Biomedical subjects

Kenji Uéda

Publications and source records attributed to Kenji Uéda.

16 recordsLinked to original sources

PubMed2006

Oxidative stress induces nuclear translocation of C-terminus of alpha-synuclein in dopaminergic cells.

Growing evidence suggests that oxidative stress is involved in the neuronal degeneration and can promote the aggregation of alpha-synuclein. However, the role of alpha-synuclein under physiological and pathological conditions remains poorly understood. In the present study, we examined the possible interaction between the alpha-synuclein and oxidative stress. In a dopaminergic cell line MES23.5, we have found that the 200microM H(2)O(2) treatment induced the translocation of alpha-synuclein from cytoplasm to nuclei at 30min post-treatment. The immunoactivity of alpha-synuclein became highly intensive in the nuclei after 2h treatment. The protein translocated to nucleus was a 10kDa fragment of C-terminus region of alpha-synuclein, while full-length alpha-synuclein remained in cytoplasm. Thioflavine-S staining suggested that the C-terminal fragment in the nuclei has no beta-sheet structures. Our present results indicated that 200microM H(2)O(2) treatment induces the intranuclear accumulation of the C-terminal fragment of alpha-synuclein in dopaminergic neurons, whose role remains to be investigated.

Active Transport, Cell Nucleus↗

PubMed2005

Alpha-synuclein and dopamine metabolism.

alpha-Synuclein (alpha-Syn), a 140-amino-acid protein richly expressed in presynaptic terminals in the central nervous system, has been shown to play a central role in the pathogenesis of Parkinson's disease. Although the normal functions of alpha-Syn remain elusive, accumulating evidence shows that the molecule is involved in multiple steps related to dopamine metabolism, including dopamine synthesis, storage, release, and uptake. The regulatory effect of alpha-Syn on dopamine metabolism is likely to tone down the amount of cytoplasmic dopamine at nerve terminals, thereby limiting its conversion to highly reactive oxidative molecules. Formation of alpha-Syn protofibrils triggered by factors such as gene mutations and environmental toxins can make the molecule lose its normal functions, leading to disrupted homeostasis of dopamine metabolism, increased cytoplasmic dopamine levels, and enhanced oxidative stress in dopaminergic neurons. The enhanced oxidative stress will, in turn, exacerbate the formation of alpha-Syn protofibrils and drive the neurons into a vicious cycle, which will finally result in the selective degeneration of the dopaminergic neurons associated with Parkinson's disease.

Animals↗

PubMed2004

Inhibition of tyrosine hydroxylase expression in alpha-synuclein-transfected dopaminergic neuronal cells.

Although the aberrant expression of alpha-synuclein (alpha-Syn) is toxic to dopaminergic neurons, little is known about the correlation between the abnormality of alpha-Syn and the expression of tyrosine hydroxylase (TH), a rate-limiting enzyme for the synthesis of dopamine neurotransmitter. In this study, the MES23.5 rat dopaminergic cell line transfected with wild-type human alpha-Syn cDNA (h alpha-Syn) construct was used to investigate the association between alpha-Syn and TH. Immunocytochemical staining and Western blot for TH showed that the TH expression was greatly decreased in h alpha-Syn-transfected cells. Northern blot confirmed that the TH mRNA level was also dramatically reduced. Reduction of TH protein levels did not affect the growth and proliferation of the transfected cells. No apparent cell injury or death was observed. These results suggest that an abnormal expression of alpha-Syn may inhibit TH synthesis in dopaminergic cells.

Animals↗

PubMed2004

Increased expression of neuronal cyclooxygenase-2 in the hippocampus in amyotrophic lateral sclerosis both with and without dementia.

The pathophysiological basis of cognitive dysfunction, including frontotemporal dementia (FTD), in patients with amyotrophic lateral sclerosis (ALS) and ALS with dementia (ALSD) remains unclear. On the other hand, increased expression of cyclooxygenase-2 (COX-2) in the spinal cord is thought to play a pivotal role in motor neuron degeneration in ALS. In this study, to assess the relationship between the neuronal COX-2 expression in the cerebrum, the formation of tau- and alpha-synuclein-negative but ubiquitin-positive neuronal inclusions (UPIs), and dementia in motor neuron disease (MND), we examined neuronal COX-2 immunoreactivity in the frontal cortex and hippocampus of patients with non-demented ALS without UPIs ( n=11), ALSD with UPIs ( n=6), and normal controls ( n=24) using a quantitative immunohistochemical technique. Neuronal COX-2 expression in all CA1-4 in the hippocampus was significantly up-regulated in the ALSD group, and, to lesser degree but significantly, in the ALS group. Neuronal COX-2 expression in the frontal cortex was also significantly up-regulated in the ALSD group but not in the ALS group. These findings suggest that (1) the frontal cortex and hippocampus of MND are involved in the same pathogenic process associated with COX-2 induction that has been observed in spinal anterior horn cells, (2) COX-2 induction in the cerebrum is a pathogenic process that can occur even in the absence of UPI formation in MND, and (3) COX-2 expression in the cerebrum may be associated with cognitive dysfunction in MND.

