Transgenic mice with Alzheimer presenilin 1 mutations show accelerated neurodegeneration without amyloid plaque formation

Familial Alzheimer disease mutations of presenilin 1 (PS-1) enhance the generation of A beta1-42, indicating that PS-1 is involved in amyloidogenesis. However, PS-1 transgenic mice have failed to show amyloid plaques in their brains. Because PS-1 mutations facilitate apoptotic neuronal death in vitro, we did careful quantitative studies in PS-1 transgenic mice and found that neurodegeneration was significantly accelerated in mice older than 13 months (aged mice) with familial Alzheimer disease mutant PS-1, without amyloid plaque formation. However, there were significantly more neurons containing intracellularly deposited A beta42 in aged mutant transgenic mice. Our data indicate that the pathogenic role of the PS-1 mutation is upstream of the amyloid cascade.

Effects of presenilin N-terminal fragments on production of amyloid beta peptide and accumulation of endogenous presenilins

To clarify the effects of the proteolytic cleavage of presenilin 1 (PS1) and presenilin 2 (PS2) proteins on their functions, we established stable cell lines which expressed the physiologically cleaved N-terminal fragment (NTF) with or without mutations of familial Alzheimer's disease (FAD). We found that exogenous expression of the PS1-NTF or PS2-NTF harboring FAD mutations was insufficient for increased production of amyloidogenic A beta X-42 peptide and that the overexpressed NTFs had no effect on the accumulation of endogenous presenilin fragments.

Isolation of human delta-catenin and its binding specificity with presenilin 1

We screened proteins for interaction with presenilin (PS) 1, and cloned the full-length cDNA of human delta-catenin, which encoded 1225 amino acids. Yeast two-hybrid assay, GST binding assay and immunoprecipitation demonstrated that delta-catenin interacted with a hydrophilic loop region in the endoproteolytic C-terminal fragment of PS1, but not with that of PS-2. These results suggest that PS1 and PS2 partly differ in function. PS1 loop fragment containing the pathogenic mutation retained the binding ability. We also found another armadillo-protein, p0071, interacted with PS1.

A distinct familial presenile dementia with a novel missense mutation in the tau gene

We report a Japanese family with early onset hereditary frontotemporal dementia and a novel missense mutation (Ser305Asn) in the tau gene. The patients presented with personality changes followed by impaired cognition and memory as well as disorientation, but minimal Parkinsonism. Imaging studies showed fronto-temporal atrophy with ventricular dilatation more on the left, and postmortem examination of the brain revealed numerous neurofibrillary tangles (NFTs) with an unusual morphology and distribution. Silver-stained sections showed ring-shaped NFTs partially surrounding the nucleus that were most prominent in frontal, temporal, insular and postcentral cortices, as well as in dentate gyrus. Cortical NFTs were restricted primarily to layer II, and were composed of straight tubules. Numerous glial cells containing coiled bodies and abundant neuropil threads were detected in cerebral white matter, hippocampus, basal ganglia, diencephalon and brain stem, but no senile plaques or other diagnostic lesions were seen. Both the glial and neuronal tangles were stained by antibodies to phosphorylation-independent and phosphorylation-dependent epitopes in tau. Thus, this novel mutation causes a distinct familial tauopathy.

X11L2, a new member of the X11 protein family, interacts with Alzheimer's beta-amyloid precursor protein

We screened proteins for interaction with Alzheimer's beta-amyloid precursor protein (APP) and cloned a new member of the X11 protein family, X11L2. The PID/PTB element of X11L2 protein interacted with the intracellular domain of APP by GST binding assay, and in vivo interaction was confirmed by coimmunoprecipitation from cell extracts overexpressing APP and HA-tagged X11L2. This gene encoded 575 amino acids and the deduced amino acid sequence was highly homologous to rat Mint3. Three protein-protein interaction domains, a PID/PTB and two PDZ elements, were conserved among the X11 protein family, and the N-terminal region of X11L2 protein had several putative SH3 binding motifs, PXXP. Unlike other members of the X11 protein family, X11L2 mRNA was expressed in various tissues.

Molecular cloning of human Fe65L2 and its interaction with the Alzheimer's beta-amyloid precursor protein

We report the cDNA sequence of human Fe65L2. The human Fe65L2 encoded 486 amino acids; the deduced amino acid sequence was shorter by 18 amino acids than the rat protein and had 86% identity to the rat protein Three protein-protein interaction domains, a WW and two PID/PTB elements, were conserved among the Fe65 protein family. Human Fe65L2 mRNA was expressed in various tissues; a transcript of about 2.2 kb was mainly expressed in the brain. A splicing variant lacking two amino acids in the first PID/PTB element was detected. We also confirmed that the carboxyl-terminal region of PID/PTB of the Fe65L2 interacted with the intracellular domain of the Alzheimer's beta-amyloid precursor protein (APP) and APP-like proteins.

