Faculty Bibliography

A diverse group of biochemically distinct proteins give rise to amyloids, each of which is associated with a different disease. These amyloid proteins share numerous properties and typically arise from the abnormal processing of an amyloid precursor protein. The classification, mechanisms and biochemistry of amyloid fibril formation are reviewed here, and two inherited types of amyloid affecting the nervous system are described

beta-Amyloid (A beta) deposition in fibril form is the central event in a number of diseases, including Alzheimer's disease (AD) and hereditary cerebral hemorrhage with amyloidosis - Dutch type (HCHWA-D). A beta is produced by degradation of a larger amyloid precursor protein (APP). Recently a mutation in the APP gene has been found in HCHWA-D causing a glutamine for glutamic acid substitution at residue 22 of A beta. The influence of this mutation on fibrillogenesis is not known, although it is clear that affected patients have accelerated cerebrovascular amyloid deposition, with disease symptoms early in life. We report the in vitro demonstration of accelerated fibril formation in a 28 residue synthetic peptide homologous to the Dutch variant A beta. Furthermore, in eight residue peptides homologous to A beta the presence of the mutation is necessary for fibril formation. These findings provide a mechanism for accelerated amyloid formation in the Dutch variant of APP

Familial amyloidosis, Finnish type (FAF), is an autosomal dominant form of amyloidosis which is related to a point mutation in the gelsolin gene localized on chromosome 9. The mutation corresponds to codon 187 of the secreted form of gelsolin, and is expressed in the amyloid fibril at residue 15. Our original FAF patient was demented, and neuropathological analysis showed Alzheimer type brain lesions associated with both classical and cortical Lewy bodies. Furthermore, antiserum against the gelsolin-derived FAF amyloid reacted strongly with both classical and cortical Lewy bodies of this FAF patient. In preliminary experiments similar results were obtained in cases of Parkinson's disease and diffuse Lewy body disease. These observations may indicate a role for gelsolin in the pathogenesis of Parkinson's disease and related conditions