Molecular Mechanisms of Toxin-InducedBiliary Atresia

项目摘要 胆道闭锁（BA）是一种新生儿胆管病，是肝移植的主要适应症， 儿科人群。人类BA的病因尚不清楚，但BA在新生儿中流行 澳大利亚牲畜与母体摄入的Dysphania种植物支持毒性病因。 使用体内斑马鱼胆汁分泌测定，我们分离出了胆甾松，一种新的植物生物碱， 选择性肝外胆道毒性，可能导致BA综合征（1）。这种毒素- 介导的BA模型概括了人类BA的主要特征，因此可以用于模型 这种罕见但重要的儿科肝病。 胆汁酸是一种强亲电试剂，我们已经证明氧化还原应激和蛋白质组应激起关键作用 在胆固醇酯毒性中的作用。具体来说，我们发现：1）肝外胆管细胞表现出一种 在基线时和用以下药物治疗后，氧化型谷胱甘肽（GSH）的氧化还原电位显著更高 与肝内胆管细胞和肝细胞相比，胆汁酸酯;和2）胆汁酸酯毒性可 通过药理学和遗传学操纵GSH氧化还原稳态而改变（2）。总体 该建议的目的是继续使用胆甾酯作为定义胆管细胞应激的损伤模型 对毒性损伤的反应，并探讨应激反应和胆源性疾病遗传易感性之间的联系。 损伤该提案包括两个具体目标。在目标1中，我们将定义肝脏氧化还原的机制 在斑马鱼模型中赋予对毒性损伤不同敏感性的异质性。在目标2中，我们将 确定胆管细胞蛋白质组学和氧化还原应激反应与氧化还原遗传易感性之间的联系， 使用斑马鱼和来自诱导多能干细胞的人胆管细胞诱导胆管细胞损伤 细胞 拟议的实验将揭示有关其分子机制的新信息 我们希望这将刺激BA和其他疾病的新治疗策略的发展。 胆管疾病

PROJECT SUMMARY Biliary atresia (BA) is a neonatal cholangiopathy that is the leading indication for liver transplantation in the pediatric population. The etiology of human BA remains obscure, however, BA epidemics in newborn Australian livestock associated with maternal ingestion of the Dysphania species plant support a toxic etiology. Using an in vivo zebrafish biliary secretion assay, we have isolated biliatresone, a novel plant isoflavonoid with selective extrahepatic biliary toxicity that is likely responsible for the Dysphania BA syndrome (1). This toxin- mediated BA model recapitulates the cardinal features of human BA and thus can be used to model this rare but important pediatric liver disease. Biliatresone is a strong electrophile and we have shown that redox stress and proteomic stress play critical roles in biliatresone toxicity. Specifically, we have found that: 1) extrahepatic cholangiocytes exhibit a significantly more oxidized glutathione (GSH) redox potential both at baseline and after treatment with biliatresone compared to intrahepatic cholangiocytes and hepatocytes; and 2) biliatresone toxicity can be altered through pharmacologic and genetic manipulation of GSH redox homeostasis (2). The overarching goals of this proposal are to continue use biliatresone as an injury model for defining cholangiocyte stress responses to toxic insults and to explore the links between stress responses and genetic susceptibility to biliary injury. The proposal consists of two specific aims. In Aim 1, we will define mechanisms of liver redox heterogeneity that confer differential susceptibility to toxic injury in the zebrafish model. In Aim 2, we will define links between cholangiocyte proteomic and redox stress responses and genetic susceptibility to redox- induced cholangiocyte injury using zebrafish and human cholangiocytes derived from induced pluripotent stem cells. The proposed experiments will reveal novel information about the molecular mechanisms underlying the pathogenesis of BA that we hope will spur the development of new therapeutic strategies for BA and other cholangiopathies.