Identification of autoimmune T cells among in vivo expanded CD25+ T cells in multiple sclerosis

Although clonal expansion of autoimmune T cells has been reported in multiple sclerosis (MS), very limited information is available on specificities, clonal size, or activation state of the expanded clones. Here we address the issue of clonal expansion by using a novel technique demonstrating clonotypes defined by single-strand conformation polymorphism of TCR beta-chain cDNAs. Examination of activated T cells (CD3+CD25+) isolated from the peripheral blood of MS revealed limited numbers (20 approximately 82) of expanded clones defined by single-strand conformation polymorphism clonotype. To estimate the Ag specificities of dominant clonotypes in the activated T cells, these samples were examined in parallel with Th1 T cell clones specific for myelin basic protein or proteolipid protein (PLP) derived from the same patients. Analysis of two patients demonstrated that the dominant clonotypes would contain those specific for myelin basic protein or PLP. Although the majority of the clonotypes could be detected only transiently, a PLP95-116-specific clonotype was found to persist for over 1 yr. Thus, single-strand conformation polymorphism clonotype analysis allows us to monitor the kinetics of given T cell clones in vivo and could provide useful information for designing clonotype (Id)-specific manipulation of human diseases such as MS.

FTDP-17 mutations N279K and S305N in tau produce increased splicing of exon 10

Missense mutations and intronic mutations in the tau gene cause frontotemporal dementia and Parkinsonism linked to chromosome 17 (FTDP-17). Known missense mutations reduce the ability of tau to promote microtubule assembly. Intronic mutations lead to increased mRNA splicing of the alternatively spliced exon 10, resulting in an overproduction of tau isoforms with four microtubule-binding repeats. We show here that the recently identified FTDP-17 missense mutations N279K and S305N do not reduce the ability of tau to promote microtubule assembly. Instead they lead to increased splicing of exon 10, like the intronic mutations. The N279K and S305N mutations define a class of missense mutations in tau whose primary effects are at the RNA level.

Familial Alzheimer's disease genes in Japanese

More than 40 missense mutations and a splice-site mutation in the presenilin 1 (PS-1) gene, two missense mutations of presenilin 2 (PS-2), and more than three missense mutations of amyloid precursor protein (APP) cosegregate with early onset familial Alzheimer's disease (FAD). In order to determine the incidence of mutations of these genes in Japanese patients, we screened 25 early onset FAD families, one late-onset FAD case, 33 early onset AD cases and five late-onset AD cases for mutations in the coding regions of the genes using SSCP analysis. Four different missense mutations of the PS-1 gene, including a novel mutation, Glu273Ala, were identified in five early onset FAD families and one missense mutation of PS-1 in one isolated AD patient. While no missense mutations of PS-2 were detected, four silent nucleotide substitutions were observed. Our data indicate that PS-1 mutations account for 20.0% of early onset FAD cases in Japan. Since mutations in PS-2 and APP genes were not found in the remaining cases, which could be explained only partially by apolipoprotein E epsilon4, important FAD genes or risk-factor genes remain to be identified.

Both N-terminal and C-terminal fragments of presenilin 1 colocalize with neurofibrillary tangles in neurons and dystrophic neurites of senile plaques in Alzheimer's disease

Presenilin 1 (PS1) is a causative gene for chromosome 14-linked familial Alzheimer's disease. The gene product is known to be cleaved into N-terminal fragments (PS1-N) and C-terminal fragments (PS1-C). To understand the pathophysiological role of PS1, we conducted immunohistochemical studies using antibodies specific for PS1-N and PS1-C in sporadic Alzheimer's disease (AD). Both antibodies showed punctuate staining exclusively in neurons and their processes in both control and AD brains. PS1-N immunolabeling colocalized with neurofibrillary tangles (NFTs) in 36% of NFT-bearing neurons and with dystrophic neurites in 28% of senile plaques (SPs). PS1-C immunolabeling colocalized with dystrophic neurites in 70% of NFT-bearing SPs and with intraneuronal NFTs in 32% of NFT-bearing neurons. Both antibodies did not detect PHF-tau-positive neuropil threads and Abeta amyloid fibrils. The colocalization was also found in 33-38 % of NFT-bearing neurons in progressive supranuclear palsy. These results indicate that both PS1-N and PS1-C fragments are deposited in part of NFT-bearing neurons and dystrophic neurites in SPs; both are the pathologic hallmarks of AD.

