Max-Planck Unit for Structural Molecular Biology, Hamburg, Germany.
Neurodegener Dis. 2010;7(1-3):103-7. doi: 10.1159/000285516. Epub 2010 Feb 18.
We have studied the mechanism of aggregation in an inducible cell model of Tau pathology. When the repeat domain of human Tau (Tau(RD)) carrying the FTDP-17 mutation DeltaK280 is expressed, the cells develop aggregates, as seen by thioflavin S fluorescence, electron microscopy, and sarkosyl extraction methods. By contrast, mutants of Tau(RD) that are unable to generate beta-structure do not aggregate. Enhanced aggregation leads to enhanced toxicity, visible by live cell microscopy and LDH release assay. The aggregation process is initiated by the sequential cleavage of Tau(RD) which yields highly amyloidogenic fragments. This cleavage occurs only with proaggregant Tau(RD), and not with the nonaggregating mutants, indicating that beta-structure makes Tau(RD) vulnerable to both proteolytic degradation and aggregation. Aggregation is reversed by switching off the expression of Tau(RD), by inhibitor compounds, and by certain protease inhibitors. In all cases, the enhanced toxicity is rescued. The clearance of the aggregates involves autophagy, whereas proteasomal degradation plays only a minor role.
我们研究了 Tau 病诱导细胞模型中聚集的机制。当携带 FTDP-17 突变 DeltaK280 的人 Tau（Tau(RD)）重复结构域表达时，细胞会产生聚集物，这可以通过硫黄素 S 荧光、电子显微镜和 Sarkosyl 提取方法观察到。相比之下，无法产生β-结构的 Tau(RD)突变体不会聚集。增强的聚集导致毒性增强，通过活细胞显微镜和 LDH 释放测定可见。聚集过程由 Tau(RD)的顺序切割引发，产生高度淀粉样的片段。这种切割仅发生在促聚集 Tau(RD)上，而不会发生在非聚集突变体上，表明β-结构使 Tau(RD)容易受到蛋白水解降解和聚集的影响。通过关闭 Tau(RD)的表达、抑制剂化合物和某些蛋白酶抑制剂可以逆转聚集。在所有情况下，增强的毒性都得到了挽救。聚集物的清除涉及自噬，而蛋白酶体降解仅起次要作用。
