The Journal of Neuroscience, November 28, 2007, 27(48):13092-13097; doi:10.1523/JNEUROSCI.4244-07.2007
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Neurobiology of Disease
Enhanced Accumulation of Phosphorylated
-Synuclein and Elevated β-Amyloid 42/40 Ratio Caused by Expression of the Presenilin-1
T440 Mutant Associated with Familial Lewy Body Disease and Variant Alzheimer's Disease
Hiroyuki Kaneko,1,4
Akiyoshi Kakita,2
Kensaku Kasuga,1,4
Hiroaki Nozaki,1,4
Atsushi Ishikawa,6
Akinori Miyashita,3
Ryozo Kuwano,3
Genta Ito,7
Takeshi Iwatsubo,7
Hitoshi Takahashi,5
Masatoyo Nishizawa,4
Osamu Onodera,1
Sangram S. Sisodia,8 and
Takeshi Ikeuchi1
Departments of 1Molecular Neuroscience, 2Pathology Neuroscience, and 3Bioresource Science Branch, Center for Bioresources, and Departments of 4Neurology and 5Pathology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan, 6Department of Neurology, Brain Disease Center Agano Hospital, Agano 959-2221, Japan, 7Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan, and 8Department of Neurobiology, The University of Chicago, Chicago, Illinois 60637
Correspondence should be addressed to Dr. Takeshi Ikeuchi, Department of Molecular Neuroscience, Brain Research Institute, Niigata University, 1 Asahimachi, Chuou-ku, Niigata 951-8585, Japan. Email: ikeuchi{at}bri.niigata-u.ac.jp
Mutations in the PSEN1 gene encoding presenilin 1 (PS1) are linked to a vast majority of pedigrees with early-onset, autosomal dominant forms of familial Alzheimer's disease (FAD). Lewy body (LB) pathology is frequently found in the brains of FAD patients harboring PSEN1 mutations. We recently reported on a novel PS1 mutation with the deletion of threonine at codon 440 (
T440) in a familial case diagnosed as having the neocortical type of dementia with LBs (DLB) and variant AD. In this report, we investigated the possible involvement of PS1
T440 mutation in aberrant
-synuclein accumulation. We established cell lines that stably express either wild-type (WT) PS1 or the FAD-linked PS1 H163R, E280A,
E9, and PS1
T440 mutants and now demonstrate that the expression of the PS1
T440 mutant led to a marked elevation in the ratio of β-amyloid (Aβ) 42/40 peptides in a conditioned medium. More importantly, we report here that the levels of phosphorylated
-synuclein increase in neuronal and non-neuronal cells expressing the PS1
T440 mutant compared with cells that express WT PS1 or the PS1 H163R and E280A variants that are not associated with LB pathology. This finding is consistent with our demonstration of elevated levels of phosphorylated
-synuclein in the detergent-resistant fraction prepared from a patient's brain with PS1
T440 mutation. These observations raise the intriguing suggestion that the mechanism(s) by which the PS1
T440 mutant causes DLB and variant AD are by enhancing the phosphorylation of
-synuclein and the ratio of Aβ42/40 peptides, respectively, in the brain.
Key words: presenilin;
-synuclein; β-amyloid; Lewy body;
-secretase; variant Alzheimer's disease
Received May 26, 2007;
revised Oct. 9, 2007;
accepted Oct. 10, 2007.
Correspondence should be addressed to Dr. Takeshi Ikeuchi, Department of Molecular Neuroscience, Brain Research Institute, Niigata University, 1 Asahimachi, Chuou-ku, Niigata 951-8585, Japan. Email: ikeuchi{at}bri.niigata-u.ac.jp