Investigation of mechanism of tauopathy and application for clinical diagnosis

1)制备了一种选择性识别四重复序列tau蛋白的抗体。(4R-tau)。用此抗体对进行性核上性麻痹(PSP)患者脑组织进行检测，发现tau阳性的簇状星形胶质细胞、小脑角星形胶质细胞和星形胶质细胞由4R-tau和4R-tau阳性的簇状星形胶质细胞组成，抗GFAP抗体不反应。2)利用4R-tau抗体建立了检测脑脊液中4R-tau的方法。该方法是基于ELISA的。3)我们发现了一个新的tau基因突变(L266V)，在一个家族性tau病(与17号染色体连锁的额颞性痴呆和帕金森病)中，我们检查了该家系患者的大脑，发现了Pick体样包涵体和独特的tau阳性星形细胞。4)我们报告了两个表现不同表型的P301L tau突变的患者。他们的tau基因在三个位点的基因分型不同，研究表明他们并不共享P301L突变的共同创建者，在患者2中观察到的两种较不常见的基因突变中的任何一种可能是将P301L突变的表型改变为显著帕金森病临床特征的因素。5)采用定量RT-PCR方法，检测PSP和皮质基底性变性(CBD)患者额叶皮质和苍白球中tau mRNA亚型的表达水平。PSP组和CBD组的额叶皮质和苍白球的4R/3R比值显著高于对照组。Tau mRNA亚型的表达模式与p-tau的积累量之间无相关性。我们的发现表明，PSP和CBD的神经退行性变可以通过tau mRNA的选择性剪接来调节，从而产生高的4R/3R比率，但其他因素，如转录后或翻译修饰，可能在PSP和CBD的特异性神经退行性变的发病机制中发挥作用。

1)We have made an antibody which selectively recognized the four-repeat tau protein. (4R-tau). Using this antibody, we examined the brain tissue of the patients with progressive supranuclear palsy (PSP) and demonstrated that tau-positive tufted astrocyte, pretangle and theads were composed of 4R-tau and 4R-tau-positive tufted astrocytes were not reactive for anti-GFAP antibody.2)Using the antibody for 4R-tau, we are establishing the method for measure of 4R-tau in cerebrospinal fluid. The method is based on ELISA.3)We have found a new mutation of the tau gene (L266V) in a familial tauopathy (frontotemporal dementia and parkinsonism linked to chromosome 17) and we examined the brain of a patient of this kindred and demonstrated Pick body-like inclusions and unique tau-positive astrocytes.4)We have reported two patients of the two families with P301L tau mutation, who showed different phenotype. Their genotypes of the tau gene were different at three sites, and the studies suggested they do not share a common founder for P301L mutation and either of the two less prevalent genotypes observed in patient 2 may be the factor to modify the phenotype of P301L mutation into those unusual clinical features with prominent parkinsonism.5)Using quantitative RT-PCR method, we investigated the expression level of tau mRNA isoforms in the frontal cortex and globus pallidus of patients with PSP and corticobasal degeneration (CBD). The 4R/3R ratios in frontal cortices of CBD and globus pallidus of PSP and CBD were significantly higher than the control. There was no correlation between the expression patterns of tau mRNA isoforms and p-tau accumulation. Our findings suggest that neurodegeneration of PSP and CBD could be regulated by alternative splicing of tau mRNA to yield high 4R/3R ratio but also other factors such as post-transcriptional or translational modifications may play a role in the pathogenesis of specific neurodegeneration in PSP and CBD.