Mechanism of T Cell Receptor Mediated Activation of NFkappaB

转录因子NF-κ B在T细胞受体（TCR）参与后的活化是重要的 在适应性免疫应答期间T细胞增殖和活化。最近的报告描述了 一种涉及激酶PKC θ、支架蛋白CARD 11（也称为 CARMA-1）、含有CARD结构域的蛋白BcMO和paracaspase（与CARMA-1相关的蛋白酶）。 半胱天冬酶）MALT 1作为连接TCR与IkappaB激酶（IKK）复合物的关键中间体。然而，在这方面， 该信号通路激活后发生的事件的确切顺序仍然不清楚 定义了我们最近证明，3-磷酸肌醇依赖性激酶1（PDK 1）有一个与细胞凋亡相关的功能。 通过调节PKC θ的活化和通过信号依赖性的 招募PKC θ和CARD 11到脂筏。PDK 1相关的PKCq募集IKK复合体， 而PDK 1相关的CARD 11募集Bcl 10-MALT 1复合物，从而允许激活 IKK复合物通过称为NEMO的IKK复合物亚基的Bcl 10-MALT 1依赖性泛素化。 因此，PDK 1通过使T细胞中TCR诱导的NF-κ B活化途径成核而发挥关键作用。 在本提案中，我们将进一步扩展我们的观察，以更好地了解PDK-1如何招募 PKC θ和CARD 11。我们将识别这些交互中涉及的领域，并使用这些知识 从这些研究中设计出抑制T细胞活化的新方法。此外，我们还 发现PKC θ参与了TCR参与后LFA 1的激活，通过由内而外的 通路我们将通过建立新的遗传模型来确定这一途径的重要性， 我相信这将使PKC θ作为IKK募集的适配器的能力与其作为IKK募集的能力分离， 通过对LFA 1的作用促进稳定的结合和免疫突触。我们认为 这些研究将提供对关键细胞通路的更全面理解，并有机会 开发免疫抑制的新方法。

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.