Natural History and Functional Evolutionary Studies of A-to-I pre-mRNA Editing

0091142 Robert ReenanAdenosine-to-Iosine(A-to-I)前信使核糖核酸通过作用于RNA的腺苷脱氨酶(ADAR)的作用，水解性地脱氨基。肌苷在翻译过程中被解释为鸟苷，由此产生的遗传信息的非模板化重新编码可能会导致单一氨基酸的变化，对蛋白质功能产生巨大影响。在无脊椎动物和脊椎动物中都已经证明了A-to-I前mRNA编辑的过程，主要是在编码神经系统的电压和配体门控离子通道和受体的转录本中。这个项目的目标是利用果蝇和其他昆虫属来创建RNA编辑的自然历史。这样的记录将被用来直接解决这个进化上保守但神秘的过程的三个重要领域。首先，将比较来自不同物种的DNA序列数据，以确定在Pre-mRNA中形成ADAR底物所需的最高度保守的序列元件，并确定编辑位点在物种之间的分布。其次，由于每个编辑站点的修改频率不同，物种之间对给定站点的编辑级别将被量化，编辑效率将与结构元素相关。最后，这些数据将被用于对体内特定部位或部位子集的基因编辑进行修改。这样的实验将解决个人编辑站点的修改如何影响生物行为和神经系统功能。这里总结的项目不仅将提供一种新的分子系统数据，而且有望对RNA编辑的过程和目的提供更深入的理解。此外，像这样的RNA编辑的详细系统发育研究也可能为新的群体遗传学和分子生物地理学研究编辑过程中变异的分布提供弹药。此外，这些进展将有助于开发不仅适用于果蝇的方法，而且还适用于识别和研究人类的RNA编辑位点。

0091142 Robert ReenanAdenosine-to-inosine (A-to-I) pre-mRNA editing hydrolytically deaminates A-to-I in target messenger RNA through the action of adenosine deaminases that act on RNA (ADARs). Inosine is interpreted as guanosine during translation, and the resulting non-templated recoding of the genetic information can introduce single amino acid changes that have dramatic effects on protein function. The process of A-to-I pre-mRNA editing itself has been demonstrated in both invertebrates and vertebrates, primarily in transcripts encoding voltage- and ligand-gated ion channels and receptors of the nervous system. It is the goal of this project to utilize Drosophila and other insect genera to create a natural history of RNA editing. Such a record will be used to directly address three important areas of this evolutionarily conserved but mysterious process. First, DNA sequence data from different species will be compared to identify the most highly conserved sequence elements necessary to form an ADAR substrate in a pre-mRNA and to determine the distribution of editing sites among species. Secondly, because each editing site is modified at a different frequency, levels of editing for given sites between species will be quantitated, and editing efficiency will be correlated with structural elements. Lastly, these data will be employed to genetically modify editing of particular sites or subsets of sites in vivo. Such experiments will address how the modification of individual editing sites affects organismal behavior and nervous system function. The project summarized here will not only provide molecular systematic data of a novel kind, but promises to deliver a deeper understanding of the process and purpose of RNA editing. Also, a detailed phylogenetic study of RNA editing such as this may also provide ammunition for new population genetic and molecular biogeographic studies into the distribution of variation in the editing process. Moreover, such advances will serve to assist in developing methods that would apply not only to Drosophila, but also in identifying and studying RNA editing sites in humans.