Characterization of target RNAs of the tumor suppressor protein Pdcd4

Pdcd 4是一种进化上高度保守的RNA结合蛋白，其抑制特异性mRNA的翻译，并且在不同类型的肿瘤的发展中被认为是肿瘤抑制因子。Pdcd 4影响特定mRNA翻译的机制以及Pdcd 4作为翻译调节因子的功能如何有助于肿瘤抑制仍然是难以捉摸的，因为只有很少的mRNA被鉴定为Pdcd 4的翻译靶点。基于对已知Pdcd 4靶RNA的分析，似乎Pdcd 4通过作用于翻译起始或翻译延伸水平的不同机制影响特定mRNA的翻译，并且直接Pdcd 4-RNA相互作用在Pdcd 4靶向特定mRNA中起关键作用。在这个项目中，我们将使用PAR-CLIP和核糖体分析来深入了解Pdcd 4作为转录组水平上的翻译调节因子的作用。PAR-CLIP和核糖体分析是新的方法，可以确定所有细胞RNA上RNA结合蛋白的结合位点，并绘制细胞中所有mRNA上所有核糖体的位置，从而提供翻译过程的转录组范围视图。通过比较Pdcd 4表达和缺陷的细胞，我们将能够识别所有Pdcd 4调节的mRNA，并研究其调节Pdcd 4在系统的方式下的分子机制。该项目将为Pdcd 4调控的生物和分子过程及其与肿瘤发生的相关性提供基本见解。

Pdcd4 is an evolutionarily highly conserved RNA-binding protein, that suppresses the translation of specific mRNAs and has been implicated as a tumor suppressor in the development of different kinds of tumors. The mechanisms by which Pdcd4 influences the translation of specific mRNAs and how the function of Pdcd4 as a translation regulator contributes to tumor suppression are still elusive because only very few mRNAs have been identified as translational targets of Pdcd4. Based on the analysis of the known Pdcd4 target RNAs it appears that Pdcd4 affects the translation of specific mRNAs by different mechanisms acting on the level of translational initiation or translational elongation and that direct Pdcd4-RNA-interactions play an key role in the targeting of Pdcd4 to specific mRNAs. In this project we will use PAR-CLIP and ribosome profiling to gain insight into the role of Pdcd4 as a translational regulator on a transcriptome-wide level. PAR-CLIP and Ribosome profiling are new methods that allow to determine the binding sites of an RNA-binding protein on all cellular RNAs, and to map the positions of all ribosomes on all mRNAs in the cell, thereby providing a transcriptome-wide view of the translation process. By comparing Pdcd4-expressing and -deficient cells we will be able to identify all Pdcd4-regulated mRNAs and to study the molecular mechanisms underlying their regulation by Pdcd4 in a systematic way. This project will provide fundamental insight into the biological and molecular processes regulated by Pdcd4 and their relevance for tumorigenesis.