Cholesterol Research Today is a free monthly online journal that collates and summarizes the latest research about Cholesterol, including details on high cholesterol, hdl, ldl, diet, risks.

The cholesterol transporter ABCG1 modulates the subcellular distribution and proteolytic processing of beta-amyloid precursor protein.

Tansley GH, Burgess BL, Bryan MT, Su Y, Hirsch-Reinshagen V, Pearce J, Chan JY, Wilkinson A, Evans J, Naus KE, McIsaac S, Bromley K, Song W, Yang HC, Wang N, DeMattos RB, Wellington CL

Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.

Although intracellular cholesterol levels are known to influence the proteolysis of beta-amyloid precursor protein (APP), the effect of specific genes that regulate cholesterol metabolism on APP processing remains poorly understood. The cholesterol transporter ABCG1 facilitates cholesterol efflux to HDL and is expressed in brain. Notably, the human ABCG1 gene maps to chromosome 21q22.3, and individuals with Down syndrome (DS) typically manifest with Alzheimer's disease (AD) neuropathology in their 30s. Here, we demonstrate that expression of ABCG1 enhances amyloid-beta protein (Abeta) production in transfected HEK cells in a manner that requires functional cholesterol transporter activity. ABCG1-expressing cells also exhibit increased secreted APP (sAPP)alpha and sAPPbeta secretion and display increased cell surface-associated APP. These results suggest that ABCG1 increases the availability of APP as a secretase substrate for both the amyloidogenic and nonamyloidogenic pathways. In vivo, ABCG1 mRNA levels are 2-fold more abundant in DS brain compared with age- and sex-matched normal controls. Finally, both Abeta and sAPPalpha levels are increased in DS cortex relative to normal controls. These findings suggest that altered cholesterol metabolism and APP trafficking mediated by ABCG1 may contribute to the accelerated onset of AD neuropathology in DS.

Published 2 May 2007 in J Lipid Res, 48(5): 1022-34.
Full-text of this article is available online (may require subscription).

© 2004-2008 Cholesterol Research Today. All Rights Reserved.