Curcumin Inhibits the AKT/NF-κB Signaling via CpG Demethylation of the Promoter and Restoration of NEP in the N2a Cell Line
Curcumin Inhibits the AKT/NF-κB Signaling via CpG Demethylation of the Promoter and Restoration of NEP in the N2a Cell Line
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DOI：
10.1208/s12248-014-9605-8
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发表时间：
2014-07-01
期刊：
影响因子：
4.5
通讯作者：
Yu, Gang
中科院分区：
文献类型：
--
作者：
Deng, Yushuang;Lu, Xi;Yu, Gang
姜黄素(Cur)是从姜黄中提取的一种无毒多酚，具有抗炎和抗氧化作用，是治疗阿尔茨海默病(AD)的有效药物。然而，目前尚不清楚Cur在AD中的抗炎作用是否与其CpG去甲基化有关，而CpG去甲基化是近年来研究最多的Cur的另一个功能。Neprilysin(NEP，EP24.11)是一种锌依赖的金属肽酶，在脑中表达相对较低，是AKT/蛋白激酶B的有效抑制剂。此外，NEP的高甲基化启动子已被报道与NEP表达的减少有关。在本研究中，我们利用亚硫酸氢盐测序聚合酶链式反应(BSP)分析，发现NEP基因的CpG位点在野生型小鼠神经母细胞瘤N2a细胞(N2a/wt)和稳定表达与家族性早发性AD相关的人瑞典突变淀粉样前体蛋白(APP)的N2a细胞(N2a/APPswe)中都发生了高甲基化。Cur通过CpG去甲基化诱导NEP基因修复。Cur介导的NEP表达上调还伴随着对AKT的抑制，进而抑制N2a/APPswe细胞的核转录因子-kappa B(NF-kappa B)及其下游的促炎靶标COX-2、iNOS。本研究首次证明了CpG对NEP的去甲基化作用与Cur的抗炎作用之间的联系，为Cur的抗炎作用提供了新的机制见解，也为Cur作为AD的治疗干预措施提供了新的依据。
Curcumin (CUR), a non-toxic polyphenol from Curcuma longa, has been investigated as a potential therapy with anti-inflammatory and anti-oxidative effects for Alzheimer's disease (AD), which depicts features of chronic inflammatory environment resulting in cellular death. However, it remains largely unknown whether the anti-inflammatory effect of CUR in AD is associated with its property of CpG demethylation, which is another function of CUR with the most research interest during recent years. Neprilysin (NEP, EP24.11), a zinc-dependent metallopeptidase expressed relatively low in the brain, is emerging as a potent inhibitor of AKT/Protein Kinase B. In addition, hypermethylated promoter of NEP has been reported to be associated with decreases in NEP expression. In the present study, using bisulfite-sequencing PCR (BSP) assay, we showed that the CpG sites in NEP gene were hypermethylated both in wild-type mouse neuroblastoma N2a cells (N2a/wt) and N2a cells stably expressing human Swedish mutant amyloid precursor protein (APP) (N2a/APPswe) associated with familial early onset AD. CUR treatment induced restoration of NEP gene via CpG demethylation. This CUR-mediated upregulation of NEP expression was also concomitant with the inhibition of AKT, subsequent suppression of nuclear transcription factor-kappa B (NF-kappa B) and its downstream pro-inflammatory targets including COX-2, iNOS in N2a/APPswe cells. This study represents the first evidence on a link between CpG demethylation effect on NEP and anti-inflammation ability of CUR that may provide a novel mechanistic insight into the anti-inflammatory actions of CUR as well as new basis for using CUR as a therapeutic intervention for AD.