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ABSTRACT: AIMS: We investigated the pathological relevance of the "Aβ oligomer (AβO) cascade hypothesis" in 3xTg-AD mice. This study was also designed to elucidate the molecular mechanism underlying the toxic action of AβOs. MAIN METHODS: To target the extracellular AβOs in vivo, a monoclonal antibody specific for AβOs was developed using a novel method. Monoclonal 72D9 was intravenously administered to aged 3xTg-AD mice bearing the human AD pathology to investigate the relevance of the AβO cascade hypothesis. To further identify the AβO-binding molecule on the cell surface, small interfering RNA (siRNA) for sortilin was transfected into SH-SY5Y cells. The sortilin-dependent molecular mechanism underlying toxic action of AβOs and/or AβO endocytosis was also assessed in cultured cortical neurons forming synapses. KEY FINDINGS: The 72D9 immunotherapy of aged 3xTg-AD mice revealed that extracellular and intraneuronal AβOs are related, and that intraneuronal AβOs act upstream of tau. We also found that extracellular AβOs first act as a sortilin ligand, and then induce p75(NTF)-mediated apoptosis, endocytosis-induced attenuation of autophagy, or accumulation of AβOs in autophagosomes. SIGNIFICANCE: Taken together, these findings provide novel lines of evidence that sortilin governs the toxic action of extracellular AβOs, which affects the degradation and/or clearance of either intraneuronal AβOs or tau. Thus, therapeutic intervention targeting extracellular AβOs themselves or for preventing the interaction between intraneuronal AβOs and tau is a promising strategy to be developed for AD treatment.
Life sciences 05/2012; · 2.56 Impact Factor
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ABSTRACT: Here we report a female patient with elderly-onset cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). At age 71, she developed gait disturbance, followed by memory disturbance 1 year later. She had been treated for hypertension and diabetes mellitus for 19 years. There apparently was low penetrance of disease. Magnetic resonance imaging (MRI) findings showed typical features of CADASIL, and the R607C mutation was detected in exon 11 in NOTCH3. This case strongly indicates that CADASIL should be considered when typical findings are observed on MRI even in cases of elderly onset with multiple cerebrovascular risk factors.
Journal of stroke and cerebrovascular diseases: the official journal of National Stroke Association 02/2012; 21(2):143-5.
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ABSTRACT: Aβ immunotherapy brought us not only hope for but also led to greater attention to the mechanism underlying the clearance of amyloid β (Aβ), which provided fascinating insights into disease-relevant molecules such as toxic Aβ oligomers (AβOs). Accumulated lines of evidence indicate that AβOs play a causative role in the pathogenesis of Alzheimer's disease (AD), leading to a synaptic failure, which is considered a major cellular mechanism underlying the cognitive deficits in patients with mild cognitive impairment and AD. In this mini review, we focus on recent knowledge of the possible mechanisms underlying the action of the anti-Aβ antibody to clarify the toxic action of AβOs.
Journal of Gerontology & Geriatric Research. 01/2012;
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ABSTRACT: G(M1) -gangliosidosis is a fatal neurodegenerative disorder caused by deficiency of lysosomal acid β-galactosidase (β-gal). Accumulation of its substrate ganglioside G(M1) (G(M1) ) in lysosomes and other parts of the cell leads to progressive neurodegeneration, but underlying mechanisms remain unclear. Previous studies demonstrated an essential role for interaction of G(M1) with tropomyosin receptor kinase (Trk) receptors in neuronal growth, survival and differentiation. In this study we demonstrate accumulation of G(M1) in the cell-surface rafts and lysosomes of the β-gal knockout (β-gal-/-) mouse brain association with accumulation of Trk receptors and enhancement of its downstream signaling. Immunofluorescence and subcellular fractionation analysis revealed accumulation of Trk receptors in the late endosomes/lysosomes of the β-gal-/- mouse brain and their association with ubiquitin and p62. Administration of a chemical chaperone to β-gal-/- mouse expressing human mutant R201C protein resulted in a marked reduction of intracellular storage of G(M1) and phosphorylated Trk. These findings indicate that G(M1) accumulation in rafts causes activation of Trk signaling, which may participate in the pathogenesis of G(M1) -gangliosidosis.
