The Role of eIF4E Family Members in Zebrafish

翻译起始因子eIF4E是真核细胞翻译起始和调控的核心成分。EIF4E通过与mRNA5‘端结构及其翻译伙伴eIF4G相互作用，将mRNAs募集到核糖体中。脊椎动物EST和基因组序列的快速积累使得eIF4E家族的多个成员得以识别。根据序列同源性和/或功能，已经识别了三类eIF4E：I类(原型eIF4E及其亚型)、II类(eIF4ELP/HP)和III类(eIF4E-3，仅脊椎动物)。多个eIF4E相关蛋白的发现表明了脊椎动物中mRNA招募步骤及其调控的意想不到的复杂性，并例证了仅根据序列同源性来注释DNA序列的困难。一种假设是，每种形式都填充了核糖体招募有上限的mRNAs的专门利基。或者，并不是所有的eIF4E家族成员都直接作为启动因子或在翻译调控中发挥作用，而是在RNA/RNP输出或RNA剪接等无关的功能中发挥作用。该项目的总体目标是利用Jagus实验室积累的eIF4E家族成员和独特试剂的知识，阐明它们在高等真核生物基因表达调控中的各自作用。本研究的目的是通过以下具体目标确定eIF4E家族成员的功能并确定它们在基因表达调控中的作用：1)分析每个家族成员在不同组织和不同发育阶段的表达模式；2)使用各种已建立的分析方法确定每个eIF4E家族成员(来自斑马鱼和哺乳动物)在翻译中的功能；以及3)动力学分析每个类别与帽结构、eIF4G和4EBPs的相互作用。细胞蛋白质的产生始于以mRNA形式复制的模板遗传密码。由mRNA编码的信息在核糖体上被翻译成蛋白质。核糖体对mRNA募集的调控是动物细胞基因表达调控的重要形式。核糖体对mRNA的募集需要几种蛋白质因子，其中最重要的是翻译因子eIF4E。EIF4E识别并结合到mRNA 5‘端的帽子结构。DNA序列数据的积累使Jagus实验室能够识别三类eIF4E：I类(典型eIF4E及其亚型)、II类(eIF4ELP/HP)和III类(eIF4E-3，仅限脊椎动物)。该项目的总体目标是确定eIF4E家族成员的功能，并确定它们在斑马鱼发育系统基因表达调控中的作用。

The translational initiation factor eIF4E is a central component in the initiation and regulation of translation in eukaryotic cells. Through its interaction with the 5' cap structure of mRNA and its translation partner, eIF4G, eIF4E functions to recruit mRNAs to the ribosome. The rapid accumulation of vertebrate EST and genome sequences has allowed the identification of multiple eIF4E family members. Based on sequence homologies and/or function, three classes of eIF4E have been recognized; Class I (archetypal eIF4E and sub-types), Class II (eIF4ELP/HP) and Class III (eIF4E-3, vertebrates only). The uncovering of multiple eIF4E related proteins suggests an unexpected complexity of the mRNA recruitment step and its regulation in vertebrates and has exemplified the difficulties in annotating DNA sequences on the basis of sequence homologies only. One hypothesis is that each form fills a specialized niche in the recruitment of capped mRNAs by the ribosome. Alternatively, it is possible that not all eIF4E family members function as initiation factors or in translational regulation directly, but in an unrelated function such as RNA/RNP export or RNA splicing. The overall goal of this project is to use the knowledge of eIF4E family members and unique reagents accumulated by the Jagus laboratory to elucidate their respective roles in the regulation of gene expression in higher eukaryotes. The objectives are to characterize the functions of eIF4E family members and determine their role in the regulation of gene expression through the following specific aims: 1) analysis of expression pattern of each family member in different tissues and at various developmental stages; 2) determination of the function of each eIF4E family member (from zebrafish and mammals) in translation using a variety of established assays; and 3) kinetic analyses of the interaction of each class with cap-structures, eIF4G and the 4EBPs.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. 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. The accumulation of DNA sequence data has allowed the Jagus laboratory to recognize three classes of eIF4E; Class I (prototypical eIF4E and sub-types), Class II (eIF4ELP/HP) and Class III (eIF4E-3, vertebrates only). The overall goal of this project is to characterize the functions of eIF4E family members and determine their role in the regulation of gene expression in the zebrafish developmental system.