Aged↗

PubMed2004

Demonstration of a role for alpha-synuclein as a functional microtubule-associated protein.

Alpha-synuclein is a major constituent of pathological intracellular inclusion bodies, a common feature of several neurodegenerative diseases. Two missense mutations in the alpha-synuclein gene have been identified in confirmed autosomal-dominant familial Parkinson's disease, which segregate with the illness. However, the physiological function of alpha-synuclein remains unknown. After biochemical investigations we have revealed tubulin to be an alpha-synuclein associated/binding protein. Here, we show that alpha-synuclein induces polymerization of purified tubulin into microtubules. Mutant forms of alpha-synuclein lose this potential. The binding site of alpha-synuclein to tubulin is identified, and co-localization of alpha-synuclein with microtubules is shown in cultured cells. To our knowledge, this is the first demonstration of microtubule-polymerizing activity of alpha-synuclein. Now we can see a striking resemblance between alpha-synuclein and tau: both have the same physiological function and pathological features, making abnormal structures in diseased brains known as synucleinopathies and tauopathies. The discovery of a physiological role for alpha-synuclein may provide a new dimension in researches into the mechanisms of alpha-synuclein-associated neurodegenerative diseases.

Alcohol Oxidoreductases↗

PubMed2003

Variability and heterogeneity in Alzheimer's disease with cotton wool plaques: a clinicopathological study of four autopsy cases.

We describe three cases of early- (cases 1-3, 28-39 years) and one of late-onset (case 4, 76 years) Alzheimer's disease (AD) with 'cotton wool' plaques (CWPs) but without a family history indicating autosomal dominant inheritance. The early-onset cases, but not the late-onset case, showed remarkable aggression, disinhibition, and impulsiveness. Spastic paraparesis was observed in only one early-onset case. Hematoxylin-eosin-stained sections showed numerous CWPs, especially in the temporal cortex, in all cases. Bielschowsky-stained sections showed neurofibrillary tangles and minor neuritic changes surrounding the CWPs in three cases, but not in case 2. Gallyas-Braak-stained sections showed weak argyrophilia in homogeneous material of the CWPs in cases 2 and 4. Quantitative analysis demonstrated that Abeta42 was deposited more predominantly than Abeta40 in three cases. However, in case 2, approximately twice as much Abeta40 as Abeta42 was deposited. Tau immunostaining demonstrated neuritic changes in three cases, but not in case 2. alpha-Synuclein-positive Lewy bodies (LBs) and astrocytic lesions containing non-Abeta component of AD amyloid (NAC), a central fragment of alpha-synuclein, were found in case 3. In conclusion, (1) a frontal lobe syndrome-like personality change may be one of the characteristic clinical features of early-onset CWP-AD, (2) the deposition pattern of Abeta40 and Abeta42 in CWP-AD is more variable than that of presenilin-1-linked cases, (3) Abeta deposition can result in development of dementia without tau pathology, and (4) CWP-AD with LBs and several other neurodegenerative disorders with LBs share a common process involving alpha-synuclein and NAC deposition.

Adult↗

PubMed2003

Alpha-synuclein aggregation and neurodegenerative diseases.

Alpha-synuclein is a neuronal protein originally identified in Alzheimer's disease (AD) amyloid plaques in 1993 and named non-Abeta component precursor (NACP) [92]. Later, the discovery of two missense mutations (G88C and G209A), which resulted in Ala30Pro (A30P) and Ala53Thr (A53T) substitutions, of the alpha-synuclein gene in certain autosomal-dominant early onset familial Parkinson's disease (PD) has greatly promoted the understanding of the role of alpha-synuclein in the pathogenesis of neurodegenerative diseases, such as PD, dementia with Lewy bodies (DLB) and multiple system atrophy (MSA) [5,6,51,75]. At present, it is widely accepted that alpha-synuclein may play a central role in several neurodegenerative disorders because of the presence of insoluble alpha-synuclein as the major fibrillar component of inclusion bodies. From the cloning of the human alpha-synuclein cDNA in 1993 to the present, alpha-synuclein has been carefully documented in many aspects. In this article, we review the progress of studies on alpha-synuclein and its role in alpha-synuclein-related neurodegenerative diseases.

