Role of Epstein-Barr virus LMP2A protein in maintaining oncogenic IgM signaling in EBV+ B cell lymphomas

项目总结 爱泼斯坦-巴尔病毒(EBV)引起多种淋巴瘤，包括霍奇金淋巴瘤、伯基特淋巴瘤和弥漫性大淋巴瘤。 细胞淋巴瘤(DLBCL)。EBV+淋巴瘤的比例急剧上升，发病率和死亡率也在#年上升。 艾滋病毒感染者尽管接受了联合抗逆转录病毒治疗(CART)，但表明具体未能控制病毒 导致淋巴瘤。然而，促进EBV驱动的淋巴瘤发生的机制过程仍然存在。 人们对此知之甚少。这项提案将调查一个概念上的新假设，即LMP2A病毒 癌基因与B细胞受体(BCR)相互作用，维持其促进生长的IgM亚型。 这一假设预测，表达LMP2A的EBV转化细胞依赖于它们的构成 激活抗原诱导的信号传递的细胞介质，因此将容易受到靶向药物的影响 这个信号级联，而EBV转化的不表达LMP2A的细胞将对这种 毒品。我们的建议源于我们对淋巴母细胞的两个令人兴奋的观察 (LCLS)由缺乏LMP2A的EB病毒突变体(∆LMP2A-EBV)转化。首先，我们发现，与 正常LCL，∆LMP2A-LCL的生长不依赖于抗原诱导的信号转导介质 BLNK和BTK。第二，与正常LCL相比，∆LMP2A-LCLS不能维持促生长的免疫球蛋白M BCR的形式，而不是表达Ig G-BCR。由于通过Ig G-BCR传递的抗原信号促进 分化成分泌高水平抗体但增殖能力有限的浆细胞， 我们的中心假设是LMP2a通过促进EBV的生长而促进淋巴肿大的发生 转化的B淋巴细胞表达促生长素Ig M-BCR。这份提案将分析机械论 EBV转化LCLS的途径和基因表达谱及人源化淋巴瘤形成试验 为了区分LMP2a的直接贡献和由IgM-bcr介导的贡献，以及 评估每一种方法产生的治疗脆弱性。具体地说，我们将(1)调查 LMP2A和BCR Ig亚型对B淋巴细胞转化的影响；(2)抗原刺激对小鼠B淋巴细胞转化的影响 LMP2A表达的存在或不存在，以及(3)决定LMP2A介导的易感性 信号分子的治疗抑制。总之，这些研究为LMP2A如何 与BCR互动，促进EBV转化，为治疗提供新的机会 EBV相关淋巴瘤的干预。

PROJECT SUMMARY Epstein-Barr virus (EBV) causes a wide spectrum of lymphomas including Hodgkin, Burkitt, and diffuse large cell lymphomas (DLBCL). The proportion of EBV+ lymphomas rises sharply as does morbidity and mortality in HIV-infected persons despite combined antiretroviral therapy (cART), suggesting specific failure to control viral driven lymphomas. However, the mechanistic processes contributing to EBV-driven lymphomagenesis remain poorly understood. This proposal will investigate a conceptually novel hypothesis that the LMP2A viral oncogene interacts with the B cell receptor (BCR), serving to maintain it in its growth promoting IgM isotype. This hypothesis predicts that EBV transformed cells expressing LMP2A are dependent upon their constitutive activation of cellular mediators of antigen-induced signaling, and thus will be susceptible to agents that target this signaling cascade, whereas EBV-transformed cells that do not express LMP2A will be resistant to such drugs. Our proposal stems from two exciting observations that we have made about lymphoblastoid cells (LCLs) transformed by an EBV mutant that lacks LMP2A (∆LMP2A-EBV). First, we discovered that, unlike normal LCLs, the growth of ∆LMP2A-LCLs is not dependent on mediators of antigen-induced signaling like BLNK and BTK. Second, in contrast to normal LCLs, ∆LMP2A-LCLs fail to maintain the growth promoting IgM form of the BCR and instead express the IgG-BCR. Since antigen signaling through IgG-BCR promotes differentiation into plasma cells which secrete high levels of antibodies but have limited proliferative potential, our central hypothesis is that LMP2A contributes to lymphomagenesis by facilitating outgrowth of EBV transformed B lymphocytes expressing the growth promoting IgM-BCR. This proposal will analyze mechanistic pathways and gene expression profiles in EBV-transformed LCLs and test lymphoma formation in humanized mice in order to distinguish the direct contributions of LMP2A from those mediated by the IgM-BCR, and assess the therapeutic vulnerability that arise from each. Specifically, we will (1) Investigate intersection of LMP2A and BCR Ig isotype on B lymphocyte transformation, (2) Characterize impact of antigenic stimulation in the presence or absence of LMP2A expression, and (3) Determine LMP2A-mediated susceptibility to therapeutic inhibition of signaling molecules. Together these studies provide a framework for how LMP2A interacts with the BCR to promote EBV transformation and provide new opportunities for therapeutic intervention in EBV-associated lymphomas.