Immunohistochemical evidence for the derivation of a peptide ligand from the amyloid beta-protein precursor of Alzheimer disease

A monoclonal antibody to a synthetic peptide consisting of residues 8-17 of the amyloid beta protein of Alzheimer disease was used in immunohistochemical studies to reveal binding sites for this peptide in vesicular elements in the islets of Langerhans of the pancreas and the zona reticularis of the adrenal gland. These binding sites may represent a specific membrane receptor. These results, together with similarities in structural features between the precursors for epidermal growth factor and beta protein, suggest that the beta-protein precursor may be processed to release an active peptide ligand rather than acting as a membrane receptor. In Alzheimer disease, abnormal processing of this active peptide precursor may result in the deposition of beta-protein amyloid fibrils in the brain.

Amyloid beta-protein gene duplication is not common in Alzheimer's disease: analysis by polymorphic restriction fragments

The amyloid beta-protein(BP) is an important component of amyloid fibrils of both Alzheimer's disease(AD) and adult Down syndrome(DS). It has been hypothesized that sporadic AD may involve the duplication of a subregion of chromosome 21 containing the BP locus. However, an improved method for detection of the BP gene duplication using polymorphic Hind III fragments led us to a conclusion that BP gene duplication is rare, if any, in (Japanese) sporadic AD patients, indicating that the duplication of the BP gene itself is not the common underlying genetic defect in AD.

Immunogold labeling of cerebrovascular and neuritic plaque amyloid fibrils in Alzheimer's disease with an anti-beta protein monoclonal antibody

A monoclonal antibody raised to a synthetic peptide consisting of residues 8 to 17 of the amyloid beta protein of Alzheimer's disease was employed for immunogold electron microscopic studies on amyloid fibrils of cerebrovascular walls and neuritic plaques in this disease. Electron microscopy revealed a specific gold labeling of the amyloid fibrils in these structures. This provides ultrastructural evidence that beta protein is intimately associated with the amyloid fibril. With previous chemical evidence, this observation supports the concentration that it is an intrinsic component of the fibril.

Neuritic plaques and cerebrovascular amyloid in Alzheimer disease are antigenically related

A synthetic peptide (Asp-Ala-Glu-Phe-Arg-His-Asp-Ser-Gly-Tyr), homologous to the amino terminus of a protein purified from cerebrovascular amyloid (beta protein), induced antibodies in BALB/c mice that were used immunohistochemically to stain not only amyloid-laden cerebral vessels but neuritic plaques as well. These findings suggest that the amyloid in neuritic plaques shares antigenic determinants with beta protein of cerebral vessels. Since the amino acid compositions of plaque amyloid and cerebrovascular amyloid are similar, it is likely that plaque amyloid also consists of beta protein. This possibility suggests a model for the pathogenesis of Alzheimer disease involving beta protein.

Alzheimer's disease and Down's syndrome: sharing of a unique cerebrovascular amyloid fibril protein

The cerebrovascular amyloid protein from a case of adult Down's syndrome was isolated and purified. Amino acid sequence analysis showed it to be homologous to that of the beta protein of Alzheimer's disease. This is the first chemical evidence of a relationship between Down's syndrome and Alzheimer's disease. It suggests that Down's syndrome may be a predictable model for Alzheimer's disease. Assuming the beta protein is a human gene product, it also suggests that the genetic defect in Alzheimer's disease is localized on chromosome 21.

Alzheimer's disease: initial report of the purification and characterization of a novel cerebrovascular amyloid protein

A purified protein derived from the twisted beta-pleated sheet fibrils in cerebrovascular amyloidosis associated with Alzheimer's disease has been isolated by Sephadex G-100 column chromatography with 5 M guanidine-HC1 in 1 N acetic acid and by high performance liquid chromatography. Amino acid sequence analysis and a computer search reveals this protein to have no homology with any protein sequenced thus far. This protein may be derived from a unique serum precursor which may provide a diagnostic test for Alzheimer's disease and a means to understand its pathogenesis.