Copper mediates dityrosine cross-linking of Alzheimer's amyloid-β
Copper mediates dityrosine cross-linking of Alzheimer's amyloid-β
复制标题
DOI：
10.1021/bi0358824
复制
发表时间：
2004-01-20
期刊：
影响因子：
2.9
通讯作者：
Bush, AI
中科院分区：
文献类型：
--
作者：
Atwood, CS;Perry, G;Bush, AI
我们之前已经报道过，淀粉样蛋白Abeta是阿尔茨海默病(AD)老年斑的主要成分，它通过组氨酸和酪氨酸残基与铜结合，具有高亲和力[Atwood，C.S.，et al.(1998)J.Biol.化学。273,12817-12826；阿特伍德，C.S.等人(2000)J.Neurochem.75,12191233]，并通过催化铜(II)或铁(III)的还原产生H_2O_2[Huang，X.等]。(1999)生物化学38,7609-7616；黄新，等。(1999)J.Biol.化学。274、37111-37116]。与铜孵育诱导耐十二烷基硫酸钠的Abeta寡聚[Atwood，C.S.，et al.(2000)J.Neurochem.75,1219-1233]，这是从AD脑中提取的神经毒性可溶性Abeta的特征。由于与铜配位的残基最容易氧化，我们调查了这些残基的修饰是否导致了Abeta的交联。通过与铜孵育引起的Abeta的SDS抗性齐聚，发现诱导了具有酪氨酸交联特征的荧光信号。利用ESI-MS和双酪氨酸特异性抗体，我们证实了铜(II)(浓度低于与淀粉样斑块相关的浓度)可以诱导人而不是大鼠的双酪氨酸交联型的、抗十二烷基硫酸钠的寡聚体的产生。H_2O_2的加入强烈促进了铜诱导的Abeta1-28、Abeta1-40和Abeta1-42的双酪氨酸交联，表明氧化偶联是由H_2O_2与酪氨酸铜(II)相互作用引起的。Dityroine的修饰意义重大，因为它高度抵抗蛋白质分解，并已知在增加结构强度方面起到了作用。鉴于衰老斑块中铜的浓度升高，我们的结果表明，铜与Abeta的相互作用可能是导致这些结构中Abeta共价交联的原因。
We have previously reported that amyloid Abeta, the major component of senile plaques in Alzheimer's disease (AD), binds Cu with high affinity via histidine and tyrosine residues [Atwood, C. S., et al. (1998) J. Biol. Chem. 273, 12817-12826; Atwood, C. S., et al. (2000) J. Neurochem. 75, 12191233] and produces H2O2 by catalyzing the reduction of Cu(II) or Fe(III) [Huang, X., et al. (1999) Biochemistry 38, 7609-7616; Huang, X., et al. (1999) J. Biol. Chem. 274, 37111-37116]. Incubation with Cu induces the SDS-resistant oligomerization of Abeta [Atwood, C. S., et al. (2000) J. Neurochem. 75, 1219-1233], a feature characteristic of neurotoxic soluble Abeta extracted from the AD brain. Since residues coordinating Cu are most vulnerable to oxidation, we investigated whether modifications of these residues were responsible for Abeta cross-linking. SDS-resistant oligomerization of Abeta caused by incubation with Cu was found to induce a fluorescence signal characteristic of tyrosine cross-linking. Using ESI-MS and a dityrosine specific antibody, we confirmed that Cu(II) (at concentrations lower than that associated with amyloid plaques) induces the generation of dityrosine-cross-linked, SDS-resistant oligomers of human, but not rat, Abeta peptides. The addition of H2O2 strongly promoted Cu-induced dityrosine cross-linking of Abeta1-28, Abeta1-40, and Abeta1-42, suggesting that the oxidative coupling is initiated by interaction of H2O2 with a Cu(II) tyrosinate. The dityrosine modification is significant since it is highly resistant to proteolysis and is known to play a role in increasing structural strength. Given the elevated concentration of Cu in senile plaques, our results suggest that Cu interactions with Abeta could be responsible for causing the covalent cross-linking of Abeta in these structures.