The Role of Unc119 in T Cell Antigen Receptor Signaling1

描述（由申请人提供）：T细胞在免疫应答中起核心作用。T细胞受体（TCR）信号传导机制的第一步是激活酪氨酸激酶Src家族——Lck和Fyn。虽然对TCR的信号转导机制了解甚多，但Lck和Fyn激活的确切分子机制尚不清楚。通过酵母双杂交筛选，我们最近克隆了一种名为Unc119的新型SH3配体。在初步结果中，我们发现Unc119与TCR复合物（CD3和CD4）相关，在体外和体内激活Lck和Fyn。缺乏Unc119的细胞不能激活Lck和Fyn，不能产生IL-2，增殖能力差。本课题旨在研究Unc119对T细胞功能的信号功能，以及Unc119在特发性CD4淋巴细胞减少症（一种罕见的免疫缺陷疾病）发病机制中的作用。我们的具体目标是1)。研究Unc119活化Lck/Fyn的分子机制。2）. 探讨Unc119在T细胞分化和功能中的重要性。3）. 目的探讨Unc119在特发性CD4淋巴细胞减少症发病机制中的作用。我们将通过突变方法绘制Unc119的CD4和激酶（Lck/Fyn）结合位点，并研究这些位点对激酶激活的重要性。为了建立生物学相关性，我们将产生Unc119敲除小鼠，研究胸腺生成和T细胞功能。我们已经确定了一名ICL患者unc119缺乏和Lck激活受损。该患者在编码序列中有Arg50- >Lys突变，在3'非翻译区有另一个突变。我们将通过预先建立的合作在全国范围内筛选ICL患者，并检查这种和其他突变的存在。我们将通过研究蛋白质的翻译和衰变来研究这些突变的功能相关性。生物学相关性将通过在正常T细胞中表达突变基因来研究，反之亦然。该提案很重要，因为它描述了一种新的tcr相关酪氨酸激酶激活剂的鉴定和表征。此外，它还研究了特发性CD4淋巴细胞减少症的分子机制，这可能为这种罕见的免疫缺陷疾病的基因治疗铺平道路。

DESCRIPTION (provided by applicant): T cells play a central role in immune response. The first step in the signaling mechanism of the T cell receptor (TCR) is the activation of Src family of tyrosine kinases--Lck and Fyn. Although much is known about signal transduction mechanism of TCR, the exact molecular mechanism of Lck and Fyn activation is unknown. Through yeast two-hybrid screening we have recently cloned a novel SH3 ligand called Unc119. In preliminary results we show that Unc119 is associated with the TCR complex (CD3 and CD4) activates Lck and Fyn in vitro and in vivo. Unc119 deficient cells are unable to activate Lck and Fyn, fail to produce IL-2 and proliferate poorly. The objective of this research proposal is to study the signaling function of Unc119 for T cell function and the role of Unc119 in the pathogenesis of idiopathic CD4 lymphopenia, a rare immunodeficiency disorder. Our specific aims are 1). To study the molecular mechanism of Unc119 activation of Lck/Fyn. 2). To examine the importance of Unc119 for T cell differfentiation and function. 3). To investigate the role of Unc119 in the pathogenesis of idiopathic CD4 lymphopenia. We will map the CD4 and kinase (Lck/Fyn) binding sites of Unc119 through mutational approaches and study the importance of these sites for kinase activation. In order to establish the biological relevance, we will generate Unc119 knockout mice and study thymopoiesis and T cell function. We have identified one ICL patient with Unc119deficiency and impaired Lck activation. This patient has an Arg50-->Lys mutation in the coding sequence and has another mutation in the 3' untranslated region. We will screen ICL patients nationwide through preestablished collaboration and examine the presence of this and other mutations. We will examine the functional relevance of these mutations by studying translation and decay of the protein. The biological relevance will be studied by expressing the mutated gene in normal T cells and vice versa. The proposal is important because it describes the identification and characterization of a novel activator of TCR-associated tyrosine kinases. Further, it examines the molecular mechanism of idiopathic CD4 lymphopenia, which may pave the way to gene therapy for this rare immunodeficiency disorder.