Modulation of RNA Binding Proteins in Xenobiotic-induced Hepatotoxicity

项目摘要 在国家职业安全研究所确定的近700种工作场所化学品中， 安全和健康（NIOSH）袖珍指南与肝毒性相关。其中几个与 不同职业环境中工人的肝病死亡率增加， 设备操作员、扫烟囱工人和化学工人。异源性肝毒性是 以氧化应激、炎症和纤维化为特征，在后期阶段可能导致肝衰竭 和肝细胞癌（HCC）。虽然转录干扰与炎症有关， 转录后调控在外源性肝纤维化发生中的作用 炎症和纤维化尚不清楚。RNA结合蛋白（RBP）的三曲脯氨酸（TTP）家族 包括通常称为TTP的锌指蛋白36（ZFP 36），锌指蛋白36样1（ZFP 36 L1）， 和锌指蛋白36样2（ZFP 36 L2）是大分子转录后调节的关键参与者 炎症相关mRNA的数量。这些蛋白质与3 '非翻译区上的富含AU的元件（战神）结合。 区域（3 'UTR），并促进其衰变。TTP家族RBP在人HCC中失调。 工业化学品，包括毒死蜱、四氯二苯并二恶英（TCDD）和四氯化碳（CCl 4）， 也失调TTP家族RBP的表达。然而，下游的分子和细胞效应 这些失调对宿主的影响仍然未知。在这个提议中，我们将测试我们的新假设， 外源性物质诱导TTP家族RBP表达失调导致转录后调节改变 它决定了肝脏炎症和纤维化的发病机制。我们将使用四氯化碳诱导的肝脏 炎症和纤维化作为肝毒性模型，并通过三个具体目标来检验我们的假设。在 目的1，我们将采用小鼠肝脏特异性消融三种RBP和新的“组学”方法来测试RBP的表达。 这些RBP调节外源性诱导的肝脏炎症和纤维化的致病机制。目的 2将表征TTP家族RBP调节上皮细胞的细胞和分子机制， 间质转化，纤维化和肿瘤转移的主要原因，最后，目标3将测试是否 增加TTP家族RBP在肝脏中的表达可以保护肝脏免受外源性诱导的肝损伤。 炎症和纤维化。这项研究的总体目标是了解TTP家族RBP的作用。 介导的转录后调控的外源性诱导的肝毒性的发病机制。成功 完成拟议的研究将对机械的理解产生重大影响， 外源性肝病的病理生理学和TTP家族RBP作为 内源性抗炎/抗纤维化蛋白，其活性可能被增强以延迟或 预防肝衰竭的发生。

Project Summary Approximately 33% of the nearly 700 workplace chemicals identified in the National Institute of Occupational Safety and Health (NIOSH) Pocket Guide are associated with hepatotoxicity. Several of these have been linked to increased liver disease mortality in workers in different occupational settings such as heavy construction equipment operators, chimney sweepers, and chemical workers. Xenobiotic-induced hepatotoxicity is characterized by oxidative stress, inflammation, and fibrosis, which, in later stages, may result in hepatic failure and hepatocellular carcinoma (HCC). While transcriptional perturbations have been implicated in inflammation and fibrosis; the role of post-transcriptional regulation in the development of xenobiotic-induced hepatic inflammation and fibrosis is unclear. The tristetraprolin (TTP) family of RNA binding proteins (RBPs) including zinc finger protein 36 (ZFP36) commonly referred to as TTP, zinc finger protein 36 like 1 (ZFP36L1), and zinc finger protein 36 like 2 (ZFP36L2), are the key players in post-transcriptional regulation of a large number of inflammation-relevant mRNAs. These proteins bind to AU-rich elements (AREs) on the 3’untranslated regions (3’UTRs) of target mRNAs and promote their decay. TTP family RBPs are dysregulated in human HCC. Industrial chemicals including chlorpyrifos, tetrachlorodibenzo-p-dioxin (TCDD), and carbon tetrachloride (CCl4), also dysregulate the expression of TTP family RBPs. However, the downstream molecular and cellular effects of these dysregulations on the host remain unknown. In this proposal, we will test our novel hypothesis that xenobiotic-induced dysregulation of TTP family RBPs expression results in altered post-transcriptional regulation that determines the pathogenesis of hepatic inflammation and fibrosis. We will use CCl4-induced liver inflammation and fibrosis as a model of hepatotoxicity and test our hypothesis through three specific aims. In Aim 1, we will employ liver-specific ablations of the three RBPs in mice and novel “omics” approaches to test the pathogenic mechanisms by which these RBPs regulate xenobiotic-induced liver inflammation and fibrosis. Aim 2 will characterize the cellular and molecular mechanisms by which TTP family RBPs regulate epithelial- mesenchymal transition, a lead cause of fibrosis and tumor metastasis, and finally, Aim 3 will test whether increasing the expression of TTP family RBPs in the liver protects against xenobiotic-induced hepatic inflammation and fibrosis. The overall goal of the proposed research is to understand the role of TTP family RBP mediated post-transcriptional regulation in the pathogenesis of xenobiotic-induced hepatotoxicity. Successful completion of the proposed studies will have a significant impact on the mechanistic understanding of the pathophysiology of xenobiotic-induced liver disease and the potential identification of TTP family RBPs as endogenous anti-inflammatory/anti-fibrotic proteins whose activity could be possibly enhanced to delay or prevent the onset of liver failure.