| Project/Area Number |
63480131
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
General medical chemistry
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| Research Institution | The Jikei University School of Medicine |
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Principal Investigator |
HAYASHI Shin-ichi Professor, Department of Nutrition, The Jikei University School of Medicine, 医学部, 教授 (50028297)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUFUJI Senya Instructor, Department of Nutrition, The Jikei University School of Medicine, 医学部, 助手 (50192753)
MURAKAMI Yasuko Associate Professor, Department of Nutrition, The Jikei University School of Med, 医学部, 助教授 (30056709)
T.G Baby 東京慈恵会医科大学, 医学部, 外国人招へい研究者
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 1989: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1988: ¥5,000,000 (Direct Cost: ¥5,000,000)
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| Keywords | Ornithine decarboxylase / Antizyme / cDNA / Translational regulation / Frame-shift / mRNA / Half-life / Polyamines / アンチザイムインヒビター / 酵素分解 / ラット / カエル |
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| Research Abstract |
Ornithine decarboxylase (ODC) antizyme is a unique regulatory protein involved in feedback inhibition and possibly degradation of the enzyme. Following results were obtained in this second year of supported research.
(1) Determination of base sequence of antizyme MRNA
Sequence analysis of newly cloned CDNA and genomic DNA indicated that rat liver antizyme is consisted of 227 amino acids and that translation of antizyme MRNA is likely to involve a frame-shift, a very unusual process in bukaryotic cells. (Matsufuji)
(2) Tissue distribution of antizyme MRNA
Northern blot analysis demonstrated that a single species of antizyme MRNA of 1.3 kb was widely and amply distributed in various murine tissues. The MRNA was quite stable in vivo (T_<1/2> = 12 h) and its amount did not increase upon putrescine treatment, indicating that the induction of antizyme by polyamines is due to translational stimulation. (Matsufuji)
Role of antizyme
Protein synthesis inhibitors like emetine and pactamycin inhibited antizyme synthesis as well as polyamine-caused acceleration of ODC decay, while amino acid analogs like ethionine and 5-fluorotryptophan inhibited neither antizyme induction nor polyamine-caused acceleration of ODC decay, indicating a close relationship between these two processes. An antizyme overproducing variant cell line was obtained from ODC-overproducing CHO cells. Studies on half-lives of free and antizyme-bound ODC in this cell line strongly suggested antizyme-mediated degradation of ODC. (Murakami)
(4) Presence and role of antizyme in the frog Xenopus laevis
Induction of antizyme and acceleration of ODC decay were both observed in primary cultured frog hepatocytes. (Hayashi & Murakami)
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