Premium
Oligomerization of amyloid β‐protein occurs during the isolation of lipid rafts
Author(s) -
Yu Wenxin,
Zou Kun,
Gong JianSheng,
Ko Mihee,
Yanagisawa Katsuhiko,
Michikawa Makoto
Publication year - 2005
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.20428
Subject(s) - lipid raft , raft , biochemistry , cell fractionation , chemistry , homogenization (climate) , amyloid (mycology) , microbiology and biotechnology , cholesterol , biophysics , biology , membrane , biodiversity , ecology , inorganic chemistry , organic chemistry , copolymer , polymer
Cholesterol‐ and glycosphingolipid‐rich microdomains, called “lipid rafts,” are suggested to initiate and promote the pathophysiology of Alzheimer's disease by serving as a platform for generation, aggregation, or degradation of amyloid‐β protein (Aβ). However, methods for biochemical isolation of these microdomains may produce artifacts. In this study, when synthetic Aβ1– 40 monomers were added to the brain fragment at a final concentration of 2.1 μM, followed by homogenization and isolation of lipid rafts by an established method, Aβ1– 40 accumulated as oligomers in the lipid raft fraction. However, in the absence of a brain homogenate, synthetic Aβ1– 40 did not accumulate in the lipid raft fraction. When fractionation was performed in the absence of synthetic Aβ1–40 and synthetic Aβ1–40 was incubated in an aliquot of each fraction, a marked oligomerization of Aβ1– 40 was observed in the lipid raft aliquot. These results indicate that exogenous Aβ associates with lipid rafts, and Aβ bound to rafts forms oligomers during the isolation of lipid rafts. In addition, endogenous Aβ1–40 in a Triton X‐100‐insoluble fraction of a brain homogenate of the Tg2576 transgenic mouse model of Alzheimer's disease formed oligomers when the fraction was incubated at 4°C for 20 hr. Thus, one should be careful when one discusses the role of lipid rafts in amyloid precursor protein processing and in the generation, aggregation, and degradation of Aβ. © 2005 Wiley‐Liss, Inc.