Signaling pathways influencing liver disease phenotype in antitrypsin deficiency

摘要 在经典的抗胰蛋白酶缺乏症(ATD)中，点突变会导致肝脏的错误折叠 分泌蛋白及其变异体抗胰蛋白酶Z(ATZ)以聚合物的形式聚集在肝细胞的ER中，并 集合体。肝纤维化和肝细胞癌发生在受影响的纯合子亚组中，由 功能获得性“蛋白毒性”机制。肝脏的表型有很大的变化，大约有10%受到影响。 在婴儿期/幼儿期和另一个亚组在生命的第6-7个十年期间发生肝病 明显的年龄依赖性过程。我们研究的中心假设有3个组成部分：1)在 肝脏表型由遗传和环境修饰物决定；2)这些修饰物的目标是 内质网的质量控制机制，细胞蛋白质平衡调控网络的一部分；3)两个主要的 蛋白沉积机制的类型包括蛋白质降解途径，如蛋白酶体和自噬， 以及旨在保护细胞免受蛋白毒性的信号通路。在这笔赠款中，我们建议 蛋白稳态调控机制中3条信号通路的作用研究 预防肝损伤，包括胰岛素和核因子B信号通路以及G调节因子 信令16(RGS16)。该建议是基于初步结果显示，这3条路径是 在几个模型系统中以独特的方式激活，包括哺乳动物细胞系和小鼠模型 ATZ的诱导性表达和一种新的线虫模型 快速基因工程和药物发现。我们将确定这些通路是如何激活的，以及如何 它们通过利用新型小鼠模型通过靶向干扰每个基因来影响ATD的肝脏表型 途径以及影响途径的药理策略。我们还将确定是否 在使用iPS来源的ATD患者个体中，这些通路的激活存在差异。 肝细胞系。

Abstract In the classical form of ¿1antitrypsin deficiency (ATD) a point mutation leads to misfolding of a hepatic secretory protein and the variant, ¿1antitrypsin Z (ATZ), accumulates in the ER of liver cells as polymers and aggregates. Liver fibrosis and hepatocellular carcinoma develops in a subgroup of affected homozygotes by a gain-of-function 'proteotoxic' mechanism. There is wide variability in the hepatic phenotype with ~10% affected in infancy/early childhood and another subgroup that develop liver disease in the 6th-7th decade of life by an apparent age-dependent process. The central hypothesis of our research has 3 components: 1) variability in hepatic phenotype is determined by genetic and environmental modifiers; 2) the targets of these modifiers are the quality control mechanisms of the ER, part of the cell's proteostasis regulatory network; 3) the 2 major types of protestasis mechanisms are protein degradation pathways, such as the proteasome and autophagy, and signaling pathways that are designed to protect cells from proteotoxicity. In this grant we propose investigation of the role of 3 signaling pathways that are putative proteostasis regulatory mechanisms designed to prevent liver damage, including the insulin and NF¿B signaling pathways as well as the regulator of G signaling 16 (RGS16). The proposal is based on preliminary results showing that these 3 pathways are activated in unique ways in several model systems including mammalian cell line and mouse models with inducible expression of ATZ and a novel C. elegans model that facilitates mechanistic interrogation through rapid genetic engineering and drug discovery. We will determine how these pathways are activated and how they affect the hepatic phenotype of ATD by utilizing novel mouse models with targeted disruption of each pathway as well as by pharmacological strategies that influence the pathways. We will also determine whether there is variation in activation of these pathways among individual patients with ATD using iPS-derived hepatocyte cell lines.