Animals↗

PubMed2002

Glial involvement in diffuse Lewy body disease.

Diffuse Lewy body disease (DLBD) is characterized by the presence of Lewy bodies (LB) in the neurons and neurites of cortical, subcortical, and brain stem structures. Recently, alpha-synuclein (alphaS) has been found to be a central constituent of LB. In DLBD, abnormal accumulation of alphaS has been reported in both neurons and glia, but studies on glial lesions in DLBD have been limited. We examined in detail the constituents and distribution of glial lesions in eight patients with DLBD and report the pathogenesis of the glial lesions. alphaS-positive neuronal cytoplasmic inclusions (NI), neuropil threads (NT), and coiled bodies (CB) showed similar immunostaining profiles. Without pretreatment, NI, NT, and CB were detected by all antibodies against alphaS. The immunostaining profile of star-like astrocytes (SLA) was quite different from those of NI, NT, and CB. A few SLA were stained by an antibody against the non-Abeta component portion of alphaS without pretreatment, but formic acid pretreatment dramatically enhanced SLA immunoreactivity. SLA and CB were found in all eight brains with DLBD. SLA were scarce in the brain stem, but there were hundreds of SLA per visual field at x100 magnification in the temporal cortex of most cases, while CB were found diffusely in both the cerebral cortex and brain stem, similar to NI. This suggests that the pathogenesis of SLA is different from those of NI and CB.

Aged↗

PubMed2002

NACP/alpha-synuclein, NAC, and beta-amyloid pathology of familial Alzheimer's disease with the E184D presenilin-1 mutation: a clinicopathological study of two autopsy cases.

Approximately 60% of familial and sporadic Alzheimer's disease (AD) cases manifest Lewy bodies (LBs), of which a major component is alpha-synuclein. Although the pathogenic role of alpha-synuclein in AD remains unclear, LB formation might be associated with pathological beta-amyloid (Abeta) overproduction. Here, we present the clinical and pathological characteristics of two affected family members from a pedigree with the E184D mutation of presenilin-1. One case presented with typical clinical features of AD, but the other case also developed clinical characteristics of dementia with Lewy bodies (DLB), including visual hallucinations, delusions, and parkinsonism. In both cases, neuropathological examination revealed numerous neurofibrillary tangles and severe Abeta deposition in senile plaques and amyloid angiopathy, in which Abeta42 rather than Abeta40 was predominant. Furthermore, remarkable alpha-synuclein pathology, including LBs and the accumulation of the non-Abeta component of AD amyloid (NAC) in plaques and astrocytes, was detected only in the case that presented with the symptoms of DLB. These findings suggest that (1) LB pathology can influence the clinical features of familial AD, (2) the E184D mutation of presenilin-1 may be associated with the LB formation through Abeta overproduction, although the process of LB formation is strongly affected by other unknown mechanisms, (3) in neurodegenerative disorders with LBs, there is a common pathophysiological background inducing NAC accumulation in neuritic plaques and astrocytes, and (4) the NAC accumulation in neuritic plaques is modulated by the abnormally aggregated tau protein.

Adult↗

PubMed2002

Immunohistochemical study of synphilin-1 in brains of patients with dementia with Lewy bodies - synphilin-1 is non-specifically implicated in the formation of different neuronal cytoskeletal inclusions.

Dementia with Lewy bodies brains were immunohistochemically investigated using anti-synphilin-1 antibodies. The alpha-synuclein-positive brainstem type and well-defined cortical type Lewy bodies (LB) were positive for synphilin-1, while ill-defined LB and LB-related neurites were negative, suggesting that synphilin-1 does not directly associate with alpha-synuclein. Synphilin-1-positive LB were double-positive for phosphorylated neurofilament. In addition, tau-positive neurofibrillary tangles (NFT) were positive for synphilin-1, while neuropil threads were negative. Immunoelectron microscopically, synphilin-1 was located on filamentous components in cortical type LB and on paired helical filaments in NFT. It is likely that synphilin-1 accumulates in the cell body according to the axonal transport blockage, and associates with abnormal cytoskeltons during the formation of LB or NFT, suggesting that synphilin-1 is non-specifically implicated in the formation of different neuronal cytoskeletal inclusions.

