Biology of HHV-8 interactions with host cells

描述(申请人提供)：任何病毒趋向性的主要决定因素之一是与细胞表面分子的相互作用和随后的进入。总的目标是破译HHV-8靶细胞相互作用对病毒进入和感染至关重要的分子事件，并确定HHV-8‘S在KS发病机制中的分子基础。 HHV-8通过内吞作用进入内皮细胞、B细胞和成纤维细胞。HHV-8通过其囊膜糖蛋白gB和gpK8.1a与普遍存在的细胞表面硫酸乙酰肝素样分子结合，通过其gB与细胞表面的α3β1整合素相互作用，将其作为进入受体之一，诱导整合素依赖的粘着斑激酶(FAK)的磷酸化。由于FAK、Src家族激酶和其他激酶的激活是整合素、肌动蛋白组装和内吞作用中由外向内信号传递的核心，我们假设HHV-8通过与整合素的相互作用，利用先前存在的FAK和相关的信号通路来促进其进入，将其基因组运送到细胞核中，并调节促进感染的细胞状态。我们的研究表明，纯化的HHV-8能够激活整合素诱导的信号通路的关键介质，如FAK、Src、Shc、PI-3K和RhoGTP酶。纯化的可溶性HHV-8 gB还可诱导FAK依赖的靶细胞黏附、整合素依赖的FAK-Src-PI-3K-RhoGTPase信号通路和细胞骨架重排。HHV-8还以整合素-FAK依赖的方式激活PI-3K-PKC-Delta，-MEK-ERK信号通路。为了进一步验证我们的假设，这项资助的重点是确定HHV-8诱导的关键信号介质如FAK、Src和PI-3K在HHV-8进入靶细胞、随后的细胞质移动和病毒DNA进入感染细胞的核中的作用，并制定了两个特定的目标：1.确定HHV-8诱导的FAK、Src和PI-3K在病毒进入靶细胞中的作用。2.明确HHV-8诱导的FAK、Src、PI-3K和RhoGTP酶在感染细胞的衣壳/被膜迁移和病毒基因组向核传递中的作用。 这些研究意义重大，因为它们将为HHV-8与宿主细胞相互作用的生物学提供一个洞察力。进一步了解HHV-8细胞信号转导机制将拓宽我们对HHV-8相关疾病的认识，并最终导致新的抗HHV-8药物和治疗KS的药物的出现。

DESCRIPTION (provided by applicant): One of the major determinants of tropism of any virus is the interactions with cell surface molecules and the subsequent entry. The overall objective is to decipher the molecular events of HHV-8 target cell interactions vital for virus entry and infection, and to define the molecular basis for HHV-8's role in the pathogenesis of KS. HHV-8 enters the endothelial, B, and fibroblast cells via endocytosis. HHV-8 binds to the ubiquitous cell surface heparan sulfate (HS)-Iike molecules via its envelope glycoproteins gB and gpK8.1A, interacts with the cell surface alpha3beta1 integrins via its gB, utilizes it as one of the entry receptor, and induces the phosphorylation of integrin-dependent focal adhesion kinase (FAK). Since activation of FAK, Src-family kinases, and other kinases is central to many paradigms of outside-in signaling by integrins, actin assembly and endocytosis, we hypothesize that by its interaction with integrins, HHV-8 takes advantage of the pre-existing FAK and the associated signaling pathways to promote its entry, to deliver its genome into the nucleus and to modulate a cellular state facilitating the infection. Our studies show the activation of key mediators of integrin-induced signal pathways such as FAK, Src, Shc, PI-3K and RhoGTPases by the purified HHV-8. Purified soluble HHV-8 gB also inducted the FAK dependent target cell adhesion, and integrin-dependent FAK-Src-PI-3K-RhoGTPase signal pathways and cytoskeletal rearrangements. In an integrin-FAK-dependent manner, HHV-8 also activated the PI-3K-PKC-delta,-MEK-ERK signal pathway. To test our hypothesis further, the focus of this grant is to define the role of HHV-8-induced key signal mediators such as FAK, Src and PI-3K in HHV-8 entry into the target cells, subsequent movement in the cytoplasm and delivery of viral DNA into the nuclei of infected cells, and two specific aims were formulated: 1.To define the role of HHV-8 induced FAK, Src and PI-3K in the entry of virus into the target cells. 2. To define the role of HHV-8 induced FAK, Src, PI-3K and RhoGTPases in the migration of capsid/tegument in the cytoplasm of the infected cells and in the delivery of viral genome to the nucleus. These studies are significant since they will provide an insight in the biology of HHV-8 interactions with the host cells. Further understanding of HHV-8-cell signaling will broaden our knowledge of HHV-8 related diseases and eventually lead to new anti-HHV-8 agents, and therapeutic agents against KS.