Geng Junhua, Xia Lu, Li Wanjie, Zhao Changqi, Dou Fei
State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, College of Life Sciences, Beijing Normal University, Beijing, China.
Key Laboratory of Cell Proliferation and Regulation Biology, Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing, China.
J Alzheimers Dis. 2016;49(4):1161-8. doi: 10.3233/JAD-150423.
Neurofibrillary tangles are the main pathological feature of Alzheimer's disease. Insoluble tau protein is the major component of neurofibrillary tangles. Defects in the tau protein degradation pathway in neurons can lead to the accumulation of tau and its subsequent aggregation. Currently, contradictory results on the tau degradation pathway have been reported by different groups. This discrepancy is most likely due to different cell lines and methods used in those studies. In this study, we found that cycloheximide treatment induced mild activation of a ZVAD-sensitive protease in Drosophila Kc cells, resulting in cleavage of tau at its C-terminus; this cleavage could generate misleading tau protein degradation pattern results depending on the antibodies used in the assay. Because cycloheximide is a broadly used chemical reagent for the study of protein degradation, the unexpected artificial effect we observed here indicates that cycloheximide is not suitable for the study of tau degradation. Other methods, such as inducible expression systems and pulse-chase assays, may be more appropriate for studying tau degradation under physiological conditions.
神经原纤维缠结是阿尔茨海默病的主要病理特征。不溶性tau蛋白是神经原纤维缠结的主要成分。神经元中tau蛋白降解途径的缺陷会导致tau蛋白积累及其随后的聚集。目前，不同研究小组报道了关于tau蛋白降解途径的相互矛盾的结果。这种差异很可能是由于这些研究中使用的细胞系和方法不同。在本研究中，我们发现放线菌酮处理可诱导果蝇Kc细胞中一种ZVAD敏感蛋白酶的轻度激活，导致tau蛋白在其C末端被切割；根据检测中使用的抗体，这种切割可能会产生误导性的tau蛋白降解模式结果。由于放线菌酮是一种广泛用于蛋白质降解研究的化学试剂，我们在此观察到的意外人为效应表明放线菌酮不适用于tau蛋白降解的研究。其他方法，如诱导表达系统和脉冲追踪分析，可能更适合于研究生理条件下的tau蛋白降解。
