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: 7777190
• 负责人: JAMES M PIPAS
• 金额: $ 5.06万
• 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/7777190
• 关键词: ATP Hydrolysis; ATP phosphohydrolase; Adopted; Amino Acids; Apoptosis; Binding; Biochemical; Biological; Cell Cycle Regulation; Cell Proliferation; Cell physiology; Chemicals; Chromatin; Complex; Crystallization; Crystallography; DNA biosynthesis; Data; Development; Discrimination; Disease; E2F transcription factors; Family; Family member; Gene Mutation; Genes; Genetic; Genetic Transcription; Goals; Growth; Homeostasis; Homologous Gene; Host Defense; In Vitro; Infection; Location; Malignant Neoplasms; Mediating; Modeling; Molecular; Molecular Chaperones; Molecular Conformation; Oncogene Proteins; Participant; Phosphorylation; Play; 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; flexibility; genetic regulatory protein; in vivo; interest; member; metaplastic cell transformation; mutant; promoter; research study; sialosyl-T antigen; three dimensional structure; transcription factor; viral DNA

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.

肿瘤抑制因子是调节蛋白，其接收和整合不同的信号并发挥功能， 对关键的细胞过程如细胞增殖、分化和凋亡发挥控制作用。因为 其活性的丧失或干扰通常导致癌症或其他疾病，并且由于其核心作用， 这些蛋白质在控制生物体发育和组织内环境稳定方面具有重要意义。的 视网膜母细胞瘤蛋白（pRb）是一种特征明确的肿瘤抑制因子，与两种相关的 p130和p107蛋白部分通过调节E2 F家族的活性来控制细胞周期的进入和退出 转录因子。 许多病毒，包括猿猴病毒40（SV 40）编码的癌蛋白结合Rb家族成员 并干扰它们调节E2 F的能力。由SV 40编码的大肿瘤抗原（T抗原）结合 通过LXCXE基序与pRb、p107和p130结合，并阻断这些蛋白抑制E2 F依赖性细胞凋亡的能力。 转录并诱导生长停滞。视网膜母细胞瘤家族已被深入研究，但很少有研究。 我们知道病毒（如SV 40）阻断其作用的分子基础。事实上，与T 抗原对每个Rb蛋白具有不同的结果。例如，p130在SV 40之后降解 感染或转化，而pRb水平保持不变。因此，T抗原似乎能够 区分不同的Rb-E2 F复合物，但这种区分的基础是未知的。 与许多调节蛋白一样，pRb和E2 F转录因子并不孤立存在。宁愿他们 作为包括染色质修饰剂在内的大型多蛋白组装体的一部分， 设备，以及其他因素，这些复合体的动态组装和拆卸是至关重要的 他们的规则。T抗原具有J结构域，并且已显示作为DnaJ分子起作用 监护人J结构域对于重要的DNA复制、转录控制和病毒体组装是必需的。 重要的是，T抗原需要J结构域来阻断Rb蛋白的功能，从而激活Rb蛋白。 E2 F依赖性转录。本申请寻求理解用于以下目的的机械和结构基础： T抗原识别和破坏Rb-E_2F复合物作用。首先，生物化学研究将 探索T抗原伴侣机器区分和作用于p130-E2 F4-DP 1、pRb- E2 F4-DP 1和pRb-E2 F1-DP 1复合物。第二，J域的定向性和灵活性的作用将是 使用核磁共振和X射线晶体学的组合进行检查。最后，一个基因和 生物化学方法将用于鉴定分子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因子如何控制细胞增殖和存活的理解， 以及病毒或基因突变如何破坏这些机制，从而导致癌症。