Alzheimer Disease: Ihara Y

Ihara Y. · Department of Neuropathology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Tokyo 113, Japan. · J Alzheimers Dis. · Pubmed #16914860 No free full text.

Abstract: Neurofibrillary tangles, one of the hallmarks of Alzheimer's disease, had been a target of modern neuropathology based on electron microscopy. In 1960s their unit fibrils were found to be paired helical filaments (PHF), the unique appearance of which attracted many researchers to their nature. In the late 1970s, a keen interest in their constituents at the molecular levels had increasingly grown, but electron microscopic approach failed to address the issue. I describe here what was going on at the turning point when electron microscopic study yielded immunocytochemical approach and direct characterization by isolation, with some emphasis on the situation in Japan. Personal memories are provided about Dr Selkoe's lab (1981-1982) in Mailman Research Center, Belmont, Boston, where we encountered a series of remarkable properties of PHF. How insolubility of PHF, and smearing on the blot was found is described.

Hamaguchi T, Kitamoto T, Sato T, Mizusawa H, Nakamura Y, Noguchi M, Furukawa Y, Ishida C, Kuji I, Mitani K, Murayama S, Kohriyama T, Katayama S, Yamashita M, Yamamoto T, Udaka F, Kawakami A, Ihara Y, Nishinaka T, Kuroda S, Suzuki N, Shiga Y, Arai H, Maruyama M, Yamada M. · Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Science, Takara-machi, Kanazawa, Japan. · Neurology. · Pubmed #15728285 No free full text.

Abstract: BACKGROUND: No method for the clinical diagnosis of MM2-type sporadic Creutzfeldt-Jakob disease (sCJD) has been established except for pathologic examination. OBJECTIVE: To identify a reliable marker for the clinical diagnosis of MM2-type sCJD. METHODS: CSF, EEG, and neuroimaging studies were performed in eight patients with MM2-type sCJD confirmed by neuropathologic, genetic, and western blot analyses. RESULTS: The eight cases were pathologically classified into the cortical (n = 2), thalamic (n = 5), and combined (corticothalamic) (n = 1) forms. The cortical form was characterized by late-onset, slowly progressive dementia, cortical hyperintensity signals on diffusion-weighted imaging (DWI) of brain, and elevated levels of CSF 14-3-3 protein. The thalamic form showed various neurologic manifestations including dementia, ataxia, and pyramidal and extrapyramidal signs with onset at various ages and relatively long disease duration. Characteristic EEG and MRI abnormalities were almost absent. However, all four patients examined with cerebral blood flow (CBF) study using SPECT showed reduction of the CBF in the thalamus as well as the cerebral cortex. The combined form had features of both the cortical and the thalamic forms, showing cortical hyperintensity signals on DWI and hypometabolism of the thalamus on [18F]2-fluoro-2-deoxy-d-glucose PET. CONCLUSION: For the clinical diagnosis of MM2-type sporadic Creutzfeldt-Jakob disease, cortical hyperintensity signals on diffusion-weighted MRI are useful for the cortical form and thalamic hypoperfusion or hypometabolism on cerebral blood flow SPECT or [18F]2-fluoro-2-deoxy-d-glucose PET for the thalamic form.

Morishima-Kawashima M, Ihara Y. · Department of Neuropathology, Faculty of Medicine, University of Tokyo, Tokyo, Japan. · J Neurosci Res. · Pubmed #12391602 No free full text.

