AGING AND ALZHEIMER DEMENTIA--ROLE OF FIBROUS PROTEINS

描述：(改编自申请者摘要)阿尔茨海默病(AD) 以异常细丝的渐进性积累为特征， 在神经元核膜内称为成对螺旋丝(PHF)。 和细胞突起，以神经原纤维缠结(NFT)的形式， 老年斑中的神经纤维线和营养不良的轴突。成对的 螺旋状细丝和生化相似的直径为15-18 nm的直线 细丝由微管相关蛋白tau组成。 生化研究表明，一些PHF可溶于钠 十二烷基硫酸酯(十二烷基硫酸酯)虽然其他都是不溶的，但其基础 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， 等电荷量、异构体数目和分子量 溶解度。此外，一组不正常的tau蛋白 与PHF相关联，但具有类似于PHF-tau的性质，一直是 在公元后表现出来。最具特点的是两者的区别 PHF-tau和正常tau是磷酸化的程度和部位。在……里面 除了磷酸化，PHF-tau与正常tau的不同之处在于 D-天冬氨酸含量增加，赖氨酸含量降低 残留物。这些观察结果令人感兴趣的是消旋是 在长寿命蛋白质和一种特殊类型的修饰中增加 长寿蛋白质中的赖氨酸基团，即非酶糖基化， 最近被认为在PHF的形成中发挥了作用。进一步 对这些性质的研究可能有助于揭示其形成机制。 并稳定成异常的细丝。这一行动的具体目标 建议是确定翻译后修改，如 糖基化和外消旋，参与PHF的形成、聚集 并稳定到组成神经纤维束的异常细丝中 老年斑中的线状突起和营养不良的轴突。六行 将进行调查。它们包括(1)比较 十二烷基硫酸钠可溶的PHF、不溶于十二烷基硫酸钠的PHF、NO-PHF的糖基化程度 异常tau和胞浆tau(相当于正常tau)，(2) Tau和PHF糖基化位点的测定 溶解度，(3)NFT中AGE免疫反应性的比较 细丝的凝聚或聚结(4)氦的比较 不同形式的tau对糖基化的敏感性，(5)测定 糖基化对tau-微管蛋白和tau-tau相互作用的影响，以及 (6)外消旋作用(D-天冬氨酸)的测定 Tau的功能，以及D-天冬氨酸在植物体内的分布和含量 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.