1997 Fiscal Year Final Research Report Summary
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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| Keywords | IGF-I / IGFBP-1 / protein metabolism / dexamethasone / streptozotocin / IGF-binding protein / diabetes / insulin-like growth factor-I |
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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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Research Products
(10 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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「研究成果報告書概要(欧文)」より
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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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「研究成果報告書概要(欧文)」より
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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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「研究成果報告書概要(欧文)」より
