Individual and Collaborative Roles in T Cell Activation

T 细胞激活中的个体和协作作用

• 批准号: 6532033
• 负责人: Renren Wen
• 金额: $ 14.83万
• 依托单位: VERSITI WISCONSIN, INC.
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2006-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6532033
• 关键词: T cell receptor; T lymphocyte; autoimmunity; biological signal transduction; cell differentiation; enzyme activity; genetically modified animals; laboratory mouse; phospholipase C

DESCRIPTION (provided by the applicant): Development of T cells is an ordered process tightly controlled by signals emanating from the T cell receptor (TCR) or pre-TCR. The transition of CD4-CD8- double negative (DN) to CD4-CD8+ double positive (DP) thymocytes is governed by the pre-TCR. At the DP stage, thymocytes that have successfully rearranged their TCR undergo a selection process that allows self MHC-restricted and functionally competent but not autoreactive T cells to survive and mature. The current accepted hypothesis proposes that the avidity of TCR engagement determines the outcome of the selection. It is presumed that the degrees of affinity of TCR/MHC interaction determine the levels of TCR signaling strength, which consequently result in thymic selection. However, it is not clear what signaling molecules are involved in regulating the distal TCR signaling pathways linked to cellular responses. One of the early events in T cell activation is stimulation of phospholipid-specific phospholipase C (PLC)-gamma, which mediates calcium mobilization, PKC activation and activation of the Ras pathway, all of which are important for TCR signaling. PLCgamma has two isoforms, PLC-gamma1 and PLC-gamma2. It is believed that PLC-gamma1 accounts for all the PLC-gamma activity in T cells. However, our preliminary data suggest that PLC-gamma2 is also involved in TCR signaling, but its role is only revealed when PLC-gamma1 expression is reduced. Although previous cell line studies indicated an important role of PLC-gamma1 in TCR signaling, the function of PLC-gamma1 in T cell development has not been directly examined in vivo. Here, we propose that PLC-gamma activity is crucial for T cell development at both the pre-TCR and TCR signaling stages. We believe PLC-gamma activity is important for T cell positive and negative selection, and quantitative stimulation of PLC-gamma results in differential activation of the downstream signaling pathways relevant to thymic selection. The finding that both PLC-gamma1 and PLC-gamma2 are involved in TCR signaling provides us a model to analyze the influence of progressive reduction of PLC-gamma on T cell development and TCR activation. We propose to study the role of PLC-gamma in T cell positive and negative selection in Aim 1. The influence of quantitative PLC-gamma activation on the distal TCR signaling events related to T cell selection will be examined in Aim 2. In Aim 3 we will examine the role of PLC-gamma1 and PLCgamma2 in pre-TCR and TCR signaling by examining T cell development in mice null for PLC-gamma1 alone or for both PLC-gamma1 and PLC-gamma2 in the T cell lineage. Overall, these studies should define the role of PLC-gamma1 as well as PLC-gamma2 in TCR signaling and T cell development, and may provide the basis for the design of drugs that can selectively inhibit PLC-gamma downstream pathways and thus manipulate T cell activation.

描述（由申请人提供）：T细胞的开发是一个有序的过程，该过程由从T细胞受体（TCR）或TRE-TCR发出的信号紧密控制。 CD4-CD8-双负（DN）向CD4-CD8+双阳性（DP）胸腺细胞的过渡受PRE-TCR的控制。在DP阶段，成功重新排列其TCR的胸腺细胞经历了一个选择过程，该过程允许自我MHC限制和功能胜任，但不能自动反应性T细胞生存和成熟。当前接受的假设提出，TCR参与的亲和力决定了选择的结果。假定TCR/MHC相互作用的亲和力决定了TCR信号强度的水平，从而导致胸腺选择。但是，尚不清楚哪些信号分子在调节与细胞反应有关的远端TCR信号通路中涉及哪些信号分子。 T细胞激活中的早期事件之一是刺激磷脂特异性磷脂酶C（PLC）-Gamma，它介导了RAS途径的钙动员，PKC激活和激活，所有这些都对TCR信号很重要。 PLCGAMMA具有两个同工型PLC-GAMMA1和PLC-GAMMA2。据信，PLC-GAMMA1解释了T细胞中所有PLC-GAMMA活性。但是，我们的初步数据表明，PLC-GAMMA2也参与了TCR信号传导，但仅当PLC-Gamma1表达降低时才揭示其作用。尽管以前的细胞系研究表明PLC-GAMMA1在TCR信号传导中的重要作用，但PLC-GAMMA1在T细胞发育中的功能尚未在体内直接检查。在这里，我们提出PLC-GAMMA活性对于TCR和TCR信号阶段的T细胞发育至关重要。我们认为，PLC-GAMMA活性对于T细胞阳性和阴性选择很重要，并且定量刺激PLC-GAMMA会导致与胸腺选择相关的下游信号通路的差异激活。 PLC-GAMMA1和PLC-GAMMA2都参与TCR信号传导的发现为我们提供了一个模型，可以分析PLC-GAMMA逐渐减少T细胞发育和TCR激活的影响。我们建议研究PLC-gamma在目标1中的T细胞阳性和负选择中的作用。定量PLC-plc-plc-plc-plc-plc-plc-plc-plc-plc-plc-plc-plc-plc-plc-plc-plc-plc-gamma激活对与T细胞选择相关的远端TCR信号传导事件的影响将在目标2中检查。在目标3中，我们将研究PLC-GAMMA1和PLC-GAMMA1和PLCMAMMA2在PRC-TCR和TCR中的作用。和T细胞谱系中的PLC-GAMMA2。总体而言，这些研究应定义PLC-GAMMA1以及PLC-GAMMA2在TCR信号传导和T细胞发育中的作用，并可能为可以选择性抑制PLC-GAMMA下游途径的药物设计提供基础，从而操纵T细胞激活。