Preservation of liver function through modulation of Fas-binding proteins

通过调节 Fas 结合蛋白来保护肝功能

• 批准号: 8095442
• 负责人: FELIPE SAMANIEGO
• 金额: $ 19.75万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-15 至 2014-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8095442
• 关键词: Antibodies; Apoptosis; Apoptotic; Area; Binding; Binding Proteins; Biological Preservation; Boxing; CD95 Antigens; Cell Death; Cells; Cellular Stress; Cessation of life; Cleaved cell; Clinical; Complex; Dominant-Negative Mutation; Dose; Event; Genetic Transcription; Goals; Hepatocyte; In Situ Nick-End Labeling; Infection; Ionizing radiation; Liver; Liver diseases; Lymphocyte; Maps; Mediating; Mediator of activation protein; Modeling; Mus; Nuclear; Outcome; Pathology; Phenotype; Plasmids; Play; Prevention; Protein Binding; Receptor Activation; Regulation; Research; Role; Signal Transduction; Site; Staining method; Stains; System; Testing; Therapeutic; Tissues; Toxin; Transforming Growth Factors; Tumor Suppressor Proteins; carcinogenesis; caspase-3; cell injury; chemotherapy; irradiation; liver function; mutant; protein function; receptor; reconstitution; response; transcription factor PML

DESCRIPTION (provided by applicant): This project, which builds on our recent observations of regulation of Fas death receptor, takes us to a new area of research, the analysis of liver cells, where Fas plays a critical role mediating liver disorders. Death receptors have key roles in numerous cell death/proliferation decisions. More specifically, the Fas death receptor plays a pivotal role in liver tissue to determine the outcomes of challenges induced by cell stress due to infection and toxins. The Fas system is an important cell elimination system that has several established functions, including the elimination of autoreactive lymphocytes, infected and defective cells and cells damaged by chemotherapy and irradiation. Without the Fas system, for example, in Fas -/- cells, many clinical chemotherapies and ionizing radiation are no longer effective in eradicating cells. Given the common expression of Fas, the common inability to eliminate some cells that express Fas, we suspect Fas to be under tight control. While Fas activation serves as a clinically beneficial mediator of chemotherapy, inadvertent Fas signaling can perpetuate liver damage and death. In this project we searched for potential binding regulators of Fas and identified a tumor suppressor protein promyelocytic leukemia protein (PML), which is associated with enhanced apoptosis. We chose to test the dominant-negative PMLRARa because its phenotype is easier to visualize. We found that PMLRARa (and PML) binds to Fas and potently blocks apoptosis in cells. When express in mouse liver, PMLRARa effectively protects mice from death induced by a lethal dose of agonistic anti-Fas antibody. The B-box domain of PML is necessary for binding to Fas, suggesting that PML and PMLRARa use this site to bind Fas. A model of opposing effects of PML and PMLRARa on regulation of transforming growth factor 2 receptor (TGF2R) has been established and we suspect that Fas operates in a similar model. Our hypothesis is that PML positively regulates Fas signaling, which plays a critical role in death and proliferation decisions. We will use PML dominant-negative mutant PMLRARa as a probe to characterize the blocking effects on Fas. We anticipate that PML will express have Fas-promoting effects and will explain the widely known apoptosis enhancement effect of PML. Our hypothesis is that PML is a binding regulator of Fas and this interaction can be modulated to preserve liver tissue function. The long-term goal of this project is to understand apoptosis regulation of liver cells to reverse liver pathology driven by the Fas receptors. PUBLIC HEALTH RELEVANCE: The Fas system is an important cell elimination system that has several established functions, including the elimination of autoreactive lymphocytes and infected and defective cells and cells damaged by chemotherapy and irradiation. We have identified promyelocytic leukemia protein as a binding and potential key regulator of Fas signaling. This project will characterize the binding with Fas and demonstrate how Fas is regulated in liver cells and in mice; thus by showing the site of regulation of Fas, we will be able to identify an effective therapeutic approach for liver disorders driven by Fas signaling.

描述（由申请人提供）：该项目建立在我们最近对Fas死亡受体调节的观察基础上，将我们带入一个新的研究领域，即肝细胞分析，其中Fas在肝脏疾病中起关键作用。死亡受体在许多细胞死亡/增殖决定中起关键作用。更具体地说，Fas死亡受体在肝组织中起关键作用，决定由感染和毒素引起的细胞应激引起的挑战的结果。Fas系统是一种重要的细胞消除系统，具有多种既定功能，包括消除自身反应性淋巴细胞、感染和缺陷细胞以及因化疗和照射而受损的细胞。没有Fas系统，例如，在Fas -/-细胞中，许多临床化疗和电离辐射不再有效地根除细胞。考虑到Fas的普遍表达，以及无法消除一些表达Fas的细胞，我们怀疑Fas受到严格控制。虽然Fas激活是临床上有益的化疗介质，但无意的Fas信号传导可使肝损伤和死亡永久化。在这个项目中，我们寻找Fas的潜在结合调节因子，并鉴定出一种肿瘤抑制蛋白早幼粒细胞白血病蛋白（PML），它与细胞凋亡的增强有关。我们选择测试显性阴性PMLRARa，因为它的表型更容易可视化。我们发现PMLRARa（和PML）与Fas结合并有效阻断细胞凋亡。PMLRARa在小鼠肝脏中表达后，可有效保护小鼠免受致死性抗fas抗体致死剂量诱导的死亡。PML的B-box结构域是与Fas结合所必需的，表明PML和PMLRARa利用该位点与Fas结合。PML和PMLRARa对转化生长因子2受体（TGF2R）调控的相反作用的模型已经建立，我们怀疑Fas在类似的模型中起作用。我们的假设是PML正调控Fas信号，这在死亡和增殖决策中起关键作用。我们将使用PML显性阴性突变体PMLRARa作为探针来表征对Fas的阻断作用。我们预计PML将表达具有促fas作用，这将解释PML广泛存在的促凋亡作用。我们的假设是PML是Fas的结合调节剂，这种相互作用可以调节以保持肝组织功能。该项目的长期目标是了解肝细胞凋亡调控，以逆转由Fas受体驱动的肝脏病理。