Radiation-induced translational control of gene expression

描述(由申请人提供)：对辐射诱导的基因表达变化的全基因组评估通常使用细胞总mRNA的微阵列分析来评估，这反映了基因转录的修改。然而，基因表达不仅依赖于转录活性，而且依赖于最终控制mRNA翻译的各种转录后事件。我们最近使用多聚体结合mRNA的微阵列分析产生的数据表明，基因翻译比转录更容易受到辐射诱导的修饰。重要的是，这项研究表明，其翻译活性受到影响的基因与其相应蛋白质的表达之间存在相关性。这项建议的总体目标是阐明辐射诱导的基因表达翻译调控在细胞辐射反应中的重要性。为此，辐射诱导的翻译基因表达谱将作为细胞类型的函数产生。这些研究将涉及从肿瘤细胞系中分离出多聚体结合的mRNA的微阵列分析，这些细胞系来自与放射治疗相关的组织学以及从各种正常细胞中分离出来。这种全基因组的询问将检验这样的假设，即辐射诱导的基因表达的翻译控制是细胞辐射反应的基本特征，以及受辐射诱导的翻译控制的基因中存在肿瘤类型和/或谱系特异性。此外，还将描述调节辐射诱导的翻译调控的分子和过程。这些研究将确定一般翻译机制的贡献，以及已被证明调节特定mRNA亚群翻译的特定RNA结合蛋白的作用。最后，将测试介导辐射诱导的翻译控制过程的分子以及与其翻译受辐射影响的mRNAs相对应的蛋白质在辐射后细胞生存中的作用。这些分析，除了确定辐射敏感性的基本决定因素外，还将确定辐射诱导的基因表达的翻译控制是否为辐射修饰剂提供了新的靶点来源。虽然修饰结构性表达蛋白的放射生物学意义已经明确，但拟议的研究提供了一个机会来研究和潜在地利用辐射诱导的基因表达的翻译控制，这是以前未被探索的细胞辐射反应的组成部分。

DESCRIPTION (provided by applicant): The genome-wide evaluation of radiation-induced changes in gene expression has typically been evaluated using microarray analysis of total cellular mRNA, which reflects modifications in a gene's transcription. However, gene expression is dependent not only on transcriptional activity, but on a variety of post-transcriptional events that ultimately control mRNA translation. Our recent data generated using the microarray analyses of polysome bound mRNA indicate that gene translation is considerably more susceptible to radiation induced modifications than is transcription. Importantly, this study showed that there is a correlation between the genes whose translational activity was affected and the expression of their corresponding proteins. The overall goal of this proposal is to delineate the significance of radiation-induced translational control of gene expression in cellular radioresponse. Towards this end, radiation-induced translational gene expression profiles will be generated as a function of cell type. These studies will involve microarray analysis of polysome-bound mRNA isolated from tumor cell lines originating from histologies relevant to radiotherapy as well as from a variety of normal cells. This genome wide interrogation will test the hypotheses that radiation induced translational control of gene expression is a fundamental characteristic of cellular radioresponse and that there is tumor type and/or lineage specificity in the genes subject to radiation-induced translational control. In addition, to define the molecules and processes that mediate radiation-induced translational control will be delineated. The studies will define the contribution of the general translational machinery as well as selected RNA binding proteins that have been shown to regulate the translation of specific mRNA subpopulations. Finally, the molecules mediating the process of radiation-induced translational control and the proteins corresponding to the mRNAs whose translation is affected by radiation will be tested for their role in cell survival after irradiation. These analyses, in addition to identifying fundamental determinants of radiosensitivity, will determine whether radiation-induced translational control of gene expression provides a novel source of targets for radiation modifiers. Whereas the radiobiological significance of modifying constitutively expressed proteins has been clearly established, the proposed studies offer an opportunity to investigate and potentially exploit radiation-induced translational control of gene expression, a previously unexplored component of cellular radioresponse.