Role of a Novel E3-Ubiquitin Ligase in Chemoprevention

新型 E3-泛素连接酶在化学预防中的作用

• 批准号: 7846963
• 负责人: MARK HANNINK
• 金额: $ 53.58万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-30 至 2011-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7846963
• 关键词: Adaptor Signaling Protein; Amino Acids; Axonal Neuropathy; BTB/POZ Domain; Binding; Biological Models; Biological Process; Broccoli - dietary; C-terminal; Carcinogens; Cardiovascular Diseases; Cell Nucleus; Cell physiology; Cells; Chemicals; Chemoprevention; Chemopreventive Agent; Complex; Cytoplasm; DNA Damage; Data; Disease; Enzyme Induction; Enzymes; Food; Gene Targeting; Genes; Genetic Programming; Genetic Transcription; Glioblastoma; Glutathione; Health; Homeostasis; Human; Isothiocyanates; Malignant - descriptor; Malignant Neoplasms; Malignant neoplasm of brain; Mediating; Modeling; Muscular Atrophy; Mutation; N-terminal; NF-E2-related factor 2; Nerve Degeneration; Neuropathy; Oxidation-Reduction; Oxidative Stress; Pathway interactions; Peptides; Pharmaceutical Preparations; Post-Translational Protein Processing; Preventive; Proteins; Publishing; Repression; Research; Role; Signal Transduction Pathway; Skeletal Muscle; Specificity; Structure; Sulforaphane; Ubiquitin; Ubiquitination; Work; base; cancer prevention; cancer risk; design; dietary supplements; driving force; fruits and vegetables; insight; novel; reconstitution; research study; transcription factor; ubiquitin ligase; ubiquitin-protein ligase

The work in this proposal is focused on a major cancer-preventive signal transduction pathway that triggers transcriptional induction of enzymes that protect cells from reactive chemical species, including carcinogens and oxidative stress. This pathway is activated by both naturally occuring chemopreventive agents found in a wide variety of fruits and vegetables and by synthetic molecules. We believe that a fundamental understanding of this signal transduction pathway will facilitate the identification of foods, dietary supplements and drugs that will significantly decrease the risk of cancer in humans. Furthermore, as oxidative stress is a driving force of many pathophysiological conditions, including neurodegeneration, cardiovascular disease and skeletal muscle atrophy,the proposed research will have a broad impact on human health. The critical target of this pathway, the transcription factor Nrf2, is normally repressed by the BTB-Kelch protein, Keapl. Chemopreventive agents enable Nrf2 to escape Keapl-mediated repression andactivate transcription of its target genes that eliminate reactive species and restore cellular redox homeostasis. Our preliminary data suggest the hypothesis that Keapl functions as a substrate adaptor protein for a Cul3- dependent E3 ubiquitin ligase complex. This hypothesis represents a new paradigm for understanding how Keapl is able to repress Nrf2-dependent transcription and provides a productive framework for defining how chemopreventive agents enable Nrf2 to escape Keapl-mediated repression. This hypothesis also provides novel insight into the biological functions of all BTB-Kelch proteins. We propose to examine this hypothesis further by characterizing disease-associated mutations within GAN1 and ENC1 that are responsible for giant axonal neuropathy and contribute to brain cancers, respectively. The proposed experiments will (1) define how Nrf2 is targeted for ubiquitin-dependent degradation by a Keapl :Cul3:Rbx1 complex, (2) define how Nrf2 escapes Keapl-mediated repression, (3) use Keapl as a model system to define how disease-associated mutations perturb the substrate adaptor function of BTB- Kelch proteins, and (4) define the structural basis for substrate recognition by Keapl.

该提案的工作重点是一个主要的癌症预防信号转导途径，该途径触发 保护细胞免受活性化学物质（包括致癌物）侵害的酶的转录诱导 和氧化应激。该途径由两种天然存在的化学预防剂激活 多种水果和蔬菜以及合成分子。我们相信，一个根本的 了解这一信号转导途径将有助于识别食物、膳食 补充剂和药物将显着降低人类患癌症的风险。此外，如 氧化应激是许多病理生理状况的驱动力，包括神经变性、 心血管疾病和骨骼肌萎缩，所提出的研究将对 人类健康。 该通路的关键靶标转录因子 Nrf2 通常受到 BTB-Kelch 的抑制 蛋白质，凯普尔。化学预防剂使 Nrf2 能够逃脱 Keapl 介导的抑制并激活 其目标基因的转录消除活性物质并恢复细胞氧化还原稳态。 我们的初步数据表明，Keapl 的功能是作为 Cul3- 的底物衔接蛋白。 依赖的 E3 泛素连接酶复合物。这个假设代表了理解如何 Keapl 能够抑制 Nrf2 依赖性转录，并为定义如何抑制 Nrf2 转录提供了一个富有成效的框架 化学预防剂使 Nrf2 能够逃避 Keapl 介导的抑制。这个假设还提供了 对所有 BTB-Kelch 蛋白的生物学功能的新见解。我们建议检验这个假设 进一步描述了 GAN1 和 ENC1 中与疾病相关的突变，这些突变负责巨 分别导致轴突神经病变和脑癌。 拟议的实验将 (1) 定义 Nrf2 如何通过泛素依赖性降解来靶向 Keapl :Cul3:Rbx1 复合体，(2) 定义 Nrf2 如何逃避 Keapl 介导的抑制，(3) 使用 Keapl 作为 模型系统来定义疾病相关突变如何扰乱 BTB- 的底物接头功能 Kelch 蛋白，(4) 定义了 Keapl 底物识别的结构基础。