Functional Characterization of a Novel Mammalian Homologue of eIF4E

eIF4E 的新型哺乳动物同源物的功能表征

• 批准号: 9808401
• 负责人: Rosemary Jagus
• 金额: $ 30万
• 依托单位: University of Maryland Biotechnology Institute
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-01 至 2002-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9808401&HistoricalAwards=false
• 关键词: Functional; Characterization; Novel; Mammalian; Homologue

Jagus MCB 9808401 1. Technical The aim of this study is to characterize the function(s) of a novel protein that shares homology with the translational initiation factor eIF4E. The goal is to establish the role(s) of the protein in the regulation of mRNA recruitment. The experimental strategy is designed to determine whether this eIF4E-like protein (4E-LP) stimulates or inhibits the recruitment of mRNAs for translation and identify the proteins with which 4E-LP interacts to perform its function(s). This will extend our understanding of the control of gene expression at this important step. cDNA sequences have been established for human, mouse and zebrafish 4E-LP. Sequence comparisons have shown the 4E-LP is present in a wide range of animal and plant species and is highly conserved. Northern analysis has shown that the mRNA for 4E-LP is present in all tissues tested to date and is under regulation during early development. Similarly, the protein appears to be in all tissues tested, although at a lower level than eIF4E. Like eIF4E, 4E-LP can bind cap structures and interact with eIF4G. Unlike eIF4E, 4E-LP does not have the regulatory phosphorylation site at the carboxy-terminus. It remains to be determined whether the role of 4E-LP is that of an alternate initiation factor which facilitates the translation of specific mRNAs (or all mRNAs under specific physiological conditions), or whether the protein functions in a regulatory capacity to modulate the activity of eIF4E (by competing with eIF4E interacting proteins). The developmental regulation which suggests a role for 4E-LP in the regulation of gene expression during early development, is investigated in the zebrafish developmental model, from which eIF4E and eIF4G have been obtained. eIF4E plays a pivotal role in the regulation of gene expression by controlling mRNA recruitment. eIF4E recruits RNAs by binding to the 5' m7Gppp cap structure. The activity of eIF4E is highly regulated and the factor has been shown to be a major t arget of signals transduced from growth factor receptors and proto-oncogenes. eIF4E functions in conjunction with eIF4G, to which it binds. Together these factors recruit mRNAs to the ribosomes for translation. The regulation of the recruitment of mRNAs by eIF4E and eIF4G is regulated by the MAP kinase and rapamycin-sensitive signalling pathways which control phosphorylation of eIF4E and the regulatory eIF4E binding protein 1, 4E-BP1. Regulation of eIF4E/4G function can also occur through the intervention of proteins that share homology with eIF4G. These proteins either encroach upon the interaction of eIF4E with eIF4G (eIF4E binding proteins or 4E-BPs) or sequester other initiation factors required for the recruitment of mRNA (NAT1, DAP-5, or p97). The discovery of 4E-LP adds yet another facet to the regulation of mRNA recruitment and has implications for the regulation of diverse cellular functions. Jagus 2. Non-technical The production of cellular proteins begins with the template genetic code that is copied in the form of mRNA. The information encoded by mRNA is translated on the ribosomes into proteins. Control of the recruitment of mRNA by ribosomes is an important form of regulation of gene expression in animal cells. Loss of control of this step can lead to developmental abnormalities and the loss of growth control. Several protein factors are required for the recruitment of mRNA by the ribosome, the most important of which is the translation factor eIF4E. eIF4E recognizes and binds to the cap structure at the 5' end of mRNA. eIF4E is under heavy regulation by reversible modification (phosphorylation) and by interaction with other proteins. The aim of this study is to characterize a novel protein, 4E-LP, that shares homology with eIF4E. The mRNA encoding 4E-LP is present in all tissues tested and is under regulation during early development. Like eIF4E, 4E-LP can bind to cap structures and interact with other components of translation. The big question is whether it function as an eIF4E look-alike or as a competitive inhibitor of eIF4E function. The developmental significance of 4E-LP will be investigated in zebrafishdevelopmepmental systems.of translation. The big questio n is whether it functions as an eIF4E look-alike or as a competive inhibitor of eIF4E function. The developmental significance of 4E-LP will be investigated in the zebrafish developmental system. Jagus, R., Ph.D. A. PROJECT SUMMARY 4 Jagus, R. C. PROJECT DESCRIPTION NSF FORM 1360 (1/94) 5

