Virus manipulation of host non-coding RNA regulatory networks

多年来，人们已经知道，只有约2%的人类基因组编码蛋白质，而约80%的基因组被主动转录成没有明显编码能力的rna，即非编码rna （ncRNAs）。由于ncrna在许多人类疾病（包括衰老、癌症、自身免疫和感染）中经常发生改变，因此强调了这种非编码转录组的重要性。功能研究表明，ncrna是基因表达的关键调控因子。例如，一组被称为microrna （miRNAs）的短ncrna通过结合其靶蛋白编码转录物来调节基因表达，从而导致转录物的翻译抑制、切割或衰变。因此，该领域的研究主要集中在确定特定mirna与其靶转录物之间的相互作用。然而，现在新出现的证据表明，不同的ncrna之间存在一种意想不到的相互作用，这种相互作用强烈地影响着，例如，miRNA如何与其靶标结合。在这种情况下，其他ncRNA物种，如环状rna和其他长链ncRNA，作为竞争的内源性rna，与miRNA相互作用，以海绵或诱骗miRNA，从而抑制miRNA与靶mRNA的结合，防止其被抑制。因此，这种ncRNA-ncRNA相互作用的网络可以对许多细胞过程中基因表达的调节产生深远的影响。我们有令人兴奋的初步数据表明，疱疹病毒已经进化出操纵这些ncRNA调控网络的方法，以增强病毒基因表达并调节宿主对感染的反应。我们已经证明，在疱疹病毒感染期间，一些环状rna被上调，而大多数失调的mirna被下调。这表明，这些病毒诱导的环状rna可以吞噬特定的mirna，以战胜它们与靶蛋白编码转录物的结合，并阻止它们的抑制或降解。我们现在的目标是进一步研究这些观察结果，并确定ncRNA物种及其受病毒操纵的相关调控网络之间的相互作用。此外，我们将通过确定靶蛋白编码转录本的作用来确定这些调节网络在感染期间被改变的原因，这些转录本由于各自的网络被操纵而异常表达。此外，我们将研究病毒在感染过程中如何增强环状RNA水平的新机制。最后，我们发现了一组mirna，与大多数下调的mirna相反，它们在感染期间实际上是增加的，这表明病毒增强了它们的产生，以抑制或降解可能对病毒感染有害的细胞转录物。我们将确定病毒如何上调这些mirna，并确定它们的靶mrna在病毒复制中的抑制作用。总之，该项目将确定病毒操纵宿主细胞以增强自身复制的新方法，并提供更好地理解不同ncRNA物种之间的相互作用如何调节基因表达。更好地了解这些基本过程有可能对我们对细胞和发育生物学过程的理解产生深远的影响，人类疾病的发展，并为重要的人类病原体的治疗干预提供新的策略。

It has been known for some years that only ~2% of the human genome encodes for proteins, whereas ~80% is actively transcribed into RNAs with no obvious coding capacities, known as non-coding RNAs (ncRNAs). The importance of this non-coding transcriptome is emphasised due to the fact that ncRNAs are frequently altered in many human diseases, including aging, cancer, auto-immunity and infections. Functional studies have shown that ncRNAs are critical regulators of gene expression. For example, a group of short ncRNAs known as microRNAs (miRNAs), modulate gene expression by binding to their target protein coding transcript, which leads either to the transcript's translation repression, cleavage or decay. As such, research in this area has mainly focussed on identifying the interaction between specific miRNAs and their target transcript(s). However, emerging evidence now suggests the existence of an unexpected interplay between different ncRNAs that strongly influences, for example, how a miRNA can bind to its target. In this case, other ncRNA species, such as circular RNAs and other long ncRNAs, function as competing endogenous RNAs, interacting with miRNAs to sponge or decoy the miRNA, thus inhibiting the miRNA from binding to the target mRNA and preventing its repression. As such, this network of ncRNA-ncRNA interactions can have a profound effect on the regulation of gene expression in many cellular processes.We have exciting preliminary data suggesting that a herpesviruses has evolved ways to manipulate these ncRNA regulatory networks to enhance virus gene expression and modulate the host response to infection. We have demonstrated that during herpesvirus infection several circular RNAs are upregulated whereas the majority of dysregulated miRNAs are downregulated. This suggests that these virus-induced circular RNAs could sponge specific miRNAs to outcompete their binding to target protein coding transcripts and prevent their repression or degradation. We now aim to further investigate these observations and identify the interplay between ncRNA species and their associated regulatory networks which are manipulated by the virus. Furthermore, we will determine why these regulatory networks are altered during infection by determining the role of the target protein-coding transcripts that are aberrantly expressed due to the manipulation of their respective networks. Moreover, we will investigate novel mechanisms of how a virus enhances circular RNA levels during infection. Finally, we have identified a group of miRNAs that in contrast to the majority of downregulated miRNAs are actually increased during infection, which suggests the virus enhances their production to repress or degrade cellular transcripts which are probably detrimental to virus infection. We will determine how the viruses upregulates these miRNAs and also determine the inhibitory role of their target mRNAs in virus replication.In summary, this project will identify novel ways a virus can manipulate the host cell to enhance its own replication and provide a better understanding how the interplay between different ncRNA species can regulate gene expression. A better knowledge of these fundamental processes has the potential for far reaching impacts on our understanding of cell and developmental biology processes, the development of human disease and provide new strategies for therapeutic interventions of important human pathogens.