Molecular Mechanisms of Toxin-InducedBiliary Atresia

项目总结 胆道闭锁(BA)是一种新生儿胆管疾病，是肝移植的主要适应症。 儿科人口。人类BA的病因尚不清楚，但BA在新生儿中的流行 与母体摄入Dysphania物种植物有关的澳大利亚家畜支持有毒病因学。 利用斑马鱼体内胆汁分泌试验，我们分离出了一种新的植物异黄酮类化合物胆红素。 选择性肝外胆汁毒性可能导致BA综合征(1)。这种毒素- 介导性BA模型概括了人类BA的基本特征，因此可以用于建模 这种罕见但重要的儿科肝病。 胆红素是一种强亲电体，我们已经证明氧化还原应激和蛋白质组应激起着关键作用。 胆红素中毒的作用。具体地说，我们发现：1)肝外胆管细胞表现出 在基线和治疗后，氧化谷胱甘肽(GSH)氧化还原电位显著增加 胆红素与肝内胆管细胞和肝细胞的比较；以及2)胆红素的毒性 通过GSH氧化还原动态平衡的药理和遗传操作而改变(2)。最重要的是 这项提案的目标是继续使用胆红素作为确定胆管细胞应激的损伤模型 对有毒侮辱的反应，并探索应激反应与胆汁遗传易感性之间的联系 受伤。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，对毒性损伤具有不同敏感性的异质性。在目标2中，我们将 明确胆管细胞蛋白质组和氧化还原应激反应与氧化还原遗传易感性之间的联系。 斑马鱼和诱导多能干细胞来源的人胆管细胞对胆管细胞的损伤作用 细胞。 拟议中的实验将揭示关于支持这一机制的新信息 BA的发病机制，我们希望能刺激BA和其他疾病的新治疗策略的发展 胆管病。

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.