Modulation of RNA Binding Proteins in Xenobiotic-induced Hepatotoxicity

项目摘要 在美国国家职业研究所确定的近700种工作场所化学品中，约有33% 安全与健康(NIOSH)袖珍指南与肝脏毒性有关。其中几个已经被联系在一起 导致不同职业环境(如繁重建筑)工人的肝病死亡率增加 设备操作员、烟囱清洁工和化学工人。异种生物诱导的肝毒性是 以氧化应激、炎症和纤维化为特征，在后期可能导致肝功能衰竭 和肝细胞癌(HCC)。虽然转录紊乱被认为与炎症有关 转录后调控在异种诱导性肝损伤中的作用 炎症和纤维化尚不清楚。Tristetraprolin(TTP)家族RNA结合蛋白(RBPs) 包括通常被称为TTP的锌指蛋白36(ZFP 36)、锌指蛋白36样蛋白1(ZFP 36L1)、 和锌指蛋白36样2(Zfp36l2)，是大分子转录后调控的关键分子 炎症相关的mRNAs数量。这些蛋白质与3‘端未翻译的富含AU的元素(ARE)结合 靶向mRNAs的区域(3‘UTRs)，并促进其衰变。TTP家族限制性商业惯例在人肝细胞癌中表达异常。 工业化学品，包括毒死蜱、四氯二苯并对二恶英(TCDD)和四氯化碳(CCl4)； 此外，TTP家族限制性商业惯例的表达也存在失调。然而，下游的分子和细胞效应 这些对寄主的失调尚不清楚。在这个提案中，我们将测试我们的新假设 异种生物诱导的TTP家族RBPs表达失调导致转录后调控改变 这决定了肝脏炎症和纤维化的发病机制。我们将使用CCl4诱导的肝脏 炎症和纤维化作为肝脏毒性的模型，并通过三个特定的目标来检验我们的假设。在……里面 目的1，我们将使用小鼠肝脏特异的三种限制性商业惯例的消融和新的组学方法来测试 这些限制性商业惯例调节异物诱导的肝脏炎症和纤维化的致病机制。目标 2将描述TTP家族限制性商业惯例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 增加TTP家族RBPs在肝脏中的表达对异物诱导的肝脏的保护作用 炎症和纤维化。拟议研究的总体目标是了解TTP家族RBP的作用 异种生物肝毒性发病机制中的转录后调控。成功 拟议研究的完成将对从机制上理解 异物性肝病的病理生理及TTP家族限制性商业惯例的潜在鉴定 内源性抗炎/抗纤维化蛋白，其活性可能被增强以延迟或 预防肝功能衰竭的发生。

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.