Abstract: Research on the molecular pathogenesis of Alzheimer's disease (AD) has made great strides over the last decade. This progress is the result of protein chemical analysis of two extracellular and intracellular fibrillary lesions in AD brain conducted during the 1980s, which identified beta-amyloid protein (A beta) and tau as their major components, respectively. Linkage analysis of familial AD identified four responsible genes: three causative genes (beta-amyloid precursor protein, presenilin 1, and presenilin 2) and one susceptibility gene (apolipoprotein E epsilon 4). All those genes causing and predisposing to AD exhibit a common phenotype: an increased production of A beta 42, a longer, more amyloidogenic A beta species, and/or its enhanced deposition. This observation was substantiated when presenilins were shown to be directly involved in A beta production. Whereas A beta deposition is relatively specific for AD, tau deposition is observed in various neurodegenerative diseases and is assumed to be intimately associated with neuronal loss. The genetic analysis of frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) revealed the presence of mutations in the tau gene in affected members. Thus, tau can lead to intracellular tau deposits and neuronal loss, although the mechanism remains to be clarified. Taken together, A beta might exert neurotoxicity through tau, leading to neuronal loss in the AD brain.

Ihara Y. · Department of Neuropathology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033. · Seikagaku. · Pubmed #12138705 No free full text.

This publication has no abstract.

Morishima-Kawashima M, Ihara Y. · Department of Neuropathology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033. · Seikagaku. · Pubmed #11831025 No free full text.

This publication has no abstract.

Morishima-Kawashima M, Saido TC, Ihara Y. · · Tanpakushitsu Kakusan Koso. · Pubmed #11579581 No free full text.

This publication has no abstract.

Ihara Y. · No affiliation provided · Nippon Ronen Igakkai Zasshi. · Pubmed #11109833 No free full text.

This publication has no abstract.

Shoji M, Kuwano R, Asada T, Imagawa M, Higuchi S, Urakami K, Arai H, Ihara Y, Anonymous00237, Anonymous00238. · Department of Neurology, Neuroscience, Biophysiological Science, Okayama University Graduate School of Medicine and Dentistry. · Rinsho Shinkeigaku. · Pubmed #15782613 No free full text.

Abstract: To clarify the risk and associated genes of Alzheimer's disease by genome-wide screening, a Japanese study group was organized in 2000 under Yasuo Ihara, Tokyo University, supported by a Grant-in-Aid for Science Research on Priority Areas (C) -Advanced Brain Science Project from Ministry of Education, Culture, Sports, Science and Technology, Japan. This is the first Japanese consortium study under permission of the ethical committees of the enrolled institutes based on the ethics guidelines for human genome/gene analysis research, Ministry of Education, Culture, Sports, Science and Technology Ministry of Health, Labor and Welfare Ministry of Economy, Trade and Industry. In this project, 2,000 genome samples from patients with Alzheimer's disease, 2,000 control subjects, and 200 siblings affected with Alzheimer's disease are collected and analyzed. For this purpose, it is necessary to analyze samples from accurately diagnosed Alzheimer patients and controls using standard criteria for diagnosis and neuropsychological evaluation, which have been confirmed by an evidence-based studying a Japanese population. Here, we propose criteria for the diagnosis and clinical assessment of Alzheimer's disease. This proposal consists of a definition of Alzheimer's disease based on recent advances in research, diagnostic criteria based on DSM-IV, NINCDS-ADRDA and ICD-10, exclusion criteria for other dementia disorders, routine and detailed tests for neuropsychological and laboratory evaluations, criteria for neuroimaging and biomarkers, definitive diagnostic criteria and classification of clinical subtypes.

Takei N, Miyashita A, Tsukie T, Arai H, Asada T, Imagawa M, Shoji M, Higuchi S, Urakami K, Kimura H, Kakita A, Takahashi H, Tsuji S, Kanazawa I, Ihara Y, Odani S, Kuwano R, Anonymous00084. · Department of Molecular Genetics, Bioresource Science Branch, Center for Bioresources, Brain Research Institute, Niigata University, Niigata 951-8585, Japan. · Genomics. · Pubmed #19442637 No free full text.

