Regulation of cholangiocytes by InsP3 receptor isoforms

胆汁分泌是肝脏的主要功能之一。为了保持胆汁流动，不仅必须 肝细胞分泌胆汁，但这必须随后被胆管上皮细胞进一步修饰和调节， 细胞或胆管细胞。胆管细胞功能异常导致胆汁淤积，这是一个主要的 肝脏疾病的表现。胆汁淤积性肝病是20%的肝移植的原因， 是儿科移植患者中最常见的肝病原因。此外，本发明还提供了一种方法， 异常的胆管细胞功能是囊性纤维化的肝脏表现的原因，囊性纤维化是肝硬化的一种。 最常见的遗传性疾病 胆管细胞的胆汁分泌部分受胞质Ca ~（2+）调节。一般来说，细胞受到调节， 通过随时间变化的Ca 2+信号的模式和通过其中Ca 2+信号发生的细胞的区域两者。 然而，对胆管细胞中Ca 2+信号的时间或空间方面知之甚少， 关于这些Ca 2+信号是如何调节的还不清楚。肌醇1，4，5-三磷酸受体 （InsP 3R）介导上皮细胞中的Ca 2+信号传导，胆管细胞表达这三种亚型。 受体的这一建议的假设是，胆管细胞中的Ca 2+信号受 InsP 3R亚型的亚细胞分布。这一假设将通过以下方式进行研究： 具体目标： 1. InsP 3R的功能和调节将在单通道水平上进行比较。 2.将检查每种受体对胆管细胞中Ca 2+信号传导的贡献 在经修饰以表达这些受体之一或组合的胆管细胞系中。 3.这些发现将与天然细胞中Ca ~（2+）信号的组织和分泌功能有关。 胆管细胞，如在分离的微灌注胆管段中确定的。 这项工作不仅应该确定负责Ca 2+信号转导的分子机制， 胆管细胞，但作为一个模型，如何分子组织的信号通路是 负责调节导管分泌。

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: 1. The function and regulation of the InsP3Rs will be compared at the single channel level. 2. 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. 3. 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.