Mechanisms of eIF3-mediated translation regulation

项目摘要 对细胞中表达的蛋白质进行精细的空间和时间控制对于正确 分化和细胞生长的决定。尽管是基因表达的中心步骤，但信使核糖核酸的翻译 是否受到监管仍然知之甚少。我们对专门化的分子基础的理解存在差距。 特定转录本的翻译，以及这一调控对细胞反应的整体功能意义 信号提示。在这里，我们建议研究信使核糖核酸翻译调节对动态的贡献。 作为细胞生理学基础的基因表达程序。我们将关注的系统是由13个亚基组成的eIF3 翻译启动因子复合体，在一般翻译过程中充当组织互动的脚手架 在小核糖体蛋白和其他启动因子之间。我们最近发现eIF3也可以 通过新的RNA结合和帽子结合活性控制选定的细胞转录本的翻译。这些 研究结果表明，规范的翻译启动因素在一般翻译之外的作用是兼职的 以驱动不同基因程序的表达。尽管有这些耐人寻味的发现，但eIF3是最大的 翻译机器的组成部分，除了核糖体外，将功能归因于大多数亚基具有 一直很有挑战性。标准的基因技术不能应用于eIF3；eIF3亚单位对 活性，多亚基eIF3复合体的组装受到亚基水平的改变的阻碍。这些 方法也不能将一般翻译活动与专门翻译活动分开。我们将开发一种创新的 一套高吞吐量方法来解决这些困难，并全面了解eIF3 在细胞分化和细胞对外部信号的反应过程中控制动态的基因程序。通过 将这些广泛的方法与详细的生化和基于细胞的方法相结合，我们将提供 对翻译调控网络的分子理解，该网络协调所需的精确控制 正确的细胞功能和信号。这项研究将对基因的基本原理产生新的见解 监管。由于eIF3和其他启动因子在基因上与癌症、衰老、先天性疾病、 这项工作还将指导针对疾病中的翻译调控的非传统方法。

Project Summary Exquisite spatial and temporal control of the proteins that are expressed in a cell is essential for correct differentiation and cell growth decisions. Despite being a central step in gene expression, how mRNA translation is regulated remains poorly understood. There is a gap in our understanding of the molecular basis of specialized translation of specific transcripts, and of the overall functional significance of this regulation on cellular responses to signaling cues. Here we propose to investigate the contribution of mRNA translation regulation to the dynamic gene expression programs that underlie cell physiology. The system we will focus on is the 13-subunit eIF3 translation initiation factor complex, which acts as a scaffold during general translation to organize interactions between the small ribosomal proteins and other initiation factors. We recently discovered that eIF3 can also control the translation of select cellular transcripts through novel RNA-binding and cap-binding activities. These findings demonstrate that canonical translation initiation factors moonlight in roles outside of general translation to drive expression of distinct gene programs. Despite these intriguing findings, and eIF3 being the largest component of the translation machinery besides the ribosome, ascribing functions to the majority of subunits has been challenging. Standard genetic techniques cannot be applied to eIF3; eIF3 subunits are essential for viability, and the assembly of the multi-subunit eIF3 complex is hindered by alterations to subunit levels. These methods also cannot segregate activities in general versus specialized translation. We will develop an innovative set of high-throughput methodologies to address these difficulties and comprehensively discover how eIF3 controls the dynamic gene programs during cell differentiation and cellular response to extrinsic signals. By combining these broad approaches with detailed biochemical and cell-based approaches, we will provide molecular understanding of the translation regulation networks that coordinate the precise control required for correct cellular function and signaling. This research will create new insights into fundamental principles of gene regulation. As eIF3 and other initiation factors are genetically associated with cancer, aging, congenital disorders, this work will also guide unconventional approaches to target translation regulation in disease.