Abstract: The epsilon4 allele of APOE is a well-characterized genetic risk factor for late-onset Alzheimer disease (LOAD). Nevertheless, using high-density single nucleotide polymorphisms (SNPs), there have only been a few studies involving genetic association and linkage disequilibrium (LD) analyses of in and around the APOE. Here, we report fine mapping of a genomic region (about 200 kb) including the APOE in Japanese using 260 SNPs (mean intermaker distance, 0.77 kb). A case-control study demonstrated that 36 of these SNPs exhibited significance after adjustment for multiple testing. These SNPs are located in a genomic region including four genes, PVRL2, TOMM40, APOE and APOC1. Recombination rate estimation revealed that the associated region is firmly sandwiched between two recombination hotspots. Strong LD between these SNPs was observed (mean |D'|=0.914). These data suggest that the three genes other than APOE, i.e. PVRL2, TOMM40 and APOC1, could also yield a predisposition to LOAD.

Shimojo M, Sahara N, Mizoroki T, Funamoto S, Morishima-Kawashima M, Kudo T, Takeda M, Ihara Y, Ichinose H, Takashima A. · Laboratory for Alzheimer's Disease, RIKEN Brain Science Institute, Wako-shi, Saitama 351-0198, Japan. · J Biol Chem. · Pubmed #18430735 links to  free full text

Abstract: Presenilin (PS)/gamma-secretase-mediated intramembranous proteolysis of amyloid precursor protein produces amyloid beta (Abeta) peptides in which Abeta species of different lengths are generated through multiple cleavages at the gamma-, zeta-, and epsilon-sites. An increased Abeta42/Abeta40 ratio is a common characteristic of most cases of familial Alzheimer disease (FAD)-linked PS mutations. However, the molecular mechanisms underlying amyloid precursor protein proteolysis leading to increased Abeta42/Abeta40 ratios still remain unclear. Here, we report our findings on the enzymatic analysis of gamma-secretase derived from I213T mutant PS1-expressing PS1/PS2-deficient (PS(-/-)) cells and from the brains of I213T mutant PS1 knock-in mice. Kinetics analyses revealed that the FAD mutation reduced de novo Abeta generation, suggesting that mutation impairs the total catalytic rate of gamma-secretase. Analysis of each Abeta species revealed that the FAD mutation specifically reduced Abeta40 levels more drastically than Abeta42 levels, leading to an increased Abeta42/Abeta40 ratio. By contrast, the FAD mutation increased the generation of longer Abeta species such as Abeta43, Abeta45, and >Abeta46. These results were confirmed by analyses of gamma-secretase derived from I213T knock-in mouse brains, in which the reduction of de novo Abeta generation was mutant allele dose-dependent. Our findings clearly indicate that the mechanism underlying the increased Abeta42/Abeta40 ratio observed in cases of FAD mutations is related to the differential inhibition of gamma-site cleavage reactions, in which the reaction producing Abeta40 is subject to more inhibition than that producing Abeta42. Our results also provide novel insight into how enhancing the generation of longer Abetas may contribute to Alzheimer disease onset.

Ihara Y. · Planning office, Department of Life and Medical Sciences, Doshisha University. · Rinsho Shinkeigaku. · Pubmed #18210830 No free full text.

Abstract: It is now one hundred years since the first publication on Alzheimer's disease by Alois Alzheimer. Since 1980's deciphering Alzheimer's disease has greatly quickened, and investigators currently think that it becomes possible to treat or prevent Alzheimer's disease that is the major socioeconomical concern in all the developed countries. We owe this current understanding to three major advances, development of Abeta vaccination and gamma-modifiers, and a series of large-scale prospective studies. J-ADNI is being undertaken from this fall, which follows the protocols by US-ADNI. The major goal is establishment of the surrogate marker for AD based on MRI data. In addition, this project would provide more clarification of MCI and dementia themselves and their differentiation. In view of the temporal profile of Alzheimer disease, it is essential to detect at-risk people who carry senile plaques (amyloid) but are cognitively normal. Even in MCI more than 50% of neurons in layer 2 is already lost. For such very early detection of at-risk people biomaker would be helpful. According to sink hypothesis, there is chemical equilibrium of Abeta between in plasma, CSF and senile plaques. Thus what we should do is to find insoluble Abeta-specific fragments or modifications in the peripheral blood.

