tRNA-derived stress-induced RNAs and translational control

总结 转运RNA（tRNA）传统上被认为是帮助核糖体合成的衔接分子 通过解码连接mRNA序列和蛋白质氨基酸序列的核苷酸三联体来编码蛋白质。最近 研究结果表明，tRNA也是小的非编码RNA的主要来源，所谓的tRNA- 衍生片段（tRFs）。分子生物学中的新兴概念是这些tRF执行调节 功能，尽管对它们在细胞生理学中的确切作用知之甚少。 我们和其他实验室的工作表明，在应对各种非生物胁迫（例如， 当脊椎动物受到氧化或营养应激时，脊椎动物特异性核糖核酸酶（RNase）血管生成素（ANG）被激活， 靶向tRNA的反密码子环，产生一种特定的tRF亚类，称为tRNA衍生应激- 诱导的RNA（tiRNAs）。自2009年发现以来，已发现tiRNAs在压力中发挥作用 适应、细胞存活和凋亡。一个相对较好的研究的作用，选择子集的tiRNAs （来源于tRNAAla和tRNACys）是通过干扰翻译起始的功能来抑制翻译起始。 帽结合复合物eIF 4F（Ivanov等人，Mol Cell 2011）。 基于我们资助的提案的工作将进一步研究小说的功能， 未探索的，tiRNAs在翻译调控中的作用。我们的初步数据表明， 存在与tiRNAAla/Cys使用的机制不同的翻译调节。R 01的目标2，将 通过采用候选和无偏方法鉴定和表征tiRNAs的mRNA靶。我们 初步数据表明，特定的tiRNAs靶向特定的mRNAs库， 翻译.通过核糖体分析，我们可以寻找由tiRNAs调控的候选mRNA 以公正的方式。 我们的建议是高度创新的，将广泛影响RNA生物学。成功完成 所提出的研究将导致表征在应激期间起作用的新的翻译控制机制。 从治疗的角度来看，我们的研究也很重要，因为多种病理生理条件 与tiRNA产生的变化有关。在患者中发现了影响ANG RNA酶活性的突变 患有神经退行性疾病肌萎缩性侧索硬化症和帕金森病。此外，ANG是 在多种癌症中过表达，其表达与不平衡的tiRNA产生相关，表明 这是理解tiRNAs功能的必要条件。最后，这一提议将产生许多资源， 整个RNA/tRNA社区，我们将确保这些资源可供未来使用。

Summary Transfer RNA (tRNA) is traditionally viewed as an adaptor molecule that helps ribosomes synthesize proteins by decoding nucleotide triplets linking mRNA sequence to amino acid sequence of protein. Recent findings demonstrate that tRNAs also serve as a major source of small non-coding RNAs, so called tRNA- derived fragments (tRFs). The emerging concept in molecular biology is that these tRFs perform regulatory functions, although relatively little is known about their precise roles in cell physiology. Work from our and other laboratories has shown that in response to a variety of abiotic stresses (e.g. oxidative or nutrient stress), the vertebrate-specific ribonuclease (RNase) angiogenin (ANG) is activated to target the anticodon loops of tRNAs to produce a specific subclass of tRFs, known as tRNA-derived stress- induced RNAs (tiRNAs). Since their discovery in 2009, tiRNAs have been found to play roles in stress adaptation, cell survival and apoptosis. One of the relatively well studied roles of selected subset of tiRNAs (derived from tRNAAla and tRNACys) is inhibition of translation initiation via interference with functions of the cap-binding complex eIF4F (Ivanov et al. Mol Cell 2011). The work based on our funded proposal will further investigate functions of novel, previously unexplored, tiRNAs in regulation of translation. Our preliminary data suggest that alternative mechanisms of translation modulation exist that are different from the mechanisms used by tiRNAAla/Cys. Aim 2 of the R01, will identify and characterize mRNA targets of tiRNAs by employing candidate and unbiased approaches. Our preliminary data suggest that specific tiRNAs target specific pool of mRNAs thus reprogramming cellular translation. By employment of ribosome profiling, we can search for the mRNA candidates regulated by tiRNAs in unbiased manner. Our proposal is highly innovative and will broadly impact RNA biology. Successful completion of the proposed studies will result in characterization of novel translational control mechanisms acting during stress. Our studies are also important from a therapeutic point of view because multiple pathophysiological conditions are linked to changes in tiRNA production. Mutations affecting the RNase activity of ANG are found in patients with the neurodegenerative diseases Amyotrophic Lateral Sclerosis and Parkinson's disease. Also, ANG is over-expressed in multiple cancers and its expression correlates with misbalanced tiRNA production, indicating a necessity to understand the function of tiRNAs. Finally, this proposal will generate many resources for the entire RNA/tRNA community and we will ensure that these resources are available for future use.