Determining the role of RNA abasic sites in gene regulation

RNA基本位点是最近发现的RNA的修饰，由 甲基嘌呤糖基酶调节基因表达。它们含有丰富的RNA，它们 稳定RNA但我们对它们是如何形成的、它们的前体和它们的 功能。 DNA基本位点在20世纪60年代被发现，这些发现导致了 DNA损伤中的碱基切除修复途径。但核糖核酸的基本位置在很大程度上是未知的， 除了核糖体RNA中由植物毒素--蓖麻毒素产生的那些。在研究蛋白质时 与核酸结构R-loop结合，我们发现了RNA修饰酶和 已知的甲基嘌呤糖基酶以及脱嘌呤/脱嘧啶核酸内切酶I 处理DNA基本位点。 我们现在已经证明，甲基嘌呤糖基酶裂解RNA中的糖苷键，形成 在R环的RNA/DNA杂交物中，这些反应发生在RNA上。按质量计算 光谱分析发现，RNA基本位点相当丰富，有几十个到几百个 在每个牢房里有数千个这样的人。我们还在APOE的增强子RNA中发现了N6- 甲基腺苷被甲基嘌呤糖基酶裂解，形成R-R上的RNA碱基。 循环。然后，碱性位点稳定R-环，并暂停RNA聚合酶II的转录。我们 证明了这一机制使非编码RNA能够激活APOE在 对蜂窝需求的响应。 鉴于我们有早期证据表明RNA基本位点在调节 非编码RNA，有必要更好地理解它们。我们建议1)研究 核酸介导的暂停对非编码RNA的全基因组影响，2)识别其他 形成RNA基本位点的糖基酶，以及3)确定其他修饰的RNA碱基是什么 核糖核酸基本位点的前体。总之，这些结果将通过以下方式来表征RNA基本位点 找出它们是如何形成的以及它们做了什么。

RNA abasic sites are recently identified modifications in RNA that are generated by methylpurine glycosylase to regulate gene expression. They are abundant in RNA and they stabilize RNA yet we do not know much about how they form, their precursors, and their functions. DNA abasic sites were identified in the 1960s and those discoveries led to the elucidation of the base excision repair pathway in DNA damage. But RNA abasic sites were largely unknown, except those generated by the plant poison, ricin, in ribosomal RNA. While studying proteins that bind to the nucleic acid structure, R-loop, we identified RNA modification enzymes and methylpurine glycosylase as well as apurinic/apyrimidinic endonuclease I that were known to process DNA abasic sites. We have now shown that methylpurine glycosylase cleaves the glycosidic bond in RNA to form abasic sites and these reactions occur on RNA in RNA/DNA hybrids of R-loops. By mass spectrometry, we found that RNA abasic sites are rather abundant, there are tens to hundreds of thousands of them in each cell. We also found in an enhancer RNA of APOE, N6- methyladenosines are cleaved by methylpurine glycosylase to form RNA abasic sites on R- loops. The abasic sites then stabilize R-loops and pause RNA Polymerase II transcription. We show that this mechanism keeps the noncoding RNA poised to activate APOE expression in response to cellular demands. Given that we have early evidence for the role of RNA abasic sites in the regulation of noncoding RNA, it is necessary to better understand them. We propose to 1) examine the genome-wide effect of nucleic-acid-mediated pausing on noncoding RNA, 2) identify other glycosylases that form RNA abasic sites, and 3) determine what other modified RNA bases are precursors of RNA abasic sites. Together, these results will characterize RNA abasic sites by finding how they form and what they do.