REGULATION OF SECRETION BY BILE DUCT EPITHELIAL CELLS

描述：肝内胆管对肝体积和 由肝脏分泌的胆汁的组成。 本文中描述的研究 建议解决胆管细胞，上皮细胞， 排列在这些导管的管腔内并负责胆汁分泌的细胞 阵 胆管细胞顶膜Cl-通道的开放 代表分泌调节的一个点，并涉及Cl-流出 通过囊性纤维化基因的蛋白质产物CFTR。 分离 胆管细胞还表达丰富的其他通道， 受受体依赖性（分泌素，ATP）和非依赖性（胆汁）调节 酸、细胞体积）途径。 拟议的研究将评估 工作假设，跨上皮运输的氯离子代表了一个 是跨肝内导管上皮分泌的重要驱动力; 局部（自分泌、旁分泌）因素和全身（激素）因素 这些因素共同调节胆汁的体积和成分 通过直接作用于导管细胞 膜片钳和其他技术将 用于评价分离的胆管细胞中的转运电流， 胆管细胞的极化模型，以前几乎没有应用于 调查这些问题。 具体目标是：1）本地化 膜离子通道的顶端或基底域，并严格评估 Cl-转运作为小管分泌驱动力的作用; 2） 评估Ca 2 +/钙调蛋白依赖性激酶在 分泌调节和蛋白激酶C调节细胞体积; 并评估3）细胞外ATP和4）胆汁酸作为局部调节 调节细胞膜Cl-渗透性的因素 生理需求。 这些研究的长期目标是确定 参与调节小管分泌的细胞机制。 总的来说，这些发现与诊断直接相关， 管理以受损为特征的多种疾病 胆管细胞运输，并开发新的治疗 旨在通过以下方式调节胆汁的体积和组成的方法 直接作用于导管细胞。

DESCRIPTION: Intrahepatic ducts contribute importantly to the volume and composition of bile secreted by the liver. The studies described in this proposal address the specialized functions of cholangiocytes, the epithelial cells that line the lumen of these ducts and are responsible for bile formation. Opening of Cl- channels in the apical membrane of cholangiocytes represents one point for regulation of secretion and involves Cl- efflux through CFTR, the protein product of the cystic fibrosis gene. Isolated cholangiocytes also express a rich array of other channels that are regulated by both receptor-dependent (secretin, ATP) and -independent (bile acids, cell volume) pathways. The proposed studies will evaluate the working hypothesis that transepithelial transport of Cl- ions represents an important driving force for secretion across intrahepatic duct epithelium; and that both local (autocrine, paracrine) factors and systemic (hormonal) factors work in concert to modulate the volume and composition of bile through direct effects on duct cells. Patch clamp and other techniques will be utilized to evaluate transport currents in isolated cholangiocytes and polarized models of biliary cells which have had little prior application to investigation of these issues. The specific aims are 1) to localize membrane ion channels to the apical or basal domains and critically evaluate the role of Cl- transport as a driving force for ductular secretion; 2) to assess the complementary roles of Ca2+/calmodulin-dependent kinases in regulation of secretion, and protein kinase C in regulation of cell volume; and to evaluate 3) extracellular ATP and 4) bile acids as local regulatory factors which modulate membrane Cl-permeability in response to changing physiologic demands. The long-term goal of these studies is to define the cellular mechanisms involved in regulation of ductular secretion. Collectively, the findings are directly relevant to the diagnosis and management of a broad range of disorders characterized by impaired cholangiocyte transport, and to the development of new therapeutic approaches aiming to modulate the volume and composition of bile through direct effects on duct cells.