Action of the SV40 T Antigen Chaperone Machine on Tumor Suppressors

SV40 T 抗原伴侣机对肿瘤抑制剂的作用

• 批准号: 7382592
• 负责人: JAMES M PIPAS
• 金额: $ 30.75万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-14 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7382592
• 关键词: ATP Hydrolysis; ATP phosphohydrolase; Adopted; Amino Acids; Apoptosis; Binding; Biochemical; Biochemical Genetics; Biological; Cell Cycle Regulation; Cell Proliferation; Cell physiology; Chemicals; Chromatin; Complex; Crystallization; Crystallography; DNA biosynthesis; Data; Development; Discrimination; Disease; Disruption; E2F transcription factors; Elevation; Family; Family member; Gene Mutation; Genes; Genetic; Genetic Transcription; Goals; Growth; Homeostasis; Homologous Gene; Host Defense; In Vitro; Infection; Localized; Location; Malignant Neoplasms; Mediating; Modeling; Molecular; Molecular Chaperones; Molecular Conformation; Oncogene Proteins; Participant; Phosphorylation; Play; Pliability; Production; Protein Binding; Proteins; RBL2 gene; Reaction; Recruitment Activity; Regulation; Relaxation; Resolution; Rest; Retinoblastoma; Retinoblastoma Protein; Role; Signal Transduction; Simian virus 40; Staging; System; Testing; Tissues; Transcriptional Activation; Transcriptional Regulation; Tumor Antigens; Tumor Suppressor Proteins; Viral; Viral Tumor Antigens; Virion; Virus; Virus Diseases; Work; X-Ray Crystallography; antigen binding; base; genetic regulatory protein; human RBL2 protein; in vivo; interest; member; metaplastic cell transformation; mutant; promoter; research study; sialosyl-T antigen; three dimensional structure; transcription factor

Tumor suppressors are regulatory proteins that receive and integrate diverse signals and function to exert control over key cellular processes such as cell proliferation, differentiation, and apoptosis. Because loss or perturbation of their activity often results in cancer or other diseases, and because of their central role in governing organismal development and tissue homeostasis, these proteins are of great interest. The retinoblastoma protein (pRb) is a well characterized tumor suppressor that, in concert with two related proteins, p130and p107,control cell cycle entry and exit, in part, by regulating the activity of the E2F family of transcription factors. Many viruses, including Simian virus 40 (SV40) encode oncoproteins that bind Rb-family members and interfere with their ability to regulate E2Fs. The large tumor antigen (T antigen) encoded by SV40 binds to pRb, p107, and p130via an LXCXE motif and blocks the ability of these proteins to inhibit E2F-dependent transcription and to induce growth arrest. The retinoblastoma family has been studied intensively, yet little is known about the molecular basis by which viruses, such as SV40, block their action. In fact, interaction with T antigen has different consequences for each Rb protein. For example, p130 is degraded following SV40 infection or transformation, while the levels of pRb remain unchanged. Thus, T antigen appears to be able to distinguish different Rb-E2F complexes, but the basis for this discrimination is unknown. Like many regulatory proteins pRb and E2F transcription factors do not exist in isolation. Rather they function as part of large multiprotein assemblages that include chromatin modifiers, the basal transcription apparatus, as well as other factors, and the dynamic assembly and disassembly of these complexes is critical to their regulation. T antigen has a J domain and has been shown to function as a DnaJ molecular chaperone. The J domain is required for a vital DNA replication, transcriptional control, and virion assembly. Importantly, the J domain is required for T antigen to block the function of Rb proteins and thus to activate E2F-dependent transcription. This application seeks to understand the mechanistic and structural basis for the action of T antigen's recognition and disruption of Rb-E2F complexes.' First, biochemical studies will explore the ability of the T antigen chaperone machine to distinguish and act upon p130-E2F4-DP1, pRb- E2F4-DP1, and pRb-E2F1-DP1 complexes. Second, the role of J domain orientation and flexibility will be examined using a combination of NMR and X-ray crystallography. Finally, a combined genetic and biochemical approach will be used to identify additional protein participants in the chaperone reaction. These studies will enhance our understanding of how these tumor suppressors govern cell proliferation and survival, and how subversion of these mechanisms by viruses or genetic mutation, contribute to cancer.

抑制肿瘤是调节蛋白，接收并整合多种信号和功能到 对关键细胞过程（例如细胞增殖，分化和凋亡）发挥控制。因为 其活动的丧失或扰动通常会导致癌症或其他疾病，并且由于其核心作用 在管理生物体发育和组织稳态时，这些蛋白质引起了极大的兴趣。这 视网膜母细胞瘤蛋白（PRB）是一种特征良好的肿瘤抑制剂，与两个相关的肿瘤抑制剂 蛋白质，P130和P107，控制细胞周期的进入和出口，部分通过调节E2F家族的活性 转录因子。 许多病毒，包括结合RB家族成员 并干扰他们调节E2F的能力。由SV40编码的大肿瘤抗原（T抗原）结合 对于PRB，P107和P130VIA A lxCXE基序，并阻止这些蛋白抑制E2F依赖性的能力 转录并引起生长停滞。视网膜母细胞瘤家族已经进行了深入的研究，但几乎没有 关于病毒（例如SV40）阻止其作用的分子基础已知。实际上，与t的互动 抗原对每种RB蛋白都有不同的后果。例如，SV40后P130降解 感染或转化，而PRB的水平保持不变。因此，T抗原似乎能够 区分不同的RB-E2F复合物，但是这种歧视的基础尚不清楚。 像许多调节蛋白一样，PRB和E2F转录因子不存在。而是他们 功能是包括染色质修饰剂的大型多蛋白组合的一部分，基础转录 设备以及其他因素以及这些复合物的动态组装和拆卸是至关重要的 对他们的监管。 T抗原具有J结构域，已被证明充当DNAJ分子 伴侣。 J域是重要的DNA复制，转录控制和病毒体组件所必需的。 重要的是，t抗原需要阻断RB蛋白的功能，从而激活J域需要J结构域 E2F依赖性转录。该应用程序旨在了解 T抗原识别和破坏RB-E2F复合物的作用。首先，生化研究将 探索T抗原伴侣机的能力区分和作用于P130-E2F4-DP1，PRB- E2F4-DP1和PRB-E2F1-DP1复合物。其次，J域取向和灵活性的作用将是 使用NMR和X射线晶体学的组合检查。最后，一个遗传和 生化方法将用于鉴定伴侣反应中的其他蛋白质参与者。这些 研究将增强我们对这些肿瘤抑制剂如何控制细胞增殖和生存的理解， 以及这些机制如何通过病毒或遗传突变颠覆，导致癌症。