| Project/Area Number |
12680759
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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 |
Neurochemistry/Neuropharmacology
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| Research Institution | KITASATO UNIVERSITY |
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Principal Investigator |
HAMAZAKI Hideaki Kitasato Univ. School of Medicine ; Assoc. Prof., 医学部, 助教授 (00050526)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2002: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2001: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2000: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | Alzheimer / Amyloid / Protease |
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| Research Abstract |
1. The cerebral deposition of 42-residue amyloid β-protein (Aβ42) is a histopathological characteristic of Alzheimer's disease. The present study is aimed at finding proteinases responsible for the intracellular clearance of Aβ. Amino termical sequence analysis indicated the Aβ-degrading proteinase was cathepsin D. Purified cathepsin D hydrolyzed Aβ between Phe19 and Phe20. Cathepsin D is likely to be involved in the intracellular clearance of aggregated Aβ, since Aβ fragments with Phe20 at the amino-terminus have been reported to be secreted from several lines of cultured cells. 2. Cathepsin D hydrolyzes wild-type Aβ 20 times faster than a variant Aβ with a substitution at residue 21 from Ala to Gly. Since the substitution has been linked to familial Alzheimer's disease and hereditary cerebral hemorrhage with amyloidosis, the observations suggest that the inefficient elimination of Aβ by cathepsin D is capable of being one of causes of the amyloid fibril formation. 3. Rat brain contains a carboxypeptidase that efficiently deletes three amino acids from Aβ1-43. The carboxypeptidase in the brain was completely inhibited by carbobenzoxy-Leu-ceucinal, carbobenzoxy-Leu-Leu-leucinal, and carbobenzoxy-Leu-Leu-norvalinal, and weakly by antiapin. The purified enzyme from rat brain was cathepsin A. The data suggest that cathepsin A contributes to the genation of Aβ40 from Aβ42/43 and is important in the clearance of Aβ42/43. 4. Aβ25-35 was generally thought to be amyloidogenic and cytotoxic. However, Aβ39-42 (the C-terminal tetrapeptide of Aβ42) was more toxic than Aβ25-35 to PC-12 cells and SK-N-SH cells. The present data indicate cytotoxity of Aβ peptides does not always depend on the amyloidogenec property.
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