Jagus MCB 9808401 1. 技术 本研究的目的是表征与翻译起始因子 eIF4E 具有同源性的新型蛋白质的功能。 目标是确定蛋白质在 mRNA 募集调节中的作用。 实验策略旨在确定这种 eIF4E 样蛋白 (4E-LP) 是否刺激或抑制 mRNA 的翻译募集，并鉴定与 4E-LP 相互作用以执行其功能的蛋白质。 这将扩展我们对这一重要步骤中基因表达控制的理解。 人类、小鼠和斑马鱼 4E-LP 的 cDNA 序列已确定。 序列比较表明4E-LP存在于多种动植物物种中并且高度保守。 Northern 分析表明，4E-LP 的 mRNA 存在于迄今为止测试的所有组织中，并且在早期发育过程中受到调节。 同样，该蛋白质似乎存在于所有测试的组织中，尽管其水平低于 eIF4E。 与 eIF4E 一样，4E-LP 可以结合帽结构并与 eIF4G 相互作用。 与 eIF4E 不同，4E-LP 在羧基末端没有调节性磷酸化位点。 4E-LP 的作用是否是促进特定 mRNA（或特定生理条件下所有 mRNA）翻译的替代起始因子，或者该蛋白是否具有调节 eIF4E 活性的调节能力（通过与 eIF4E 相互作用蛋白竞争），仍有待确定。 在斑马鱼发育模型中研究了发育调节，表明 4E-LP 在早期发育过程中基因表达调节中的作用，并从中获得了 eIF4E 和 eIF4G。 eIF4E 通过控制 mRNA 募集在基因表达调控中发挥关键作用。 eIF4E 通过结合 5' m7Gppp 帽结构来招募 RNA。 eIF4E 的活性受到高度调控，并且该因子已被证明是生长因子受体和原癌基因转导信号的主要目标。 eIF4E 与其结合的 eIF4G 一起发挥作用。 这些因素共同将 mRNA 招募到核糖体进行翻译。 eIF4E 和 eIF4G 对 mRNA 募集的调节受到 MAP 激酶和雷帕霉素敏感信号通路的调节，这些信号通路控制 eIF4E 的磷酸化和调节性 eIF4E 结合蛋白 1、4E-BP1。 eIF4E/4G 功能的调节也可以通过与 eIF4G 具有同源性的蛋白质的干预来实现。 这些蛋白要么侵犯 eIF4E 与 eIF4G（eIF4E 结合蛋白或 4E-BP）的相互作用，要么隔离 mRNA 募集所需的其他起始因子（NAT1、DAP-5 或 p97）。 4E-LP 的发现为 mRNA 募集的调节增添了另一个方面，并对多种细胞功能的调节具有影响。 Jagus 2. 非技术性 细胞蛋白质的生产始于以 mRNA 形式复制的模板遗传密码。 mRNA 编码的信息在核糖体上翻译成蛋白质。 核糖体募集 mRNA 的控制是动物细胞中基因表达调节的重要形式。 失去对这一步骤的控制可能会导致发育异常和生长失去控制。 核糖体募集 mRNA 需要多种蛋白质因子，其中最重要的是翻译因子 eIF4E。 eIF4E 识别并结合 mRNA 5' 端的帽子结构。 eIF4E 受到可逆修饰（磷酸化）以及与其他蛋白质相互作用的严格调控。 本研究的目的是表征一种与 eIF4E 具有同源性的新型蛋白质 4E-LP。 编码 4E-LP 的 mRNA 存在于所有测试的组织中，并在早期发育过程中受到调节。 与 eIF4E 一样，4E-LP 可以结合帽结构并与翻译的其他组件相互作用。 最大的问题是它的功能是与 eIF4E 相似，还是作为 eIF4E 功能的竞争性抑制剂。 将在斑马鱼翻译发育系统中研究 4E-LP 的发育意义。 最大的问题是它的功能是与 eIF4E 相似，还是作为 eIF4E 功能的竞争性抑制剂。 将在斑马鱼发育系统中研究 4E-LP 的发育意义。 贾格斯，R.，博士 A. 项目摘要 4 Jagus, R.C. 项目描述 NSF 表格 1360 (1/94) 5