Journal of Neurochemistry 05/2011; 118(3):399-406. · 4.06 Impact Factor
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Katsumi Higaki,
Linjing Li,
Udin Bahrudin,
Soichiro Okuzawa, Ayumi Takamuram,
Koichi Yamamoto,
Kaori Adachi,
Rubigilda C Paraguison,
Tomoko Takai,
Hiroki Ikehata,
Lika Tominaga,
Ichiro Hisatome,
Masami Iida,
Seiichiro Ogawa,
Junichiro Matsuda,
Haruaki Ninomiya,
Yasubumi Sakakibara,
Kousaku Ohno,
Yoshiyuki Suzuki,
Eiji Nanba
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ABSTRACT: β-Galactosidase deficiency is a group of lysosomal lipid storage disorders with an autosomal recessive trait. It causes two clinically different diseases, G(M1) -gangliosidosis and Morquio B disease. It is caused by heterogeneous mutations in the GLB1 gene coding for the lysosomal acid β-galactosidase. We have previously reported the chaperone effect of N-octyl-4-epi-β-valienamine (NOEV) on mutant β-galactosidase proteins. In this study, we performed genotype analyses of patients with β-galactosidase deficiency and identified 46 mutation alleles including 9 novel mutations. We then examined the NOEV effect on mutant β-galactosidase proteins by using six strains of patient-derived skin fibroblast. We also performed mutagenesis to identify β-galactosidase mutants that were responsive to NOEV and found that 22 out of 94 mutants were responsive. Computational structural analysis revealed the mode of interaction between human β-galactosidase and NOEV. Moreover, we confirmed that NOEV reduced G(M1) accumulation and ameliorated the impairments of lipid trafficking and protein degradation in β-galactosidase deficient cells. These results provided further evidence to NOEV as a promising chaperone compound for β-galactosidase deficiency.
Human Mutation 04/2011; 32(7):843-52. · 5.69 Impact Factor
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Yasuhito Wakasaya,
Takeshi Kawarabayashi,
Mitsunori Watanabe,
Yukiko Yamamoto-Watanabe, Ayumi Takamura,
Tomoko Kurata,
Tetsuro Murakami,
Koji Abe,
Kiyofumi Yamada,
Koichi Wakabayashi,
Atsushi Sasaki,
David Westaway,
Peter St George Hyslop,
Etsuro Matsubara,
Mikio Shoji
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ABSTRACT: TgTauP301L mice that overexpress the mutant human tauP301L present in FTDP-17 reproduce neurofibrillary tangles (NFTs), neuronal cell losses, memory disturbance, and substantial phenotypic variation. To demonstrate factors responsible for NFT formation and neuronal cell losses, sets of TgTauP301L for comparison with or without NFTs and neuronal cell losses were studied with oligonucleotide microarrays. Gene expressions were altered in biological pathways, including oxidative stress, apoptosis, mitochondrial fatty acid betaoxidation, inflammatory response pathway, and complement and coagulation cascade pathways. Among 24 altered genes, increased levels of apolipoprotein D (ApoD) and neuronal PAS domain protein 4 (Npas4) and decreased levels of doublecortin (DCX) and potassium channel, voltage-gated, shaker-related subfamily, β member 1 (Kcnab1) were found in the TgTauP301L with NFTs and neuronal cell losses, Alzheimer's brains, and tauopathy brains. Thus, many biological pathways and novel molecules are associated with NFT formation and neuronal cell losses in tauopathy brains.
