| Project/Area Number |
11670157
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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 |
Pathological medical chemistry
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| Research Institution | Tokyo Metropolitan Institute of Gerontology |
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Principal Investigator |
SHIRASAWA Takuji Tokyo Metropolitan Institute of Gerontology, Department of Molecular Genetics, Head., 分子遺伝学部門, 室長 (80226323)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2000: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1999: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | Aging / Posttranslational modification / Isoaspartic acid / PIMT / Knockout mice / Transgenic mice / Neurodegeperation / Gene therapy / メチル転移酵素 / 電顕 / シナプス / 空砲変性 / 苔状線維 |
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| Research Abstract |
Protein isoaspartyl methyltransferase (PIMT) has been suggested to play a role in the repair of aged proteins spontaneously incorporated with isoaspartyl residues. Thus the lack of this repair system was expected to show an abnormal accumulation of isoaspartate in the brain of knockout animals with reference to the pathological implications of protein isomerization during aging. Recently, we reported knockout mice lacking the enzymatic activity for PIMT.The PIMT-deficient mice unexpectedly showed a fatal epileptic seizure at a rather young age and failed to survive beyond 12 weeks, making it impossible to investigate the pathological implications of isomerized proteins in aged brains. Therefore, we next investigated the dynamics of accumulated isoaspartate in the brain during the development of PIMT-deficient mice. Biochemical analysis revealed that isomerized proteins have already accumulated in neonatal brains of PIMT-deficient mice compared to control mice. The accumulation of isomerized proteins then markedly progressed after 2 weeks of age and continued to increase as long as we could observe it until 9 weeks of age. These data indicated that protein isomerization is not restricted to long-lived proteins of aged brains, but is observed in as early as embryonic stage of PIMT-deficient mice. In order to identify the isomerized proteins, we developed the anti-isoAsp antibody using isoAsp containing tripeptide as an immunogen. Using this antibody, apparent molecular weight 43 kDa proteins (p43) were selectively detected in brain extract of PIMT-deficient mice. p43 proteins were detected from 4 weeks after birth and concentrated in synaptosomal fraction. The result suggests that modification of p43 protein may have a pathogenic role for the fatal epileptic seizure of PIMT-deficient mice. The identification of p43 protein should clarify this issue of PIMT-deficient mice.
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