Signaling Pathways Influencing Liver Disease Phenotype in Antitrypsin Deficiency

描述（由申请方提供）：在α 1抗胰蛋白酶缺乏症（ATD）的经典形式中，点突变导致肝分泌蛋白错误折叠，变体1抗胰蛋白酶Z（ATZ）在肝细胞ER中以聚合物和聚集体形式蓄积。肝纤维化和肝细胞癌的发展在一个亚组的受影响的纯合子通过获得功能的“蛋白毒性”机制。肝脏表型存在广泛的变异性，约10%在婴儿期/幼儿期受影响，另一个亚组在生命的第6 - 7个十年中通过明显的年龄依赖性过程发生肝病。我们研究的中心假设有3个组成部分：1）肝脏表型的变异性是由遗传和环境修饰剂决定的; 2）这些修饰剂的靶点是ER的质量控制机制，ER是细胞蛋白质稳态调节网络的一部分; 3）2种主要类型的蛋白质抑制机制是蛋白质降解途径，例如蛋白酶体和自噬，以及旨在保护细胞免受蛋白毒性的信号通路。在这项资助中，我们提出了3个信号通路的作用，这是假定的蛋白质稳态调节机制，旨在防止肝损伤的调查，包括胰岛素和NFκB信号通路以及G信号调节器16（RGS 16）。该建议是基于初步结果，显示这3个途径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，具有ATZ和一种新的C. elegans模型，通过快速基因工程和药物发现促进机械审讯。我们将确定这些途径是如何激活的，以及它们如何影响ATD的肝脏表型，通过利用新的小鼠模型，有针对性地破坏每种途径，以及通过影响途径的药理学策略。我们还将使用iPS衍生的肝细胞系确定ATD患者个体中这些通路的激活是否存在变化。

DESCRIPTION (provided by applicant): In the classical form of α1antitrypsin 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 NFκB 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.