Sulforaphane prevents angiotensin II-induced cardiomyopathy by activation of Nrf2 through epigenetic modification

Nuclear factor erythroid 2-related factor (Nrf2) is an important regulator of cellular antioxidant defence. We previously showed that SFN prevented Ang II-induced cardiac damage via activation of Nrf2. However, the underlying mechanism of SFN’s persistent cardiac protection remains unclear. This study aimed to explore the potential of SFN in activating cardiac Nrf2 through epigenetic mechanisms. Wild-type mice were injected subcutaneously with Ang II, with or without SFN. Administration of chronic Ang II-induced cardiac inflammatory factor expression, oxidative damage, fibrosis and cardiac remodelling and dysfunction, all of which were effectively improved by SFN treatment, coupled with an up-regulation of Nrf2 and downstream genes. Bisulfite genome sequencing and chromatin immunoprecipitation (ChIP) were performed to detect the methylation level of the first 15 CpGs and histone H3 acetylation (Ac-H3) status in the Nrf2 promoter region, respectively. The results showed that SFN reduced Ang II-induced CpG hypermethylation and promoted Ac-H3 accumulation in the Nrf2 promoter region, accompanied by the inhibition of global DNMT and HDAC activity, and a decreased protein expression of key DNMT and HDAC enzymes. Taken together, SFN exerts its cardioprotective effect through epigenetic modification of Nrf2, which may partially contribute to long-term activation of cardiac Nrf2.     

核转录因子相关因子2的活化在肿瘤代谢中的作用

核转录因子(NF-E2)相关因子2（nuclear factor erythroid 2 related factor 2, Nrf2）是细胞应对外界应激的主要调控因子,通过调控多种靶基因的表达,在生理条件下减轻氧化应激,维持细胞稳态。其上游受多种因素调控,包括氧化与亲电应激、外界营养状态、细胞内代谢中间产物和能量状态等。在肿瘤细胞中,异常活跃的Nrf2使其抗氧化能力增强,并且通过介导代谢重编程（metabolic reprogramming）,促进肿瘤细胞增殖和生长。Keap1 (Kelch-like ECH-associated protein 1)是氧化和亲电应激感受器,通过募集泛素降解系统,对Nrf2的活性起主要调控作用。本文介绍Keap1依赖与非依赖条件下Nrf2的活化途径,着重介绍在肿瘤中Nrf2的异常活化,以及如何调控代谢重编程进而调节肿瘤细胞的合成代谢,最终促进肿瘤的进展。     

Nrf2抗氧化的分子调控机制

Nrf2是调控细胞氧化应激反应的重要转录因子,同时也是维持细胞内氧化还原稳态的中枢调节者。Nrf2通过诱导调控一系列抗氧化蛋白的组成型和诱导型表达,可以减轻活性氧和亲电体引起的细胞损伤,使细胞处于稳定状态,维持机体氧化还原动态平衡。本研究为了从分子层面深入探讨剖析Nrf2发挥抗氧化功能的作用机制,通过查找阅读大量相关文献并进行整理归纳,最终从Nrf2的结构与激活、Nrf2抗氧化功能以及Nrf2抗氧化的分子调控机制三个方面进行了概述分析。其中在对Nrf2抗氧化的分子调控机制的探讨部分,既探析了对Nrf2起激活作用的相关调节因子的作用机制,又分析了Nrf2被激活后对其下游多种抗氧化因子及谷胱甘肽氧化还原系统的诱导调控机制,以期较深入了解Nrf2抵抗机体氧化应激损伤作用及其抗氧化分子调控机制。     

Singlet-oxygen-derived products from linoleate activate Nrf2 signaling in skin cells

Linoleates are required for normal mammalian health and development, but they are also prone to oxidation, resulting in biologically active metabolites such as hydroxyoctadecadienoic acids (HODEs). To investigate the biological activity of 9-EZ-HODE, 10-EZ-HODE, 12-ZE-HODE, and 13-ZE-HODE, the metabolites of singlet-oxygen-derived products from linoleates, we assessed adaptive cytoprotection in HaCaT skin cells. Treating HaCaT cells with sublethal concentrations of 10-EZ-HODE and 12-ZE-HODE, which are singlet-oxygen-mediated specific oxidation metabolites of linoleates, but not 9-EZ-HODE and 13-ZE-HODE, caused resistance to hydrogen peroxide-induced oxidative damage. Microarray analysis of HaCaT cells revealed that 10-EZ-HODE and 12-ZE-HODE induced cellular antioxidant genes that are responsive to nuclear factor-erythroid 2 p45-related factor 2 (Nrf2), such as heme oxygenase-1 and glutathione synthesis enzymes. Although 10-EZ-HODE and 12-ZE-HODE did not induce Nrf2 mRNA, treatment with these metabolites increased the intranuclear expression of Nrf2. These results suggest that 10-EZ-HODE and 12-ZE-HODE initiate adaptive responses that reduce the damage caused by oxidative stress.     

