Publications (2)11.09 Total impact
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Article: A new amyloid beta variant favoring oligomerization in Alzheimer's-type dementia.
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ABSTRACT: Soluble oligomers of amyloid beta (Abeta), rather than amyloid fibrils, have been proposed to initiate synaptic and cognitive dysfunction in Alzheimer's disease (AD). However, there is no direct evidence in humans that this mechanism can cause AD. Here, we report a novel amyloid precursor protein (APP) mutation that may provide evidence to address this question. A Japanese pedigree showing Alzheimer's-type dementia was examined for mutations in APP, PSEN1, and PSEN2. In addition, 5,310 Japanese people, including 2,121 patients with AD, were screened for the novel APP mutation. The pathogenic effects of this mutation on Abeta production, degradation, aggregation, and synaptotoxicity were also investigated. We identified a novel APP mutation (E693Delta) producing variant Abeta lacking gulutamate-22 (E22Delta) in Japanese pedigrees showing Alzheimer's-type dementia and AD. Although the secretion of total Abeta was markedly reduced by this mutation, the variant Abeta was more resistant to proteolytic degradation. The mutant peptides showed the unique aggregation property of enhanced oligomerization but no fibrillization, and inhibited hippocampal long-term potentiation more potently than wild-type peptide in rats in vivo. Consistent with the nonfibrillogenic property of the variant Abeta, a very low amyloid signal was observed in the patient's brain on positron emission tomography using Pittsburgh compound-B. The E693Delta mutation has been suggested as a cause of dementia because of enhanced formation of synaptotoxic Abeta oligomers. Our findings may provide genetic validation in humans for the emerging hypothesis that the synaptic and cognitive impairment in AD is primarily caused by soluble Abeta oligomers.Annals of Neurology 04/2008; 63(3):377-87. · 11.09 Impact Factor -
Article: A new amyloid β variant favoring oligomerization in Alzheimer's-type dementia
Annals of Neurology - ANN NEUROL. 01/2008; 63(3):377-387. -
Article: ＜Symposium IV＞Oligomeric Aβ is the sole culprit molecule to cause Alzheimer's disease?
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ABSTRACT: Alzheimer's disease (AD) is the major and common disease usually for aged people to show progressive neurodegenerative disorder with the dementia. Amyloid-beta （also β-protein and referred here to as Aβ） is a wellestablished seminal peptide in AD that is produced from the amyloid precursor protein （APP） by consecutive digestions with β-secretase of BACE and gamma-secretase of the presenilin complex. Abnormal cerebral accumulation of Aβ such as insoluble fi brils in senile plaques and cerebral amyloid angiopathy （CAA） are observed as a neuropathological hallmark of AD. In contrast to such insoluble fi brillary Aβ, a soluble oligomeric complex is discussed as ADDLs, Aβ oligomer, low-n oligomer Aβ, Aβ*56 or so. Despite their diff erent names, it is proposed as the current hypothesis that oligomeric Aβ is the direct molecule to cause synaptic toxicity and cognitive dysfunction in the early stages of AD. We identifi ed a novel APP mutation （E693delta; referred to as the Osaka mutation） in a pedigree with probable AD resulting in a variant Aβ lacking glutamate at position 22. Based on theoretical prediction and in vitro studies on synthetic mutant Aβ peptides, the mutated Aβ peptide showed a unique aggregation property of enhanced oligomerization but no fi brillization. This was further confi rmed by PiB-PET analysis on the proband patient. Collectively together, we conclude that the Osaka mutation is the fi rst human evidence for the hypothesis that oligomeric Aβ is involved in AD.
