Apolipoprotein E forms stable complexes with recombinant Alzheimer's disease beta-amyloid precursor protein
Apolipoprotein E forms stable complexes with recombinant Alzheimer's disease beta-amyloid precursor protein
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DOI：
10.1042/bj3250169
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发表时间：
1997-07-01
影响因子：
4.1
通讯作者：
Vazquez, J
中科院分区：
文献类型：
--
作者：
Haas, C;Cazorla, P;Vazquez, J
载脂蛋白E(ApoE)是一种在基因上与阿尔茨海默病发病相关的蛋白质，它在体外与老年斑的主要成分β-淀粉样多肽(Aβ)形成十二烷基硫酸钠稳定的复合体。在本研究中，我们研究了apoE是否能够与全长Aβ前体蛋白(APP)结合。利用麦芽糖结合蛋白-APP融合蛋白和人极低密度脂蛋白(VLDL)，我们检测到apoE与APP的相互作用被Aβ或抗apoE抗体抑制。饱和结合实验表明，其化学计量比为1：1，解离常数为15 nm，为单一结合平衡。从脑脊液或脱脂的极低密度脂蛋白中提取的载脂蛋白E与重组载脂蛋白E之间也存在相互作用。APP.apoE复合体是十二烷基硫酸钠稳定的，其形成不受还原条件的抑制，但在还原条件下被十二烷基硫酸钠解离。ApoE.APP复合体形成了高分子质量的聚集体，竞争实验表明Aβ的14-23个氨基酸参与了复合体的形成。最后，在研究APP与apoE3或apoE4的相互作用时，没有发现差异。综上所述，我们的结果表明apoE可能与APP的Aβ部分形成稳定的络合物，其特征类似于与分离的Aβ形成的络合物，并表明apoE-APP相互作用在体内可能具有病理相关性。
Apolipoprotein E (apoE), a protein genetically linked to the incidence of Alzheimer's disease, forms SDS-stable complexes in vitro with beta-amyloid peptide (A beta), the primary component of senile plaques. In the present study, we investigated whether apoE was able to bind full-length A beta precursor protein (APP). Using a maltose-binding-protein-APP fusion protein and human very-low-density lipoprotein (VLDL), we detected an interaction of apoE with APP that was inhibited by A beta or anti-apoE antibody. Saturation-binding experiments indicated a single binding equilibrium with an apparent 1:1 stoichiometry and a dissociation constant of 15 nM. An interaction was also observed using apoE from cerebrospinal fluid or delipidated VLDL, as well as recombinant apoE. APP.apoE complexes were SDS-stable, and their formation was not inhibited by reducing conditions; however, they were dissociated by SDS under reducing conditions. ApoE.APP complexes formed high-molecular-mass aggregates, and competition experiments suggested that amino acids 14-23 of A beta are responsible for complex-formation. Finally, no differences were found when studying the interaction of APP with apoE3 or apoE4. Taken together, our results demonstrate that apoE may form stable complexes with the A beta moiety of APP with characteristics similar to those of complexes formed with isolated A beta, and suggest the intriguing possibility that apoE-APP interactions may be pathologically relevant in vivo.