Molecular mechanisms of auxin response in Arabidopsis

拟南芥生长素反应的分子机制

• 批准号: 8038062
• 负责人: WILLIAM M GRAY
• 金额: $ 26.07万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8038062
• 关键词: Address; Affect; Alleles; Arabidopsis; Auxins; Binding; Binding Proteins; Biochemical; Biological Assay; Biological Models; Biological Process; Cell physiology; Cells; Cloning; Collection; Complex; Conflict (Psychology); Cullin Proteins; Defect; Degradation Pathway; Development; Disease; Disease Pathway; Enhancers; Enzymes; Eukaryota; Eukaryotic Cell; Exhibits; F-Box Proteins; Family; Food; Gene Expression; Genes; Genetic; Genetic Screening; Goals; Health; Homologous Gene; Human; Knowledge; Ligase; Malignant Neoplasms; Maps; Mediating; Metabolism; Missense Mutation; Modeling; Modification; Molecular; Molecular Cloning; Molecular Genetics; Mouse-ear Cress; Mutation; Nature; Organism; Pathogenesis; Pathway interactions; Plant Growth Regulators; Plant Model; Plants; Production; Proteins; Regulation; Resistance; Role; SKP Cullin F-Box Protein Ligases; Screening procedure; Signal Transduction; Stimulus; System; Techniques; Transcription Repressor/Corepressor; Transcriptional Regulation; Ubiquitin; Ubiquitin-mediated Proteolysis Pathway; Viral; base; computerized data processing; design; emerin; human disease; improved; in vivo; isopeptidase; mutant; novel; novel therapeutics; plant growth/development; protein degradation; protein function; research study; resistance mutation; response; tool; trait; ubiquitin ligase

DESCRIPTION (provided by applicant): SCF and other cullin-ring ligases (CRLs) have been implicated in numerous human developmental and disease pathways. These enzymes function in the ubiquitin proteolytic pathway, catalyzing the transfer of ubiquitin to specific proteins and thus targeting these proteins for degradation. Previous studies have revealed that SCF activity is highly regulated, with numerous proteins including CAND1, SGT1, the COP9 signalosome (CSN), and the RUB/NEDD8 conjugation pathway all acting to modulate SCF activity. While some understanding into the nature of the regulation by these factors has been achieved, many questions remain, and it seems likely that additional SCF regulatory mechanisms are yet to be discovered. The plant hormone auxin regulates virtually every aspect of plant growth and development. The SCFTIR1 ubiquitin-ligase regulates auxin response by targeting a family of transcriptional repressors for ubiquitin- mediated proteolysis in response to an auxin stimulus. Auxin signaling in the model plant Arabidopsis thaliana is exquisitely sensitive to perturbations in SCFTIR1 activity, and has proven to be an extremely powerful genetic system for studying how eukaryotic organisms regulate SCF ubiquitin-ligase activity. Mutations in virtually every known SCF component and regulator have been isolated in genetic screens for mutants exhibiting reduced auxin response. This system provides several novel genetic tools, including viable mutant alleles of CAND1 and CSN subunits, which are not available in other multicellular eukaryotic model systems. The long-term goal of this project is to thoroughly elucidate the molecular mechanisms underlying auxin- mediated control of plant growth and development. Such knowledge will facilitate the manipulation of plant growth and development to improve food production and other plant traits of benefit to human health. More broadly, SCF complexes and the regulatory mechanisms controlling their activity are highly conserved throughout higher eukaryotes. The proposed studies include genetic, molecular, and biochemical approaches to elucidate the regulatory mechanisms controlling SCFTIR1 activity. First, the control of SCFTIR1 activity by regulated cycles of assembly and disassembly will be examined using novel genetic tools and simple biochemical assays. Second, a novel activity of either the CSN or a unique complex containing the CSN3 subunit that is required for auxin-inducible gene expression will be characterized. Third, a collection of mutants isolated in a genetic screen designed to identify negative regulators of SCF activity will be characterized and incorporated into current models for auxin signaling and SCF regulation. The findings from the proposed experiments will almost certainly have direct parallels to the mechanisms human cells employ to regulate SCF activity and other signaling processes, thus increasing understanding of disease pathogenesis and potentially leading to novel therapeutic strategies for modulating SCF activity in cancer and other diseases. PUBLIC HEALTH RELEVANCE: The highly conserved ubiquitin protein degradation pathway regulates many fundamental cellular processes, and defects in this pathway have been implicated in dozens of human diseases. The model plant Arabidopsis thaliana provides a powerful genetic system for studying conserved biological processes. We will utilize novel genetic tools provided by Arabidopsis to elucidate the mechanisms employed by eukaryotic cells to regulate protein degradation.

描述（由申请人提供）：SCF和其他cullin-ring连接酶（CRL）与许多人类发育和疾病途径有关。这些酶在泛素蛋白水解途径中起作用，催化泛素转移到特定蛋白质，从而靶向这些蛋白质进行降解。先前的研究表明，SCF活性受到高度调节，包括CAND 1、SGT 1、COP 9信号体（CSN）和RUB/NEDD 8缀合途径在内的许多蛋白质都起到调节SCF活性的作用。虽然已经对这些因素的调节性质有了一些了解，但仍存在许多问题，而且似乎还没有发现其他SCF调节机制。 植物激素生长素几乎调节植物生长和发育的各个方面。SCFTIR 1泛素连接酶通过靶向一个转录抑制因子家族来调节生长素应答，该转录抑制因子家族用于响应生长素刺激的泛素介导的蛋白水解。生长素信号在模式植物拟南芥中对SCFTIR 1活性的扰动非常敏感，并且已被证明是研究真核生物如何调节SCF泛素连接酶活性的非常强大的遗传系统。几乎所有已知的SCF组分和调节剂中的突变都已在遗传筛选中分离出表现出降低的生长素反应的突变体。该系统提供了几种新的遗传工具，包括CAND 1和CSN亚基的可行突变等位基因，这在其他多细胞真核模型系统中是不可用的。 本项目的长期目标是彻底阐明生长素介导的植物生长和发育调控的分子机制。这些知识将有助于操纵植物生长和发育，以提高粮食产量和其他有益于人类健康的植物性状。更广泛地说，SCF复合物和控制其活性的调节机制在整个高等真核生物中高度保守。拟议的研究包括遗传，分子和生化方法来阐明控制SCFTIR 1活性的调节机制。首先，将使用新的遗传工具和简单的生物化学测定来检查SCFTIR 1活性通过调节组装和拆卸周期的控制。第二，一种新的活性的CSN或一个独特的复合物含有CSN 3亚基，生长素诱导的基因表达所需的特征。第三，收集的突变体分离的遗传筛选，旨在确定负调控SCF活性的特征，并纳入目前的模型生长素信号和SCF调节。从拟议的实验中的发现几乎肯定会有直接的平行机制，人类细胞用来调节SCF活性和其他信号传导过程，从而增加对疾病发病机制的理解，并可能导致新的治疗策略，用于调节SCF活性在癌症和其他疾病。 公共卫生关系：高度保守的泛蛋白蛋白降解途径调节许多基本的细胞过程，该途径的缺陷与数十种人类疾病有关。模式植物拟南芥（Arabidopsis thaliana）为研究保守的生物学过程提供了一个强大的遗传系统。我们将利用拟南芥提供的新的遗传工具来阐明真核细胞调节蛋白质降解的机制。