The role of keratins in the liver

角蛋白(keratins，K)是一个细胞保护蛋白大家族，角蛋白突变易导致多种人类疾病的发生。在肝脏中，成年肝细胞只产生K8/K18，而导管细胞和肝祖细胞(HPC)也表达K7/K19。K7/K19是由导管细胞和造血祖细胞组成的导管反应(DR)最成熟的标志物，代表了肝脏对损伤的基本再生反应。在之前的资助期间，我们分析了角蛋白在肝脏损伤中的变化，并研究了遗传性角蛋白变异对人类肝病发展的影响。我们还确认K23是一种新的DR标志物，并证明K19的缺失可以减轻DR并促进胆汁淤积性肝损伤的发展。这些发现构成了当前更新方案的基础，该方案将系统地分析K7/K19在DR以及DR相关肝癌中的作用。为此，我们建立了K7/K19双基因敲除动物，并将它们与已建立的小鼠DR和肝癌模型(mdr2-KOS)杂交。动物的表型特征将得到胆汁成分和角蛋白结构分析的补充。利用分离的原代细胞进行的实验，以及对单个角蛋白的敲除/转染，将能够对K7/K19在DR和肿瘤形成中的作用进行详细的功能评估。拟议的研究将对DR以及角蛋白在再生和肿瘤形成中的重要性产生新的见解，这些都是新兴的课题。

Keratins (K) constitute a large family of cytoprotective proteins and keratin mutations predispose to development of multiple human diseases. In the liver, adult hepatocytes produce K8/K18 only, while ductal cells and hepatic progenitor cells (HPCs) also express K7/K19. K7/K19 are the most established markers of ductular reaction (DR) that consists of ductal cells and HPCs and represents the basic regenerative response of the liver to injury.In the previous funding period, we analyzed the alteration of keratins during hepatic injury and studied the impact of inherited keratin variants on the development of human liver disease. We also identified K23 as a novel DR marker and demonstrated that loss of K19 attenuates DR and promotes the development of cholestatic liver injury. These findings constitute the rationale for the current renewal proposal that will systematically analyze the role of K7/K19 in the DR as well as in DR-related liver cancer. To that end, we generated K7/K19 double-knockout animals and crossbreed them with an established murine DR and liver cancer model (Mdr2-KOs). The phenotypic characterization of the animals will be complemented with analyses of bile composition and keratin architecture. Experiments with isolated primary cells together with knockdown/transfection of individual keratins will enable a detailed functional assessment of the role of K7/K19 in the DR as well as tumor formation. The proposed studies will yield novel insights into the DR as well as the importance of keratins in regeneration and tumor formation that are emerging topics.