HJ22, a Novel derivative of piperine,Attenuates ibotenic acid-induced cognitive impairment,oxidativestress, apoptosis and inflammation via inhibiting the protein-protein interaction of Keap1-Nrf2

Kelch-like ECH-associated protein (Keap1)-nuclear factor erythroid-2-related factor 2 (Nrf2) protein-protein interaction has become an important drug target for the treatment of Alzheimer’s disease. In this study, we found a novel piperine derivative (HJ22) synthesized by our group with great ability to bind to Keap-1 and activate Keap1-Nrf2-ARE signaling pathway in vitro, driving us to investigate the beneficial effects of HJ22 on ibotenic acid (IBO)-induced neurological disorders in rats and underlying mechanisms. Interestingly, HJ22 significantly ameliorated IBO-induced cognitive impairment in Morris water maze, Y-maze and passive avoidance tests. Moreover, HJ22 significantly attenuated cholinergic dysfunction and neuronal morphological changes via inhibiting apoptotic cell death induced by IBO. Notably, HJ22 inhibited the interaction between Keap1 and Nrf2, and subsequently up-regulated nuclear Nrf2 expression, thereby inhibiting oxidative stress and Thioredoxin-interacting protein (TXNIP)-mediated Nod-like receptor protein 3 (NLRP3) inflammasome activation. These findings demonstrated that HJ22 exhibited potent therapeutic effects against IBO-induced cognitive impairment by alleviating cholinergic damage, oxidative stress, apoptosis and neuroinflammation, which might be partly attributed to its inhibitory activity on Keap1-Nrf2 protein-protein interaction.     

Nrf2-ARE信号通路功能与临床疾病及相关药物的研究新进展

Nrf2（NF-E2-related factor 2）核因子E2相关因子是一种机体抵抗内界和外界氧化或化学等刺激的中枢调节者。Nrf2-ARE则是近年来新发现的细胞氧化应激反应的关键传导通路,当其在体内被有毒有害物质激活后转位进入细胞核能与抗氧化反应元件（antioxidant response element,ARE）结合形成Nrf2-ARE信号通路,从而调控下游抗氧化蛋白、氧化酶和Ⅱ相解毒酶等。研究发现该通路在抗衰老、抗肿瘤、抗炎症、神经损伤、眼科等多方面均有重要作用。以Nrf2为靶点的药物有望用于肿瘤、糖尿病、神经退行性疾病等。本文综述了Nrf2-ARE信号通路功能及以其为靶点的药物研究的进展。     

Targeting the cell signaling pathway Keap1-Nrf2 as a therapeutic strategy for adenocarcinomas of the lung

Introduction: Kelch-like ECH associated protein 1/Nuclear factor erythroid 2-like factor 2 (Keap1-Nrf2) signaling plays a pivotal role in response to oxidative stress in lung cancer. Mutations in KEAP1/NFE2L2 genes always cause persistent Nrf2 activation in lung cancer cells that confer therapeutic resistance and aggressive tumorigenic activity, dictating either poor prognosis or short duration of response to chemotherapy in clinical observations.

Areas covered: We provide a review of the mechanisms underlying the regulation of Keap1-Nrf2 at different stages, including genetic mutations, epigenetic modifications, translational/post-translational alterations, and protein–protein interactions. Based on the current knowledge, we discuss the possibilities of intervening Keap1-Nrf2 in lung adenocarcinoma as a therapeutic target.

Expert opinion: It is prevalently conceived that Keap1-Nrf2 signaling plays different roles at diverse stages of cancer. Although various Nrf2 or Keap1 inhibitors have been reported during the last decades, none of these inhibitors are currently under clinical studies or in clinical applications, suggesting that sole inhibition of Nrf2 might not be sufficient to suppress tumor growth. On the basis of current studies, we suggest that the rational combination of Nrf2 suppression with chemical agents which cause enhanced oxidative imbalance or abnormal metabolism would be promising in the treatment of lung adenocarcinoma.     

癌症预防中的Keap1-Nrf2-ARE通路

癌症的治疗至今仍未取得重大进展,因此做好癌症的预防工作就尤为关键。目前有很多自然物质（如从植物中提取的抗氧化剂）或化学合成物质（如添加在食品中的抗氧化剂）被用来预防癌症。最近发现,有些癌症预防物是通过诱导二相抗氧化酶来清除体内的致癌物质或其它毒物,而且这种诱导作用是通过Keap1-Nrf2-ARE信号通路。因此,对这一通路的了解有利于拓展癌症的研究及预防。     

Nrf2/ARE信号通路及其调控的抗氧化蛋白

机体在应对活性氧(reactive oxygen species,ROS)损害时形成了一套复杂的氧化应激应答系统,当暴露于ROS时,机体自身能诱导出一系列保护性蛋白,以缓解细胞所受的损害。这一协调反应是由这些保护性基因上游调节区的抗氧化反应元件(antioxidant responsive element,ARE)来调控的。而近年来的研究发现,核因子NF-E2相关因子(nuclear fac-tor erythroid 2-related factor 2,Nrf2)是ARE的激活因子。Nrf2是外源性有毒物质和氧化应激的感受器,在参与细胞抗氧化应激和外源性有毒物质诱导的主要防御机制中发挥重要的作用。Nrf2-ARE通路是迄今为止发现的最为重要的内源性抗氧化应激通路。     

Nrf2/HO-1 pathway activation by manganese is associated with reactive oxygen species and ubiquitin-proteasome pathway, not MAPKs signaling