Baló's concentric sclerosis in a 4-year-old Japanese infant

We report the youngest known case with Baló's concentric sclerosis (Baló's disease), a variant of multiple sclerosis. This 4-year-old Japanese boy was diagnosed by clinical manifestations and by characteristic findings on magnetic resonance imaging (MRI). Dexamethasone was given intravenously, 3 mg twice daily for 10 days. The clinical manifestations were resolved within 2 weeks, and the MRI findings were markedly improved after 3 weeks. Following the initiation of steroid therapy, he showed remarkable clinical and physical improvement. It cannot be excluded that the clinical improvement resulted from the steroid therapy.

Interleukin-3 and interleukin-3 receptors in the brain

We have previously demonstrated that interleukin 3 (IL-3) has a neurotrophic effect on central cholinergic neurons and have demonstrated the presence of IL-3 receptor (IL-3R)beta subunits in septal cholinergic neurons by reverse-transcribed polymerase chain reaction (RT-PCR) and immunohistochemistry. In order to confirm that the expressed IL-3R is functional, we conducted experiments to show an alpha subunit of IL-3R. The alpha subunit was clearly demonstrated by RT-PCR in the central cholinergic neuronal hybrid cell line SN6, but not in its mother cell line N18TG2, and the expression was slightly upregulated after IL-3 treatment. Choline acetyltransferase and vesicular acetylcholine transporter mRNAs were significantly increased in SN6 after treatment with IL-3. Immunohistochemically, IL-3R alpha-positive cells were mainly present in the medial septal and basal forebrain region, and the stained cells were similar to choline acetyltransferase-positive cells in shape and distribution. The IL-3R alpha-positive cells slightly increased two days after fimbria-fornix transection and decreased seven days after. These findings suggest that functional IL-3 receptors are expressed in the central cholinergic neurons and contribute to some physiological roles such as the differentiation and maintenance of these neurons.

Cloning of the cDNA encoding rat presenilin-2

We report here the cDNA sequence of rat homologue of presenilin-2 (PS-2). The rat PS-2 cDNA encoded 448 amino acids, and the deduced amino acid sequence was highly homologous to those of the human (94.9%), mouse (96.4%) and Xenopus (70.8%). A minor splicing variant lacking a single glutamate was detected, while the product corresponding to the exon 9 deleted splicing variant observed in human was not detected.

Alpha-1-antichymotrypsin is not associated with the increased frequency of apolipoprotein-E-epsilon-4 allele in elderly non-demented leprosy patients

In our previous study, elderly leprosy patients showed a low prevalence of senile dementia of the Alzheimer type, but the frequency of apolipoprotein E (APO-E) epsilon 4 was elevated in non-demented elderly leprosy patients. Recent study has shown that Alzheimer's disease risk associated with APO-E epsilon 4 is significantly increased by the alpha 1-antichymotrypsin (ACT) genotype AA. Therefore we examined an association between ACT polymorphism and the APO-E epsilon 4 allele in 350 leprosy patients. None of our data showed an association of ACT genotype and APO-E epsilon 4 allele in leprosy patients. The allelic frequencies of the ACT gene did not differ even between demented patients with leprosy and age-matched controls. Our present data suggest that ACT polymorphism is not associated with the increased frequency of APO-E epsilon 4 in leprosy patients.

Genetic risk factors in Japanese Alzheimer's disease patients: alpha1-ACT, VLDLR, and ApoE

We studied the polymorphism of alpha1-antichymotrypsin (ACT), very low density lipoprotein receptor (VLDLR) and apolipoprotein E (ApoE) genes in 200 control subjects and 65 patients with Alzheimer's disease (AD) in Japanese. The subjects consisted of 30 patients with early onset familial Alzheimer's disease (FAD), a patient with late onset FAD, 29 patients with an early onset isolated form of AD, and 5 patients with late onset AD. ApoE genotypes were significantly different between controls and FAD (p < 0.0005) or AD (p < 0.05), and patients carrying at least one ApoE epsilon4 allele were found in 44% of FAD and 34.3% of AD; both were significantly different (p < 0.001) from the controls (12.5%). ACT genotypes and allele frequencies were not different among these groups except for genotypes between ApoE epsilon4 FAD and ApoE epsilon4 controls (p = 0.019). There was a slight but significant increase of the 5 repeat allele of VLDLR in AD (p = 0.014), but the difference was rather diminished in the presence of an ApoE epsilon4 allele. None of combinations of ACT and VLDLR genotypes in the presence or absence of an ApoE epsilon4 allele gave significant difference. Thus, we conclude that among the reported genetic risk factors, ApoE epsilon4 is the only definite risk factor for both FAD and AD, and the VLDLR polymorphism might be associated with AD cases in Japanese.

