Allele-specific overexpression in astrocytes of an Alzheimer's disease associated alpha-1-antichymotrypsin promoter polymorphism

Alpha-1-antichymottypsin (ACT), a serine proteinase inhibitor is synthesised predominantly in the liver and in other tissues including the brain. ACT is a major component of the senile plaques (SP) characteristic of Alzheimer's disease (AD). Increased production locally in the brain may be associated with Alzheimer's disease as ACT acts as a "pathological chaperone", promoting beta-amyloid assembly into neurotoxic fibrils. Recent reports suggest that the T allele of a G/T polymorphism at position -51 of ACT is associated with cognitive decline in AD patients. We demonstrate that the T allele is markedly overexpressed by almost 225% in an astrocytic cell line in response to oncostatin M (OSM) compared with a 35% increase in a mixed population of brain-derived cells. This effect is probably mediated by a higher binding affinity of the transcription initiation complex to the higher expressing allele and overexpression of ACT by astrocytes could thus contribute to increased beta-amyloid fibril formation in AD. (C) 2004 Elsevier B.V. All rights reserved.