Regulation of proteasome assembly in auxin signaling

生长素信号传导中蛋白酶体组装的调节

• 批准号: 0544222
• 负责人: Hen-ming Wu
• 金额: $ 45万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-15 至 2012-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0544222&HistoricalAwards=false
• 关键词: Regulation; proteasome; assembly; auxin; signaling

The hormone auxin is essential for a large number of cellular and developmental processes in plants. Auxin achieves many of its actions by inducing the expression of a large number of genes to carry out the necessary functions. The Aux/IAA protein family normally suppresses auxin-responsive gene expression. An intermediate step in auxin induced gene expression is the degradation of these proteins through a ubiquitination/ 26S proteasome regulated process that depends on the interaction of several multi-component protein complexes. The intervening steps for this auxin response pathway are far from being understood. Prior studies revealed the contribution of the Rac/Rop GTPases in relating the auxin stimulus to the intracellular machinery for Aux/IAA degradation. The auxin induced Aux/IAA protein degradation process involves impromptu assembly of the degradation apparatus in response to the signal and is regulated by the presence of the Aux/IAA substrates. Observations from cell culture and whole plant studies suggest that auxin and substrates together induce formation of protein complexes that appear as protein bodies in the nucleus (referred to as nuclear protein bodies, NPBs). Substrates and components of SCFTIR1, CSN and 26S proteasome are recruited into and co-exist in these protein complexes, although the dynamics of their recruitment into and exit out of the NPBs remain to be elucidated. These NPBs are biologically active since the level of substrates has been observed to decline from within these structures in response to auxin treatment. The main focus of the proposed research is to examine the biochemical property of these NPBs, their composition and activity, and to examine the presence of high molecular weight protein complexes involved in auxin signaling, or other more amenable signaling pathways that are known to be regulated by ubiquitination and 26S proteasome-mediated proteolysis under endogenous conditions.Broader Impact. Ubiquitination and 26S proteasome-regulated proteolysis underlies a large number of cellular and developmental processes in all eukaryotes, including cell division, growth and differentiation, and developmental pathways from embryogenesis to reproduction, senescence and programmed cell death. Malfunctioning of this system results in severe developmental problems, including debilitating neurological diseases and cancer in human and compromised ability to cope with stress and pathogens in plants. A regulated and dynamic process for assembly and disassembly of the molecular machinery to carry out degradation of selected proteins has been speculated. Information obtained will be important toward understanding auxin signaling, which in itself is a significant aspect of plant biology and represents a paradigm in plant cell signaling. The knowledge should also be applicable to other ubiquitination/26S proteasome regulated processes. The proposed research will provide training opportunities for postdocs, graduate students and undergraduates. The current group of undergraduates in the PIs laboratories includes four women and two men (including US citizens but natives of Afghanistan, Nepal and Ukraine); three of them are participating in the research related to the proposed studies. New students from a campus-wide NSF supported program for minority students (SPUR), will be recruited to start this summer.

激素生长素是植物中大量细胞和发育过程所必需的。 生长素通过诱导大量基因的表达来实现其许多作用，以执行必要的功能。 Aux/IAA蛋白家族通常抑制生长素应答基因的表达。 生长素诱导的基因表达的中间步骤是通过泛素化/26 S蛋白酶体调节的过程降解这些蛋白质，该过程取决于几种多组分蛋白质复合物的相互作用。 这种生长素反应途径的干预步骤还远未被理解。 先前的研究揭示了Rac/Rop GTPases在将生长素刺激与Aux/IAA降解的细胞内机制相关中的贡献。 生长素诱导的Aux/IAA蛋白质降解过程包括降解装置响应信号的即兴组装，并受Aux/IAA底物的存在调节。 来自细胞培养和整个植物研究的观察表明，生长素和底物一起诱导蛋白质复合物的形成，所述蛋白质复合物在细胞核中以蛋白质体的形式出现（称为核蛋白体，NPB）。 SCFTIR 1、CSN和26 S蛋白酶体的底物和组分被募集到这些蛋白质复合物中并共存，尽管它们募集到NPB中和从NPB中退出的动力学仍有待阐明。 这些NPB是生物活性的，因为已经观察到响应于生长素处理，底物的水平从这些结构内下降。 拟议研究的主要重点是检查这些NPB的生化特性，它们的组成和活性，并检查参与生长素信号传导的高分子量蛋白质复合物的存在，或其他更容易接受的信号传导途径，已知这些途径在内源性条件下受泛素化和26 S蛋白酶体介导的蛋白水解的调节。 泛素化和26 S蛋白酶体调节的蛋白水解是所有真核生物中大量细胞和发育过程的基础，包括细胞分裂、生长和分化，以及从胚胎发生到生殖、衰老和程序性细胞死亡的发育途径。 这一系统的功能失调会导致严重的发育问题，包括人类的衰弱性神经疾病和癌症，以及植物科普压力和病原体的能力受损。 已经推测了分子机器的组装和拆卸以进行所选蛋白质的降解的受调节的动态过程。 获得的信息将是重要的了解生长素信号，这本身是植物生物学的一个重要方面，并代表了植物细胞信号的范例。 这些知识也适用于其他泛素化/26 S蛋白酶体调节过程。 这项研究将为博士后、研究生和本科生提供培训机会。 目前在PI实验室的本科生群体包括四名女性和两名男性（包括美国公民，但阿富汗，尼泊尔和乌克兰的本地人）;其中三人正在参与与拟议研究有关的研究。 来自全校NSF支持的少数民族学生计划（SPUR）的新生将于今年夏天开始招募。