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Abeta42-peptide assembly on lipid bilayers
Christopher M Yip1, Audrey A Darabie, JoAnne McLaurin
1Department of Chemical Engineering and Applied Chemistry, Institute for Biomaterials and Biomedical Engineering and Centre for Studies in Molecular Imaging, University of Toronto, Toronto, Ontario, Canada M5S 3G9.
Journal of Molecular Biology
|June 11, 2002
Summary
Alzheimer's disease (AD) amyloid-beta 42 (Abeta42) peptide interacts with brain lipid membranes, forming aggregates and fibers. Membrane composition, particularly cholesterol, influences Abeta42 assembly and associated membrane changes.
Area of Science:
- Neuroscience
- Biochemistry
- Cell Biology
Background:
- Alzheimer's disease (AD) pathology involves amyloid plaques, primarily composed of amyloid-beta (Abeta) peptides.
- Diffuse plaques in AD are rich in Abeta42, suggesting its critical role in early plaque formation.
- The hypothesis posits that Abeta42 initially binds to plasma membranes, initiating plaque development.
Purpose of the Study:
- To investigate the interactions between Abeta42 and lipid membranes.
- To understand how membrane composition affects Abeta42 aggregation and fiber formation.
Main Methods:
- In situ atomic force microscopy (AFM) to visualize Abeta42-membrane interactions.
- Fluorescence spectroscopy, including anisotropy and fluorimetry, to detect membrane changes.
- Utilized planar bilayers composed of total brain lipids with varying cholesterol content.
Main Results:
- Demonstrated direct association of Abeta42 with brain lipid bilayers, leading to peptide aggregation and fiber formation.
- Cholesterol content modulation correlated with the extent of Abeta42 assembly on the bilayer surface.
- Abeta42 induced membrane changes, even when not directly visualized on cholesterol-depleted bilayers.
Conclusions:
- The lipid bilayer composition significantly governs the outcome of Abeta interactions.
- Membrane-bound Abeta42 plays a role in the initial stages of amyloid plaque formation in Alzheimer's disease.
- Cholesterol is a key factor in modulating Abeta42 aggregation on neuronal membranes.