Journal of Neuroscience Research 04/2011; 89(4):576-84. · 2.74 Impact Factor
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Ayumi Takamura,
Takeshi Kawarabayashi,
Tatsuki Yokoseki,
Masao Shibata,
Maho Morishima-Kawashima,
Yuko Saito,
Shigeo Murayama,
Yasuo Ihara,
Koji Abe,
Mikio Shoji,
Makoto Michikawa,
Etsuro Matsubara
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ABSTRACT: Monoclonal 2C3 specific to β-amyloid (Aβ) oligomers (AβOs) enabled us to test our hypothesis that the alteration of lipoprotein-Aβ interaction in the central nervous system (CNS) initiates and/or accelerates the cascade favoring Aβ assembly. Immunoprecipitation of frontal cortex employing 2C3 unequivocally detected soluble 4-, 8-, and 12-mers in Alzheimer's disease (AD) brains. Immunoblot analysis of the entorhinal cortex employing 2C3 revealed that the accumulation of soluble 12-mers precedes the appearance of neuronal loss or cognitive impairment and is enhanced as the Braak neurofibrially tangle (NFT) stages progress. The dissociation of soluble Aβ from lipoprotein particles occurs in cerebrospinal fluid (CSF), and the presence of lipoprotein-free oligomeric 2C3 conformers (4- to 35-mers) was evident, which mimic CNS environments. Such CNS environments may strongly affect conformation of soluble Aβ peptides, resulting in the conversion of soluble Aβ(42) monomers into soluble Aβ(42) assembly. The findings suggest that functionally declined lipoproteins may accelerate the generation of metabolic conditions leading to higher levels of soluble Aβ(42) assembly in the CNS.
Journal of Neuroscience Research 03/2011; 89(6):815-21. · 2.74 Impact Factor
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Ayumi Takamura,
Yasuhide Okamoto,
Takeshi Kawarabayashi,
Tatsuki Yokoseki,
Masao Shibata,
Akihiko Mouri,
Toshitaka Nabeshima,
Hui Sun,
Koji Abe,
Tsuneo Urisu,
Naoki Yamamoto,
Mikio Shoji,
Katsuhiko Yanagisawa,
Makoto Michikawa,
Etsuro Matsubara
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ABSTRACT: Several lines of evidence indicate that memory loss represents a synaptic failure caused by soluble amyloid β (Aβ) oligomers. However, the pathological relevance of Aβ oligomers (AβOs) as the trigger of synaptic or neuronal degeneration, and the possible mechanism underlying the neurotoxic action of endogenous AβOs remain to be determined.
To specifically target toxic AβOs in vivo, monoclonal antibodies (1A9 and 2C3) specific to them were generated using a novel design method. 1A9 and 2C3 specifically recognize soluble AβOs larger than 35-mers and pentamers on Blue native polyacrylamide gel electrophoresis, respectively. Biophysical and structural analysis by atomic force microscopy (AFM) revealed that neurotoxic 1A9 and 2C3 oligomeric conformers displayed non-fibrilar, relatively spherical structure. Of note, such AβOs were taken up by neuroblastoma (SH-SY5Y) cell, resulted in neuronal death. In humans, immunohistochemical analysis employing 1A9 or 2C3 revealed that 1A9 and 2C3 stain intraneuronal granules accumulated in the perikaryon of pyramidal neurons and some diffuse plaques. Fluoro Jade-B binding assay also revealed 1A9- or 2C3-stained neurons, indicating their impending degeneration. In a long-term low-dose prophylactic trial using active 1A9 or 2C3 antibody, we found that passive immunization protected a mouse model of Alzheimer's disease (AD) from memory deficits, synaptic degeneration, promotion of intraneuronal AβOs, and neuronal degeneration. Because the primary antitoxic action of 1A9 and 2C3 occurs outside neurons, our results suggest that extracellular AβOs initiate the AD toxic process and intraneuronal AβOs may worsen neuronal degeneration and memory loss.
Now, we have evidence that HMW-AβOs are among the earliest manifestation of the AD toxic process in mice and humans. We are certain that our studies move us closer to our goal of finding a therapeutic target and/or confirming the relevance of our therapeutic strategy.