Aged↗

PubMed2002

NACP/alpha-synuclein immunoreactivity in diffuse neurofibrillary tangles with calcification (DNTC).

Diffuse neurofibrillary tangles with calcification (DNTC) is a rare tangle-predominant dementia, as well as one of the tauopathies lacking Abeta deposition. It is characterized by temporo-frontal lobar atrophy, Fahr-type calcification and, histopathologically, numerous neurofibrillary tangles in the limbic system and neocortex. Recently, accumulation of alpha-synuclein (alphaS), the precursor of the non-beta amyloid component (NAC) of Alzheimer's disease, has been shown in diverse neurodegenerative disorders, including Parkinson's disease, dementia with Lewy bodies, Alzheimer's disease, multiple system atrophy and parkinsonism-dementia complex of Guam. To clarify whether alphaS accumulates in other neurodegenerative disorders, we investigated eight DNTC brains using immunohistochemistry and demonstrated remarkable alphaS deposition in the neurons and astrocytes in many anatomical regions. Abundant Lewy bodies were observed in the amygdala (seven cases) and hippocampus (seven cases), and, to a lesser degree, in the substantia nigra (six cases) and dorsal vagal nucleus (five cases). In the hippocampus, many Lewy neurites were distributed in the stratum oriens and stratum pyramidale in the CA2-3 and the subiculum. Furthermore, numerous NAC-positive astrocytes were detected in the hippocampus and temporal cortex. This investigation reveals that neurons and astrocytes are extensively involved in remarkable alphaS pathology in the DNTC brain, and that the alphaS pathology compounds the cardinal pathological features of tau pathology. These findings suggest that (1) DNTC shares a common pathophysiological background with Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy in which abnormal alphaS aggregation is observed, and (2) there is an interaction between alphaS and tau pathology that does not involve amyloid in DNTC.

Adult↗

PubMed2002

Progression and staging of Lewy pathology in brains from patients with dementia with Lewy bodies.

Using alpha-synuclein-immunohistochemistry, 27 brains of dementia with Lewy bodies (DLB) were investigated to identify the progression of Lewy pathology including Lewy bodies (LB) and LB-related neurites in the cerebrum. The numbers of alpha-synuclein-positive LB and LB-related neurites were semiquantitatively evaluated in the amygdala, hippocampus, entorhinal cortex, transentorhinal cortex, insular cortex, middle temporal cortex and superior frontal cortex. The results indicated that Lewy pathology within the neuron progresses first in the axonal terminal, subsequently in the cell body and finally in the dendrite, that Lewy pathology in the cerebral cortex progresses first in layers V-VI, subsequently in layer III and finally in layer II, and that Lewy pathology in the cerebrum progresses first in the amygdala, subsequently in the limbic cortex and finally in the neocortex. In addition, Lewy pathology was graded from stage I to stage IV based on the progression of Lewy pathology. The 27 brains examined were classified into 3 brains showing stage I, 11 showing stage II, 7 showing stage III and 6 showing stage IV. Comparing these stages with the pathological subtypes of DLB brains, brains of the subtype showing severe Alzheimer pathology corresponded to brains showing an advanced stage, suggesting that Alzheimer pathology exacerbates Lewy pathology.

Aged↗

PubMed2002

Relationship in the formation process between neurofibrillary tangles and Lewy bodies in the hippocampus of dementia with Lewy bodies brains.

Using tau immunohistochemistry and alpha-synuclein immunohistochemistry, we quantitatively investigated the most frequent sites and the formation process of neurofibrillary tangles (NFT) and Lewy bodies (LB) in the hippocampus from 20 patients with dementia with Lewy bodies (DLB). NFT were most frequently found in the CA2 and the subiculum-pre-CA1, while LB were most frequently found in the CA3-4 and the subiculum-pre-CA1. In the intrahippocampal routes of the perforant pathway, tau immunoelectron microscopy demonstrated distal axons containing aggregated tau-positive microtubules, while alpha-synuclein immunoelectron microscopy revealed terminal axons containing aggregated alpha-synuclein-positive tubular or filamentous components. These findings suggest that NFT and LB are first formed in the CA2 and the CA3-4 related to degeneration of the nonperforating route of the perforant pathway, respectively, and subsequently in the subiculum-pre-CA1 chiefly related to degeneration of the perforating route. Coexistence of NFT and LB in the same neurons was found most frequently in the subiculum-pre-CA1. In addition, coexistence of tau and alpha-synuclein was found in terminal axons of the perforant pathway, and tau accumulated not in paired helical filaments but in the periphery of alpha-synuclein-positive components immunoelectron-microscopically, suggesting that alpha-synuclein stimulates the accumulation of phosphorylated tau in terminal axons.

Aged↗

PubMed2001

Characterization of the human alpha-synuclein gene: Genomic structure, transcription start site, promoter region and polymorphisms.

The human NACP/alpha-synuclein gene has been cloned. This gene consists of 6 exons ranging in size from 42 to 1110 bp. The translation start codon ATG is encoded by exon 2 and the stop codon TAA is encoded by exon 6. The non-Abeta component of Alzheimer's disease amyloid (NAC) is encoded by exon 4. The two previously reported minor isoforms of NACP/alpha-synuclein, NACP112 [29] and NACP126 [6], are alternatively spliced products, in which exon 5 and exon 3 are spliced out, respectively. Exon 1 was found to have different splicing sites, producing different 5'-untranslated sequences in the cDNAs. A previously reported dinucleotide repeat polymorphic marker has been mapped to 8kb upstream of the transcription start site. A highly TC-rich sequence in intron 4 was found to be polymorphic by length and four alleles, A0, A1, A2 and B have been identified in the Caucasian population. Genotyping this polymorphism among pure Alzheimer's, Lewy body variant and Parkinson's subjects and aged normal control subjects did not reveal any significant differences.

Journal Article↗

PubMed2001

Limited proteolysis of NACP/alpha-synuclein.

The NAC region of NACP/alpha-synuclein is a secondary component of Alzheimer's disease amyloid. alpha-Synuclein is a major component of Lewy bodies, a typical neuropathological feature of Parkinson's disease. However, the physiological role and deposition mechanisms of alpha-synuclein are unknown. Structural analyses of alpha-synuclein should provide a better understanding of its biochemical characteristics. We investigated the digestion of alpha-synuclein withalpha-chymotrypsin and cathepsin D, which are reported to be involved in amyloidogenesis, under various conditions in vitro. There are many putative cleavage sites for these enzymes in alpha-synuclein, including in the NAC region. However, most of the predicted sites remained undigested, and the NAC region was found to be intact even after extensive digestion. This peculiar characteristic of alpha-synuclein may be relevant to the abnormal deposition of this molecule in alpha-synuclein-associated neurodegenerative diseases.

Journal Article↗

PubMedDate not supplied

Motor dysfunction and gliosis with preserved dopaminergic markers in human alpha-synuclein A30P transgenic mice.

Alpha-synuclein is a major component of Lewy bodies (LBs) in the substantia nigra and cortex in Parkinson's disease (PD) and dementia with Lewy bodies (DLB), and in glial inclusions in multiple systems atrophy (MSA). Mutations in alpha-synuclein have been associated with autosomal dominant forms of PD. We investigated the clinical and neuropathological effects of overexpression of human alpha-synuclein, alpha-synuclein A30P, and alpha-synuclein A53T under the control of the hamster prion protein (PrP) promoter; 5-15x endogenous levels of protein expression were achieved with widespread neuronal, including nigral, transgene expression. High expression of alpha-synuclein A30P in the Tg5093 line was associated with a progressive motor disorder with rigidity, dystonia, gait impairment, and tremor. Histological analysis of this line showed aberrant expression of the protein in cell soma and progressive CNS gliosis, but no discrete Lewy body-like alpha-synuclein inclusions could be identified. Biochemical analysis demonstrated alpha-synuclein fragmentation. Despite strong expression of the transgene in the nigra, there was no specific deterioration of the nigrostriatal dopaminergic system as assessed by quantitation of nigral tyrosine hydroxylase (TH) containing neurons, striatal TH immunoreactivity, dopamine levels, or dopamine receptor number and function. Lower expressing lines had no specific behavioral or histopathological phenotype. Thus, high expression of mutant human alpha-synuclein resulted in a progressive motor and widespread CNS gliotic phenotype independent of dopaminergic dysfunction in the Tg5093 line.

Animals↗