Miyashita A, Arai H, Asada T, Imagawa M, Matsubara E, Shoji M, Higuchi S, Urakami K, Kakita A, Takahashi H, Toyabe S, Akazawa K, Kanazawa I, Ihara Y, Kuwano R, Anonymous00354. · Center for Bioresources, Brain Research Institute, Niigata University, Niigata, Japan. · Hum Mol Genet. · Pubmed #17761686 links to  free full text

Abstract: Alzheimer's disease (AD), the most common form of dementia in the elderly, was found to exhibit a trend toward a higher risk in females than in males through epidemiological studies. Therefore, we hypothesized that gender-related genetic risks could exist. To reveal the ones for late-onset AD (LOAD), we extended our previous genetic work on chromosome 10q (genomic region, 60-107 Mb), and single nucleotide polymorphism (SNP)-based genetic association analyses were performed on the same chromosomal region, where the existence of genetic risk factors for plasma Abeta42 elevation in LOAD was implied on a linkage analysis. Two-step screening of 1140 SNPs was carried out using a total of 1408 subjects with the APOE-epsilon3*3 genotype: we first genotyped an exploratory sample set (LOAD, 363; control, 337), and then genotyped some associated SNPs in a validation sample set (LOAD, 336; control, 372). Seven SNPs, spanning about 38 kb, in intron 9 of CTNNA3 were found to show multiple-hit association with LOAD in females, and exhibited more significant association on Mantel-Haenszel test (allelic P-values(MH-F) = 0.000005945-0.0007658). Multiple logistic regression analysis of a total of 2762 subjects (LOAD, 1313; controls, 1449) demonstrated that one of the seven SNPs directly interacted with the female gender, but not with the male gender. Furthermore, we found that this SNP exhibited no interaction with the APOE-epsilon4 allele. Our data suggest that CTNNA3 may affect LOAD through a female-specific mechanism independent of the APOE-epsilon4 allele.

Iwatsubo T, Ihara Y, Kanazawa I. · Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo 113-0033, Japan. · Nat Med. · Pubmed #16829946 No free full text.

This publication has no abstract.

Kuwano R, Miyashita A, Arai H, Asada T, Imagawa M, Shoji M, Higuchi S, Urakami K, Kakita A, Takahashi H, Tsukie T, Toyabe S, Akazawa K, Kanazawa I, Ihara Y, Anonymous00173. · Genome Science Branch, Center for Bioresource-Based Researches, Brain Research Institute, Niigata University, Niigata, Japan. · Hum Mol Genet. · Pubmed #16740596 links to  free full text

Abstract: The apolipoprotein E (APOE) gene has been consistently shown to be a major genetic risk factor; however, all cases of Alzheimer's disease (AD) cannot be attributed to the epsilon4 variant of APOE, because about half of AD patients have the APOE-epsilon3*3 genotype. To identify an additional genetic risk factor(s), we performed large-scale single nucleotide polymorphism (SNP)-based association analysis of 1526 late-onset AD patients and 1666 control subjects in a Japanese population. We prepared two independent sets consisting of exploratory and validation samples, respectively, with only the APOE-epsilon3*3 genotype, and first carried out genotyping for the exploratory set with 1206 SNPs in the region between 60 and 107 Mb on chromosome 10q that is implicated by linkage studies as containing an AD susceptibility locus. Thirty-five SNPs that showed significant values (P<0.01) were followed-up to detect any association with the validation samples. Finally, six SNPs exhibited replicated significant associations (P=0.000035-0.00048) on meta-analysis of both sets. These SNPs were clustered in a locus spanning 220 kb at genomic position 101 Mb, and three of the six SNPs were located in the dynamin-binding protein (DNMBP) gene. Quantitative real-time RT-PCR analysis demonstrated that neuropathologically confirmed AD brains exhibit a significant reduction of DNMBP mRNA compared with age-matched ones (P<0.0169). Thus, we confirmed the association of DNMBP with AD individuals with the APOE-epsilon3*3 genotype or lacking the epsilon4 allele, and DNMBP may be one of the susceptibility genes for AD.

