Familial Alzheimer's disease cells abnormally accumulate beta-amyloid-harbouring peptides preferentially in cytosol but not in extracellular fluid.
The proteolytic processing of beta-amyloid precursor protein (APP) was analyzed and compared for familial Alzheimer's disease and normal lymphoid cells, focusing on beta-amyloid-harbouring peptides and the extracellular fragments released into the medium. Tris/tricine gel electrophoresis of anti-beta A4-(8-17)-immunoprecipitated peptides and subsequent N-terminal amino acid sequencing revealed previously unidentified peptides; the 14-kDa peptide with a beta A4 N-terminus and the 12-kDa peptide with an Esch's-site N-terminus in the cytosols, and the same 12-kDa peptide predominating in the media. Moreover, some early onset familial Alzheimer's disease cells, but not normal cells, express a 4-kDa peptide with a beta-amyloid N-terminus in the cytosol. Two-dimensional gel electrophoresis of the extracellular APP peptides immunoprecipitated with anti-APP-(144-654)-peptide showed that familial Alzheimer's disease cells are deficient in processing, especially the 50-53-kDa peptides with the Kunitz-protease-inhibitor domain. This may reflect their unique expression of a serine protease identified as cleaving APP at the beta-amyloid N-terminus.
Department of Radiation Biophysics and Genetics, Kobe University School of Medicine, Japan.
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Matsumoto
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Matsumoto
D000544:Alzheimer Disease / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D011233:Precipitin Tests; D011499:Protein Processing, Post-Translational; D012697:Serine Endopeptidases / Q000378:metabolism
D016564:Amyloid beta-Protein Precursor; D010446:Peptide Fragments; D012697:Serine Endopeptidases