Control of T cell activation by the TSAd adapter protein

描述（由申请人提供）：T细胞对微生物、肿瘤细胞和正常自身细胞的反应，发生在自身免疫性疾病中，其特征是T细胞克隆扩增和针对相关外源或自身抗原的效应和记忆功能的发展。为了设计更有效的治疗传染病、癌症和自身免疫的药物疗法，了解不同T细胞表面受体接收的信号能够指导这些反应的细胞内机制是很重要的。与其他细胞类型一样，T细胞中有许多不同种类的细胞内分子参与信号转导。其中包括通过与催化活性分子形成信号复合物而在信号传导中起作用的细胞质适配器蛋白。最近发现的一种T细胞中的适配蛋白是T细胞特异性适配蛋白（TSAd），在小鼠中也称为lck相关适配蛋白（LAD）。该分子在诱导T细胞细胞因子、白细胞介素-2 (IL-2)（驱动T细胞增殖和记忆形成）和干扰素γ (ifn - γ)（参与T辅助i型效应T细胞的功能）中发挥重要作用。TSAd如何参与细胞内信号传导尚不清楚。然而，我们已经证明，TSAd是一种非典型的适配器蛋白，具有主要的核定位，可能至少部分地作为T细胞基因转录的直接调节剂。这项建议的长期目标是更详细地了解TSAd如何控制靶基因的转录。在这些研究中，我们将重点研究该蛋白的两个不同结构域，Src同源-2 （SH2）结构域和氨基末端区域。在一篇文章中，我们将验证SH2结构域通过识别p95-100 kDa的单个酪氨酸磷酸化配体的能力，作为TSAd核输入和转录活性的动态调节剂的假设。在第二个特定目标中，我们将测试假设，即氨基末端区域作为一个模块，赋予TSAd识别靶基因启动子中特定DNA序列的能力。这两个结构域对原代T细胞中TSAd转录功能和整个动物正常T细胞免疫的重要性将在本提案的第三个特定目标中进行测试。总之，这些研究应该导致对T细胞基因转录控制机制的新见解，此外，应该强调在某些类型的T细胞介导的免疫疾病中，异常T细胞反应性可能被预防的方法。

DESCRIPTION (provided by the applicant): T cell responses to microorganisms, neoplastic cells and normal self cells, as occurs in autoimmune diseases, are characterized by T cell clonal expansion and development of effector and memory function which is targeted toward the relevant foreign or self antigen. So as to design more effective drug therapies for the treatment of infectious diseases, cancer, and autoimmunity, it is important to understand the intracellular mechanisms by which signals received by different T cell surface receptors are able to instruct these responses. As in other cell types, numerous different classes of intracellular molecules are involved in signal transduction in T cells. Amongst these are cytoplasmic adapter proteins that function in signaling through the formation of signaling complexes with catalytically active molecules. One recently described adapter protein in T cells is the T cell-specific adapter protein (TSAd), also known as LCK-associated adapter protein (LAD) in mice. This molecule plays an important role in the induction of the T cell cytokines, interleukin-2 (IL-2), which drives T cell proliferation and memory formation, and interferon gamma (IFN-gamma), which is involved in the function of T helper-I-type effector T cells. How TSAd participates in intracellular signaling is unknown. However, we have demonstrated that TSAd is an atypical adapter protein that has a predominant nuclear localization that probably acts, at least in part, as a direct regulator of T cell gene transcription. The long-term objectives of this proposal are to understand in greater detail how TSAd controls the transcription of target genes. In these studies, we will focus upon two different domains of the protein, the Src homology-2 (SH2) domain and the amino-terminal region. In one Specific Aim, we will test the hypothesis the SH2 domain functions as a dynamic regulator of TSAd nuclear import and transcription activity through its ability to recognize a single tyrosine-phosphorylated ligand of p95-100 kDa. In a second Specific Aim, we will test the hypothesis that the amino-terminal region functions as a module that confers upon TSAd an ability to recognize specific DNA sequences in target gene promoters. The importance of these two domains for the transcription function of TSAd in primary T cells and for normal T cell immunity in whole animals will be tested in a third Specific Aim of this proposal. Together, these studies should lead to novel insights into mechanisms of T cell gene transcription control and, in addition, should highlight means by which aberrant T cell reactivity in certain types of T cell-mediated immune disease might be prevented.