Molecular Neurodegeneration 03/2011; 6(1):20. · 4.28 Impact Factor
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Yusuke Seino,
Takeshi Kawarabayashi,
Yasuhito Wakasaya,
Mitsunori Watanabe, Ayumi Takamura,
Yukiko Yamamoto-Watanabe,
Tomoko Kurata,
Koji Abe,
Masaki Ikeda,
David Westaway,
Tetsuro Murakami,
Peter St George Hyslop,
Etsuro Matsubara,
Mikio Shoji
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ABSTRACT: In Alzheimer's disease, Aβ deposits are considered the initial cardinal events that induce tauopathy secondarily. However, the relationship between Aβ amyloidosis and tauopathy has not been determined in detail. We produced double transgenic mice, 2×TgTau(+/-) APP(+/-) , by mating Tg2576 mice that exhibit Aβ amyloidosis and TgTauP301L mice that show tauopathy, and statistically analyzed the effect of Aβ accumulation on tauopathy. There was no significant difference in theprogression of Aβ accumulation among 2×TgTau(+/-) APP(+/-) and 1×TgTau(-/-) APP(+/-) , and tau accumulation among 2×TgTau(+/-) APP(+/-) and 1×Tg Tau(+/-) APP(-/-) . The appearance rates of phosphorylated tau developing in neurons and processes were significantly accelerated in 2×TgTau(+/-) APP(+/-) mice compared with those in 1×TgTau(+/-) APP(-/-) mice at 23 months of age. Accumulation of phosphorylated and confomationally altered tau and GSK3β in neuronal processes was accelerated in the white matter in 2×TgTau(+/-) APP(+/-) . The level of phosphorylated tau in the sarkosyl-insoluble fraction was increased in 2×TgTau(+/-) APP(+/-) brains compared with that in 1×TgTau(+/-) APP(-/-) brains. Thus, Aβ amyloid partially enhances tauopathy through accumulation of insoluble, phosphorylated, and conformationally changed tau in neuronal cytoplasm and processes in the late stage.
Journal of Neuroscience Research 10/2010; 88(16):3547-54. · 2.74 Impact Factor
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ABSTRACT: Glioma includes astrocytoma, oligodendroglioma, ependymoma and glioblastoma. We previously reported the epigenetic silencing of paternally expressed gene 3 (PEG3) in glioma cell lines. In this study, we investigated methylation of an exonic CpG island in the promoter region and the expression of PEG3 gene in 20 glioma and 5 non-tumor tissue samples. We found wide variations in the methylation level. Hypomethylaiton and hypermethylation was found in 3 and 4 glioma tissue samples, respectively. Monoallelic expression, which is an evidence of an imprinted gene, was maintained in eight out of nine informative cases which have T/C polymorphisms in PEG3. The lower gene expression, which suggested epigenetic silencing of PEG3, was confirmed statistically in glioblastoma using quantitative reverse-transcription polymerase chain reaction. Interestingly, we found higher expression of PEG3 in two out of three oligodendrogliomas. A negative correlation between the methylation level and gene expression was shown by regression analysis. These results suggest that the abnormal regulation of PEG3 is associated with several glioma subtypes and that it plays an important role in tumorigenesis.
Proceedings of the Japan Academy Ser B Physical and Biological Sciences 02/2009; 85(4):157-65. · 2.77 Impact Factor
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Yasuhito Wakasaya,
Mitsunori Watanabe,
Masahiko Tomiyama,
Chieko Suzuki,
Mandy Jackson,
Masahiro Fujimuro,
Tamaki Kimura,
Yusuke Seino,
Takeshi Kawarabayashi,
Yukiko Yamamoto-Watanabe,
Etsuro Matsubara,
Ikumi Shirahama, Ayumi Takamura,
Naoko Nakahata,
Mikio Shoji
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ABSTRACT: A 55-year-old man underwent radiation therapy due to malignant lymphoma of the neck. Eight years after the therapy he developed tetanus. It appears that the radiation therapy resulted in mandibular necrosis, and that this lesion may have been the infectious focus of tetanus. Treatment with penicillin G was very effective in the acute stage, and chronic administration of metronidazole prevented relapse of the disease. However in spite of injections of tetanus toxoid, symptoms of tetanus returned when the administration of metronidazole was discontinued because the infectious focus could not be completely removed. This is the first report of chronic relapsing tetanus associated with radiation-induced mandibular osteomyelitis, and demonstrates that tetanus can occur due to mandibular focus but the chronic administration of metronidazole can prevent relapse.