[Molecular genetics of Alzheimer's disease--presenilin and other genes]

We examined mutations of presenilin 1 (PS1), presenilin 2 (PS2) and amyloid precursor protein (APP) in 30 Japanese familial Alzheimer's disease (FAD) and 34 isolated cases of Alzheimer's disease (AD). We found mutations of PS1 in 17% of early onset FAD (H163R, H163R, R269H, E273A, G384A) and in a case (H163R) of isolated AD. The remaining cases were free from mutations in PS1, PS2 and APP. Since only a part of them could he explained by ApoE epsilon 4, we concluded that important genes are missing. We also examined association of apolipoprotein E (ApoE)epsilon 4, allele A of alpha 1-antichymotrypsin (ACT), 5 repeat allele of very low density lipoprotein receptor (VLDLR) and Alzheimer's disease. We confirmed that ApoE espilon 4 is significantly more frequent in both FAD and isolated AD cases than controls. We could not see any significant association in the ACT polymorphism. The 5 repeat allele of VLDLR was slightly but significantly more frequent in AD cases than controls. However, association with ApoE epsilon 4 was not seen in our study.

Determination of a cleavage site of presenilin 2 protein in stably transfected SH-SY5Y human neuroblastoma cell lines

Mutations in the presenilin 1 (PS1) and presenilin 2 (PS2) genes are associated with early-onset autosomal dominant familial Alzheimer's disease, and the gene products are endoproteolytically processed to yield N-terminal fragments (NTF) and C-terminal fragments (CTF). We have studied the cleavage site of the PS2 protein in stably transfected human neuroblastoma cells. The 23 kD PS2-CTF was isolated by a combination of anion exchange chromatography and affinity chromatography and directly sequenced. The N-terminus of the PS2-CTF started at residue 307, which indicated that the cleavage occurs between Lys306 and Leu307 in the proximal portion of the large hydrophilic loop. This site is close to the cleavage positions observed in the PS1 protein.

Regulation of experimental autoimmune encephalomyelitis by natural killer (NK) cells

In this report, we establish a regulatory role of natural killer (NK) cells in experimental autoimmune encephalomyelitis (EAE), a prototype T helper cell type 1 (Th1)-mediated disease. Active sensitization of C57BL/6 (B6) mice with the myelin oligodendrocyte glycoprotein (MOG)35-55 peptide induces a mild form of monophasic EAE. When mice were deprived of NK cells by antibody treatment before immunization, they developed a more serious form of EAE associated with relapse. Aggravation of EAE by NK cell deletion was also seen in beta 2-microglobulin-/- (beta 2m-/-) mice, indicating that NK cells can play a regulatory role in a manner independent of CD8+ T cells or NK1.1+ T cells (NK-T cells). The disease enhancement was associated with augmentation of T cell proliferation and production of Th1 cytokines in response to MOG35-55. EAE passively induced by the MOG35-55-specific T cell line was also enhanced by NK cell deletion in B6, beta 2m-/-, and recombination activation gene 2 (RAG-2)-/- mice, indicating that the regulation by NK cells can be independent of T, B, or NK-T cells. We further showed that NK cells inhibit T cell proliferation triggered by antigen or cytokine stimulation. Taken together, we conclude that NK cells are an important regulator for EAE in both induction and effector phases.

Identifying monoaminergic, GABAergic, and cholinergic characteristics in immortalized neuronal cell lines

We measured the concentration of neurotransmitters in immortalized neural cell lines of hippocampal, septal, brainstem and cerebellar origin. While in most of the cell lines, concentrations of monoamines, gamma-aminobutyric acid (GABA) and acetylcholine were low, in some they were markedly higher. This made it quite easy to identify possible monoaminergic, GABAergic or cholinergic cell lines. However all the cell lines contained glutamate and aspartate and there were no outstanding differences in levels of these amino acids differences between the cell lines. Deprivation of serum, which made the cells acquire a more differentiated morphology, caused an increase in the intracellular concentrations of some compounds and a switch from multiple to a single transmitter in the case of some cell lines. It suggested that measurement of transmitter concentrations combined with serum deprivation studies, may provide an indication of the neurochemical characteristics of immortalised neuronal cell lines.

Sequence analysis of presenilin-1 gene mutation in Japanese Alzheimer's disease patients

The mutations of presenilins (PSs) gene and their clinicopathological correlations to Alzheimer's disease (AD) have lately attracted considerable attention. In this report we analyzed fifteen Japanese familial Alzheimer's disease (FAD) including 12 early-onset FAD and 13 sporadic AD patients for the mutation of PS-1 gene by direct sequence analysis. We found the mutations, G384A, E280A in two FAD and H163R in one sporadic AD patient, and no N1411 or M239V mutation in PS-2 gene, and no mutation in exons 16 and 17 in amyloid precursor protein (APP) gene. Families in which we failed to find the mutation by this screening may have mutations elsewhere in PSs or in APP gene, or yet unidentified other AD loci may exist. This is the first report to find a sporadic AD patient having PS-1 mutation.