Miyasaka T, Watanabe A, Saito Y, Murayama S, Mann DM, Yamazaki M, Ravid R, Morishima-Kawashima M, Nagashima K, Ihara Y. · Department of Neuropathology, Faculty of Medicine, University of Tokyo, Tokyo, Japan. · J Neuropathol Exp Neurol. · Pubmed #16106214 No free full text.

Abstract: Neurofibrillary tangles (NFTs) and neuropil threads (NTs), the major hallmark of Alzheimer disease (AD), are composed of the microtubule-associated protein tau that has undergone posttranslational modifications, including deamidation and isomerization on asparaginyl or aspartyl residues. Because such modifications represent protein aging, we generated 2 antibodies, TM4, specific for Asp-387 of tau, and iD387, specific for isoAsp-387 of tau, to investigate the evolution of NFTs and NTs. On Western blots of Sarkosyl-insoluble fractions, TM4 strongly labeled paired helical filament-tau (PHF-tau), whereas iD387 preferentially labeled PHF smear. Thus, it is reasonable to postulate that TM4-labeled tau (unmodified tau species) represents more recent deposition, and iD387-labeled tau (modified tau species) represents earlier deposition. Unexpectedly, TM4 immunostained even highly evolved NFTs, suggesting that deposition of newly produced tau continues until neuronal death. iD387 labeled the whole profile of NFTs up to distal dendritic branches, whereas TM4 staining was localized to particular portions of NFTs in proximal dendrites and neuronal perikarya. In NTs, TM4 preferentially labeled the outer portion, whereas iD387 intensely labeled the core portion. Based on TM4-positive NFT counts and total NFT counts, we speculate that NFTs in the human hippocampus are produced at a constant rate irrespective of the disease stage.

Nakaya Y, Yamane T, Shiraishi H, Wang HQ, Matsubara E, Sato T, Dolios G, Wang R, De Strooper B, Shoji M, Komano H, Yanagisawa K, Ihara Y, Fraser P, St George-Hyslop P, Nishimura M. · Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan. · J Biol Chem. · Pubmed #15764596 links to  free full text

Abstract: Familial Alzheimer disease-causing mutations in the presenilins increase production of longer pathogenic amyloid beta-peptides (A beta(42/43)) by altering gamma-secretase activity. The mechanism underlying this effect remains unknown, although it has been proposed that heteromeric macromolecular complexes containing presenilins mediate gamma-secretase cleavage of the amyloid beta-precursor protein. Using a random mutagenesis screen of presenilin-1 (PS1) for PS1 endoproteolysis-impairing mutations, we identified five unique mutants, including R278I-PS1 and L435H-PS1, that exclusively generated a high level of A beta43, but did not support physiological PS1 endoproteolysis or A beta40 generation. These mutants did not measurably alter the molecular size or subcellular localization of PS1 complexes. Pharmacological studies indicated that the up-regulation of activity for A beta43 generation by these mutations was not further enhanced by the difluoroketone inhibitor DFK167 and was refractory to inhibition by sulindac sulfide. These results suggest that PS1 mutations can lead to a wide spectrum of changes in the activity and specificity of gamma-secretase and that the effects of PS1 mutations and gamma-secretase inhibitors on the specificity are mediated through a common mechanism.

Uchida Y, Ohshima T, Sasaki Y, Suzuki H, Yanai S, Yamashita N, Nakamura F, Takei K, Ihara Y, Mikoshiba K, Kolattukudy P, Honnorat J, Goshima Y. · Department of Molecular Pharmacology and Neurobiology, Yokohama City University Graduate School of Medicine, Yokohama 236-0004, Japan. · Genes Cells. · Pubmed #15676027 No free full text.

