ROLE OF SH2D1A/SAP IN NKT CELL DEVELOPMENT AND FUNCTION

描述(由申请人提供)：包含Src同源2结构域的基因1A(SH2D1A)编码一种称为SAP的接头分子，该分子在X连锁淋巴增殖性疾病(XLP)患者中存在缺陷，XLP是一种与抗病毒和抗肿瘤免疫异常相关的疾病。SAP表达于T细胞和NK细胞，调节Th1和Th2细胞因子的产生，并发挥细胞毒作用。为了确定SAP是否控制NKT细胞的活性，NKT细胞是一种与T和NK细胞共享特征的淋巴细胞亚群，我们研究了SAP-/-小鼠和人类XLP患者是否存在这种谱系。值得注意的是，NKT细胞显著减少或缺失，这表明，除了在成熟的T和NK细胞中发挥重要作用外，SAP对NKT细胞的发育也是必需的。与缺乏NKT细胞一致，SAP-/-小鼠未能对α-半乳糖基神经酰胺(一种专门激活这些细胞的糖脂抗原)上调细胞因子。基于这些新的发现，我们假设SAP是一个关键的信号分子，它是协调控制NKT细胞个体发育的生化途径所必需的。我们还认为，NKT细胞的严重减少，当与功能异常的T和NK细胞相结合时，有助于XLP的发病。在这项提案中，我们的目标是严格剖析SAP在NKT细胞发育和成熟NKT细胞激活过程中的作用。为了确定人类NKT细胞分化过程中是否需要SAP，在目标1中，我们将使用基于细胞和分子的分析方法来评估更多XLP患者和相关免疫学缺陷患者的NKT细胞数量。在目标2中，我们将研究SAP是否是成熟NKT细胞功能所必需的。在SAP-/-小鼠重建NKT细胞发育后，WT和SAP-/-细胞将通过体外和体内实验进行研究。AIM 3中的结构-功能分析将定义SAP内部的域如何调节其参与NKT细胞信号传递。这些研究将增加我们对NKT细胞发育的了解，并可能为XLP或其他与NKT细胞定量或定性缺陷相关的人类疾病设计新的治疗方法，包括免疫缺陷、自身免疫和癌症。

DESCRIPTION (provided by applicant): The Src homology 2 domain-containing gene 1A (SH2D1A) encodes an adaptor molecule known as SAP that is defective in patients with X-linked lymphoproliferative disease (XLP), a disorder associated with abnormal antiviral and antitumor immunity. SAP is expressed in T cells and Natural Killer (NK) cells, where it regulates Thl and Th2 cytokine production, as well as cytotoxic function. To determine whether SAP controls the activity of NKT cells, a lymphocyte subset sharing features with T and NK cells, we examined SAP -/- mice and human XLP patients for the presence of this lineage. Remarkably, NKT cells were dramatically reduced or absent, suggesting that, in addition to its essential role in mature T and NK cells, SAP is required for NKT cell development. Consistent with the lack of NKT cells, SAP -/- mice failed to upregulate cytokines in response to a-galactosyl ceramide, a glycolipid antigen that specifically activates these cells. Based on these new findings, we hypothesize that SAP is a critical signaling molecule that is required for coordinating the biochemical pathways controlling NKT cell ontogeny. We also propose that the severe reduction in NKT cells, when combined with abnormally functioning T and NK cells, contributes to the pathogenesis of XLP. In this proposal, we aim to rigorously dissect the role of SAP during NKT cell development and mature NKT cell activation. To firmly establish whether SAP is required during human NKT cell differentiation, in Aim 1 we will use cell-based and molecular assays to evaluate NKT cell number in a larger spectrum of patients with XLP and related immunological defects. In Aim 2, we will study whether SAP is required for mature NKT cell function. After reconstituting NKT cell development in SAP -/- mice, WT and SAP -/-cells will be investigated using in vitro and in vivo assays. Structure-function analyses in Aim 3 will define how the domains within SAP mediate its participation in NKT cell signaling. These investigations will increase our understanding of NKT cell development and may enable the design of new treatments for XLP or other human diseases associated with quantitative or qualitative NKT cell defects, including immunodeficiency, autoimmunity and cancer.