BIOLOGY OF ALZHEIMER PAIRED HELICAL FILAMENTS

阿尔茨海默病(AD)的特点是 神经原纤维缠结(NFTs)、老年斑(SP)和神经纤维束 (NTS)在特别容易感染的特定端脑区域 退化。以前的研究已经确定了一种共同的结构 NFT、NTS和SP周围营养不良的轴突中的元素 称为成对螺旋长丝(PHF)。最近，我们展示了一个 可溶于十二烷基硫酸钠的PHF由A68组成，A68是一组可能的AD 特定的蛋白质。此外，我们发现A68蛋白是异常的。 Tau的磷酸化变体，一组低分子质量的微管 结合蛋白，并且tau中的单一KSPV是磷酸盐 A68的受体位点，但在正常人tau中不存在。 这项建议描述了确定tau正常程度的适时实验。 转化为A68，组装成PHF，随后并入 进入AD NFT。具体地说，我们将确定A68和 在氨基酸水平上是相同的，以便排除 A68的一级结构可能不同于tau的一级结构。我们 将阐明A68中异常磷酸化的确切位置 将它与正常的tau区分开来。我们还将定义In的条件 高纯度可溶性A68体外重组为PHF。最后，我们 将评估类NFT结构是否可以由 A68PHF与NFTs其他可疑蛋白质组分的相互作用 在规定的条件下进行体外实验。这些项目的顺利完成 研究将导致A68的完整特征，主要 它们将为PHF和NFT提供新的洞察 是由A68单独或与其他神经元蛋白共同形成的。

Alzheimer's disease (AD) is characterized by the accumulation of neurofibrillary tangles (NFTs), senile plaques (SPs) and neuropil threads (NTs) in selected telencephalic regions that are especially vulnerable to degeneration. Previous studies have identified a common structural elements in NFTs, NTs and the dystrophic neurites around SPs that are referred to as paired-helical filaments (PHFs). Recently, we showed that a form of SDS-soluble PHFs are composed of A68, a group of putative AD specific proteins. Further, we showed that A68 proteins are abnormally phosphorylated variants of tau, a group of low molecular weight microtubule associated proteins, and that the single KSPV in tau is a phosphate acceptor site in A68 but not in normal human tau. This proposal describes timely experiments to determine how normal tau is transformed into A68, assembled into PHFs and subsequently incorporated into AD NFTs. Specifically, we will determine the extent to which A68 and tau are identical at the amino acid levels in order to exclude the possibility that the primary structure of A68 differs from that of tau. We will elucidate the exact sites of abnormal phosphorylation in A68 that distinguish it from normal tau. We will also define conditions for the in vitro reassembly of highly purified soluble A68 into PHFs. Finally, we will assess whether or not NFT-like structures can be formed by the interaction of A68 PHFs with other suspected protein components of NFTs under defined conditions in vitro. The successful completion of these studies will lead to the complete characterization of A68, the major subunit of PHFs, and they will provide new insight into how PHFs and NFTs are formed from A68 alone or in concert with other neuronal proteins.