Activation of KGFR-Akt-mTOR-Nrf2 signaling protects human retinal pigment epithelium cells from Ultra-violet

Ultra-violet (UV) radiation causes oxidative injuries to human retinal pigment epithelium (RPE) cells. We tested the potential effect of keratinocyte growth factor (KGF) against the process. KGF receptor (KGFR) is expressed in ARPE-19?cells and primary human RPE cells. Pre-treatment with KGF inhibited UV-induced reactive oxygen species (ROS) production and RPE cell death. KGF activated nuclear-factor-E2-related factor 2 (Nrf2) signaling in RPE cells, causing Nrf2 Ser-40 phosphorylation, stabilization and nuclear translocation as well as expression of Nrf2-dependent genes (HO1, NOQ1 and GCLC). Nrf2 knockdown (by targeted shRNAs) or S40T mutation almost reversed KGF-induced RPE cell protection against UV. Further studies demonstrated that KGF activated KGFR-Akt-mTORC1 signaling to mediate downstream Nrf2 activation. KGFR shRNA or Akt-mTORC1 inhibition not only blocked KGF-induced Nrf2 Ser-40 phosphorylation and activation, but also nullified KGF-mediated RPE cell protection against UV. We conclude that KGF-KGFR activates Akt-mTORC1 downstream Nrf2 signaling to protect RPE cells from UV radiation.     

内皮细胞和平滑肌细胞氧化应激时Nrf2/ARE信号通路对抗氧化基因表达的调控:与动脉粥样硬化和先兆子痫的关系

动脉粥样硬化、糖尿病、慢性肾功能衰竭和先兆子痫等血管疾病时活性氧(reactive oxygen species,ROS)生成增加,容易导致内皮依赖性血管舒张功能的损害和血管损伤,而细胞可以诱导多种编码Ⅱ相解毒酶和抗氧化蛋白的基因表达,从而减轻ROS和亲电子物质介导的细胞损伤。一个被称为抗氧化反应元件(antioxidant response element,ARE)或亲电子反应元件(electrophile response element,EpRE)的顺式转录调控元件,可以介导诸如亚铁血红素加氧酶1、γ-谷氨酰半胱氨酸合成酶、硫氧还蛋白还原酶、谷胱甘肽-S转移酶和NAD(P)H:苯醌氧化还原酶等基因的转录。其他抗氧化酶,如超氧化物歧化酶、过氧化氢酶和非酶清除剂(如谷胱甘肽)等也参与ROS的清除。转录因子NF-E2相关因子2(nuclear factor-erythroid 2-related factor 2, Nrf2)是属于Cap‘n’Collar家族的转录因子,具有碱性亮氨酸拉链(basic region-leucine zipper,bZIP),它在ARE介导的抗氧化基因表达中起重要的作用。在正常情况下,Kelch样环氧氯丙烷相关蛋白-1(Kelch-like ECH-associated protein-1,Keapl)与Nrf2耦联,并与肌动蛋白细胞骨架结合被锚定于胞浆,但是在半胱氨酸残基发生氧化的情况下,Nrf2和Keapl解耦联,进入细胞核并与ARE结合,从而激活多种抗氧化基因和Ⅱ相解毒酶基因的转录。蛋白激酶C、丝裂原活化蛋白激酶和磷脂酰肌醇-3激酶参与Nrf2／ARE信号转导的调控。本文综述了有关Nrf2／ARE信号转导通路在血管稳态和动脉硬化、先兆子痫等疾病情况下内皮及平滑肌细胞对抗持续性氧化应激中起的作用。     

Nrf2在阿尔茨海默病中的研究现状

阿尔茨海默病(Alzheimer's disease,AD)是最常见的神经系统变性疾病,主要病理特征为细胞外老年斑(senile plaques,SP)和细胞内神经原纤维缠结(neurofibrillary tangles,NFT)形成.但其发病机制不清,涉及多种病理学变化如炎症反应、氧化应激、线粒体功能障碍、细胞凋亡以及突触功能障碍等.核因子E2相关因子2(nuclear factor erythroid 2-related factor 2,Nrf2)是经典的调控机体抗氧化应激反应的核转录因子.Nrf2激活后诱导抗氧化蛋白的表达,提高机体的抗氧化应激能力.随着Nrf2抗氧化应激作用研究的深入,发现Nrf2不仅能够通过抗氧化应激延缓AD的发生发展,且在AD的病理性沉积物的清除、抗炎、抗凋亡、神经营养等方面扮演着重要的角色.近年来,由于多种针对单一靶点的抗AD药物临床试验的失败,有学者提出Nrf2可能是实现AD多靶点疗法的重要因子.因此,本文对Nrf2在AD中的研究现状做一综述,为寻找治疗AD潜在的生物学靶点提供理论依据.     

