Ca2+ waves in hepatocytes: Mechanisms and effects

肝细胞中的 Ca2 波：机制和作用

• 批准号: 10388244
• 负责人: MICHAEL H NATHANSON
• 金额: $ 51.46万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-04-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10388244
• 关键词: Animal Model; Apical; Bile fluid; Binding; Biological; Biology; Calcium; Calcium Channel; Calcium Oscillations; Calcium Signaling; Cell model; Childhood; Cholestasis; Cytosol; Disease; Endoplasmic Reticulum; Epigenetic Process; Epithelial; Event; Genetic; Health; Hepatocyte; Human; Impairment; Inositol; Laboratories; Liver diseases; Mediating; Membrane; MicroRNAs; Molecular; Molecular Biology; Organic Anion Transporters; Patients; Physiology; Property; Protein Isoforms; Regulation; Role; Signal Transduction; Testing; Therapeutic; Translating; Work; bile acid transporter; clinically significant; epigenetic regulation; histone methylation; liver function; liver transplantation; new therapeutic target; novel therapeutics; receptor; transcription factor

PROJECT SUMMARY Bile secretion is one of the principal functions of the liver. Cholestasis, or impaired bile flow, is a cardinal manifestation of liver disease. Cholestatic liver diseases are an important group of disorders, which collectively represent the most common indication for pediatric liver transplant and account for one in ten of all liver transplants. This project investigates a basic biological mechanism in epithelial biology that is directly relevant for the regulation of secretion in hepatocytes in health and disease. Calcium signals in hepatocytes are formed largely by calcium release from the inositol 1,4,5-trisphosphate (InsP3) receptor (InsP3R), which is an InsP3- gated calcium channel in the endoplasmic reticulum (ER). The type II InsP3R (InsP3R-2) is the predominant isoform in hepatocytes, constituting 80% of the total pool of InsP3Rs, and is most concentrated in a specialized region of the ER beneath the canalicular membrane. Calcium signals in hepatocytes generally begin as calcium waves that originate in this region, and the apical pool of InsP3R-2 in hepatocytes is important for mediating calcium waves and canalicular secretion. In contrast, the type I InsP3R (InsP3R-1), which constitutes the remaining 20% of the InsP3R pool in hepatocytes, preferentially localizes to a different subcellular region and does not affect secretion. The hypothesis of this project is that the factors that regulate the expression and subcellular distribution of InsP3R-2 also regulate hepatocyte secretion, so that cholestasis is mediated by these effects on InsP3R-2. In particular, we will test whether cholestatic liver diseases are due in part to impaired expression and/or peri-canalicular targeting of InsP3R-2, which in turn impairs polarized calcium waves in the cytosol and downstream events including regulation of the bile acid transporter Bsep and the organic anion transporter Mrp2. This hypothesis will be tested through the following specific aims: (1) We will determine the genetic and epigenetic factors that regulate expression of InsP3R-2 in hepatocytes. (2) We will determine the molecular basis for, and cellular effects of, targeting InsP3R-2 to the ER-canalicular membrane interface. (3) We will determine whether and how InsP3R-2 expression and/or pericanalicular targeting is impaired in hepatocytes during canalicular cholestasis. We also will determine whether the efficacy of new therapies being developed for treatment of cholestatis disorders is mediated in part by modulating InsP3R-2. Collectively, these studies will break new ground in our understanding of the ways in which signaling microdomains are established in hepatocytes, and have the potential to establish new paradigms for translating these observations into understanding the mechanistic basis for a range of clinically significant human liver diseases.

项目概要 胆汁分泌是肝脏的主要功能之一。胆汁淤积或胆汁流动受损是一个主要问题 肝脏疾病的表现。胆汁淤积性肝病是一组重要的疾病，统称为 代表儿科肝移植最常见的适应症，占所有肝脏移植的十分之一 移植。该项目研究与上皮生物学直接相关的基本生物学机制 用于调节健康和疾病中肝细胞的分泌。肝细胞内形成钙信号 主要通过肌醇 1,4,5-三磷酸 (InsP3) 受体 (InsP3R) 释放钙，该受体是一种 InsP3- 内质网 (ER) 中的门控钙通道。 II 型 InsP3R (InsP3R-2) 是主要的 肝细胞中的亚型，占 InsP3R 总库的 80%，并且最集中于专门的 位于小管膜下方的 ER 区域。肝细胞中的钙信号通常以钙开始 起源于该区域的波，肝细胞中 InsP3R-2 的顶端池对于介导很重要 钙波和小管分泌。相比之下，I 型 InsP3R (InsP3R-1) 构成 肝细胞中剩余 20% 的 InsP3R 池优先定位于不同的亚细胞区域，并且 不影响分泌。该项目的假设是调节表达和表达的因素 InsP3R-2的亚细胞分布也调节肝细胞分泌，因此这些介导胆汁淤积 对 InsP3R-2 的影响。特别是，我们将测试胆汁淤积性肝病是否部分归因于受损 InsP3R-2 的表达和/或小管周围靶向，这反过来又损害了 细胞质和下游事件，包括胆汁酸转运蛋白 Bsep 和有机阴离子的调节 运输者Mrp2。该假设将通过以下具体目标进行检验：（1）我们将确定 调节肝细胞中 InsP3R-2 表达的遗传和表观遗传因素。 (2) 我们将确定 将 InsP3R-2 靶向 ER-小管膜界面的分子基础和细胞效应。 (3) 我们 将确定肝细胞中 InsP3R-2 表达和/或细管周围靶向是否受损以及如何受损 在小管胆汁淤积期间。我们还将确定正在开发的新疗法是否有效 用于治疗胆汁淤积性疾病的药物部分是通过调节 InsP3R-2 介导的。总的来说，这些研究将 在我们对信号微结构域建立方式的理解上取得了新的突破 肝细胞，并有可能建立新的范例，将这些观察结果转化为 了解一系列具有临床意义的人类肝脏疾病的机制基础。