The molecular basis of OX40 on CD4 T cells

描述(申请人提供)：T细胞反应由细胞表面受体连接发出的细胞内信号控制。虽然第二信号的概念已经建立多年，CD28代表第二信号的初始提供者，但很明显，有效和持久的T细胞反应需要来自其他几个共刺激受体的信号。我们已经广泛研究了TNFR家族的一个成员，即OX40(CD134)，它的表达是在最初的抗原识别事件发生几小时到几天后在T细胞上诱导的。我们已经证明，0X40共刺激通过调节细胞周期进程延长了CD4和CDS T细胞的克隆性增殖，促进了T细胞的分化和细胞因子的分泌，特别是对Th2表型的诱导，并进一步通过拮抗细胞凋亡来促进T细胞的存活。在过去的5年或更长时间里，对不同疾病模型的多项体内研究证实了这些结论，并导致了CD28和OX40的协同和暂时活动代表着大多数T细胞介导的免疫反应中的关键事件的概念。在这一新的应用中，我们寻求扩展我们的功能数据，并进一步从分子上定义OX40的作用模式，以及OX40信号如何与抗原和CD28信号结合。我们已经展示了OX40的几个常见的细胞内靶点，包括调节G1-S细胞周期进程的新分子Survivin和极光B激酶，以及在T细胞分裂期间和之后控制生存的Bcl2、Bclxl和Bfl-1。我们开发了高度生理性的新型转基因和逆转录病毒系统，以了解OX40在原代T细胞中的调控。我们将研究OX40如何导致Akt和NF-KB的激活，以及这些信号部分在促进T细胞分裂和存活方面的合作程度。具体地说，我们将确定OX40是否利用PKC0、PDK1和MEK1/ERK来靶向Akt和NF-KB，以及这些信号级联如何影响Survivin和极光B激酶在调节分裂中的表达和功能，以及Bcl-2抗凋亡分子在调节生存中的作用。我们将进一步定义OX40是如何针对NFATd核聚集导致IL-4分泌和Th2分化的，然后定义OX40在脂筏T细胞膜上诱导的信号复合体。最后，我们将使用几种涉及肺部炎症和抗肿瘤活性的体内T细胞反应模型来扩展体外信号分析，并从分子上了解共刺激信号如何影响生理T细胞功能。这些研究对于确定OX40的作用和共刺激信号的整合，以及理解哪些分子途径是促进长期T细胞反应所必需的和充分的，具有极其重要的意义。

DESCRIPTION (provided by applicant): T cell responses are controlled by intracellular signals emanating from ligation of cell surface receptors. While the concept of a second signal has been established for many years, with CD28 representing the initial provider of this second signal, it is clear that signals from several other co-stimulatory receptors are needed for an effective and persistent T cell response. We have extensively studied a member of the TNFR family, namely OX40 (CD134), whose expression is induced on T cells several hours to days after the initial antigen recognition event. We have demonstrated that 0X40 costimulation prolongs clonal expansion of CD4 and CDS T cells by regulating cell cycle progression; enhances T cell differentiation and cytokine secretion particularly toward the Th2 phenotype; and furthermore promotes T cell survival by antagonizing apoptosis. Multiple in vivo studies in varying models of disease over the past 5 or more years have reinforced these conclusions and led to the concept that the synergistic and temporal activities of CD28 and OX40 represent key events in most T cell mediated immune responses. In this renewal application, we seek to extend our functional data and further define molecularly the mode of action of OX40 and how OX40 signals integrate with antigen and CD28 signals. We have shown several common intracellular targets of OX40 including novel molecules survivin and aurora B kinase that regulate G1-S cell cycle progression, and Bcl-2, Bcl-xL, and Bfl-1 that control survival during and after the phase of T cell division. We have developed highly physiological and novel transgenic and retroviral systems to understand regulation of OX40 in primary T cells. We will investigate how OX40 leads to activation of Akt and NF-KB and the extent that these signaling moieties co-operate in promoting cell division and survival of T cells. Specifically, we will determine whether OX40 utilizes PKC0, PDK1, and MEK1/ERK to target Akt and NF-KB, and how these signaling cascades impact the expression and function of survivin and aurora B kinase in regulating division, and the Bcl-2 anti-apoptotic molecules in regulating survival. We will further define how OX40 targets NFATd nuclear accumulation leading to IL-4 secretion and Th2 differentiation, and then define signaling complexes induced by OX40 at the T cell membrane in lipid rafts. Lastly, we will use several models of in vivo T cell response involving lung inflammation and anti-tumor activity to extend the in vitro signaling analyses and understand molecularly how co-stimulatory signaling impacts physiological T cell function. These studies are tremendously important in defining the action of OX40 and the integration of co-stimulatory signals, and in understanding which molecular pathways are necessary and sufficient for promoting a long-lived T cell response.