Nrf2-induced antioxidant protection: a promising target to counteract ROS-mediated damage in neurodegenerative disease?

Neurodegenerative diseases share various pathological features, such as accumulation of aberrant protein aggregates, microglial activation, and mitochondrial dysfunction. These pathological processes are associated with generation of reactive oxygen species (ROS), which cause oxidative stress and subsequent damage to essential molecules, such as lipids, proteins, and DNA. Hence, enhanced ROS production and oxidative injury play a cardinal role in the onset and progression of neurodegenerative disorders. To maintain a proper redox balance, the central nervous system is endowed with an antioxidant defense mechanism consisting of endogenous antioxidant enzymes. Expression of most antioxidant enzymes is tightly controlled by the antioxidant response element (ARE) and is activated by nuclear factor E2-related factor 2 (Nrf2). In past years reports have highlighted the protective effects of Nrf2 activation in reducing oxidative stress in both in vitro and in vivo models of neurodegenerative disorders. Here we provide an overview of the involvement of ROS-induced oxidative damage in Alzheimer's disease, Parkinson's disease, and Huntington's disease and we discuss the potential therapeutic effects of antioxidant enzymes and compounds that activate the Nrf2-ARE pathway.     

Modulation of Nrf2 expression alters high glucose-induced oxidative stress and antioxidant gene expression in mouse mesangial cells

Reactive oxygen species (ROS) play an important role in the pathogenesis of diabetic nephropathy. Nuclear factor erythroid 2-related factor 2 (Nrf2) can up-regulate the expression of antioxidant genes and protect cells from oxidative damage. The current study is aimed at examining the effect of modulation of Nrf2 expression on high glucose-induced oxidative stress and Nrf2-targeting antioxidant expression in mouse mesangial cells. In this study, mouse mesangial cells were transiently transfected with Nrf2-plasmid or the Nrf2-specific siRNA. The high glucose-induced intracellular ROS, malondialdehyde, cell proliferation, and TGF-β1 secretion were measured. The levels of Nrf2, heme oxygenase-1 (HO-1), γ-glutamylcysteine synthethase (γ-GCS) expression, and nuclear expression of Nrf2 in mouse mesangial cells were determined. We found that high glucose induced ROS and malondialdehyde generation in mouse mesangial cells. Induction of Nrf2 over-expression reduced the high glucose-induced ROS and malondialdehyde production, inhibited cell proliferation and TGF-β1 secretion, accompanied by up-regulating the expressions of HO-1 and γ-GCS in mouse mesangial cells. However, knockdown of Nrf2 expression displayed reverse effects in mouse mesangial cells. All these results indicated that Nrf2 and its downstream antioxidants, HO-1 and γ-GCS, are negative regulators of high glucose-induced ROS-related mouse mesangial cell dysfunction.     

LL202 ameliorates colitis against oxidative stress of macrophage by activation of the Nrf2/HO-1 pathway

LL202, a newly synthesized flavonoid derivative, has been confirmed to inhibit the mitogen-activated protein kinase pathway and activation protein-1 activation in monocytes; however, the anti-inflammatory mechanism has not been clearly studied. Uncontrolled overproduction of reactive oxygen species (ROS) has involved in oxidative damage of inflammatory bowel disease. In this study, we investigated that LL202 reduced lipopolysaccharide (LPS)-induced ROS production and malondialdehyde levels and increased superoxide dismutase, glutathione, and total antioxidant capacity in RAW264.7 cells. Mechanically, LL202 could upregulate heme oxygenase-1 (HO-1) via promoting nuclear translocation of nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) to regulate LPS-induced oxidative stress in macrophages. In vivo, we validated the role of LL202 in dextran sulfate sodium- and TNBS-induced colitis models, respectively. The results showed that LL202 decreased the proinflammatory cytokine expression and regulated colonic oxidative stress by activating the Nrf2/HO-1 pathway. In conclusion, our study showed that LL202 exerts an anti-inflammatory effect by enhancing the antioxidant capacity of the Nrf2/HO-1 pathway to macrophages.