Abstract: Collapsin response mediating protein-2 (CRMP2) has been identified as an intracellular protein mediating Semaphorin3A (Sema3A), a repulsive guidance molecule. In this study, we demonstrate that cyclin-dependent kinase 5 (Cdk5) and glycogen synthase kinase 3beta (GSK3beta) plays a critical role in Sema3A signalling. In In vitro kinase assay, Cdk5 phosphorylated CRMP2 at Ser522, while GSK3beta did not induce any phosphorylation of CRMP2. Phosphorylation by GSK3beta was exclusively observed in Cdk5-phosphorylated CRMP2, but barely in CRMP2T509A. These results indicate that Cdk5 primarily phosphorylates CRMP2 at Ser522 and GSK3beta secondarily phosphorylates at Thr509. The dual-phosphorylated CRMP2, but not non-phosphorylated or single-phosphorylated CRMP2, is recognized with the antibody 3F4, which is highly reactive with the neurofibrillary tangles of Alzheimer's disease. 3F4 recognized the CRMP2 in the wild-type but not cdk5-/- mouse embryonic brain lysates. The phosphorylation of CRMP2 at Ser522 caused reduction of its affinity to tubulin. In dorsal root ganglion neurones, Sema3A stimulation enhanced the levels of the phosphorylated form of CRMP2 detected by 3F4. Over-expression of CRMP2 mutant substituting either Ser522 or Thr509 to Ala attenuates Sema3A-induced growth cone collapse response. These results suggest that the sequential phosphorylation of CRMP is an important process of Sema3A signalling and the same mechanism may have some relevance to the pathological aggregation of the microtubule-associated proteins.

Qi-Takahara Y, Morishima-Kawashima M, Tanimura Y, Dolios G, Hirotani N, Horikoshi Y, Kametani F, Maeda M, Saido TC, Wang R, Ihara Y. · Department of Neuropathology, Faculty of Medicine, University of Tokyo, Tokyo 113-0033, Japan. · J Neurosci. · Pubmed #15647487 links to  free full text

Abstract: Gamma-cleavage of beta-amyloid precursor protein (APP) in the middle of the cell membrane generates amyloid beta protein (Abeta), and epsilon-cleavage, approximately 10 residues downstream of the gamma-cleavage site, releases the APP intracellular domain (AICD). A significant link between generation of Abeta and AICD and failure to detect AICD41-99 led us to hypothesize that epsilon-cleavage generates longer Abetas, which are then processed to Abeta40/42. Using newly developed gel systems and an N-end-specific monoclonal antibody, we have identified the longer Abetas (Abeta1-43, Abeta1-45, Abeta1-46, and Abeta1-48) within the cells and in brain tissues. The production of these longer Abetas as well as Abeta40/42 is presenilin dependent and is suppressed by {1S-benzyl-4R-[1S-carbamoyl-2-phenylethylcarbamoyl-1S-3-methylbutylcarbamoyl]-2R-hydroxy-5-phenylpentyl}carbamic acid tert-butyl ester, a transition state analog inhibitor for aspartyl protease. In contrast, N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester, a potent dipeptide gamma-secretase inhibitor, builds up Abeta1-43 and Abeta1-46 intracellularly, which was also confirmed by mass spectrometry. Notably, suppression of Abeta40 appeared to lead to an increase in Abeta43, which in turn brings an increase in Abeta46, in a dose-dependent manner. We therefore propose an alpha-helical model in which longer Abeta species generated by epsilon-cleavage is cleaved at every three residues in its carboxyl portion.

Watanabe A, Hong WK, Dohmae N, Takio K, Morishima-Kawashima M, Ihara Y. · Biomolecular Characterization Division, Characterization Center, RIKEN (The Institute of Physical and Chemical Research), Wako, Japan. · J Neurochem. · Pubmed #15341514 No free full text.

