Coordination of RNA cleavage with end modification and processing

摘要 程序性或无意的RNA切割导致“脏”RNA 5 '和3'末端 被RNA末端修饰酶重塑。RNA末端的产物 修饰是催化RNA的RNA加工活动的底物 修复、衰退或稳定。因为有些加工酶能识别 不同的修饰末端，RNA末端修饰酶可以促进一些 处理步骤，同时抑制其他步骤。相反，RNA加工酶 催化不同反应的细胞可能会识别并竞争底物 具有相同的末端修饰以控制RNA切割的结果。这些 不同的情况可能会被用来调节RNA的结果， 切割，但我们对RNA末端修饰在切割过程中的作用知之甚少。 RNA加工我们发现，RNA 5 ′- 酵母tRNA连接酶Trl 1的激酶活性对于调节未折叠的 蛋白质反应通过磷酸化RNA中间体， UPR激活以促进它们通过5 ′ →3 ′衰变的周转，而Trl 1 RNA 5 ′- 激酶活性介导由共刺激产生的mRNA片段的周转， 翻译“不通过”mRNA衰变。人类RNA 5 ′-激酶Clp 1具有 在神经元代谢和分化中起重要作用，但我们不知道 Clp 1的底物，因此目前尚不清楚RNA 5 ′-激酶功能障碍 活动导致疾病。我们发现Trl 1 5 ′-激酶活性介导了 mRNA切割片段的衰减也引出了Trl 1是否 连接酶也可以修复RNA，但已知的RNA修复的例子很少。 为了解决这些问题，我们将重点关注以下问题：1。是什么 人Clp 1 RNA 5 ′-激酶的底物？2. RNA如何终止 修饰和加工调节未折叠蛋白质反应？3.好吗 不去mRNA衰变产生的产物，它的生理作用是什么？ 基质？4. RNA修复是局限于特定的底物，还是作用于 其他受损的RNA？这些研究的结果将是一个改进的 了解RNA切割后如何使用RNA末端修饰， 介导的RNA加工，这些见解可能会告知我们的理解 RNA末端修饰功能障碍如何成为人类疾病的基础。

Abstract Programmed or unintentional RNA cleavage leads to "dirty" RNA 5´ and 3´ ends that are remodeled by RNA end modification enzymes. The products of RNA end modification are substrates for RNA processing activities that catalyze RNA repair, decay or stabilization. Because some processing enzymes recognize different modified termini, RNA end modification enzymes could promote some processing steps while inhibiting others. Conversely, RNA processing enzymes that catalyze different reactions might recognize – and compete for – substrates with the same end modification to control the outcome of RNA cleavage. These different scenarios could potentially be used to regulate the outcome of RNA cleavage, but we know very little about the roles of RNA end modification during RNA processing. We discovered that RNA end modification by the RNA 5´- kinase activity of the yeast tRNA ligase Trl1 is important to regulate the unfolded protein response by phosphorylating RNA intermediates during unintentional UPR activation to facilitate their turnover by 5´→3´ decay, and that Trl1 RNA 5´- kinase activity mediates the turnover of mRNA fragments created by co- translational “no-go” mRNA decay. The human RNA 5´-kinase enzyme Clp1 has an important role in neuronal metabolism and differentiation, but we do not know the substrates of Clp1 and so it is not clear how dysfunction in RNA 5´-kinase activity leads to disease. Our discovery that Trl1 5´-kinase activity mediates the decay of mRNA cleavage fragments also begs the question of whether the Trl1 ligase can also repair RNAs, but only a few examples of RNA repair are known. To address these issues, we will focus on the following questions: 1. What are the substrates of the human Clp1 RNA 5´-kinase?; 2. How do RNA end modification and processing regulate the unfolded protein response?; 3. How are the products of no-go mRNA decay created, and what are its physiological substrates?; 4. Is RNA repair restricted to specific substrates, or does it act on other damaged RNAs? The outcomes of these studies will be an improved understanding of how RNA end modification is used after RNA cleavage to mediate RNA processing, and these insights may inform our understanding of how dysfunction in RNA end modification underlies human disease.