CD73 is a multi-functional protein that regulates liver injury

抽象的。 它们对肝脏的合成、分泌和代谢功能的重要性使得肝细胞 特别容易受伤。增强肝细胞对损伤性损伤的恢复力具有阻断 肝脏疾病在早期阶段进展，与病因无关。为此，外-5 '-核苷酸酶（CD 73）是一种免疫调节剂。 有前途的新型肝病靶点，因为它在多种小鼠肝损伤模型中起关键作用， 在患有多种病因的慢性肝病的患者的肝脏中，CD 73的经典功能 是细胞外腺苷一磷酸（AMP）代谢为腺苷。我们发现，全球CD 73-/-小鼠， 对化学诱导的肝细胞损伤具有抗性，这是一个意外的发现， 在野生型小鼠中细胞表面CD 73 AMPase活性几乎完全丧失。这指向替代功能， 这也得到了我们鉴定出的一种新的、无催化活性的CD 73亚型（CD 73 S）的支持。 人类肝脏疾病我们观察到在原代肝细胞中， 两种不同的人类CD 73亚型CD 73在体外结合两种生物活性脂质，这表明它可能调节 脂质稳态我们的中心假设是，非酶和替代异构体相关的机制， 肝细胞CD 73促进肝损伤和疾病进展。该假设将通过两个具体的 目的：（i）定义CD 73在肝细胞中的非酶和亚型特异性功能;（ii）检查 在体内和组织水平的肝脏保护机制在CD 73的情况下。我们的目标1将 将高通量配体筛选、高含量成像和蛋白质组学与详细的生物化学结合起来， 分子和细胞生物学评估，以确定CD 73是否是脂质敏感受体或ER调节剂 应激，并确定非催化性CD 73 S变体在肝细胞抗应激中的特异性功能。 应力对于目标2，我们将使用两种酒精模型和两种生理盐水模型来检查体内CD 73的肝脏特异性贡献。 高脂饮食诱导的损伤和我们新产生的肝脏特异性CD 73-/-小鼠。我们将利用重组 酶在体内和精确切割的肝切片进行机械救援和功能丧失的研究。这 这项工作将导致CD 73功能在肝细胞中的彻底整合，并有可能产生新的 肝保护的机制方法。

Abstract. Their central importance to the synthetic, secretory and metabolic functions of the liver renders hepatocytes particularly vulnerable to injury. Reinforcing hepatocyte resilience to damaging insults holds potential to block liver disease progression at early stages, independent of etiology. To that end, ecto-5’-nucleotidase (CD73) is a promising novel liver disease target, as it plays critical roles in multiple mouse liver injury models, and is dysregulated in livers of patients with chronic liver diseases of multiple etiologies. The classical function of CD73 is metabolism of extracellular adenosine monophosphate (AMP) to adenosine. We found that global CD73-/- mice are resistant to chemically-induced hepatocellular injury, an unexpected finding given that liver injury induces near-complete loss of cell surface CD73 AMPase activity in wild-type mice. This points to alternative functions, which is also supported by our identification of a novel, catalytically-inactive CD73 isoform (CD73S) in advanced human liver disease. We observe differences in apoptosis-related signaling in primary hepatocytes expressing the two different human CD73 isoforms. CD73 binds two bioactive lipids in vitro, suggesting that it may regulate lipid homeostasis. Our central hypothesis is that non-enzymatic and alternative isoform-related mechanisms of hepatocyte CD73 promote liver injury and disease progression. The hypothesis will be addressed via two specific aims: (i) Define the non-enzymatic and isoform-specific functions of CD73 in hepatocytes and (ii) Examine the in vivo and tissue-level mechanisms of hepatoprotection in the absence of CD73. Our approach for Aim 1 will couple high throughput ligand screening, high content imaging, and proteomics with detailed biochemical, molecular and cell-biological assessments to determine if CD73 is a lipid-sensing receptor or a regulator of ER stress, and to determine the specific function of the non-catalytic CD73S variant in hepatocyte resistance to stress. For Aim 2, we will examine liver-specific contributions of CD73 in vivo using two models of alcohol and high fat diet-induced injury and our newly-generated liver-specific CD73-/- mice. We will utilize recombinant enzyme in vivo and precision-cut liver slices to perform mechanistic rescue and loss-of-function studies. This work will lead to a thorough integration of CD73 function in hepatocytes with the potential to yield novel mechanistic approaches for hepatoprotection.