Mechanism of T Cell Receptor Mediated Activation of NFkappaB

转录因子NF-kappaB在T细胞受体(TCR)结合后的激活是重要的 用于T细胞在获得性免疫反应中的增殖和激活。最近的报告描述了 一条涉及PKCtheta、支架蛋白CARD11(也称为 Carma-1)、含有卡片区的蛋白BcMO和副天冬氨酸蛋白酶(与 Caspase)MALT1作为连接TCR和IkappaB激酶(IKK)复合体的关键中间体。然而， 这一信号通路激活后发生的确切事件顺序仍然很差 已定义。我们最近证明了3-磷脂酰肌醇依赖的激酶1(PDK1)具有 通过调节PKCtheta的激活和信号依赖在该通路中发挥重要作用 PKCtheta和CARD11都被招募到脂筏。与PDK1相关的PKCQ招募IKKComplex， 而PDK1相关的CARD11招募Bcl10-MALT1复合体，从而允许激活 IKK复合体通过依赖Bcl10-MALT1泛素化的IKK复合体亚基NEMO。 因此，PDK1通过核化TCR诱导的T细胞中的NF-kappaB活化途径发挥关键作用。 在这项提议中，我们将进一步扩大我们的观察范围，以更准确地了解PDK-1是如何招募 PKCtheta和CARD11.我们将确定这些交互中涉及的领域，并使用这些知识 从这些研究中寻找抑制T细胞激活的新方法。此外，我们还拥有 发现PKCtheta通过由内向外的方式参与了TCR参与的LFA1的激活 路径。我们将通过生成新的遗传模型来确定这一途径的重要性 Believe将把PKCtheta作为IKK招募适配器的能力与它的能力分开 通过对LFA1的作用促进稳定的结合和免疫突触。我们相信 这些研究将提供对关键细胞途径的更全面的了解，并提供机会 开发新的免疫抑制方法。

Activation of the transcription factor NF-kappaB after engagement of the T cell receptor (TCR) is important for T cell proliferation and activation during the adaptive immune response. Recent reports have described a signaling pathway that involves the kinase PKCtheta, the scaffold protein CARD11 (also called CARMA-1), the CARD-domain containing protein BcMO, and the paracaspase (protease related to caspases) MALT1 as critical intermediates linking the TCR to the IkappaB kinase (IKK) complex. However, the exact sequence of events that occurs following the activation of this signaling pathway remains poorly defined. We have recently demonstrated that 3-phosphoinositide-dependent kinase 1 (PDK1) has an essential role in this pathway by regulating the activation of PKCtheta and through signal-dependent recruiting of both PKCtheta and CARD11 to lipid rafts. PDK1-associated PKCq recruits the IKKcomplex, whereas PDK1-associated CARD11 recruits the Bcl10-MALT1 complex, thereby allowing activation of the IKK complex through Bcl10-MALT1-dependent ubiquitination of the IKK complex subunit known as NEMO. Hence, PDK1 plays a critical role by nucleating the TCR-induced NF-kappaB activation pathway in T cells. In this proposal we will further extend our observations to better understand exactly how PDK-1 recruits PKCtheta and CARD11. We will identify the domains involved in these interactions and use the knowledge from these studies to devise novel approaches for suppressing T-cell activation. In addition we have also found that PKCtheta is involved in the activation of LFA1 following TCR-engagement through an inside-out pathway. We will establish the importance of this pathway by generating novel genetic models that we believe will dissociate the ability of PKCtheta to function as an adapter for recruitment of IKK, from its ability to promote stable conjugation and immunological synapses through its effect on LFA1. We believe that these studies will both provide a fuller understanding of a key cellular pathway, and the opportunity to develop novel approaches for immunosuppression.