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.

项目摘要 胆汁分泌是肝脏的主要功能之一。胆汁淤积或胆汁流量受损，是红衣主教 肝病的表现。胆汁淤积性肝疾病是一群重要的疾病，共同 代表小儿肝移植的最常见指示，并解释所有肝脏中十分之一 移植。该项目研究了上皮生物学的基本生物学机制，该机制直接相关 用于调节健康和疾病中肝细胞的分泌。形成肝细胞中的钙信号 在很大程度上是通过钙从肌醇1,4,5-三磷酸（INSP3）受体（INSP3R）中释放出来的，这是一个Insp3- 内质网（ER）中的门控钙通道。 II型INSP3R（INSP3R-2）是主要的 肝细胞中的同工型，占INSP3R池的80％，最集中在专业中 在管膜下方的ER区域。肝细胞中的钙信号通常从钙开始 起源于该区域的波，以及肝细胞中的insp3r-2的顶池对于介导很重要 钙波和大口腔分泌。相比之下，I型I insp3r（INSP3R-1） 在肝细胞中剩下的20％的INSP3R池，优先定位于不同的亚细胞区域和 不影响分泌。该项目的假设是调节表达的因素和 INSP3R-2的亚细胞分布还调节肝细胞分泌，因此胆汁淤积是由这些介导的 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造成 INSP3R-2的表达和/或近周的靶向靶向，进而损害了极化的钙波 细胞质和下游事件，包括调节胆汁酸转运蛋白BSEP和有机阴离子 转运蛋白MRP2。该假设将通过以下特定目的进行检验：（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子。 （2）我们将确定 靶向INSP3R-2靶向ER-斜膜膜界面的分子基础和细胞效应。 （3）我们 将确定肝细胞中的INSP3R-2表达和/或周围靶向靶向是否受损 在口腔胆汁淤积期间。我们还将确定是否开发了新疗法的功效 为了治疗胆道疾病，部分通过调节INSP3R-2进行了部分介导。这些研究总的来说 在我们理解信号传导微区域的方式时，请新的基础 肝细胞，并有可能建立新的范式将这些观察转化为 了解一系列具有临床意义的人肝病的机理基础。