SIGNAL TRANSDUCTION BY CALCINEURIN IN T LYMPHOCYTES

描述：(改编自调查人员的摘要)主要目标 这一建议是为了从分子水平上了解其发病机制 钙调神经磷酸酶在T淋巴细胞活化过程中的信号转导。这个 研究人员发现钙调神经磷酸酶是T细胞中的一种重要酶 受体(TCR)介导的白介素2信号转导途径 (IL-2)的产生和作为免疫抑制药物的共同靶点 环孢素A和FK506。已知钙调神经磷酸酶可调节 至少三类不同的转录因子，包括核因子-AT， 核因子-kB和AP-1。然而，许多信号分子参与了 钙调神经磷酸酶对核因子-kB和AP-1的激活作用尚不清楚。钙调神经磷酸酶 以多种异构体的形式存在；已经假设a异构体 钙调神经磷酸酶介导TCR信号转导。最近，钙调神经磷酸酶a被敲除。 但未观察到TCR介导的IL-2产生缺陷。在……里面 他的初步研究发现，另一种异构体，钙调神经磷酸酶b， 在T细胞中比钙调神经磷酸酶a更丰富，这表明钙调神经磷酸酶 B可能在TCR信号转导中起主导作用。使用抗FK506的 钙调神经磷酸酶突变体，他建议评估钙调神经磷酸酶b是否 足以调节TCR信号。他将使用酵母双杂交 钙调神经磷酸酶b底物及相关蛋白鉴定系统 揭示参与核因子-kB和AP-1活化的信号分子 钙调神经磷酸酶。或者，他还将使用催化非活性 从Jurkat细胞中鉴定钙调神经磷酸酶底物的钙调神经磷酸酶突变体 体外提取物。利用从酵母中获得的部分cDNA序列 从体外结合获得的双杂交筛选或寡肽序列， 编码可能的钙调神经磷酸酶底物及其相关的全长cDNA 蛋白质将被克隆，并在TCR的背景下进一步表征 发信号。通过这些分子识别新的信号分子 研究不仅将阐明转录因子受体信号的分子机制 转导，但也将提供新的目标，以设计更具体 毒性较小的免疫抑制剂。

DESCRIPTION: (Adapted from the investigator's abstract) The major goal of this proposal is to gain a molecular understanding of the mechanism of signal transduction by calcineurin during activation of T lymphocytes. The investigator has identified calcineurin as an important enzyme in the T cell receptor (TCR)-mediated signal transduction pathway leading to interleukin-2 (IL-2) production and as a common target for the immunosuppressive drugs cyclosporin A and FK506. Calcineurin is known to modulate the activities of at least three distinct classes of transcription factor including NF-AT, NF-kB and AP-1. However, many of the signaling molecules involved in the activation of NF-kB and AP-1 by calcineurin are not known. Calcineurin exists in multiple isoforms; it has been assumed that the a isoform of calcineurin mediates TCR signaling. Recently, calcineurin a was knocked out in mice, but no defect in the TCR-mediated IL-2 production was observed. In his preliminary studies, he has found that another isoform, calcineurin b, is more abundant than calcineurin a in T cells, suggesting that calcineurin b may play a dominant role in TCR signaling. Using FK506-resistant calcineurin mutants, he proposes to assess whether calcineurin b is sufficient to mediate TCR signaling. He will apply the yeast two-hybrid system to identify the substrates and associated proteins for calcineurin b to uncover signaling molecules involved in the activation of NF-kB and AP-1 by calcineurin. Alternatively, he will also employ catalytically inactive calcineurin mutants to identify calcineurin substrates from Jurkat cell extracts in vitro. Using partial cDNA sequences obtained from the yeast two-hybrid screen or oligopeptide sequences obtained from in vitro binding, the full length cDNA encoding putative calcineurin substrates and associated proteins will be cloned and further characterized in the context of TCR signaling. The identification of new signaling molecules through these studies will not only shed light on the molecular mechanism of TR signal transduction, but will also offer new targets for designing more specific and less toxic immunosuppressants.