The role of Notch signaling in T cell function

描述(申请人提供)：Notch蛋白家族由四个高度保守的膜受体组成。这些蛋白中至少有三个，Notch1，Notch2和Notch3，在淋巴发育的不同时间表达。在正常情况下，Notch的表达指导T细胞谱系的发展。Notch基因的异常表达可导致T淋巴样肿瘤，提示该基因的表达可能参与肿瘤转化。初步数据显示，通过T细胞受体(TCR)传递信号可以诱导Notch依赖的信号通路的表达和激活。为了确定TCR诱导的外周T细胞Notch表达的后果，研究了表达反义Notch结构(Notch AS)的小鼠。此外，还使用了Notch激活的药物抑制剂来抑制Notch的活性。使用这两种方法，提供的数据表明，Notch激活是TCR诱导的CD4和CD8 T细胞亚群增殖所必需的。根据我们的初步数据，我们假设外周T细胞中的Notch信号有几个重要的后果。首先，在CD4和CD8T细胞中，Notch信号驱动细胞因子的产生和增殖。我们还提出了一种通过TCR调节Notch表达并导致NF-kB激活的特定信号通路。我们认为，在CD8T细胞中，转录因子Notch对核因子-kB的活性和干扰素-γ的产生都是必需的，并提示核因子-kB可能直接调节CD8细胞中干扰素-γ的产生。我们还提出，Notch对于Th1的功能是必需的，它是通过参与初始的CD4细胞极化为Th1或在极化后驱动Th1细胞因子的产生来实现的。我们的数据还支持在CD4+、CD25-亚群和CD4+、CD25+亚群中Notch的不同激活作用，并提示这些重要的CD4T细胞亚群中Notch的表达可能具有功能后果。最后，我们认为Notch可能通过激活细胞周期蛋白D2和D3来调节T细胞的细胞周期进程。针对所提出的假设，本文提出了四个目标。目的研究TCR信号如何调节Notch的激活。AIM II询问Notch是如何调节核因子-kB的。目的III研究Notch激活在外周T细胞中的功能后果，Aim IV研究Notch如何调节T细胞中的细胞周期进程。

DESCRIPTION (provided by applicant): The Notch family of proteins is comprised of four highly conserved membrane receptors. At least three of these proteins, Notch1, Notch2 and Notch3, are expressed at various times during lymphoid development. Under normal circumstances, Notch expression directs the development of the T cell lineage. Aberrant Notch expression results in T lymphoid tumors suggesting the expression of this gene can participate in oncogenic transformation. Preliminary data presented in this proposal demonstrate that signaling via the T cell receptor (TCR) induces both the expression and activation of a Notch-dependent signaling pathway. To determine the consequences of TCR-induced Notch expression in peripheral T cells, mice expressing an antisense Notch construct (Notch AS) were examined. Additionally pharmacological inhibitors of Notch activation were used to inhibit Notch activity. Using these two approaches, data is presented demonstrating that Notch activation is required for TCR-induced proliferation of both CD4 and CD8 subsets of T cells. From our preliminary data, we hypothesize that Notch signaling in peripheral T cells has several important consequences. First of all, in both CD4 and CD8 T cells, Notch signaling drives cytokine production and proliferation. We also suggest a specific signaling pathway through the TCR that regulates Notch expression and results in activation of NF-kB. We propose that Notch is required for both NF-kB activity and IFN-gamma production in CD8 T cells and suggest that NF-kB may directly regulate IFN-gamma production in CD8 cells. We also propose that Notch is required for Th1 function either by participating in the polarization of naive CD4 cells into Th1 or by driving Th1 cytokine production following polarization. Our data also support a role for differential Notch activation in the CD4+, CD25- subset versus the CD4+, CD25+ subset and suggest that Notch expression in these important CD4 T cell subsets may have functional consequences. Lastly we propose that Notch may regulate cell cycle progression in T cells through activation of cyclin D2 and D3. Four aims are proposed to address the hypotheses presented. Aim I asks how TCR signaling regulates Notch activation. Aim II asks how Notch regulates NF-kB. Aim III examines the functional consequences of Notch activation in peripheral T cells and Aim IV asks how Notch regulates cell cycle progression in T cells.