EPIGENETIC REGULATION OF THE INITIATION OF AN SV40 LYTIC INFECTION

描述（由申请人提供）：使用SV40作为DNA病毒感染的模型，拟议的研究将有助于我们理解表观遗传学在感染开始时决定病毒染色质命运的作用。我们的中心假设是，组成染色质的DNA病毒含有组蛋白修饰，这些修饰在感染的早期阶段激活竞争性细胞过程，从而导致病毒转录的激活或进入染色质的失活。具体目的是：(1)表征感染起始时病毒粒子和小染色体中存在的SV40表观基因组，(2)将小染色体表观基因组的变化与早期转录的起始联系起来，(3)表征病毒染色质中存在的表观遗传修饰在随后感染的建立中的作用。感染早期或转录激活时分离的病毒粒子和小染色体的SV40染色质表观基因组中存在的组蛋白修饰将使用各种ChIP程序确定。SV40表观基因组将通过组蛋白修饰的不同组合的存在来定义，并与早期转录的激活相关。表观遗传修饰在决定感染SV40小染色体命运中的作用将通过sirna靶向相关组蛋白甲基化酶抑制组蛋白甲基化并表征抑制对病毒粒子形成和感染建立的影响来分析。这项工作具有创新性，因为表观遗传调控在定义病毒染色质中存在的组蛋白修饰以及感染病毒染色质的后续命运方面的作用将首次被确定。这项提议的工作意义重大，原因有二。首先，理解表观遗传学在决定染色质感染细胞的命运中的作用，可能会导致旨在减少或消除感染的治疗干预。其次，我们的中心假设的确认将导致我们对表观遗传学在调节建立感染所必需的竞争性病毒和细胞过程中的作用的理解取得重大进展。

DESCRIPTION (provided by applicant): Using SV40 as a model for infection by DNA viruses, the proposed studies will contribute to our understanding of the role that epigenetics plays in determining the fate of viral chromatin during the initiation of an infection. Our central hypothesis is that DNA viruses organized into chromatin contain histone modifications that activate competing cellular processes during the early stages of infection which result in either activation of viral transcription or inactivation of the incoming chromatin. The specific aims are: (1) To characterize the SV40 epigenomes present in virions and minichromosomes during the initiation of infection, (2) To correlate changes in the epigenomes of minichromosomes with the initiation of early transcription, and (3) To characterize the role of epigenetic modifications present in viral chromatin in the establishment of a subsequent infection. The histone modifications present in the epigenomes of SV40 chromatin from virions and minichromosomes isolated early in infection or undergoing activation of transcription will be determined using various ChIP procedures. The SV40 epigenomes will be defined by the presence of distinct combinations of histone modifications and correlated with the activation of early transcription. The role of epigenetic modifications in determining the fate of an infecting SV40 minichromosome will be analyzed by inhibiting histone methylation with siRNAs targeting the relevant histone methylases and characterizing the effects of inhibition on virion formation and establishment of an infection. The proposed work is innovative, because for the first time the role of epigenetic regulation in defining the histone modifications present in viral chromatin and the subsequent fate of the infecting viral chromatin will be determined. The proposed work is significant for two reasons. First, understanding the role of epigenetics in determining the fate of chromatin infecting a cell may lead to therapeutic interventions designed to reduce or eliminate an infection. Second, confirmation of our central hypothesis would lead to a significant advance in our understanding of the role of epigenetics in regulating the competing viral and cellular processes necessary for the establishment of an infection. PUBLIC HEALTH RELEVANCE: The proposed studies will be the first characterization of the role of epigenetics in the establishment of a viral infection. The results obtained will significantly add to our knowledge of the role of histone modifications in the initiation of early transcription and the activation of cellular processes designed to limit infection. SV40 has been an excellent model to study basic eukaryotic molecular biology and the mechanisms underlying cellular transformation by DNA tumor viruses. The proposed research will extend this use as a model to the investigation of the role of epigenetic regulation in establishing a viral infection. The results obtained will be relevant to other viral human diseases and to a basic understanding of the mechanisms and functions of epigenetic regulation.