Structural and functional implications of tau hyperphosphorylation:: Information from phosphorylation-mimicking mutated tau proteins
Structural and functional implications of tau hyperphosphorylation:: Information from phosphorylation-mimicking mutated tau proteins
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DOI：
10.1021/bi001290z
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发表时间：
2000-10-31
期刊：
影响因子：
2.9
通讯作者：
Brandt, R
中科院分区：
文献类型：
--
作者：
Eidenmüller, J;Fath, T;Brandt, R
异常的tau免疫反应细丝是tau病的标志，包括阿尔茨海默病(AD)。Tau蛋白较高的磷酸化(“过度磷酸化”)状态可能代表一个关键事件。为了确定tau过度磷酸化在这些疾病中的潜在作用，我们产生了突变的tau蛋白，其中从AD患者分离的tau细丝中已知的高度磷酸化的丝氨酸/苏氨酸残基被谷氨酸取代，以模拟成对的螺旋细丝(PHF)样的tau过度磷酸化。我们证明，与过度磷酸化一样，谷氨酸取代在tau蛋白中诱导紧凑的结构元件和耐十二烷基硫酸钠的构象结构域。过度磷酸化模拟谷氨酸突变的tau蛋白完全丧失了促进微管成核的能力，这可以通过添加类似于磷酸化tau的渗透分子三甲胺N-氧化物(TMAO)来部分克服。此外，谷氨酸突变的tau蛋白不能与主要的大脑蛋白磷酸酶2A亚型ABαC相互作用，并表现出组装成细丝的能力降低。有趣的是，野生型tau和类似磷酸化的tau在单独加入时类似地与微管结合，但突变的tau几乎完全被等摩尔浓度的野生型tau从微管表面取代。这些数据表明，谷氨酸突变的tau蛋白为分析tau过度磷酸化的功能后果提供了一个有用的模型。他们认为，在tauopy病期间观察到的tau异常积聚有几种机制，特别是过度磷酸化的tau从微管中选择性地置换，在促进微管成核方面的功能丧失，以及未能与磷酸酶相互作用。
Abnormal tau-immunoreactive filaments are a hallmark of tauopathies, including Alzheimer's disease (AD). A higher phosphorylation ("hyperphosphorylation") state of tau protein may represent a critical event. To determine the potential role of tau hyperphosphorylation in these disorders, mutated tau proteins were produced where serine/threonine residues known to be highly phosphorylated in tau filaments isolated from AD patients were substituted for glutamate to simulate a paired helical filament (PHF)-like tau hyperphosphorylation. We demonstrate that, like hyperphosphorylation, glutamate substitutions induce compact structure elements and SDS-resistant conformational domains in tau protein. Hyperphosphorylation-mimicking glutamate-mutated tau proteins display a complete functional loss in its ability to promote microtubule nucleation which can partially be overcome by addition of the osmolyte trimethylamine N-oxide (TMAO), which is similar to phosphorylated tau. In addition, glutamate-mutated tau proteins fail to interact with the dominant brain protein phosphatase 2A isoform AB alphaC, and exhibit a reduced ability to assemble into filaments. Interestingly, wild-type tau and phosphorylation-mimicking tau similarly bind to microtubules when added alone, but the mutated tau is almost completely displaced from the microtubule surface by equimolar concentrations of wild-type tau. The data indicate that glutamate-mutated tau proteins provide a useful model for analyzing the functional consequences of tau hyperphosphorylation. They suggest that several mechanisms contribute to the abnormal tau accumulation observed during tauopathies, in particular a selective displacement of hyperphosphorylated tau from microtubules, a functional loss in promoting microtubule nucleation, and a failure to interact with phosphatases.