Molecular Mechanisms of eIF4E mediated transformation

摘要 这项修订后的更新申请调查了驱动后- 癌症的转录控制。事实上，这些事件的失调可以推动生产 支持增殖、存活、侵袭和转移的蛋白质。失调可以 发生在RNA加工的许多水平，包括RNA的剪接，它们的核输出和 翻译.真核生物翻译起始因子eIF 4 E在约30%的癌症中失调 包括急性髓细胞白血病（AML），控制着RNA加工网络， 最终支撑其致癌活性的转录物。它控制这些调节子的能力 这是由于它在核出口和翻译具体的 RNA。在这里，我们发现eIF 4 E重新编程了1000个基因的剪接景观， 在AML患者中，eIF 4 E转录物作为eIF 4 E失调的函数， 在模型系统中过度表达。我们比较了高eIF 4 E表达中的选择性剪接（AS）事件， AML和eIF 4 E在细胞中过表达时，假设那些共同的将代表 eIF 4 E依赖性剪接的泛癌靶点。我们发现了一组约150个AS“核心” 转录本，其编码相同生化网络中的因子。重要的是这些 通路也在AML和更普遍的癌症中发挥作用。许多AS事件是 预测产生具有不同结构域结构的蛋白质，从而改变功能。 至于eIF 4 E调节AS的机制，我们的研究揭示了物理机制， eIF 4 E和剪接体组分之间的相互作用以及揭示了新的 用于控制拼接机器的生产的装置，即通过eIF 4 E。三个目标是 建议剖析这些新的机制原理和生物学影响， 研究结果：目标1。探索eIF 4 E依赖的剪接改变，我们将解剖 eIF 4 E的AS活性所需的生化活性，并评估 目标2：目标2。阐明eIF 4 E在重编程剪接中的生物化学作用 通过解剖eIF 4 E与剪接体组分的物理相互作用， 确定其与活性剪接体的关系;和目的3.确定影响 AML中eIF 4 E依赖性剪接失调，我们将探讨AS的影响， 鉴定eIF 4 E活性所需的剪接因子。这些研究将改变我们的观点 关于eIF 4 E失调的影响，现在包括改变eIF 4 E的形式， 转录本以及调节其蛋白质编码能力。

Abstract This revised renewal application investigates novel mechanisms driving dysregulation of post- transcriptional control in cancer. Indeed, dysregulation of these events can drive the production of proteins that underpin proliferation, survival, invasion and metastases. Dysregulation can occur at many levels of RNA processing including splicing of RNAs, their nuclear export and translation. The eukaryotic translation initiation factor eIF4E, dysregulated in ~30% of cancers including in acute myeloid leukemia (AML), governs the RNA processing of networks of transcripts that ultimately underpin its oncogenic activities. Its ability to govern these regulons has been attributed to its well-established roles in nuclear export and translation of specific RNAs. Here, we discovered that eIF4E reprograms the splicing landscape of 1000s of transcripts both as a function of eIF4E dysregulation in AML patients as well as upon eIF4E overexpression in model systems. We compared alternative splicing (AS) events in high-eIF4E AML and upon eIF4E overexpression in cells, postulating those in common would represent pan-cancer targets of eIF4E-dependent splicing. We discovered a set of ~150 AS “core” transcripts, which encoded factors in the same biochemical networks. Importantly, these pathways also play roles in AML and in cancer more generally. Many of the AS events are predicted to produce proteins with different domain structures and thus altered functionalities. As to the mechanisms by which eIF4E modulates AS, our studies unearthed physical interactions between eIF4E and components of the spliceosome as well as revealed novel means to control the production of the splicing machinery i.e. via eIF4E. Three aims are proposed to dissect the mechanistic principles and biological impacts related to these novel findings: Aim 1. Explore eIF4E-dependent alterations to splicing where we will dissect the biochemical activities of eIF4E required for its AS activity, and assess the functional outcome of this activity; Aim 2. Elucidate the biochemical role that eIF4E plays in re-programming splicing by dissecting the physical interactions of eIF4E with components of the spliceosome and ascertain its relationship with active spliceosomes; and Aim 3. Determine the impact of dysregulated eIF4E-dependent splicing in AML where we will explore the impact of AS, and identify the splicing factors required for eIF4E’s activity. These studies will transform our view with regard to the impact of eIF4E dysregulation, which would now include altering the form of the transcript as well as regulating its protein-coding capacity.