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Mechanisms of Hepatocyte Polarization and Apical Tube Formation

肝细胞极化和心尖管形成的机制

基本信息

批准号：
10598034
负责人：
Erfei Bi
金额：
$ 38.41万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-07-01 至 2025-03-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10598034
关键词：
Actin-Binding Protein Actins Adherens Junction Affect Apical Architecture Attenuated Basic Science Bile fluid Binding Biogenesis Biology Blood Circulation Candidate Disease Gene Cell model Cells Cholestasis Cytokinesis Cytoskeleton Defect Development Drug Metabolic Detoxication Epithelial Cells Epithelium Excretory function Exocytosis Filament Gene Expression Profile Genes Geometry Gold Growth Guanine Nucleotide Exchange Factors Hepatic Cord Hepatocyte Human In Vitro Kinesin Link Liver Liver diseases Location Mediating Membrane Metabolism Microfilaments Microtubules Motor Myosin Type V Natural regeneration Organ Pathway interactions Phosphatidylinositols Play Plus End of the Microtubule Primary carcinoma of the liver cells Process Production Proliferating Public Health Rattus Recycling Role Scaffolding Protein Serum Proteins Side Site Small Interfering RNA Surface Testing Tight Junctions Time Tube Tubular formation Vesicle Visceral cytohesin-1 daughter cell gene discovery in vivo interdisciplinary approach liver development liver function scaffold spatiotemporal trafficking transcriptomics vesicle transport

项目摘要

Project Summary/Abstract: The functions of the liver, including detoxification, synthesis of serum proteins, and bile production, critically depend on hepatocyte polarization and bile canaliculus (BC) formation. Defects in these processes are associated with serious liver diseases such as cholestasis and hepatocarcinoma. Using the rat hepatocyte line Can 10, the only known cells that can proliferate and form “tubular” BCs (tBCs) in vitro that resembles those in vivo, we discovered that hepatocyte polarization and “primordial” BC formation are linked to cytokinesis. This division-linked mechanism also applies to BC biogenesis during liver development. However, it remains a mystery how a primordial BC formed between two daughter cells at the division site is remodeled and grown into a tBC nestled between two rows of cells, as seen in the liver. We hypothesize that tBC formation involves spatiotemporal coordination of oriented divisions, with BC expansion driven by targeted exocytosis, elongation by pushing forces from both sides of the BC, and extension along the cell-cell contact through constant remodeling of the adherens and tight junctions. To identify the steps and key players involved, we employed two non-biased approaches. The first involves identification of genes from single-cell transcriptomic analysis of liver development that are induced or increased at stages of hepatocyte polarization and BC formation. The second involves identification of genes whose expressions are increased in the polarized Can 10 cells versus the unpolarized parental cells. These complementary approaches have led to the discovery of numerous genes that may play an important role in a process from the terminal stage of cytokinesis to tBC formation. 11 candidate genes were selected for a small siRNA-based screen, three (KIF21B, ABLIM3, and IPCEF1) were found to be required for tBC formation. None of these has been implicated previously in epithelial tube formation. In this application, we will use an interdisciplinary approach to test our hypotheses that the microtubule (MT) plus end-directed motor Kif21B and the actin-binding protein Ablim3 act in concert to drive BC expansion by controlling MT- and actin-mediated vesicle transport as well as adherens junction (AJ) assembly (Aim 1), and that the scaffold protein Ipcef1 promotes Arf6 activation by distinct cytohesins (GEFs) at distinct locations to control AJ remodeling, apical vesicle recycling, and actin-based protrusions to drive BC elongation (Aim 2). As the mechanisms of apical tube formation are highly conserved from worms to humans, the impact of our proposed study will likely reach far beyond the field of liver biology.

项目总结/文摘: