原癌基因K-Ras调控APPThr668位点磷酸化及APP的切割  

Oncogene K-Ras Affects the Processing of Amyloid Precursor Protein (APP) Through Regulating Its Phosphorylation at Thr668

作　　者：刘杨[1] 杨龙雨[1] 谢勇壮[1] 张弦[1] 许华曦[1] 张云武[1] 

机构地区：[1]厦门大学医学院,药学院,神经科学研究所,福建厦门361005

出　　处：《厦门大学学报（自然科学版）》2012年第6期1060-1065,共6页Journal of Xiamen University：Natural Science

基　　金：国家自然科学基金项目(30973150,81161120496,81000540);国家重点基础研究发展计划(973)前期研究专项(2010CB535004);国家科技重大专项项目(2009ZX09103-731);福建省自然科学基金项目(2009J06022,2010J01233,2010J01235)

摘　　要：在阿尔茨海默症(Alzheimer′s disease,AD)发病的早期,Ras蛋白所在的信号通路被激活,但具体作用机制还不清楚.探讨了K-Ras及其突变体K-RasG12V对淀粉样前体蛋白(amyloid precursor protein,APP)的剪切的影响.Western blot结果显示,过量表达K-Ras能够激活细胞外调节蛋白激酶1/2(extracellular signal-regulated kinase,ERK 1/2)、c-Jun氨基末端激酶(c-Jun N-terminal kinase,JNK)通路,并增加APP在Thr668的磷酸化;抑制JNK通路则阻断了K-Ras过表达所引起的APP Thr668磷酸化.此外,过表达K-Ras造成分泌到细胞外的sAPPα增加,而sAPPβ减少.通过生物素标记实验发现,过表达K-Ras使得APP在细胞膜上的定位增加,而细胞内APP总量没有改变.这些结果表明,过量表达K-Ras可以通过调控JNK的通路,增加APP在Thr668位点的磷酸化,造成APP在细胞膜上水平升高,导致APP向sAPPβ的切割减少,而向sAPPα的切割增加.提示K-Ras对APP切割的影响可能在AD的发病过程中起着一定的应激作用.The expression of Ras is elevated during early stages of Alzheimer＇s disease. Here we investigated the effect of K-Ras on the processing of amyloid precursor protein （APP）. The results showed that overexpression of K-Ras and its constitutively active mutant K-RasG12V could activate ERK1/2 and JNK pathways and induced phosphorylation of APP at Thr668. While inhibition of the JNK pathway blocked the phosphorylation of APP. In addition, overexpression of K-Ras reduced the levels of sAPPβ and in creased the levels of sAPPα but had no effect on the levels of ADAM10 and BACE1. Through biotin labeling experiment,we demon strated that overexpression of K-Ras increased cell surface levels of APP without affecting the levels of total APP. Together,these results suggest that K-Ras can regulate APP phosphorylation and APP trafficking for its processing through the JNK pathway,impl- ying that K-Ras may he a new target/pathway for regulating AD pathologies.

关 键 词：阿尔茨海默症 淀粉样前体蛋白 K-RAS 磷酸化 

分 类 号：Q291[生物学—细胞生物学]