Internal Medicine 02/2009; 48(15):1311-3. · 0.94 Impact Factor
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ABSTRACT: We performed a cell transplantation study to treat the brain involvement in lysosomal storage diseases. We used acid beta-galactosidase knock-out mice (BKO) from C57BL/6 as recipients. To minimize immune responses, we used cells derived from transgenic mice of C57BL/6 overexpressing the normal human beta-galactosidase. Fetal brain cells (FBC), bone marrow-derived mesenchymal stem cells (MSC), and mixed FBC and MSC cells were prepared and injected into the ventricle of newborn BKO mouse brain. The mice were examined at 1, 2, 4, and 8 weeks and 6 months after injection. In each experiment, the injected cells migrated into the whole brain effectively and survived for at least 8 weeks. Decrease in ganglioside GM1 level was also observed. FBC could survive for 6 months in recipient brain. However, the number of transplanted FBC decreased. In the brains of MSC- or mixed cell-treated mice, no grafted cells could be found at 6 months. To achieve sufficient long-term effects on the brain, a method of steering the immune response away from cytotoxic responses or of inducing tolerance to the products of therapeutic genes must be developed.
Brain & development 01/2009; 31(10):717-24. · 1.74 Impact Factor
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ABSTRACT: G(M1)-gangliosidosis is an autosomal recessive lysosomal lipid storage disorder, caused by mutations of the lysosomal beta-galactosidase (beta-gal) and results in the accumulation of G(M1). The underlying mechanisms of neurodegeneration are poorly understood. Here we demonstrate increased autophagy in beta-gal-deficient (beta-gal(-/-)) mouse brains as evidenced by elevation of LC3-II and beclin-1 levels. Activation of autophagy in the beta-gal(-/-) brain was found to be accompanied with enhanced Akt-mTOR and Erk signaling. In addition, the mitochondrial cytochrome c oxidase activity was significantly decreased in brains and cultured astrocytes from beta-gal(-/-) mouse. Mitochondria isolated from beta-gal(-/-) astrocytes were morphologically abnormal and had a decreased membrane potential. These cells were more sensitive to oxidative stress than wild type cells and this sensitivity was suppressed by ATP, an autophagy inhibitor 3-methyladenine and a pan-caspase inhibitor z-VAD-fmk. These results suggest activation of autophagy leading to mitochondrial dysfunction in the brain of G(M1)-gangliosidosis.
Biochemical and Biophysical Research Communications 04/2008; 367(3):616-22. · 2.48 Impact Factor
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ABSTRACT: Hamartomatous brain lesions are a hallmark of brain pathology of tuberous sclerosis complex (TSC). To elucidate the mechanism of tumor development in the brain of TSC, we identified NADE (p75NTR-associated cell death executor) as an interactor for TSC1 gene product hamartin using a yeast two-hybrid system. In a pull-down assay, endogenous NADE was purified with the immobilized coiled-coil domain (CCD) of hamartin from the PC12h cell lysate. Immunofluorescence and immunoprecipitation confirmed the interaction of hamartin and NADE in cultured neurons and mouse brain lysate. Hamartin constitutively associated with NADE to prevent its proteasomal degradation. Suppression of hamartin with TSC1 small interfering RNA (siRNA) caused reduction of NADE and failed to lead to NGF-induced apoptosis in PC12h cells. These results indicate that hamartin binds to NADE to regulate neuronal cell function and loss of this association is likely to contribute to the brain pathology in TSC.
Molecular and Cellular Neuroscience 06/2007; 35(1):100-8. · 3.66 Impact Factor
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ABSTRACT: GM1-gangliosidosis is an autosomal recessive lysosomal lipid storage disorder, caused by mutations of the lysosomal β-galactosidase (β-gal) and results in the accumulation of GM1. The underlying mechanisms of neurodegeneration are poorly understood. Here we demonstrate increased autophagy in β-gal-deficient (β-gal−/−) mouse brains as evidenced by elevation of LC3-II and beclin-1 levels. Activation of autophagy in the β-gal−/− brain was found to be accompanied with enhanced Akt–mTOR and Erk signaling. In addition, the mitochondrial cytochrome c oxidase activity was significantly decreased in brains and cultured astrocytes from β-gal−/− mouse. Mitochondria isolated from β-gal−/− astrocytes were morphologically abnormal and had a decreased membrane potential. These cells were more sensitive to oxidative stress than wild type cells and this sensitivity was suppressed by ATP, an autophagy inhibitor 3-methyladenine and a pan-caspase inhibitor z-VAD-fmk. These results suggest activation of autophagy leading to mitochondrial dysfunction in the brain of GM1-gangliosidosis.
Biochemical and Biophysical Research Communications.