Abstract: Smearing from high-molecular-mass regions to low-molecular-mass regions on western blot is the most striking observation of the tau making up paired helical filaments in brain tissues affected by Alzheimer's disease. Because our previous study showed site-specific deamidation/isomerization in the smeared tau in vivo, a feature of protein aging, recombinant tau was subjected to prolonged (up to 90 days) in vitro incubation. Carboxymethylated tau at approximately 50 kDa gradually disappeared and was converted to dimers and to high- and low-molecular-mass smearing. In addition, the same site-specific deamidation/isomerization as previously identified in the smeared tau in vivo emerged. Most importantly, tau was spontaneously degraded, generating fragments that start from bulky residues next to asparaginyl residues. This spontaneous degradation of tau probably represents non-enzymatic cleavage through the formation of succinimide intermediates. Similar degradation products starting from the bulky residues next to asparaginyl residues were found in the smeared tau in vivo partially purified from the homogenates from Alzheimer's disease brains.

Watanabe N, Araki W, Chui DH, Makifuchi T, Ihara Y, Tabira T. · National Institute for Longevity Sciences, 36-3 Gengo, Morioka, Obu, Aichi 474-8522, Japan. · FASEB J. · Pubmed #15084524 links to  free full text

Abstract: Previous studies have suggested that heparan sulfate proteoglycans (HSPGs) play a role in deposition of beta-amyloid protein (Abeta) in the Alzheimer's disease (AD) brain. In the present study, we demonstrated that glypican-1 can bind fibrillar Abeta, and the binding is mainly mediated by heparan sulfate (HS) chains. Further analysis revealed that glypican-1 is the major HSPG localized in detergent-insoluble glycosphingolipid-enriched (DIG) domains where all machineries for Abeta production exist and Abeta is accumulated as monomeric and oligomeric forms. Immunohistochemical studies demonstrated that glypican-1 is localized in primitive plaques as well as classic plaques. Moreover, overexpression of glypican-1 and amyloid precursor protein in SH-SY5Y cells resulted in reduced cell viability and made cells more susceptible to thapsigargin-induced stress and Abeta toxicity. The results raise the possibility that glypican-1 interacts with oligomerized or polymerized Abeta in such a specific compartment as DIG, resulting not only in amyloid deposition in senile plaques of AD brain, but also in accelerating neuronal cell death in response to stress and Abeta.

Kanamori T, Nishimaki K, Asoh S, Ishibashi Y, Takata I, Kuwabara T, Taira K, Yamaguchi H, Sugihara S, Yamazaki T, Ihara Y, Nakano K, Matuda S, Ohta S. · Department of Biochemistry and Cell Biology, Institute of Development and Aging Sciences, Graduate School of Medicine, Nippon Medical School, 1-396 Kosugi-cho, Nakahara-ku, Kawasaki, Kanagawa 211-8533, Japan. · EMBO J. · Pubmed #12805207 links to  free full text

Abstract: Dihydrolipoamide succinyltransferase (DLST) is a subunit enzyme of the alpha-ketoglutarate dehydrogenase complex of the Krebs cycle. While studying how the DLST genotype contributes to the pathogenesis of Alzheimer's disease (AD), we found a novel mRNA that is transcribed starting from intron 7 in the DLST gene. The novel mRNA level in the brain of AD patients was significantly lower than that of controls. The truncated gene product (designated MIRTD) localized to the intermembrane space of mitochondria. To investigate the function of MIRTD, we established human neuroblastoma SH-SY5Y cells expressing a maxizyme, a kind of ribozyme, that specifically digests the MIRTD mRNA. The expression of the maxizyme specifically eliminated the MIRTD protein and the resultant MIRTD-deficient cells exhibited a marked decrease in the amounts of subunits of complexes I and IV of the mitochondrial respiratory chain, resulting in a decline of activity. A pulse-label experiment revealed that the loss of the subunits is a post-translational event. Thus, the DLST gene is bifunctional and MIRTD transcribed from the gene contributes to the biogenesis of the mitochondrial respiratory complexes.

Yamaguchi H, Sugihara S, Ogawa A, Oshima N, Ihara Y. · Gunma University School of Health Sciences, Maebashi, Japan. · J Neuropathol Exp Neurol. · Pubmed #11444802 No free full text.

