BIOLOGY OF ALZHEIMER PAIRED HELICAL FILAMENTS

阿尔茨海默氏病（AD）的特征在于 神经纤维缠结（NFT）、老年斑（SP）和神经纤维丝 (NTs)在特定的端脑区域， 退化 以前的研究已经确定了一个共同的结构 NFT、NT和SP周围的营养不良神经突中的元件， 称为成对螺旋丝（PHF）。 最近，我们发现， SDS可溶性PHF的形式由A68组成，A68是一组推定的AD 特定蛋白质 此外，我们发现A68蛋白异常地 tau蛋白的磷酸化变体，一组低分子量微管 相关蛋白，并且tau中的单个KSPV是磷酸盐 在A68中有一个受体位点，但在正常人tau中没有。 这项提案描述了及时的实验，以确定如何正常tau是 转化成A68，组装成PHF，随后掺入 转化为AD NFT。 具体来说，我们将确定A68和 tau在氨基酸水平上是相同的，以排除 A68的一级结构可能与tau不同。 我们 将阐明A68中异常磷酸化的确切位点， 区别于正常的tau。 我们还将定义条件， 高度纯化的可溶性A68体外重组为PHFs。 最后我们 将评估NFT样结构是否可以由 A68 PHF与NFT的其他疑似蛋白质组分的相互作用 在规定的体外条件下。 成功完成这些 研究将导致A68的完整表征，主要 亚基的PHFs，他们将提供新的见解如何PHFs和NFT 由A68单独或与其他神经元蛋白一起形成。

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.