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Mechanism of p53 Silencing By Adenovirus E1B 55K Protein

腺病毒E1B 55K蛋白沉默p53的机制

基本信息

批准号：
8075486
负责人：
ARNOLD J BERK
金额：
$ 21.64万
依托单位：
UNIVERSITY OF CALIFORNIA LOS ANGELES
依托单位国家：
美国
项目类别：
财政年份：
1995
资助国家：
美国
起止时间：
1995-02-01 至 2013-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8075486
关键词：
ATM activation Adenovirus Infections Adenoviruses Antiviral Agents Antiviral Response Binding Biological Models Cell Nucleus Cell physiology Cells Cellular biology Clinical Treatment Clinical Trials Complex Cytoplasm DNA DNA Damage DNA Double Strand Break DNA biosynthesis Defense Mechanisms Double Strand Break Repair Eukaryotic Cell Gene Expression Gene Transduction Agent Genetic Translation Goals Human Infection Knowledge Laboratories Ligase Lytic Mammalian Cell Messenger RNA NBS1 gene Normal tissue morphology Nuclear Nuclear Export ONYX-015 Pathway interactions Patients Phase Proteins Proteolysis Publications Publishing Recombinants Repression Small Ubiquitin-Related Modifier Proteins Therapeutic Agents Transcriptional Activation Translations Tumor Cell Line Ubiquitin-Protein Ligase Complexes Ubiquitination Viral Viral Proteins Virion Virus Virus Diseases Work killings mRNA Export multicatalytic endopeptidase complex mutant neoplastic cell response tumor ubiquitin ligase ubiquitin-protein ligase viral DNA

项目摘要

DESCRIPTION (provided by applicant): Adenovirus is an important model system for understanding basic aspects of cell function. It is also being used as a vector for gene therapy, and adenovirus mutants and recombinants are being developed for use as therapeutic agents to replicate in and kill neoplastic cells, causing a spreading infection in tumor, without spreading through normal tissue. Our goal is to understand the function of the adenovirus E1B-55K protein during a productive viral infection and how this knowledge can be applied to make a more effective therapeutic agent. An E1B-55K null mutant developed in our lab, dl1520 (aka ONYX-015), has been used in clinical trials for the treatment of human tumors, with some efficacy in some patients and not others. The original rationale for this approach was that since E1B-55K functions to inactivate p53, and most tumors are defective in p53 or in the p53-pathway, a mutant virus that cannot inactivate p53 would be expected to be restricted for replication in normal p53+ cells, but able to replicate in p53-minus cells. However, further study revealed that the ability of the mutant to replicate to varying extents in different tumor cell lines was related to the expression of viral late proteins that comprise the virus particle, and not the p53-status of the cells. We found that E1B-55K assembles a ubiquitin-protein ligase with another viral protein, E4orf6, and several cellular proteins that polyubiquitinates p53, marking it for degradation by proteosomes. Others found that this adenovirus ubiquitin-protein ligase probably also causes the degradation of the cellular MRN complex involved in DNA double-strand break repair, and that if the MRN complex is not inactivated, viral DNA replication is inhibited and viral DNA is concatenated into long linear DNA molecules too long to package in the virion. Recently, we found that the activity of this ubiquitin-ligase complex is also required to stimulate viral late gene expression. Studies with cell mutants suggest that it is the MRN complex that must be inactivated to allow the normal level of viral late mRNA export from the nucleus to the cytoplasm and translation in the cytoplasm. The results imply that the MRN ? ATM/ATR ? downstream targets pathway induces an anti-viral response that inhibits viral mRNA nuclear export and translation of late viral mRNAs. We will study how ATM activation inhibits viral mRNA nuclear export and translation. Our findings may allow us to genetically characterize tumors to determine which ones might be effectively treated with dl1520.

描述（由申请人提供）：腺病毒是了解细胞功能基本方面的重要模型系统。它还被用作基因治疗的载体，正在开发腺病毒突变体和重组体，用作在肿瘤细胞中复制和杀死肿瘤细胞的治疗剂，在肿瘤中引起扩散性感染，而不会在正常组织中扩散。我们的目标是了解腺病毒E1B-55K蛋白在产性病毒感染期间的功能，以及如何将这些知识应用于制造更有效的治疗剂。我们实验室开发的E1B-55K零突变体dl1520（又名ONYX-015）已用于治疗人类肿瘤的临床试验，对某些患者有一定疗效，而对其他患者无效。该方法最初的原理是，由于E1B-55K具有灭活p53的功能，而大多数肿瘤在p53或p53通路中存在缺陷，因此无法灭活p53的突变病毒在正常p53+细胞中的复制将受到限制，但能够在p53-负细胞中复制。然而，进一步的研究表明，突变体在不同肿瘤细胞系中不同程度的复制能力与包含病毒颗粒的病毒晚期蛋白的表达有关，而与细胞的p53状态无关。我们发现E1B-55K与另一种病毒蛋白E4orf6和几种多泛素化p53的细胞蛋白组装泛素蛋白连接酶，标记其被蛋白体降解。其他人发现，这种腺病毒泛素蛋白连接酶也可能导致参与DNA双链断裂修复的细胞MRN复合体的降解，如果MRN复合体不灭活，病毒DNA复制受到抑制，病毒DNA被连接成长线性DNA分子，长得无法包装在病毒粒子中。最近，我们发现这种泛素连接酶复合物的活性也是刺激病毒晚期基因表达所必需的。对细胞突变体的研究表明，MRN复合体必须失活，才能使正常水平的病毒晚期mRNA从细胞核输出到细胞质并在细胞质中翻译。结果表明，MRN ？ATM / ATR吗?下游靶标途径诱导抗病毒反应，抑制病毒mRNA核输出和后期病毒mRNA的翻译。我们将研究ATM激活如何抑制病毒mRNA核输出和翻译。我们的研究结果可能使我们能够从基因上表征肿瘤，以确定哪些肿瘤可以用dl1520有效治疗。