Chen Li-Min, Lin Nan, Zhang Jing, Zhu Yuan-gui, Chen Xiao-chun
Fujian Institute of Geriatrics, Union Hospital, Fujian Medical University, Fuzhou 350001 China.
Zhonghua Yi Xue Za Zhi. 2012 Feb 7;92(5):330-5.
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).
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 RT-PCR (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.
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.
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.
探讨人参皂苷Rg1是否能通过核因子-κB（NF-κB）调节淀粉样前体蛋白（APP）的代谢及β淀粉样蛋白（Aβ）的生成。
使用N2a/APP695细胞，一种过表达突变型APP的神经元细胞系，在体外模拟APP代谢及Aβ生成。分别通过逆转录聚合酶链反应（RT-PCR）和蛋白质免疫印迹法检测β-分泌酶1（BACE1）的mRNA和蛋白水平。然后分别通过蛋白质免疫印迹法和共聚焦激光扫描显微镜检测NF-κB的表达水平及亚细胞定位。
2.5 μmol/L剂量的人参皂苷Rg1处理后，N2a/APP695细胞中Aβ1-40和Aβ1-42水平降低（分别为13.3±4.3 ng/ml和12.0±5.4 ng/ml），BACE1蛋白水平降低（BACE1/β-肌动蛋白为0.26±0.05），NF-κB p65蛋白水平升高（磷酸化p65/p65为0.93±0.02），并导致NF-κB从细胞质转位至细胞核。喹唑啉抑制NF-κB的激活，使N2a/APP695细胞中磷酸化p65及磷酸化p65/p65降低，并使BACE1蛋白水平升高。与单独使用喹唑啉处理相比，人参皂苷Rg1处理的N2a/APP695细胞呈现相似变化。
人参皂苷Rg1可能通过增强NF-κB与BACE1启动子的核结合及抑制BACE1的转录和翻译来调节APP代谢。
