1999 Fiscal Year Final Research Report Summary
Identification of isoaspartic acid containing proteins in aged brain
| Project/Area Number |
10832011
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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 |
老化(加齢)
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| Research Institution | Tokyo Metropolitan Institute of Gerontology |
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Principal Investigator |
SHIMIZU Takahiko Tokyo Metropolitan Institute of Gerontology, Department of Molecular Genitics, Investigator., 分子遺伝子学部門, 研究員 (40301791)
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| Co-Investigator(Kenkyū-buntansha) |
SHIRASAWA Takuji Tokyo Metropolitan Institute of Gerontology, Department of Molecular Genitics, Head., 分子遺伝子学部門, 室長 (80226323)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Isoaspartic acid / Amyloid β-protein / Alzheimer's disease / Amyloid-bearing vessels / Senile plaques / Aggregation / Isomerization / Amyloid fibril |
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| Research Abstract |
Senile plaques consisting of fibrillar amyloid β-proteins (Aβ) are a characteristic neuropathological feature of Alzheimer's disease (AD). Aβ undergoes post-translational modifications at their aspartyl residues. These modifications include isomerization, at positions 1 and 7, from an Asp to a β-linkage on the side chain to form isoAsp through a cyclic succinimide intermediate. isomerization of the Asp residue at position 23 of Aβ has not yet been reported. In this study, in order to clarify the aggregation properties of isomerized aβ peptides, Aβ1-42 and its isomers with an isoaspartyl residue at position 7 or 23 [Aβ1-42(isoAsp7) or Aβ1-42(isoAsp23), respectively] were chemically synthesized in high purity by the Fmoc-solid phase technique, followed by HPLC on a silica-based reversed-phase column under the basic conditions. Synthetic Aβ1-42(isoAsp23) aggregated more extensively than native Aβ1-42 or Aβ-42(isoAsp7) as determined by thioflavin T fluorometry and circular dichroism spectroscopy. In electron microscopy, Aβ1-42(isoAsp23) showed typical fibrillar morphology. These results indicate that isomerization of Asp residue at position 23 greatly alters the aggregation property of the Aβ1-42.
Furthermore, we developed two specific antibodies (anti-isoAsp7 and anti-isoAsp23) raised against isomers with an isoAsp residue at position 7 or 23. Immunohistochemical studies on AD brain tissues revealed that amyloid-bearing vessels were selectively stained with anti-isoAsp23 antibody. On the other hand, almost all plaques and amyloid-bearing vessels were positively stained with anti-isoAsp7 antibody. Our findings suggest that each isomerized Aβ is differentially deposited in plaques and amyloid-bearing vessels.
In conclusion, it is suggest that the isomerization of the aspartyl residues plays an important role in the fibril formation of Aβ and the distribution of amyloid in AD.
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Research Products
(2 results)
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[Publications] Fukuda, H., Shimizu, T., Nakajima, M., Mori, H., and Shirasawa, T.: "Synthesis, aggregation, and neurotoxicity of the Alzheimer's Aβ1-42 amyloid peptide and its isomers."BioMed. Chem. Lett.. 9. 953-956 (1999)
Description
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