早老素1与热休克蛋白70同源蛋白羧基端相互作用蛋白

Study on the interaction between presenilin 1 and carboxyl terminus of Hsc70 interacting protein

目的探讨早老素（PS1）蛋白突变体在阿尔茨海默病（AD）发生中的作用和PS1蛋白的正常生理功能及分子伴侣蛋白热休克蛋白70同源蛋白羧基端相互作用蛋白（CHIP）的相互作用。方法采用酵母双杂交系统筛选与PS1蛋白相互作用的蛋白。在构建pGBKT7-PS1-C203诱饵质粒和含全长CHIP的pACT2-CHIP质粒表达载体后，用β-半乳糖苷酶活性测定法检测两者的相互作用；然后转染哺乳动物细胞293T，用Co-IP和Western blot法测试其相互作用。结果获得了一个能与PS1蛋白相互作用的蛋白，即CHIP，并通过β-半乳糖苷酶活性测试、免疫共沉淀进一步证实了PS1和CHIP相互作用的特异性。结论CHIP既可以和分子伴侣蛋白相互作用，本身又具有泛素连接酶活性，可调控蛋白的折叠和降解，PS1与CHIP相互作用的证实，有助于阐明机体泛素-蛋白酶体系统对PS1的调控和进一步阐明AD的病理机制。

Objective To understand the pathological and physiological roles of Presenilin 1 （PS1） in Alzheimer＇ s disease （AD） recurrence, and the interaction between PS1 and carboxyl terminus of Hse70 interacting protein （CHIP）. Methods The yeast two hybrid system was applied to identify a novel PS1 interacting protein as CHIP. After pGBKT7-PS1-C203 bait plasmid and full fragement CHIP of pACT2-CHIP expression vector were constructed, the interaction between PSI and CHIP was tested by β-galactosidase assay, pGBKT7 PS1 C203 was co-transfected with pACT2 -CHIP into 293T cells and the interaction between PS1 and CHIP was tested by coimmunoprecipitation and Western blot. Results Specificity of the interaction between PSI and CHIP was identified by β-galactosidase assay and co-immunoprecipitation. Conclusions CHIP is able to modulate chaperone functions and the pathway of protein ubiquitination/degradation. CHIP may regulate a proper assembly of the γ-secretase complex through its interaction with PS1, which is helpful to elucidate the mechanism of AD pathology.