Li Longfei, Jiang Yanli, Wu Gang, Mahaman Yacoubou Abdoul Razak, Ke Dan, Wang Qun, Zhang Bin, Wang Jian-Zhi, Li Hong-Lian, Liu Rong, Wang Xiaochuan
Department of Pathophysiology, School of Basic Medicine, Key Laboratory of Education Ministry/Hubei Province of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, JS, China.
Mol Neurobiol. 2022 Oct;59(10):6183-6199. doi: 10.1007/s12035-022-02972-7. Epub 2022 Jul 28.
Abnormal posttranslational modifications of tau play important roles in mediating neurodegeneration in tauopathies including Alzheimer's disease. Both phosphorylation and truncation are implicated in the pathogenesis of tauopathies. However, whether phosphorylation aggravates truncated tau-induced pathology and neurodegeneration remains elusive. Here, we construct different tau fragments cleaved by delta secretase, with either phosphorylation or non-phosphorylation mimic mutations, and evaluate the contributions of phosphorylation to truncated tau-induced pathological and behavioral alterations in vitro and in vivo through biochemical methods including detergent insoluble tau extraction, western blot, immunofluorescence, flow cytometry, and behavior tests. Our results show that the self-aggregation of phospho-truncated tau is significantly influenced by the domain it contains. N-terminal inhibits, proline-rich domain promotes, and C-terminus have no impact on phospho-truncated tau aggregation. Phosphorylation of truncated tau1-368, which contains the microtubule-binding repeat domain and the proline-rich domain, induces endogenous tau phosphorylation and aggregation. In vivo, phospho-tau1-368 but not non-phospho-tau1-368 leads to a decrease in body weight of C57BL/6 J mice. Intriguingly, although tau1-368-induced anxiety behavior in C57BL/6 J mice is phosphorylation-independent, the recognition memory of mice is impaired by phospho-tau1-368, but not by non-phospho-tau1-368. Immunofluorescence staining shows that overexpressing phospho-tau1-368 results in neuronal loss and gliosis in the hippocampus, while the transmission of tau1-368 is phosphorylation-independent as revealed by the flow cytometry results in vitro and immunofluorescence staining in vivo. Our findings indicate that phosphorylation of truncated tau significantly fosters endogenous tau pathology and neurodegeneration.
tau蛋白的异常翻译后修饰在介导包括阿尔茨海默病在内的tau蛋白病的神经退行性变中起重要作用。磷酸化和截短均与tau蛋白病的发病机制有关。然而，磷酸化是否会加重截短的tau蛋白诱导的病理改变和神经退行性变仍不清楚。在此，我们构建了由δ分泌酶切割的不同tau片段，带有磷酸化或非磷酸化模拟突变，并通过生化方法，包括去污剂不溶性tau蛋白提取、蛋白质免疫印迹、免疫荧光、流式细胞术和行为测试，在体外和体内评估磷酸化对截短的tau蛋白诱导的病理和行为改变的作用。我们的结果表明，磷酸化截短的tau蛋白的自我聚集受到其所含结构域的显著影响。N端抑制，富含脯氨酸的结构域促进，而C端对磷酸化截短的tau蛋白聚集没有影响。包含微管结合重复结构域和富含脯氨酸结构域的截短tau1-368的磷酸化诱导内源性tau蛋白磷酸化和聚集。在体内，磷酸化的tau1-368而非非磷酸化的tau1-368导致C57BL/6 J小鼠体重下降。有趣的是，尽管tau1-368在C57BL/6 J小鼠中诱导的焦虑行为不依赖于磷酸化，但小鼠的识别记忆受到磷酸化的tau1-368损害，而非磷酸化的tau1-368则无此作用。免疫荧光染色显示，过表达磷酸化的tau1-368导致海马神经元丢失和神经胶质增生，而tau1-368的传递不依赖于磷酸化，这在体外流式细胞术结果和体内免疫荧光染色中均有显示。我们的研究结果表明，截短的tau蛋白的磷酸化显著促进内源性tau蛋白病理改变和神经退行性变。
