Cell-cell adhesion-mediated signaling determines epithelial polarization in the liver

细胞间粘附介导的信号传导决定肝脏中的上皮极化

• 批准号: 9906924
• 负责人: ANNE MUESCH
• 金额: $ 58.98万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-04 至 2022-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9906924
• 关键词: Adhesions; Apical; Architecture; Back; Bile Duct Epithelium; Bile fluid; Biliary; Biological Assay; Blood; Blood Coagulation Factor; Blood capillaries; Cadherins; Cell Polarity; Cell membrane; Cell-Cell Adhesion; Cells; Data; Ductal Epithelial Cell; E-Cadherin; Endocytosis; Engineering; Ensure; Epithelial; Epithelial Cells; Epithelium; Gastrointestinal tract structure; Gatekeeping; Glycogen; Hepatic Tissue; Hepatocyte; Intestines; Knowledge; Lipids; Liver; Liver diseases; Mediating; Membrane; Mesenchymal; Metabolic; Microtubule Stabilization; Microtubules; Modeling; Molecular; Monomeric GTP-Binding Proteins; Morphology; N-Cadherin; Natural regeneration; Organ; Outcome; Pathway interactions; Phenotype; Plus End of the Microtubule; Population; Proteins; Publishing; Regulation; Rest; Running; Signal Transduction; Signaling Molecule; Site; Surface; System; Testing; Tissue Stains; Toxicology; Transplantation; Xenobiotics; bile canaliculus structure; bile duct; blood filter; cell type; epithelial to mesenchymal transition; gene therapy; interstitial; liver development; loss of function; nectin; neglect; novel strategies; protein degradation; protein protein interaction; protein transport; stem cells; tissue culture; trafficking; venule

ABSTRACT The liver is our largest metabolic organ. It produces proteins, lipids, clotting factors and glycogen while dispensing bile and detoxifying xenobiotics. In order to transport these different substances, a sophisticated network of liver venules, capillaries and interstitial conduits has evolved. An essential feature of this network are the lumen-forming epithelia that give rise to two major liver cell populations: (1) mature hepatocytes - the main parenchymal cell type, and (2) bile duct cells. Hepatocytes form single-cell cords with a capillary-like luminal network (bile canaliculi) running between them. In contrast, bile duct cells form tubules, each with a central lumen that receives the content of the bile canaliculi that has formed next to hepatocytes. During initial liver development and bouts of regeneration, both hepatocytes and bile duct cells are derived from a common epithelial precursor. How hepatocytes and biliary epithelia obtain their unique morphological and functional phenotypes from this common precursor is poorly understood. Indeed, because bile canaliculi are not readily visible by conventional H&E tissue stain, the study of epithelial polarity in the liver has largely been neglected. The resulting gap in our knowledge has greatly hindered our ability to better understand the molecular basis of common liver diseases, which typically present with changes in lumen organization. It also severely limits our ongoing efforts to engineer hepatic tissue that can be used for transplantation, toxicology and gene therapy studies. To tackle these issues, we have developed a unique tissue culture model to examine and explain how hepatocyte and bile duct luminal phenotypes form. It strongly suggests lumen polarity is established in two distinct steps. First, cell-cell adhesion triggers initial lumen formation at cell-cell contact sites. Second, luminal stability is then modified through E-cadherin signaling. Strong E-cadherin signaling antagonizes these luminal cell-cell contacts to determine a bile duct epithelium with a single apical surface. In contrast, weak E-cadherin signaling fails to block these cell-cell contacts and as a result the default pathway ensures hepatocytic polarity proceeds where multiple bile canaliculi can now form luminal junctions running between them. This hypothesis is supported by published and preliminary data that we obtained by developing cell systems in which the polarity phenotype can be switched. We have furthermore established stem cell-derived biliary and hepatocyte primary cultures to compare signaling mechanisms in the two liver epithelial cell types directly. It is expected that these novel approaches will enable us to understand the fundamental core mechanisms that drive cell type-specification and polarity phenotypes in the liver.

抽象的 肝脏是我们最大的代谢器官。它产生蛋白质、脂质、凝血因子和糖原，同时 分配胆汁和解毒异生素。为了运输这些不同的物质，需要一种复杂的 肝小静脉、毛细血管和间质导管网络已经进化。该网络的一个基本特征 是形成管腔的上皮细胞，产生两种主要的肝细胞群：（1）成熟肝细胞 - 主要实质细胞类型，和（2）胆管细胞。肝细胞形成具有毛细血管样的单细胞索 它们之间有管腔网络（胆小管）。相反，胆管细胞形成小管，每个小管都有一个 接收肝细胞旁边形成的胆小管内容物的中央管腔。初始期间 肝脏的发育和再生过程中，肝细胞和胆管细胞都来源于共同的细胞 上皮前体。肝细胞和胆管上皮如何获得其独特的形态和功能 人们对这种共同前体的表型知之甚少。事实上，因为胆小管不容易 通过传统的 H&E 组织染色可见，肝脏上皮极性的研究在很大程度上被忽视了。 由此产生的知识差距极大地阻碍了我们更好地理解分子基础的能力 常见的肝脏疾病，通常表现为管腔组织的变化。也严重限制了我们的 持续努力设计可用于移植、毒理学和基因治疗的肝组织 研究。 为了解决这些问题，我们开发了一种独特的组织培养模型来检查和解释如何 肝细胞和胆管管腔表型的形成。它强烈表明流明极性建立在两个 不同的步骤。首先，细胞间粘附触发细胞间接触部位的初始管腔形成。二、光明 然后通过 E-钙粘蛋白信号传导来改变稳定性。强的 E-钙粘蛋白信号传导会拮抗这些管腔 细胞与细胞接触以确定具有单个顶端表面的胆管上皮。相比之下，E-钙粘蛋白较弱 信号传导无法阻止这些细胞与细胞的接触，因此默认途径确保了肝细胞的极性 多个胆小管现在可以在它们之间形成管腔连接。 这一假设得到了我们通过开发细胞获得的已发表的初步数据的支持 极性表型可以切换的系统。我们还建立了干细胞衍生的 胆汁和肝细胞原代培养物，比较两种肝上皮细胞类型的信号传导机制 直接地。预计这些新颖的方法将使我们能够理解基本核心 驱动肝脏细胞类型特异性和极性表型的机制。