中文摘要：

异常磷酸化Tau蛋白是神经纤维缠结的主要成分,也是老年痴呆的典型病理特征之一.本实验室前期报道了Tau蛋白具有保护DNA的作用,但磷酸化对Tau与DNA相互作用的影响需要进行探索,这对于揭示Tau蛋白异常磷酸化与神经细胞死亡之间的关系具有一定的参考价值.本文采用甲醛孵育N2a细胞,引起了细胞内Tau蛋白的过度磷酸化.实验结果进一步显示,甲醛孵育组的细胞核内磷酸化Tau蛋白与DNA非共定位存在,而对照组细胞核内Tau蛋白与DNA存在一定程度的共定位现象.电泳迁移率实验检测GSK-3β催化的磷酸化Tau蛋白与DNA的结合情况,可以观察到磷酸化减弱了Tau蛋白与DNA的相互结合.这些结果表明,异常磷酸化可以使Tau蛋白丧失对DNA的保护作用,这可能是Tau蛋白异常磷酸化引起DNA损伤甚至细胞死亡的原因之一.

英文摘要：

Hyperphosphorylation of Tau protein and related neuron death is one of the most important characteristics of Alzheimer＇s disease.Our laboratory has shown that Tau protein is able to bind and protect DNA. It is still unknown whether phosphorylation affects the binding of Tau to DNA.Therefore,it is of importance to investigate the effect of phosphorylation on the interaction of Tau with DNA in cells.In this work,we treated N2a cells with formaldehyde and found that Tau protein was hyperphosphorylated in the cells under the experimental conditions.Phosphorylation was remarkably observed at both T181 and S396 of Tau protein in the cells in the presence of formaldehyde compared with those in the absence of formaldehyde.Cytoimmunofluorescence hardly showed that most of the nuclear phosphorylated Tau protein was co-localized with DNA,while Tau protein was partially co-localized with DNA in the absence of formaldehyde as control.Electrophoretic mobility shift assay （EMSA） showed that phosphorylated Tau catalyzed by GSK-3β reduced the interaction between Tau protein and DNA in vitro.These findings reveal that hyperphosphorylation declines Tau protein to protect DNA,and may thereafter lead to damage of DNA and even cell death,giving a novel viewpoint to the pathology of Alzheimer＇s disease.