Manganese has been known to induce neurological disorders similar to Parkinson's disease. One of the features of manganese-induced neurotoxicity is oxidative stress. Accumulating data implicate NF-E2-related factor 2 (Nrf2) as a key regulator in the adaptive survival response to oxidative stress. Recent studies suggest that the activation of Nrf2 is induced by manganese in PC12 cells. In the present study, we investigated possible links between reactive oxygen species (ROS), proteasome or mitogen-activated protein kinase (MAPK) signaling and Nrf2/HO-1 activation in manganese-treated PC12 cells. After MnCl(2) treatment, there was an increase in nuclear localization and subsequent binding of Nrf2 to the antioxidant-responsive element (ARE) and upregulation of heme oxygenase-1 (HO-1) protein in PC12 cells. Pretreatment with N-acetyl cysteine, a scavenger of reactive oxygen species, suppressed MnCl(2) -induced Nrf2 activation, increase in Nrf2-ARE binding and subsequent upregulation of HO-1 expression. However, pretreatment with lactacystin, an inhibitor of proteasome activity, enhanced MnCl(2) -induced Nrf2 activation, increase in Nrf2-ARE binding and subsequent upregulation of HO-1 expression. Pretreatment of cells with a pharmacological inhibitor of MAPK (ERK inhibitor PD 98059, P38 inhibitor SB203580 or JNK inhibitor SP600125) did not affect the MnCl(2) -induced Nrf2 activation, increase in Nrf2-ARE binding or subsequent upregulation of HO-1 expression. These results suggest that Nrf2/HO-1 activation by Mn in PC12 cells is associated with ROS and the ubiquitin-proteasome pathway, not MAPK signaling.     

急性肝损伤模型及信号通路研究进展

肝脏具有物质合成、解毒和抗氧化等多种功能,同时也易于受到自由基和某些药物的攻击而产生损伤。肝脏疾病一直是临床研究的重点,而急性肝损伤是几乎所有肝脏疾病的开端。目前已有多种动物模型可以分别模仿不同发病机制的急性肝损伤,针对不同发病机制的通路研究也在不断进行。本文简述了CCl4、D-GalN/LPS、对乙酰氨基酚和酒精介导的急性肝损伤模型,并简要介绍了Keap1-Nrf2、TLR4和NLRP3通路在急性肝损伤发生发展进程中的作用。     

MitoQ alleviates triptolide-induced cardiotoxicity via activation of p62/Nrf2 axis in H9c2 cells

Triptolide (TP) is one of the major components of Tripterygium wilfordii, which is a traditional Chinese medicine widely used in the treatment of various autoimmune and inflammatory diseases. However, the cardiotoxicity induced by TP greatly limits its widespread clinical application. In view of the role of ROS-mediated oxidative stress in TP-induced cardiotoxicity, mitoQ, a mitochondria-targeted ROS scavenger, was used in this study to investigate its protective effect against TP-induced cardiomyocyte toxicity and its possible underlying mechanism. Here we demonstrated that mitoQ could significantly attenuate TP-induced cardiotoxicity in cardiomyocyte H9c2 cells, with a remarkable improvement in cell viability and reduction in ROS levels. P62-Nrf2 signaling pathway has been reported to play a critical role in regulating oxidative stress and protecting cells from harmful stimuli. In this study, we found that mitoQ significantly activated p62-Nrf2 signaling pathway in H9c2 cells with or without TP treatment. Moreover, knockdown of p62 or Nrf2 could block the protective effect of mitoQ against TP in H9c2 cells. Taken together, our study demonstrates that mitoQ can alleviate TP-induced cardiotoxicity via the activation of p62-Nrf2 signaling pathway, which provides new potential strategies to combat TP-induced cardiomyocyte toxicity.     

煤焦沥青提取物对BEAS-2B细胞Keap1-Nrf2/ARE通路的作用机制

目的研究煤焦沥青烟提取物对BEAS-2B细胞Nrf2、Keap1、NQO1的基因及其蛋白表达的影响,以探讨煤焦沥青烟提取物在造成细胞氧化损伤过程中Nrf2-Keap1/ARE通路的作用机制。方法设立未处理对照组、0.1%DMSO溶剂对照组、5μg/ml B(a)P阳性对照组、6μmol/L全反式维甲酸组、6μmol/L全反式维甲酸预处理0.5 h后5μg/ml CTP染毒组和CTP染毒组(1、5、10和20μg/ml),染毒3、6、12和24 h后提取总RNA;RT-PCR检测Nrf2、Keap1、NQO1 mRNA的相对表达量;Western blot测定Nrf2、Keap1、NQO1蛋白的相对表达量。结果不同CTP染毒剂量作用后各个基因mRNA相对表达量差异无统计学意义(P0.05),而不同时间点相对表达量差异有统计学意义(P0.05)。Western blot结果显示,随着CTP烟提取物染毒浓度的增加,Keap1蛋白无明显变化,NQO1蛋白表达量逐渐上升;Nrf2蛋白在5μg/ml染毒浓度时表达最高,在5μg/ml CTP染毒浓度作用下,BEAS-2B细胞Nrf2蛋白表达量随时间逐渐升高,在染毒6 h后达到最高,之后表达量又呈下降趋势。结论煤焦沥青烟提取物作用于BEAS-2B细胞后,代谢酶NQO1表达上调,推测Keap1-Nrf2/ARE通路可能通过上调细胞保护性基因NQO1的表达而对抗煤焦沥青毒性作用,降低细胞氧化损伤。