胰岛素信号通路磷脂酰肌醇-3激酶／丝氨酸苏氨酸蛋白激酶对海马神经元β-淀粉样前体蛋白裂解酶1表达的影响  

Effects of phosphatidylinositol-3 kinase/serine threonine kinase pathway on expression of beta-site amyloid precursor protein cleaving enzyme-1 in the hippocampus neurons

作　　者：李洁颖[1] 晏勇[1] 蔡志友[1] 冯占辉[1] 张华[1] 吴芳[1] 孟涛[1] 代政伟[1] 

机构地区：[1]重庆医科大学附属第一医院神经内科,400016

出　　处：《中华神经科杂志》2009年第11期737-741,共5页Chinese Journal of Neurology

基　　金：基金项目：国家民政部中国老年学学会资助项目（2007-18-3-05）

摘　　要：目的通过胰岛素和磷脂酰肌醇-3激酶（P13K）抑制剂渥曼青霉素（wortmannin，WORT）对P13K／丝氨酸苏氨酸蛋白激酶（P13K／Akt）信号通路的激活和抑制作用，观察P13K／Akt信号通路对海马神经元β-淀粉样前体蛋白裂解酶1（BACEI）表达的影响。方法40只sD大鼠随机分为空白对照组、假手术组、胰岛素组和WORT组（每组10只），海马立体定向注射胰岛素和PDK抑制剂WORT。免疫组织化学和Westernblot法检测P13K／Akt信号传导相关蛋白以及BACEI的表达水平。结果注射胰岛素的海马P13K信号通路下游信号分子较对照组：Akt表达增加（0．952±O．060与0．835±0．029，t=4．9150，P=0．0001），Aktser473位点磷酸化（pAkt）水平上调（0．800±O．075与0．657±0．025，t：4．5598，P=0．0002），糖原合成激酶-3α（GSK-3α）磷酸化水平降低（0．604±0．062与0．726±0．041，t=3．5871，P=0．0018），而成熟的BACEl及其裂解产物p分泌酶C末端（母-CTF）表达下调。WORT组的P13K下游信号分子Akt、pAkt表达明显被抑制，磷酸化GSK-3仪表达增加，同时成熟的BACE1（1．004±0．096）和β-CTF（1．031±0．048）的表达较对照组（分别0．498±O．064，0．786±O．101）上调（分别t=11．5980，P=0．0000；t=4．2194，P=0．0004）。结论胰岛素信号通路P13K／Akt可以调节BACE1的表达和活性并参与阿尔茨海默病的发病机制。Objective To investigate the effect of phosphatidylinositol-3 kinase/serine threonine kinase （PI3K/Akt） signaling pathway on expression of beta-slte amyloid precursor protein cleaving enzyme-1 （ BACE1 ） in the hippocampus neurons of rat brain. Methods Forty SD rats were randomly divided into 4 groups： blank control group, sham-operated group, insulin group and wortmannin group. Insulin or the specific inhibitor of PI3K, wortmannin was injected into hippoeampus neurons to activate or inhibit the signaling pathway in insulin group or wortmannin group, respectively. Immunoprecipitation and Western blot were used to ana｜yze the proteins levels of PI3K/Akt and BACE1. Results In insulin treatment group, among the proteins downstream of signaling pathway, expression of Akt increased （ 0. 952 ± 0. 060 vs 0. 835 ±0. 029,t = 4. 9150, P = O. 0001 ）, phospho-Akt ser473 increased （0. 800 ±O. 075 vs O. 657 ± O. 025,t = 4. 5598, P = 0. 0002）, phospho-GSK-3α decreased （0. 604 ＋ O. 062 vs O. 726± 0. 041, t = 3. 5871, P = O. 0018）, and the expression of mature BACE1 and 13-CTF significantly decreased. In wortmannin group, the expression of Akt and phospho-Akt sev473 were inhibited; phospho-GSK-3cx increased; mature BACE1 （ 1. 004 ± 0. 096） and β-CTF （ 1. 031±0. 048 ） increased （ t = 11. 5980, P = 0. 0000 and t = 4. 2194, P = 0. 0004, respectively ）. Conclusions PI3K/Akt signaling pathway might effect the expression of BACE1, in which impaired signaling pathway may cause the amyloid precursor protein to be easily processed by BACE1, and thus involves the pathology of Alzheimer＇ s disease.

关 键 词：阿尔茨海默病 海马 1-磷脂酰肌醇3-激酶 蛋白质丝氨酸苏氨酸激酶 天冬氨酸内肽酶类 淀粉样前体蛋白分泌酶类 胰岛素 

分 类 号：R686[医药卫生—骨科学]