Notch Signaling and Cell Fate in Embryonic and Adult Liver

描述(由申请人提供)： 肝脏是一个复杂而重要的组织。它的多种功能是由肝脏的两种主要的“实质”细胞类型--肝细胞和胆管细胞--相对于血管的复杂的三维组织所促进的。肝硬变会破坏这些细胞的正常结构排列，从而干扰血液和胆汁的正常流动，阻碍肝脏的生产性再生。肝硬变的临床后果--肝功能衰竭和肝癌--在美国每年导致数千人死亡和数十亿美元的医疗费用。这项工作的长期目标是了解肝脏分化和形态发生在发育过程中通常是如何控制的，并将这一知识应用于体内和体外肝脏再生的创新新策略。 先前的工作表明，Notch-一种高度保守的受体信号通路，在胚胎发育过程中被广泛用于控制分化-在肝脏发育中发挥着重要作用。具体地说，Notch信号缺陷的人类患者和突变小鼠都表现出胆管异常。目前尚不清楚这种异常是在分化还是在形态发生上。这项建议的目的是确定Notch在肝脏发育过程中的作用机制，并揭示Notch信号在成人肝脏中是否发挥作用。 这些目标将通过使用基因工程小鼠和培养的细胞系来实现，具体目标有三个。首先，将确定发育中的肝脏内细胞的正常谱系关系。其次，将确定Notch激活在胚胎和成年肝脏的不同区域内的细胞效应。第三，将发展研究Notch在分化中的作用的细胞培养方法。这些实验应该能更好地理解Notch活性在肝脏发育中的作用机制。此外，它们将为未来的翻译研究提供一个框架，旨在增强体内肝脏的再生和形态发生，并概述肝脏在体外的发育。 外行读者提纲：再生医学的目标是通过将必要的细胞引入适当的环境，用功能正常的组织取代失败的组织。这项研究提案的最终目标是设计合理的肝再生方法用于治疗。作为第一步，将研究Notch信号，以了解这一重要的信号通路在肝脏发育过程中和在肝脏正常功能中如何发挥作用。

DESCRIPTION (provided by applicant): The liver is a complex and essential tissue. Its multiple functions are facilitated by an intricate three- dimensional organization of the two major "parenchymal" cell types of the liver - hepatocytes and cholangiocytes - relative to blood vessels. Cirrhosis disrupts the normal architectural arrangement of these cells, thereby interfering with the normal flow of blood and bile and preventing productive regeneration of the liver. The clinical consequences of cirrhosis - liver failure and liver cancer - result in thousands of deaths and billions of dollars in health care costs within the United States annually. The long-term objective of this work is to understand how liver differentiation and morphogenesis is normally controlled during development, and to apply this knowledge to innovative new strategies for liver regeneration, both in vivo and ex vivo. Previous work has suggested that Notch - a highly conserved receptor signaling pathway that is widely used during embryogenesis to control differentiation - plays an important role in liver development. Specifically, both human patients and mutant mice with deficiencies in Notch signaling exhibit abnormalities in bile ducts. It is unknown whether such abnormalities in differentiation or morphogenesis. The goal of this proposal is to determine the mechanism of Notch action during liver development and to reveal whether Notch signaling plays a role in the adult liver. These objectives will be achieved through the use of genetically engineered mice and cultured cell lines through three specific aims. First, the normal lineage relationship of cells within the developing liver will be determined. Second, the cellular effects of Notch activation within various compartments of the embryonic and adult liver will be determined. Third, cell culture methods for studying Notch's role in differentiation will be developed. These experiments should provide greater understanding of the mechanism of Notch activity in liver development. Moreover, they will provide a framework for future translational studies aimed at augmenting liver regeneration and morphogenesis in vivo and recapitulating liver development in vitro. Outline for lay audience: The goal of regenerative medicine is to replace a failing tissue with a functioning one by introducing necessary cells into an appropriate environment. The ultimate goal of this research proposal is to devise rational approaches to liver regeneration for use in therapy. As a first step, Notch signaling will be studied to understand how this essential signaling pathway functions during liver development and in the normal function of the liver.