Mechanism of regulation of protein metabolism by insulin-like growth factor-I
| Project/Area Number |
08456063
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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 |
食品科学・栄養科学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
NOGUCHI Tadashi The University of Tokyo, Graduate School of Agricultural and Life Sciences, Professor, 大学院・農学生命科学研究科, 教授 (50011937)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥7,700,000 (Direct Cost: ¥7,700,000)
Fiscal Year 1997: ¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 1996: ¥4,900,000 (Direct Cost: ¥4,900,000)
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| Keywords | IGF-I / IGFBP-1 / protein metabolism / dexamethasone / streptozotocin / IGF-binding protein / diabetes / insulin-like growth factor-I / インスリン様成長因子結合タンパク質 / 翻訳開始因子 / タンパク質合成 / グルココルチコイド / タンパク質欠乏 |
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| Research Abstract |
Insulin-like growth factor-I (IGF-I) is a hormone the structure and function of which are similar to those of insulin. However, as we and others have proved, its physiological role is presumed to be different from that of insulin. IGF-I circulates in blood complexed with the specific binding proteins which are referred to as IGF-binding proteins (IGFBPs). Seven IGFBPs have been identified. IGFBPs have been presumed to regulate the activity of IGF-I and IGF-II.
In order to elucidate the role of IGF-I and IGFBPs in the regulation of protein metabolism, we investigated the concentration of IGF-I and IGFBP-1 in the rats fed on a protein-free diet, given streptozotocin or dexamethasone.
Plasma IGF-I concentration correlated with RNA/protein ratio in skeletal muscle except in the case of dexamethasone treatment. RNA/protein ratio has been shown to be an index of the activity of protein synthesis in tissues. Therefore, the results mean that IGF-I is an important factor which regulates muscle protein synthesis.
On the contrary, plasma IGFBP-1 concentration inverseiy correlated with the RNA/protein ratio in skeletal muscle. There was no exception in this case. these observations suggest that IGFBP-1 plays an important role directly regulating the activity of IGF-I and muscle protein synthesis.
We conclude that IGF-I regulates muscle protein synthesis and IGFBP-1 regulates the activity of IGF-I,thereby determining the activity of protein synthesis in skeletal muscle.
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Report
(3 results)
Research Products
(18 results)
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[Publications] Koide, T., Ono, Y., Ito, Y., Akahori, M., Nedachi, T., Hakuno, f., Takenaka, A., Takahashi, S.I., Noguchi, T.: "Insulin-like Growth Factor-I Potentiates Protein Synthesis Induced by Thyrotropin in FRTL-5 Cells : Comparison of Induction of Protein Synthesis and DNA Synthesis." Endocrin.J.45(2)(in press). (1998)
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[Publications] Ito, Y., Ariga, Y., Takahashi, S.I., Takenaka, A., Hidakaa, T., Noguchi, T.: "Changes in Tyrosine Phosphorylation of Insulin Receptor and Insulin Receptor Substrate-1 (IRS-1) and Association of p85 Subunit of Phosphatidylionositol 3-kinase with IRS-1 after feeding in Rat Liver in Vivo." J.Endocrinol. 154. 267-273 (1997)
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[Publications] Ito, Y., Uchijima, Y., Ariga, M., Seki, T., Takenaka, A., Hakuno, F., Takahashi, S.I., Ariga, T., Noguchi, T.: "Interaction between cAMP-Dependent and Insulin-Dependent Signal Path ways in Tyrosine Phosphorylation in Primary Cultures of Rat Hepatocytes." Biochem.J.324. 379-388 (1997)
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