The role of c-met in liver biology

c-met 在肝脏生物学中的作用

• 批准号: 8552759
• 负责人: Snorri Thorgeirsson
• 金额: $ 25.44万
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8552759
• 关键词: Address; Adhesions; Adult; Area; Biliary; Biology; CCL2 gene; Carbon Tetrachloride; Cell Differentiation process; Cell Line; Cell Proliferation; Chronic; Cytoskeletal Modeling; DNA Damage; Development; Dystrophic Calcification; Epidermal Growth Factor Receptor; Epithelial; Experimental Animal Model; Fibrosis; Gene Expression Profile; Gene Targeting; Genes; Genetic; Goals; Growth; Healed; Hepatic; Hepatic Fibrogenesis; Hepatocyte; Hepatocyte Growth Factor; Immunohistochemistry; Inflammatory; Injury; Knockout Mice; Liver; Liver Fibrosis; Liver Regeneration; Liver Stem Cell; Maintenance; Malignant neoplasm of liver; Mediating; Mediator of activation protein; Metabolism; Modeling; Monitor; Morphogenesis; Natural regeneration; Necrosis; Pathway interactions; Phase; Play; Proto-Oncogene Proteins c-akt; RANTES; Receptor Protein-Tyrosine Kinases; Regulation; Research; Resolution; Resources; Role; STAT3 gene; Signal Pathway; Signal Transduction; Stem Cell Research; Stem cells; Time; Tissue Survival; Tissues; Western Blotting; adult stem cell; biological adaptation to stress; cancer site; cholangiocyte; healing; in utero; intercellular communication; liver cell proliferation; meetings; mouse model; receptor; regenerative therapy; self-renewal; stellate cell; stem; transcriptomics; tumorigenesis

Our most recent results in this project include: (1)EGFR and c-Met are involved in both activation and differentiation of hepatic progenitor cell (HPC) . However, the underlying mechanisms have not been elucidated. Here we have addressed the impact of EGFR and c-Met signaling on the differentiation of HPC into heptatocytic and biliary epithelial lineages using clonally derived progenitor cell lines from EGFRfl/fl and Met fl/fl conditional knockout mice.Precise control of lineage commitment and maintenance of stem/progenitor cells is crucialfor regeneration of diseased liver. We have used a combination of genetic and pharmacological approaches to address the role of Egfr and Met, two principal liver receptor tyrosine kinases (RTK), in hepatocyte-billiary epithelial lineage decisions of hepatic progenitor cells (HPCs). We have shown that Met and Egfr collaborate to increase the HPC self-renewal growth through activation of ERK pathway. Met is a key RTK responsible for hepatocyte differentiation via strong activation of AKT and STAT3, whereas Egfr is an essential mediator of the Notch1 pathway required for cholangiocyte specification and branching morphogenesis. Unlike Met, genetic loss of Egfr was beneficial for HPC-mediated liver regeneration by switching HPC differentiation towards hepatocytes rather than cholangiocytes. This establishes both cooperative and uniquefunctions of Met and Egfr regulatory network as a mechanism of HPC expansion and directed differentiation with implications for regenerative therapies; and (2)HGF/c-Met signaling plays a pivotal role in hepatocyte survival and tissue remodeling during liver regeneration. HGF treatment accelerates resolution of fibrosis in experimental animal models. We have utilized Met(fl/fl);Alb-Cre(+/-) conditional knockout mice and a carbon tetrachloride(CCl(4))-induced liver fibrosis model to formally address the role of c-Met signaling in hepatocytes in the context of chronic tissue injury. Histological changes during injury (4weeks) and healing phase (4weeks) were monitored by immunohistochemistry; expression levels of selected key fibrotic molecules were evaluated by western blotting, and time-dependent global transcriptomic changes were examined using a microarray platform. Loss of hepatocyte c-Met signaling altered hepatic microenvironment and aggravated hepatic fibrogenesis. Greater liver damage was associated with decreased hepatocyte proliferation, excessive stellate cell activation and rapid dystrophic calcification of necrotic areas. Global transcriptome analysis revealed a broad impact of c-Met on critical signaling pathways associated with fibrosis. Loss of hepatocyte c-Met caused a strong deregulation of chemotactic and inflammatory signaling (MCP-1, RANTES, Cxcl10) in addition to modulation of genes involved in reorganization of the cytoskeletal network (Actb, Tuba1a, Tuba8), intercellular communications and adhesion (Adam8, Icam1, Itgb2), control of cell proliferation (Ccng2, Csnk2a, Cdc6, cdk10), DNA damage and stress response (Rad9, Rad52, Ercc4, Gsta1 and 2, Jun). Our study demonstrates that deletion of c-Met receptor in hepatocytes results in pronounced changes in hepatic metabolism and microenvironment, and establishes an essential role for c-Met in maintaining the structural integrity and adaptive plasticity of the liver under adverse conditions.

