Kenji Uéda

Bio: Kenji Uéda is an academic researcher from University of California, San Diego. The author has contributed to research in topics: Amyloid precursor protein & Promoter. The author has an hindex of 5, co-authored 5 publications receiving 1694 citations.

Molecular cloning of cDNA encoding an unrecognized component of amyloid in Alzheimer disease

Abstract: A neuropathological hallmark of Alzheimer disease (AD) is a widespread amyloid deposition. We analyzed the entire amino acid sequences in an amyloid preparation and found, in addition to the major beta/A4-protein (A beta) fragment, two unknown peptides. We raised antibodies against synthetic peptides using subsequences of these peptides. These antibodies immunostained amyloid in neuritic and diffuse plaques as well as vascular amyloid. Electron microscopic analysis demonstrated that the immunostaining was localized on amyloid fibrils. We have isolated an apparently full-length cDNA encoding a 140-amino-acid protein within which two previously unreported amyloid sequences are encoded in tandem in the most hydrophobic domain. We tentatively named this 35-amino acid peptide NAC (non-A beta component of AD amyloid) and its precursor NACP. NAC is the second component, after A beta, identified chemically in the purified AD amyloid preparation. Secondary structure predictions indicate that the NAC peptide sequence has a strong tendency to form beta-structures consistent with its association with amyloid. NACP is detected as a M(r) 19,000 protein in the cytosolic fraction of brain homogenates and comigrates on immunoblots with NACP synthesized in Escherichia coli from NACP cDNA. NACP mRNA is expressed principally in brain but is also expressed in low concentrations in all tissues examined except in liver, suggesting its ubiquitous and brain-specific functions. The availability of the cDNA encoding full-length NACP should help to elucidate the mechanisms of amyloidosis in AD.

Alz-50 recognizes a phosphorylated epitope of tau protein.

Abstract: Alz-50 is a monoclonal antibody that detects antigens enriched in the brain tissue of Alzheimer's disease (AD) patients. Although Alz-50 recognizes tau, an identified integral constituent of the AD paired helical filament (PHF), the exact nature of the antigenic site is unknown. An immunoblot analysis demonstrated that the antigenic sites to Alz-50 are diminished by acid phosphatase treatment. Consistent with this finding, Alz-50 antigens were more concentrated in brain homogenates prepared with phosphatase inhibitors. The epitope in tau with which Alz-50 reacts is located in the carboxy terminus within a 14-amino acid region from just beyond the microtubule-binding repeats to the carboxy terminus. An isolated carboxy-terminal chymotryptic peptide from bovine brain tau reactive with Alz-50 was analyzed by fast-atom-bombardment mass spectroscopy (FAB-MS) and was found to be present as both a monophosphopeptide and a nonphosphorylated peptide. The immunohistological analysis has demonstrated that Alz-50 staining of neurofibrillary tangles (NFTs) is sensitive to acid phosphatase but not to alkaline phosphatase. Furthermore, Alz-50 staining of NFTs was effectively adsorbed by a high concentration of phosphoserine but not by serine or phosphothreonine. These results strongly suggest that Alz-50 recognizes a phosphorylated epitope in the carboxy terminus of tau which has not been previously detected by using alkaline phosphatase. The strong Alz-50 staining in AD samples may represent another association between a phosphorylation state and neurofibrillary lesions. As a marker of the inchoate tangle-bearing neuron, the characterization of the Alz-50 epitope in tau offers a partial molecular basis for the modifications that contribute to the assembly of PHFs.

Decreased adhesiveness of Alzheimer's disease fibroblasts: is amyloid β-protein precursor involved?

Abstract: The adhesiveness of fibroblasts derived from Alzheimer's disease (AD) patients to a plastic substratum was assessed as the proportion of cells attached to a plastic dish bottom after a 30-minute incubation in culture medium of cells dissociated in ethylenediaminetetraacetic acid and was compared with the adhesiveness of normal fibroblasts from non-AD controls. It was found that the normal fibroblasts adhered better to plastic than did AD cells. This reduced adhesiveness was observed in fibroblasts derived from both sporadic and familial AD patients. Because of the possible involvement of amyloid beta-protein precursor (ABPP) in the process of cellular adhesion, the amount of ABPP messenger RNA was measured in these fibroblasts and was found to be decreased in the familial AD fibroblasts, although not in cells from sporadic AD patients. Furthermore, there were fewer molecules detected by an anti-ABPP antibody in conditioned media from familial AD fibroblasts as compared with media from control fibroblasts. Therefore, although it is possible that the reduced adhesiveness of familial AD fibroblasts may result from genetic deficits in ABPP gene expression, the reduced adhesiveness of sporadic AD fibroblasts most likely results from certain deficits in molecules other than the ABPP.

Characterization of the human α-synuclein gene: Genomic structure, transcription start site, promoter region and polymorphisms1

Abstract: 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.

Mutation in the α-synuclein gene identified in families with Parkinson's disease

Abstract: Parkinson's disease (PD) is a common neurodegenerative disorder with a lifetime incidence of approximately 2 percent. A pattern of familial aggregation has been documented for the disorder, and it was recently reported that a PD susceptibility gene in a large Italian kindred is located on the long arm of human chromosome 4. A mutation was identified in the α-synuclein gene, which codes for a presynaptic protein thought to be involved in neuronal plasticity, in the Italian kindred and in three unrelated families of Greek origin with autosomal dominant inheritance for the PD phenotype. This finding of a specific molecular alteration associated with PD will facilitate the detailed understanding of the pathophysiology of the disorder.

Dopaminergic Loss and Inclusion Body Formation in α-Synuclein Mice: Implications for Neurodegenerative Disorders

Abstract: To elucidate the role of the synaptic protein alpha-synuclein in neurodegenerative disorders, transgenic mice expressing wild-type human alpha-synuclein were generated. Neuronal expression of human alpha-synuclein resulted in progressive accumulation of alpha-synuclein-and ubiquitin-immunoreactive inclusions in neurons in the neocortex, hippocampus, and substantia nigra. Ultrastructural analysis revealed both electron-dense intranuclear deposits and cytoplasmic inclusions. These alterations were associated with loss of dopaminergic terminals in the basal ganglia and with motor impairments. These results suggest that accumulation of wild-type alpha-synuclein may play a causal role in Parkinson's disease and related conditions.