Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA.
Cell Death Differ. 2019 Mar;26(3):455-469. doi: 10.1038/s41418-018-0130-7. Epub 2018 May 23.
Intrahepatocytic accumulation of misfolded α1-antitrypsin Z variant (ATZ) is responsible for liver disease in some individuals with α1-antitrypsin deficiency (ATD), characterized by fibrosis/cirrhosis and predisposition to carcinogenesis. Previous results showing that accumulation of ATZ in model systems activates the NFκB signaling pathway have led us to hypothesize that downstream targets of NFκB are elements of a proteostasis response network for this type of proteinopathy. Here we show that only a subset of downstream targets within the NFκB transcriptomic repertoire are activated in model systems of this proteinopathy. Breeding of the PiZ mouse model of ATD to two different mouse models with NFκB deficiency led to greater intrahepatocytic accumulation of ATZ, more severe hepatic fibrosis, decreased autophagy and hyperproliferation of hepatocytes with massive ATZ inclusions. Specific downstream targets of NFκB could be implicated in each pathological effect. These results suggest a new role for NFκB signaling in which specific downstream targets of this pathway mediate an integrated program of proteostatic responses designed to mitigate the pathologic effects of proteinopathy, including autophagic disposal of misfolded protein, degradation of collagen and prevention of hyperproliferation.
肝内堆积的错误折叠的α1-抗胰蛋白酶 Z 变异体（ATZ）是导致某些α1-抗胰蛋白酶缺乏症（ATD）患者发生肝脏疾病的原因，其特征为纤维化/肝硬化和易发生癌变。先前的研究结果表明，ATZ 在模型系统中的积累会激活 NFκB 信号通路，这使我们假设 NFκB 的下游靶标是这种蛋白病的蛋白质稳态反应网络的组成部分。在这里，我们表明，在这种蛋白病的模型系统中，只有 NFκB 转录组谱中的一部分下游靶标被激活。将 ATD 的 PiZ 小鼠模型与两种具有 NFκB 缺陷的不同小鼠模型进行杂交，导致 ATZ 在肝内的堆积更多，肝纤维化更严重，自噬减少，以及大量 ATZ 包含物的肝细胞过度增殖。NFκB 的特定下游靶标可能与每种病理效应有关。这些结果表明 NFκB 信号通路具有新的作用，该通路的特定下游靶标介导了一种综合的蛋白质稳态反应程序，旨在减轻蛋白病的病理效应，包括错误折叠蛋白的自噬处理、胶原降解和预防过度增殖。
