Dissecting interplay between electrophilic stress and IkBz-driven inflammation

摘要 亲电应力是一种广泛的现象，由与硫醇基团(-SH)反应的化合物引起，如 作为细胞蛋白质中的半胱氨酸残基。我们发现二甲基苯引起的亲电应激反应 衣康酸(DI)，代谢产物衣康酸的衍生物，介导了一种强烈的，但非常选择性的抑制作用 免疫激活。在巨噬细胞中，DI治疗下调了一组细胞因子的产生，如 IL-6或IL-12，但不影响其他细胞因子，如肿瘤坏死因子。我们发现，这种选择性效应是通过 抑制IκBζ，一种核因子-κB家族的转录因子，通常在免疫激活过程中被诱导。 IκBζ在几个重要的环境中选择性地调节炎症：(1)在巨噬细胞中，IκBζ调节 对Toll样受体刺激的次级转录反应及其缺陷导致产物缺陷 (2)在上皮细胞中，I-κB-ζ是一种主要的调节因子。 对IL-17的转录反应；(3)在T细胞中，它是促进Th17的不可或缺的转录因子 极化。重要的是，医学和人口遗传学研究已经确定了NFΚBIZ(编码基因 IκBζ)是银屑病的主要易感基因，银屑病是一种与IL-17相关的自身免疫性疾病。我们有 证明体内注射去甲肾上腺素可完全改善小鼠模型的病理发展 牛皮癣的症状。因此，对IκBζ和亲电应激之间的联系有更深入的了解 发现治疗自身免疫性疾病(如牛皮癣)的新治疗途径的潜力很大。 此外，尽管主要研究的细胞对亲电应激的反应是Keap1/Nrf2途径，但我们 表明DI对IκBζ的影响不受NRF2的影响。我们的初步数据表明， 不连续的NRF2非依赖的分子通路始于Keap1与亲电体和 最终选择性抑制IκBζ翻译。定义这一途径的机械细节将 加深对免疫调节的总体认识，并将提供新的治疗策略 由IκBζ-IL-17轴驱动的自身免疫性疾病。我们的目标是发现关键成员和机制 该途径使用以下收敛策略：1)通过以下方式确定IκBζ抑制的机制 Keap1和2水平的亲电应激定义了Nfkbiz的翻译调控机制 在亲电应激条件下，mRNA的表达。拟议目标的完成将为未来奠定基础 对IκBζ激活程序的新型调节剂进行了详细的体外和体内研究。最终，我们 目的研究新颖的IκBζ调节剂在炎症性背景下的作用 例如牛皮癣，这将是未来R01应用的主题。

Abstract Electrophilic stress is a broad phenomenon caused by compounds that are reactive to thiol groups (-SH), such as cysteine residues within cellular proteins. We found that electrophilic stress response induced by dimethyl itaconate (DI), a derivative of the metabolite itaconate, mediates a strong, yet very selective inhibitory effect on the immune activation. In macrophages, DI treatment downregulates production of a subset of cytokines such as IL-6 or IL-12 but does not affect other cytokines such as TNF. We found that this selective effect occurs through inhibition of IκBζ, a transcription factor of the NF-κB family, which is commonly induced during immune activation. IκBζ selectively regulates inflammation in several important contexts: (1) in macrophages, IκBζ regulates the secondary transcriptional response to toll-like receptor stimulation and its deficiency leads to defective production of a subset of cytokines such as IL-6 and IL-12, but not TNF; (2) in epithelial cells, IκBζ is a primary regulator of the transcriptional response to IL-17; (3) in T-cells, it is an indispensable transcription factor facilitating Th17 polarization. Importantly, medical and population genetics studies have identified NFΚBIZ (the gene encoding IκBζ) as a major susceptibility locus for psoriasis, an IL-17-associated autoimmune condition. We have demonstrated that in vivo administration of DI completely ameliorates development of pathology in a mouse model of psoriasis. Therefore, a deeper understanding of the connection between IκBζ and electrophilic stress has the strong potential to uncover novel therapeutic avenues for treatment of autoimmune conditions, such as psoriasis. Moreover, although the major studied cellular response to electrophilic stress is the Keap1/Nrf2 pathway, we show that the effect of DI on IκBζ is independent of Nrf2. Our preliminary data suggest the existence of a discrete Nrf2-independent molecular pathway starting at Keap1 engagement by electrophiles and culminating in selective inhibition of IκBζ translation. Defining the mechanistic details of this pathway will deepen the general understanding of immune regulation and will provide novel therapeutic strategies in autoimmune diseases driven by the IκBζ-IL-17 axis. We aim to uncover key members and mechanisms of this pathway using the following converging strategies: 1) define the mechanism of IκBζ inhibition by electrophilic stress at the level of Keap1 and 2) define the mechanism of translational regulation of Nfkbiz mRNA in conditions of electrophilic stress. Completion of the proposed Aims will lay the foundation for future detailed in vitro and in vivo studies of the novel regulator/regulators of the IκBζ activation program. Ultimately, we aim to study the role of the novel IκBζ regulators identified by this proposal in the context of an inflammatory condition such as psoriasis, which will be the subject of a future R01 application.