RNA Splicing Control in Rous Sarcoma Virus

描述（由申请人提供）：表征独特的病毒-宿主相互作用是了解发病机制和开发阻断病毒生命周期的治疗方法的关键。由于它们与宿主细胞的密切联系，病毒也被用作研究许多基本细胞过程的工具，包括RNA加工。对于逆转录病毒，剪接和多聚腺苷化的控制是复制周期的重要方面。逆转录病毒初级转录物的剪接必须得到控制，因为需要高水平的未剪接RNA作为mRNA，并作为基因组并入子代病毒粒子。多聚腺苷化控制很重要，因为未能使用病毒多聚腺苷化位点会导致转录本延伸到下游基因组序列；这是致癌转化的基础，也是逆转录病毒通过捕获致癌基因获得宿主细胞序列的能力的基础。我们正在研究劳斯肉瘤病毒（RSV）正确RNA加工和复制所需的病毒顺式元件和宿主反式因子；RSV RNA加工控制模式的建立将为宿主细胞RNA加工调控提供新的见解。我们的工作部分集中在一种新的RNA加工控制元件，剪接负调节因子（NRS），它通过作为抑制剪接的伪5's来促进基因组长度RNA的积累。我们将继续研究新的snRNP与NRS相互作用所需的因子及其在剪接控制中的作用。剪接和聚腺苷化在RSV感染的细胞中偶联，提出了病毒rna如何有效地聚腺苷化的问题。我们将继续研究一种新的偶联机制，即除了剪接控制外，NRS还确保不受益于剪接的基因组长度RNA的适当聚腺苷化。RSV还含有位点特异性剪接调节因子，即src剪接抑制因子（SSS），它控制src剪接，是正确复制所必需的。我们将确定SSS活性所需的宿主因子，并探索其阻断剪接的机制。通过这项工作，我们将加强对病毒复制和发病机制所需的关键RNA加工步骤的控制的理解，并可能导致设计新的治疗方法来阻止复制。RSV系统还提供了一个强大的工具来剖析RNA加工调控的新细胞机制。公共卫生相关性：逆转录病毒是导致大量人类疾病（包括免疫缺陷和癌症）的主要动物病原体。病毒复制需要非常规地使用细胞内制造病毒RNA的机器。了解这些药物如何与操纵宿主细胞RNA加工机制相互作用，可能会导致设计新的治疗方法来阻止复制，并告诉我们宿主机器工作的新方式。

DESCRIPTION (provided by applicant): Characterizing unique virus-host interactions is key to understanding pathogenesis and developing therapeutics to block the virus life cycle. Because of their intimate associations with host cells, viruses have also been exploited as tools for studying many basic cellular processes, including RNA processing. For retroviruses, control of splicing and polyadenylation are important aspects of the replication cycle. Splicing of retroviral primary transcripts must be controlled since high levels of unspliced RNA are needed as mRNA, and for incorporation as genomes into progeny virions. Polyadenylation control is important because failure to use the viral polyadenylation site results in read-through transcripts that extend into downstream genomic sequences; this is the basis for oncogenic transformation and the ability of retroviruses to acquire host cell sequences through oncogene capture. We are studying viral cis elements and host trans-acting factors required for proper RNA processing and replication of Rous sarcoma virus (RSV); paradigms established for RSV RNA processing control will provide insights into host cell RNA processing regulation. Our work focuses in part on a novel RNA processing control element, the negative regulator of splicing (NRS), that contributes to the accumulation of genome-length RNA by acting as a pseudo 5'ss to repress splicing. We will continue investigation of factors required for novel snRNP interactions with the NRS and their role in splicing control. Splicing and polyadenylation are coupled in the cells that RSV infects, raising the question of how viral RNAs are efficiently polyadenylated. We will continue examining a novel coupling mechanism whereby the NRS, in addition to splicing control, ensures the proper polyadenylation of genome-length RNA that do not benefit from splicing. RSV also harbors a site-specific splicing regulator, the suppressor of src splicing (SSS), that controls src splicing and is required for proper replication. We will identify host factors required for SSS activity and explore the mechanism by which it blocks splicing. Through this work we will enhance our understanding of control of critical RNA processing steps required for viral replication and pathogenesis, and could lead to new therapeutics designed to block replication. The RSV system also provides a powerful tool to dissect novel cellular mechanisms of RNA processing regulation. PUBLIC HEALTH RELEVANCE: Retroviruses are major animal pathogens that cause considerable human disease, including immunodeficiencies and cancer. Viral replication requires unconventional use of the machines inside cells that make viral RNA. Understanding how these agents interact with manipulate the host cell RNA processing machinery could lead to new therapeutics designed to block replication and teach us novel ways in which the host machines work.