人参皂苷Rg1调节N2a/APP695细胞β分泌酶活性的可能机制  

Mechanism of ginsenoside Rg1 regulating the activity of β secretase in N2a/APP695 cells

作　　者：陈丽敏[1] 林楠[1] 张静[1] 朱元贵[1] 陈晓春[1] 

机构地区：[1]福建医科大学附属协和医院内科,福建省老年医学研究所,福州350001

出　　处：《中华医学杂志》2012年第5期330-335,共6页National Medical Journal of China

基　　金：国家自然科学基金（30772555）;教育部博士点专项基金（20070392004）

摘　　要：目的 观察人参皂苷Rg1能否通过核蛋白因子κB（NF-κB）影响N2a/APP695细胞β淀粉样肽（Aβ）的生成和代谢,从源头上缓解和（或）减轻阿尔茨海默病（AD）病人的神经病理改变.方法 利用稳定表达突变型APP695的N2a细胞（N2a/APP695）,通过RT-PCR、蛋白免疫印迹、激光共聚焦显微镜等方法检测人参皂苷Rg1对β分泌酶活性及上游转录因子NF-κB活性的影响.结果 2.5 mol/L人参皂苷Rg1作用6～12 h后,N2a/APP695细胞外液Aβ1-40和Aβ1-42水平较Rg1作用前均有不同程度的下降[最低值分别为（13.3±4.3 ）ng/ml及（12.0±5.4） ng/ml]；BACE1的蛋白表达水平下降（BACE1/β-肌动蛋白比值为0.26±0.05）；NF-κB p65蛋白表达水平明显增加（磷酸化p65/总p65比值为0.93±0.02）并诱导促进NF-κB的核转位；NFκB的抑制剂quinazoline预处理后可见人参皂苷Rg1对BACE1 mRNA和蛋白表达的抑制作用明显减弱.结论 人参皂苷Rg1能激活NF-κB,促进NF-κB的核转位,增加与BACE1启动子相应位点的结合,导致β分泌酶的活性减少.Objective To explore whether or not ginsenoside Rg1 can modify the metabolism of amyloid precursor protein （APP） and the generation of amyloid beta （Aβ） by nuclear factor-kappa B （NF-κB）.Methods N2a/APP695 cells,a mutated APP-overexpressing neuronal cell line,was used to mimic the APP metabolism and Aβ generation in vitro.The BACE1 mRNA and protein levels were detected by RTPCR （reverse transcription-polymerase chain reaction） and Western blot respectively.Then the expression levels and subcellular localization of NF-κB were detected by Western blot and confocal laser scanning microscope respectively.Results The treatment of ginsenoside Rg1 at a dose of 2.5 μmol/L decreased the levels of Aβ1-40 and Aβ1-42 （ 13.3 ± 4.3 ） ng/ml vs （ 12.0 ± 5.4 ） ng/ml in N2a/APP695 cells,decreased the protein level of BACE1 （ BACE1/β -actin 0.26 ± 0.05）,increased the protein level of NF-κB p65 （p-p65/p65 0.93 ± 0.02） and resulted in the translocation of NF-κB from cytoplasm to nucleus.Quinazoline inhibited the activation of NF-κB with a reduction of p-p65 and p-p65/p65 in N2a/APP695 cells and increased the BACE1 protein level.And the treatment of ginsenoside Rg1 showed similar changes in N2a/APP695 cells when compared with the treatment of quinazoline alone.Conclusion Ginsenoside Rg1 may modify the metabolism of APP by enhancing the nuclear binding of NF-κB to BACE1 promoter and inhibiting the transcription and translation of BACE1.

关 键 词：人参皂苷RG1 核蛋白因子κB Β分泌酶 N2A细胞 

分 类 号：R749.16[医药卫生—神经病学与精神病学]