The use of Seldi ProteinChip (TM) arrays to monitor production of Alzheimer's beta-amyloid in transfected cells

beta-Amyloid (A beta), a 39-43 residue peptide, is the principal component of senile plaques found in the brains of patients with Alzheimer's disease (AD). There are two main lines of evidence that its deposition is the cause of neurodegeneration. First, mutations found in three genes in familial Al zheimer's cases give rise to increased production of the longest, most toxi c. form, A beta 1-42. Second. aggregated A beta is toxic to neuronal cells in culture. Inhibitors of the proteases involved in its release from the am yloid precursor protein are, therefore. of major therapeutic interest. The best candidates for the releasing proteases are both aspartyl proteases, wh ich are integrated into the membranes of the endoplasmic reticulum and Golg i network. A sensitive assay using Ciphergen's Seldi(TM) system has been de veloped to measure all the variants of A beta in culture supernatants, whic h will be of great value in screening inhibitors of these proteases. With t his assay, it has been shown that increasing intracellular cholesterol incr eases the activities of both beta-secretase, and gamma-secretase-42. Moreov er, changing the intracellular targeting of amyloid precursor glycoprotein (APP) yields increased alpha-secretase cleavage, and increases in the amoun ts of oxidized/nitrated forms of A beta. Copyright (C) 2000 European Peptid e Society and John Wiley & Sons, Ltd.