation(pp125, pp100 and pp80). These results suggest that a cAMP stimulus can be propagated through multiple pathways including enhancement of tyrosine phosphorylation. These phenomena were also observed in primary cultures of rat hepatocytes treated with cAMP-generating agents and insulin. The purification of pp175 from the lysates of FRTL-5 cells treated with Bt_2cAMP and IGF-I is in progress in our laboratory,using DEAE-ion exchange chromatography,anti-phosphotyrosine antibody conjugated Sepharose affinity chromatography,and SDS-polyacryl amide gel electrophoresis.
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