Entry of HHV-8 Into the Target Cells

性状（由申请方提供）：HHV-8/KSHV，美国性传播媒介之一，与多种人类疾病和肿瘤有关。我们的长期目标是确定HHV-8感染靶细胞的早期事件，这对于深入了解HHV-8发病机制至关重要，这将导致控制HHV-8感染的新方法。 真核细胞与其细胞外环境的相互作用在很大程度上由暴露在细胞表面的配体诱导的信号分子介导。随之而来的众多生物过程是由高度互连的信号通路网络介导的。配体模拟是微生物破坏宿主信号分子进入宿主细胞的机会机制。关于疱疹病毒-受体相互作用促进感染的机制，目前还缺乏相关知识。疱疹病毒与细胞表面的结合可以在4 º C下以不依赖能量的方式发生。相反，进入细胞和随后将衣壳转移到核附近是活跃的、能量依赖的现象，因此必须需要宿主细胞信号传导途径。HHV-8使用其包膜gB和gPK8.1A与靶细胞表面硫酸乙酰肝素（HS）分子进行初始接触，这可能是导致与随后的病毒进入过程所必需的其它宿主细胞受体结合的第一组配体-受体相互作用。我们已经证明，HHV-8利用？三个？1整合素作为其进入受体之一。正在进行的研究表明，HHV-8也利用？v？3、？v？5整合素作为进入受体。我们的研究表明，HHV-8利用内吞途径进入人包皮成纤维细胞（HFF）。我们的研究还表明，HHV-8诱导整合素依赖性粘着斑激酶（FAK）的磷酸化。我们推测除了病毒基因组进入细胞内部的管道外，HHV-8与整合素的相互作用必须在诱导宿主细胞预先存在的信号级联中起积极作用，以快速内化病毒基因组并运输到细胞核。这项资助的具体目的是详细分析HHV-8进入不同靶细胞的各种模式，随后在细胞质中的运动，以及病毒DNA向感染细胞核的递送，并确定HHV-8诱导的信号介质在这些早期事件中的作用。 这些研究是有意义的，因为它们将提供对HHV-8感染靶细胞的早期事件的深入了解。进一步了解HHV-8进入，整合素依赖性细胞信号传导途径及其在感染中的作用将最终导致新的抗HHV-8药物的开发。

DESCRIPTION (provided by the applicant): HHV-8/KSHV, one of the sexually transmitted agents in U.S.A. is associated with a variety of human diseases and neoplasm. Our long term objective is to define the early events of HHV-8 infection of target cells with a rationale that this is vital for a through understanding of HHV-8 pathogenesis which will lead into novel methods to control HHV-8 infection. The interactions of eukaryotic cells with their extracellular environments are largely mediated by ligand-induced signaling molecules exposed at the cell surface. The ensuing multitudes of biological processes are mediated by highly interlinked networks of signaling pathways. Ligand mimicry is an opportunistic mechanism by which microbes subvert host signaling molecules for their entry into the host cells. There is a dearth of knowledge regarding the mechanism by which herpesvirus-receptor interactions facilitate infection. Binding of herpesviruses to the cell surface can occur at 4¿C in an energy independent manner. In contrast, entries into cells and the subsequent transfer of capsids to the vicinity of the nucleus are active, energy dependent phenomenon, and thus must be requiring host-cell signaling pathways. HHV-8 uses its envelope gB and gPK8.1 A to make the initial contact with the target cell surface heparan sulfate (HS) molecules, which is probably the first set of ligand-receptor interaction leading to the binding with other host cell receptors essential for the subsequent viral entry process. We have demonstrated that HHV-8 utilizes the ?3?1 integrin as one of its entry receptor. Ongoing studies show that HHV-8 also utilizes the ?v?3 and ?v?5 integrins as entry receptors. Our studies show that HHV-8 utilizes the endocytic pathway for its entry in the human foreskin fibroblast (HFF) cells. Our studies also show that HHV-8 induces the phosphorylation of integrin-dependent focal adhesion kinase (FAK). We hypothesize that besides a conduit for the entry of viral genome into the interior of the cells, interaction of HHV-8 with integrins must have an active role in the induction of host-cell pre-existing signaling cascades for the rapid internalization of viral genome and for transport to the nucleus. The specific aims of this grant are to analyze in detail the various mode of HHV-8 entry into the different target cells, subsequent movement in the cytoplasm, and delivery of viral DNA to the nuclei of infected cells, and to determine the role of HHV-8-induced signal mediators in these early events. These studies are significant, since they would provide an insight into the early events of HHV-8 infection of target cells. Further understanding of HHV-8-entry, integrin-dependent cell signaling pathways, and their role in infection would eventually lead to the development of new anti-HHV-8 agents.