Kaposi's Sarcoma-associated Herpesvirus Mimics of Cellular microRNAs

总结 卡波西肉瘤相关疱疹病毒（KSHV）导致艾滋病相关恶性肿瘤卡波西肉瘤 肉瘤（KS）和原发性渗出性淋巴瘤（PEL），由KSHV感染内皮细胞（EC）引起 和B细胞。KSHV编码一组微小RNA（miRNAs），其对KSHV的重要性尚不清楚。 KSHV相关疾病我们已经证明KSHV miRNAs miR-K11、miR-K3和miR-K10 a 分别抑制细胞miR-155、miR-23和miR-142- 3 p的mRNA靶点。这项提案的目的是 了解这种拟态对PEL和KS发病机制的潜在意义。我们的初步 数据表明miR-K3和miR-K11一起对于PEL衍生的细胞系的存活是必需的， 协同靶向存活信号传导和B细胞增殖的阻遏物。因此，在目标1中，我们建议 表型和机制上表征B细胞对miR-K3和miR-K11的需求 由KSHV改造。目的2和3解决miR-K10 a的功能。miR-K10 a表达自 Kaposin A编码序列，具有已知的致癌特性。我们的初步实验表明， miR-K10 a是这种转化活性的实际介质。因此，在目标2中，我们建议进一步 描述miR-K10 a的致癌特性并阐明其潜在机制，基于 已经确定了在转型中扮演角色的候选目标。我们对miR-K10 a靶点的分析， 初步实验表明，miR-K10 a在EC中的功能是破坏粘附连接（AJs）， 重塑肌动蛋白细胞骨架。miR-K10 a的表达引起了EC的显著延长，这让人联想到 KSHV感染的梭形细胞是KS的标志。因为AJs和连接的肌动蛋白 细胞骨架在血管完整性、血管生成和维持EC静止中起重要作用， 通过拮抗生长因子信号传导，它们被miR-K10 a的失调可能直接影响KS发病机制。在 目的3，因此，我们提出表型和机制表征miR-K10 a如何影响这些 结构和相关的信号通路。总之，拟议的实验将确定关键作用， 这些KSHV miRNAs在KSHV肿瘤发生中的作用。

Summary Kaposi's Sarcoma-associated herpesvirus (KSHV) causes the AIDS-associated malignancies Kaposi's Sarcoma (KS), and primary effusion lymphoma (PEL), resulting from KSHV-infection of endothelial cells (ECs) and B cells, respectively. KSHV encodes a set of microRNAs (miRNAs) with largely unknown significance to KSHV-associated disease. We have demonstrated that the KSHV miRNAs miR-K11, miR-K3 and miR-K10a repress mRNA targets of cellular miR-155, miR-23 and miR-142-3p, respectively. The goal of this proposal is to understand the potential significance of this mimicry to the pathogenesis of PEL and KS. Our preliminary data suggest that miR-K3 and miR-K11 together are essential for the survival of PEL-derived cell lines and synergize to target repressors of survival signaling and B-cell proliferation. In Aim 1, we therefore propose to phenotypically and mechanistically characterize the requirement for miR-K3 and miR-K11 for B-cell transformation by KSHV. Aims 2 and 3 address functions of miR-K10a. miR-K10a is expressed from the Kaposin A coding sequence, which has known oncogenic properties. Our preliminary experiments suggest that miR-K10a is the actual mediator of this transforming activity. In Aim 2, we therefore propose to further characterize the oncogenic properties of miR-K10a and to elucidate the underlying mechanism, based on already identified candidate targets with roles in transformation. Our analysis of miR-K10a targets and preliminary experiments suggest that miR-K10a functions in ECs to disrupt adherens junctions (AJs) and to remodel the actin cytoskeleton. miR-K10a expression caused a striking elongation of ECs, reminiscent of the KSHV-infected infected spindle cells that are the hallmark of KS. Because AJs and the linked actin cytoskeleton play important roles in vascular integrity, angiogenesis and the maintenance of EC quiescence by antagonizing growth factor signaling, their deregulation by miR-K10a may directly impact KS pathogenesis. In Aim 3, we therefore propose to phenotypically and mechanistically characterize how miR-K10a affects these structures and associated signaling pathways. Together, the proposed experiments will identify key roles of these KSHV miRNAs in KSHV oncogenesis.