Apolipoprotein A-I directly interacts with amyloid precursor protein and inhibits Aβ aggregation and toxicity
Apolipoprotein A-I directly interacts with amyloid precursor protein and inhibits Aβ aggregation and toxicity
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DOI：
10.1021/bi002186k
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发表时间：
2001-03-27
期刊：
影响因子：
2.9
通讯作者：
Lazo, JS
中科院分区：
文献类型：
--
作者：
Koldamova, RP;Lefterov, IM;Lazo, JS
淀粉样蛋白前体蛋白（APP）是与阿尔茨海默病相关的神经毒性淀粉样蛋白（A β）肽的来源。载脂蛋白a - i （apoA-I）是高密度脂蛋白复合物的组成部分，经酵母双杂交系统鉴定为全长APP （APPfl）的强特异性结合伙伴。apoA-I与APPfl之间的关联定位于APP的胞外结构域（APPextra）。此外，利用重组表位标记的APPextra和纯化的apoA-I通过共沉淀法证实了apoA-I与APPfl之间的相互作用。在APPextra中已经发现了几个功能域，我们关注的是apoA-1与病理上重要的AP肽之间可能的相互作用，因为APPextra含有a β的非跨膜结构域。apoA-I和A β之间的结合是饱和的（K-d = 6 nM），特异性和可逆的。APPextra还与apoA-I竞争与A β的结合。这种相互作用的直接证据是在聚丙烯酰胺凝胶中形成抗sds的A β - apoa - 1复合物。与载脂蛋白E （E2和E4亚型）的竞争实验表明，apoA-I对a β具有更高的结合亲和力。我们还发现，apoA-I抑制β β的β -薄片形成，其平均抑制浓度接近α 2-巨球蛋白。最后，我们证明了apoA-I可以减弱A β诱导的细胞毒性。这些结果表明，apoA-I结合到APP的至少一个细胞外结构域，并在控制a β聚集和毒性方面发挥功能作用。
Amyloid precursor protein (APP) is the source of the neurotoxic amyloid beta (A beta) peptide associated with Alzheimer's disease. Apolipoprotein A-I (apoA-I), a constituent of high-density lipoprotein complexes, was identified by a yeast two-hybrid system as a strong and specific binding partner of full-length APP (APPfl). This association between apoA-I and APPfl was localized to the extracellular domain of APP (APPextra). Furthermore, the interaction between apoA-I and APPfl was confirmed by coprecipitation using recombinant epitope-tagged APPextra and purified apoA-I. Several functional domains have been identified in APPextra, and we focused on a possible interaction between apoA-1 and the pathologically important AP peptide, because APPextra contains the nontransmembrane domain of A beta. The binding between apoA-I and A beta was saturable (K-d = 6 nM), specific, and reversible. APPextra also competed with apoA-I for binding to A beta. Direct evidence for this interaction was obtained by the formation of an SDS-resistant A beta -apoA-I complex in polyacrylamide gels. Competitive experiments with apolipoprotein E (isoforms E2 and E4) showed that apoA-I had a higher binding affinity for A beta. We also found that apoA-I inhibited the beta -sheet formation of A beta with a mean inhibitory concentration close to that of alpha2-macroglobulin. Finally, we demonstrated that apoA-I attenuated A beta -induced cytotoxicity. These results suggest apoA-I binds to at least one extracellular domain of APP and has a functional role in controlling A beta aggregation and toxicity.