Preservation of liver function through modulation of Fas-binding proteins

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，将我们带到了一个新的研究领域，即肝细胞分析，其中Fas在介导肝脏疾病中起着关键作用。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着关键作用，以确定由感染和毒素引起的细胞应激诱导的挑战的结果。Fas系统是一种重要的细胞清除系统，具有几种既定的功能，包括清除自身反应性淋巴细胞、感染和缺陷细胞以及由化疗和辐射损伤的细胞。例如，在Fas -/-细胞中没有Fas系统，许多临床化疗和电离辐射不再有效地根除细胞。鉴于Fas的共同表达，通常无法消除一些表达Fas的细胞，我们怀疑Fas受到严格控制。虽然Fas活化作为化疗的临床有益介质，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的潜在结合调节剂，并确定了一个肿瘤抑制蛋白早幼粒细胞白血病蛋白（PML），这是与增强凋亡。我们选择测试显性阴性PMLRARa，因为其表型更容易可视化。我们发现PMLRARa（和PML）与Fas结合并有效地阻断细胞凋亡。当在小鼠肝脏中表达时，PMLRAR α有效地保护小鼠免于由致死剂量的激动性抗Fas抗体诱导的死亡。PML的B-box结构域是与Fas结合所必需的，表明PML和PMLRAR α利用该位点结合Fas。PML和PMLRARa对转化生长因子2受体（TGF 2 R）调节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积极调节Fas信号，这在死亡和增殖的决定中起着至关重要的作用。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。我们预期PML表达具有Fas促进作用，并将解释PML广泛已知的凋亡增强作用。我们的假设是PML是Fas的结合调节剂，这种相互作用可以被调节以保护肝组织功能。该项目的长期目标是了解肝细胞的凋亡调节，以逆转Fas受体驱动的肝脏病理。

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.