The Role of the Notch Pathway in Bile Duct Development

切迹通路在胆管发育中的作用

• 批准号: 6958294
• 负责人: Kathleen Mary Loomes
• 金额: $ 36.52万
• 依托单位: CHILDREN'S HOSP OF PHILADELPHIA
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-15 至 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6958294
• 关键词: Alagille syndrome; bile ducts; cell line; developmental genetics; embryo /fetus; gene deletion mutation; gene expression; gene targeting; genetically modified animals; histogenesis; histology; immunocytochemistry; laboratory mouse; mammalian embryology; microarray technology; phenotype; tissue /cell culture; transfection

DESCRIPTION (provided by applicant): Inherited disorders of intrahepatic bile duct development are a major cause of morbidity and mortality in the pediatric population. In recent years, advances have been made toward understanding the genetic control of liver development, but relatively little is understood regarding the molecular regulation of bile duct development. Identification of Jag1 as the disease gene for Alagille syndrome (AGS), an autosomal dominant disorder characterized by bile duct paucity along with anomalies in other organ systems, has revealed a crucial role for Jag1 and the Notch pathway in bile duct development. Jag1 encodes a ligand in the Notch signaling pathway, which is involved in cell fate determination in many organ systems. Homozygous targeted disruption of Jag1 in a mouse model causes early embryonic lethality, and the heterozygous mutant mouse has no phenotype. We have generated a Jag1 conditional knockout mouse using the Cre/lox gene targeting system. This model will permit the systematic study of the role of Jag1 in the development of multiple organ systems at specified times during development. Preliminary studies have demonstrated expression of Jag1 in the primitive bile ducts, or ductal plate cells, which originate from hepatocyte precursors in developing mouse and human liver. We propose to selectively ablate Jag1 in the developing liver and bile ducts by breeding the Jag1-loxP mouse with a liver-specific Cre transgenic line. Using this mouse model, we will perform detailed studies of ductal plate remodeling and bile duct development in the absence of Jag 1. In addition, we will employ real time PCR and micro array analysis to identify unique downstream targets of the Notch pathway in bile duct development. As a complementary strategy, we propose to use a cell culture approach in which we will derive bipotential hepatoblast cell lines from embryonic wildtype and Jag1 null livers. We will assess their response to defined stimuli, and rescue the phenotype by transfecting with activated Notch

描述（由申请人提供）：肝内胆管发育的遗传性疾病是儿科人群发病和死亡的主要原因。近年来，人们在了解肝脏发育的遗传控制方面取得了进展，但对胆管发育的分子调控了解相对较少。 Jag1 被鉴定为 Alagille 综合征 (AGS) 的疾病基因，该综合征是一种常染色体显性遗传疾病，其特征是胆管缺乏以及其他器官系统异常，揭示了 Jag1 和 Notch 通路在胆管发育中的关键作用。 Jag1 编码 Notch 信号通路中的配体，该通路参与许多器官系统中的细胞命运决定。在小鼠模型中，Jag1 的纯合靶向破坏会导致早期胚胎死亡，而杂合突变小鼠则没有表型。我们使用 Cre/lox 基因打靶系统生成了 Jag1 条件敲除小鼠。该模型将允许系统研究 Jag1 在发育过程中特定时间的多器官系统发育中的作用。初步研究表明 Jag1 在原始胆管或管板细胞中表达，这些细胞起源于发育中的小鼠和人类肝脏的肝细胞前体。我们建议通过用肝脏特异性 Cre 转基因品系培育 Jag1-loxP 小鼠，选择性地消除发育中的肝脏和胆管中的 Jag1。使用该小鼠模型，我们将在没有 Jag 1 的情况下对导管板重塑和胆管发育进行详细研究。此外，我们将采用实时 PCR 和微阵列分析来识别胆管发育中 Notch 通路的独特下游靶标。作为补充策略，我们建议使用细胞培养方法，从胚胎野生型和 Jag1 无效肝脏中获得双能成肝细胞系。我们将评估他们对特定刺激的反应，并通过转染激活的 Notch 来挽救表型