AGING AND ALZHEIMER DEMENTIA--ROLE OF FIBROUS PROTEINS

描述：（改编自申请人的摘要）阿尔茨海默病（AD） 其特征在于异常细丝的逐渐积累， 称为成对螺旋丝（PHF），在神经元胞体内 和细胞过程，以神经元缠结（NFT）的形式， 老年斑中的神经纤维和营养不良的神经突。 配对 螺旋丝和生物化学上类似的直径为15-18 nm的直丝 丝由微管相关蛋白tau组成。 生物化学研究表明，一些PHF可溶于钠 十二烷基硫酸盐（SDS），而其他都不溶，但基础的 PHF异质性的重要性目前尚不清楚。 tau蛋白 在PHF（PHF-tau）中磷酸盐含量不同于正常tau， 异构体的等电荷、数量和分子量， 溶解度 此外，一个异常的tau蛋白池， 与PHF相关，但具有与PHF-tau相似的性质， 在AD中演示。 最好的特点之间的差异 PHF-tau蛋白与正常tau蛋白磷酸化程度和位点不同。 在 除了磷酸化，PHF-tau与正常tau的不同之处在于其 D-天冬氨酸含量增加，赖氨酸含量降低 残基 这些观察结果是有趣的，因为外消旋化是 增加了长寿蛋白质和一种特殊类型的修饰 长寿命蛋白质中的赖氨酸基团，即非酶糖化， 最近被认为在PHF形成中起作用。 进一步 对这些性质的研究可能有助于阐明其形成机理 并稳定为异常细丝。 具体目标是 建议是确定是否翻译后修饰，如 糖基化和外消旋化，参与PHF的形成，聚集 并稳定在构成NFT的异常纤维中， 线和老年斑中营养不良的神经突。 六行 调查将会展开。 其中包括：（1）比较 SDS-可溶性PHF、SDS-不溶性PHF、无PHF- 异常tau和胞质tau（相当于正常tau），（2） 确定tau和PHF中的糖基化位点， 溶解度，（3）NFT中AGE免疫反应性与 （4）纤维的凝聚或聚结; 不同形式的tau对糖基化的敏感性，（5）测定 糖化对tau-微管蛋白和tau-tau相互作用的影响， (6)测定外消旋化（D-天冬氨酸）对 tau蛋白的功能，以及D-天冬氨酸在 PHF-tau和非PHF异常tau。

DESCRIPTION: (adapted from Applicant's Abstract) Alzheimer's disease (AD) is characterized by the progressive accumulation of abnormal filaments, referred to as paired helical filaments (PHF), within neuronal perikarya and cell processes, in the form of neurofibrillary tangles (NFT), neuropil threads and dystrophic neurites in senile plaques. Paired helical filaments and biochemically similar 15-18 nm diameter straight filaments are composed of microtubule associated protein tau. Biochemical studies have shown that some PHF are soluble in sodium dodecyl sulfate (SDS) while other are insoluble, but the basis of significance of PHF heterogeneity is currently unknown. The tau protein in PHF (PHF-tau) differs from normal tau in phosphate content, isoelectric charge, number of and molecular weights of isoforms and solubility. Moreover, a pool of abnormal tau protein that is not associated with PHF, but has properties similar to PHF-tau, has been demonstrated in AD. The best characterized of the differences between PHF-tau and normal tau is extent and sites of phosphorylation. In addition to phosphorylation, PHF-tau differs from normal tau in its increased content of D-aspartate and decreased content of lysine residues. These observations are of interest in that racemization is increased in long-lived proteins and a particular type of modification of lysine groups in long-lived proteins, namely nonenzymatic glycation, has recently been suggested to play a role in PHF formation. Further studies of these properties may shed light on the mechanism of formation and stabilization into abnormal filaments. The specific goals of this proposal are to determine if post-translational modifications, such as glycation and racemization, are involved in PHF formation, aggregation and stabilization into the abnormal filaments that make up NFT, neuropil threads and dystrophic neurites in senile plaques. Six lines of investigation will be carried out. They include (1) comparison of the extent of glycation of SDS- soluble PHF, SDS-insoluble PHF, no-PHF- abnormal tau and cytosolic tau (equivalent to normal tau), (2) determination of the sites of glycation in tau and PHF differing in solubility, (3) comparison of AGE immunoreactivity in NFT with respect to condensation or coalescence of filaments (4) comparison of he susceptibility of different forms of tau to glycation, (5) determination of the effect of glycation on tau-tubulin, and tau-tau interactions, and (6) determination of the effect of racemization (D-aspartate) on the function of tau, and the distribution and the content of D-aspartate in PHF-tau and non- PHF abnormal tau.