Abstract: To clarify how Alzheimer disease pathology develops in the brains of nondemented subjects, we examined the interrelations among the amounts and morphology of Abeta deposition, neurofibrillary pathology, and apolipoprotein E (ApoE) genotype in the frontal association cortex of 101 autopsy brains from patients aged between 40 to 83. Senile plaque density correlated well with the logarithmic data of insoluble Abeta measured by enzyme immunoassay (EIA). The amounts of Abeta42-ETA increased dramatically in the late preclinical stage, whereas the AP42+ plaque density increased in the early preclinical stage. Neurofibrillary pathology appeared only in the areas with severe Abeta deposition and in subjects aged over 70. The ApoE epsilon4 allele enhanced the Abeta3 deposition in presenile subjects. Plaque-associated glial Abeta was prominent in subjects with mild to moderate Abeta deposition. The morphology of cerebral Abeta deposition changed from diffuse plaques with small amounts of Abeta in each plaque in the early preclinical stage to primitive/neuritic plaques with larger amounts of Abeta in each plaque in the late preclinical stage. Our findings suggest that the prevention of Abeta deposition in the late preclinical stage can be a rational therapeutic target, especially in elderly people with ApoE epsilon4 allele.

Ihara Y. · Department of Neuropathology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. · Neurobiol Aging. · Pubmed #11164285 No free full text.

This publication has no abstract.

Miyasaka T, Morishima-Kawashima M, Ravid R, Heutink P, van Swieten JC, Nagashima K, Ihara Y. · Department of Neuropathology, Faculty of Medicine, University of Tokyo, Tokyo, Japan. · Am J Pathol. · Pubmed #11159174 links to  free full text

Abstract: Frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) is a familial neurological disorder, characterized genetically by autosomal dominant inheritance, clinically by behavioral abnormalities and parkinsonism, and neuropathologically by tauopathy. Linkage analyses of affected families have led to identification of several exonic and intronic mutations in the tau gene. In this study, we analyzed molecular species of tau in the soluble and insoluble fractions of brain affected by the FTDP-17 R406W mutation. Protein chemical analysis and Western blotting using site-specific antibodies indicated that almost equal amounts of wild-type and mutant tau were present in the Sarkosyl-insoluble fraction of the R406W brain. Consistent with this, wild-type and mutant tau colocalized in neurofibrillary tangles in the frontal cortex and hippocampus of the R406W brain. In contrast to soluble R406W tau, which was less phosphorylated than soluble wild-type tau, the Sarkosyl-insoluble mutant tau was highly phosphorylated as well as the insoluble wild-type tau.

Ihara Y, Hayabara T, Sasaki K, Kawada R, Nakashima Y, Kuroda S. · Clinical Research Institute and Department of Neurology, National Minamiokayama Hospital, Okayama, Japan. · Acta Neurol Scand. · Pubmed #11125747 No free full text.

Abstract: OBJECTIVE: To investigate the relationship between oxidative stress and apoE phenotype in dementia of Alzheimer type (DAT). MATERIAL AND METHODS: Hydroxyl radical content in blood, superoxide dismutase (SOD) activity in red blood cells (RBC) and plasma, Cu,Zn-SOD protein content in RBC, and apoE phenotype were determined in 24 DAT patients and 25 controls. RESULTS: DAT patients with the apoE4 phenotype showed higher hydroxyl radical levels than DAT patients without the apoE4 phenotype or controls. SOD activities and Cu,Zn-SOD protein levels in RBC of DAT patients with and without the apoE4 phenotype showed no significant differences, but values in both patient groups were lower than in controls. The apoE4 phenotype was more prevalent in DAT patients than in controls. DAT patients with the apoE4 phenotype were younger at disease onset than DAT patients without the apoE4 phenotype. CONCLUSION: Our findings suggest that apoE4 and SOD individually influence oxidative stress in DAT.