T CELL RECEPTOR COUPLED SIGNALING AND APOPTOSIS

我们最近获得的证据表明，一种新的信号通路， 与由MTV超抗原进行的TCR连接相比， 导致瞬时激活和凋亡。 这种信号级联可能 与磷脂酶A2的MAP 2激酶依赖性活化相关 （PLA 2）和脂氧合酶，后者又催化反应性 氧中间体（R 01 s）。 我们还概述了证据表明， p50/52通路可能通过激活p50/52组分来调节基因表达 NF-kB复合物。 在具体目标1中，我们提出实验， 系统地定义了磷脂酶A2（PLA 2）激活的动力学， HPETE和羟基自由基（OH）的释放。 在具体目标2中，我们建议 以定义将TCR与PLA 2激活偶联的近端事件。 这将包括对MAP-2激酶在PLA 2中作用的初步评估。 激活，然后实验分析p21的潜在作用 Ras依赖性通路可能将这些事件与TCR连接联系起来。 描绘这条通路将使我们能够绘制出 这一途径和CD 28依赖性信号，抑制细胞凋亡， TCR连接后的反应。 在具体目标3中，我们提出实验 为了进一步定义可能导致 NF-κ B的活化。 在具体目标4中，我们将确定 羟基自由基的产生对于T细胞是必要的和充分的。 细胞凋亡或这些是否代表信号通路中的中间体 导致转录激活基因产物 细胞死亡的原因

We have recently obtained evidence for a novel signalling pathway coupled to TCR ligation by MTV superantigen an high concentrations of peptide which leads to transient activation and apoptosis. This signalling cascade may be associated with MAP2 kinase-dependent activation of phospholipase A2 (PLA2) and lipoxygenase which in turn catalyzes the generation of reactive oxygen intermediates (R01s). We also outline evidence suggesting that this pathway may regulate gene expression via activation of th p50/52 component of the NF-kB complex. In Specific Aim 1, we propose experiments to systematically define the kinetics of phospholipase A2 (PLA2) activation of HPETE and release of hydroxyl radicals (OH). In Specific Aim 2, we propose to define the proximal events which couple the TCR to PLA2 activation. This will include an initial assessment of the role of MAP-2 kinase in PLA2 activation, followed by experimental analysis of the potential roles of p21 Ras-dependent pathways that may connect these events with TCR ligation. Delineation of this pathway will allow us to map the interaction between this pathway and CD28-dependent signals which inhibit the apoptotic response following TCR ligation. In Specific Aim 3, we propose experiments to further define the distal biochemical events which may result in activation of NF-kB. In Specific Aim 4, we will determine whether generation of hydroxyl radicals is necessary and sufficient for T-cell apoptosis or whether these represent intermediates in a signalling pathway which results in transcriptional activation of gene products responsible for cell death.