AGING AND ALZHEIMER DEMENTIA--ROLE OF FIBROUS PROTEIN

该项目的长期目标是了解生物学和 阿尔茨海默病（AD）的分子发病机制，最常见的有机 老年痴呆症 AD的特征在于存在 主要由成对螺旋丝组成的神经纤维缠结 （PHF）。 PHF制剂含有异常形式的tau命名表位， 与单克隆抗tau抗体（Tau-1）的反应性不同， 针对由tau基因外显子2编码的牛tau区域的抗体。 一 用磷酸酶预处理PHF-tau可改善其与这些蛋白的结合。 抗体，这表明PHF-tau与正常tau在位点/或 磷酸化的程度。 我们最近已经表明，PHF-tau也 在分子量和等电荷上不同于正常tau。 去磷酸化对蛋白质的生化特性影响很小， PHF tau，这表明，翻译后修饰，除了 磷酸化，和/或选择性基因剪接发挥作用， PHF-tau的形成。 尚待确定的是，除了PHF-tau外， 上述两个区域包含其他异常区域，并且如果 磷酸化是唯一的生化修饰， PHF-tau与正常tau。 也不知道PHF-tau是否含有额外的 磷酸化位点，如果PHF-tau的异常磷酸化是 在正常脑中或仅在AD脑中通过蛋白激酶催化。 这些问题将通过比较PHF-tau和tau蛋白来回答 正常和AD大脑的磷酸盐含量，氨基酸 组成和序列，翻译后修饰，并通过研究 用已知的激酶使去磷酸化的PHF-tau再磷酸化， 来自脑匀浆的激酶。 谷氨酸盐或钙的亚毒性水平 离子载体A23187最近被证明可以改变tau蛋白的免疫反应性， 培养的神经元 目前还不清楚这种变化是否与 在PHF-tau中。 我们的最后一个具体目标是研究这些因素的影响。 对tau的生物化学和免疫细胞化学性质的处理，以及 影响神经元的超微结构

The long-term goal of this project is the understanding of the biology and molecular pathogenesis of Alzheimer's disease (AD), the most common organic dementia seen in old age. AD is characterized by the presence of neurofibrillary tangles which consist primarily of paired helical filaments (PHF). PHF preparations contain aberrant forms of tau named epitopes but differed in reactivity with a monoclonal anti-tau antibody (Tau-1) and antibodies to a region of bovine tau encoded by tau gene exon 2. A pretreatment of PHF-tau with phosphatase improved its binding with these antibodies, suggesting that PHF-tau differed from normal tau in the site/or the extent of phosphorylation. We have shown recently that PHF-tau also differed from normal tau in molecular mass and isoelectric charge. Dephosphorylation had very little effect on the biochemical properties of PHF tau, suggesting that post-translational modifications, besides phosphorylation, and/or alternative gene splicing play a role in the formation of PHF-tau. It remains to be determined if PHF-tau, besides the two regions mentioned above, contain other aberrant regions, and if phosphorylation is the only biochemical modification that distinguishes PHF-tau from normal tau. It is also unknown if PHF-tau contains additional phosphorylation sites and if the aberrant phosphorylation of PHF-tau is catalyzed via a protein kinase (s) in normal brains or only in AD brains. These questions will be answered by comparing PHF-tau, and tau proteins from normal and AD brains for their phosphate content, amino acid composition and sequences, post-translational modifications and by studying the rephosphorylation of dephosphorylated PHF-tau with known kinases and kinases from brain homogenates. A subtoxic level of glutamate or calcium ionophore A23187 was recently shown to alter the immunoreactivity of tau in cultured neurons. It is unclear whether this alteration is similar to that in PHF-tau. Our last specific aim is to study the effect of these treatments on the biochemical and immunocytochemical properties of tau, and on the ultrastructure of the affected neurons.