我们在该项目中的最新结果包括：（1）EGFR和C-MET参与肝祖细胞（HPC）的激活和分化。但是，尚未阐明基本机制。 Here we have addressed the impact of EGFR and c-Met signaling on the differentiation of HPC into heptatocytic and biliary epithelial lineages using clonally derived progenitor cell lines from EGFRfl/fl and Met fl/fl conditional knockout mice.Precise control of lineage commitment and maintenance of stem/progenitor cells is crucialfor regeneration of diseased liver.我们已经使用了遗传学和药理学方法的组合来解决EGFR和MET的作用，即两个主要的肝受体酪氨酸激酶（RTK），在肝细胞上皮细胞的肝细胞上皮谱系中。我们已经表明，MET和EGFR合作通过激活ERK途径来增加HPC自我更新的增长。 MET是通过AKT和STAT3的强激活肝细胞分化的关键RTK，而EGFR是胆管细胞规范和分支形态发生所需的Notch1途径的必不可少的介体。与MET不同，EGFR的遗传丧失通过将HPC分化转向肝细胞而不是胆管细胞，对HPC介导的肝脏再生是有益的。这建立了MET和EGFR调节网络的合作和独特功能，作为HPC扩展的一种机制，并指示分化，对再生疗法的影响； （2）HGF/C-MET信号传导在肝脏再生过程中在肝细胞存活和组织重塑中起关键作用。 HGF治疗在实验动物模型中加速了纤维化的分辨率。我们使用了MET（FL/FL）； Alb-CRE（+/-）条件基因敲除小鼠和四氯化碳（CCL（4）） - 诱导的肝纤维化模型，以正式解决C-MET信号在慢性组织损伤背景下在肝细胞中的作用。通过免疫组织化学监测损伤期间（4周）和愈合阶段（4周）的组织学变化；通过蛋白质印迹评估选定的关键纤维化分子的表达水平，并使用微阵列平台检查了时间依赖性的全局转录组变化。肝细胞C-MET信号传导的丧失改变了肝微环境，并加剧了肝纤维发生。更大的肝损伤与肝细胞增殖减少，星状细胞活化过多以及坏死区的营养不良钙化相关。全球转录组分析揭示了C-MET对与纤维化相关的关键信号通路的广泛影响。 Loss of hepatocyte c-Met caused a strong deregulation of chemotactic and inflammatory signaling (MCP-1, RANTES, Cxcl10) in addition to modulation of genes involved in reorganization of the cytoskeletal network (Actb, Tuba1a, Tuba8), intercellular communications and adhesion (Adam8, Icam1, Itgb2), control of cell proliferation （CCNG2，CSNK2A，CDC6，CDK10），DNA损伤和应力反应（RAD9，RAD52，ERCC4，GSTA1和2，JUN）。我们的研究表明，肝细胞中C-MET受体的缺失会导致肝代谢和微环境的明显变化，并确定C-MET在不良条件下肝的结构完整性和适应性可塑性方面的重要作用。