Regulation of cholangiocytes by InsP3 receptor isoforms

InsP3 受体亚型对胆管细胞的调节

• 批准号: 6582042
• 负责人: BARBARA E. EHRLICH
• 金额: $ 30.98万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6582042
• 关键词: bicarbonates; bile; bile ducts; calcium channel; calcium flux; calcium indicator; cell line; cell type; electrophysiology; epithelium; immunoprecipitation; immunosuppressive; inositol phosphates; laboratory rat; lipid bilayer membrane; liver function; nuclear receptors; protein isoforms; protein localization; receptor binding; receptor expression; secretion

DESCRIPTION (provided by applicant): Bile secretion is one of the principal functions of the liver. In order to maintain bile flow, not only must hepatocytes secrete bile, but this must then be modified and conditioned further by bile duct epithelial cells, or cholangiocytes. Abnormal cholangiocytes function results in cholestasis, which is a cardinal manifestation of liver disease. Cholestatic liver diseases are responsible for 20% of liver transplants in the US, and are the most common cause of liver disease among pediatric transplant patients. In addition, abnormal cholangiocyte function is responsible for the hepatic manifestations of cystic fibrosis, one of the most common inherited diseases. Bile secretion in cholangiocytes is regulated in part by cytosolic Ca2+. In general, cells are regulated both by the pattern of Ca2+ signals over time and by the regions of the cells in which Ca2+ signals occur. However, little is known about temporal or spatial aspects of Ca2+ signaling in cholangiocytes, and nothing is known about how these Ca2+ signals are regulated. Inositol 1,4,5-trisphosphate receptors (InsP3R) mediate Ca2+ signaling in epithelia, and cholangiocytes express all three isoforms of this receptor. The hypothesis of this proposal is that Ca2+ signals in the cholangiocyte are regulated by the subcellular distribution of the InsP3R isoforms. This hypothesis will be investigated through the following specific aims: The function and regulation of the InsP3Rs will be compared at the single channel level. The contribution that each of the receptors plays to Ca2+ signaling in cholangiocytes will be examined in a bile duct cell line modified to express either one or a combination of these receptors. These findings will be related to the organization of Ca2+ signals and secretory function in native cholangiocytes, as determined in isolated microperfused bile duct segments. This work should not only identify the molecular mechanisms responsible for Ca2+ signaling in cholangiocytes, but serve as a model for how the molecular organization of signaling pathways is responsible for regulation of ductular secretion.

描述（由申请人提供）：胆汁分泌是肝脏的主要功能之一。为了维持胆汁流，不仅必须分泌胆汁，而且必须通过胆管上皮细胞或胆管细胞对此进行修改并进一步修改。异常的胆管细胞功能导致胆汁淤积，这是肝病的基本表现。胆汁淤积性肝病是美国20％的肝移植，是小儿移植患者肝病的最常见原因。此外，异常的胆管细胞功能是囊性纤维化的肝脏表现，囊性纤维化是最常见的遗传疾病之一。 胆管细胞中的胆汁分泌部分由胞质Ca2+调节。通常，随着时间的流逝，CA2+信号的模式和CA2+信号发生的细胞区域都通过CA2+信号的模式来调节细胞。然而，关于胆管细胞中Ca2+信号传导的时间或空间方面知之甚少，对这些CA2+信号的调节方式一无所知。肌醇1,4,5-三磷酸受体（INSP3R）介导上皮中的Ca2+信号传导，而胆管细胞表达该受体的所有三种同工型。该提议的假设是胆管细胞中的Ca2+信号受INSP3R同工型的亚细胞分布调节。该假设将通过以下特定目的进行研究：INSP3R的功能和调节将在单个通道级别进行比较。 每个受体在胆管细胞中对Ca2+信号传导发挥作用的贡献将在修饰以表达一种或组合这些受体的胆管细胞系中进行检查。这些发现将与在本机胆管细胞中的Ca2+信号和分泌功能的组织有关，如在孤立的微填充的胆管段中确定的。这项工作不仅应确定胆管细胞中Ca2+信号传导的分子机制，而且还应作为信号传导途径分子组织如何负责调节导管分泌的模型。