Regulation of NK Cell Function by Vav-family Proteins

Vav 家族蛋白对 NK 细胞功能的调节

• 批准号: 6854460
• 负责人: WOJCIECH A SWAT
• 金额: $ 19.13万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-03-01 至 2007-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6854460
• 关键词: bioassay; biological signal transduction; cell mediated cytotoxicity; cellular immunity; gene mutation; genetically modified animals; guanine nucleotide exchange factors; immunologic receptors; immunoregulation; laboratory mouse; leukocyte activation /transformation; membrane proteins; microorganism immunology; natural killer cells; neoplasm /cancer immunology; phosphorylation; site directed mutagenesis; tissue /cell culture; tyrosine

DESCRIPTION (provided by applicant): Vav proteins are guanine nucleotide exchange factors and molecular adaptors that play a key role in signal transduction of lymphocyte antigen receptors. Several recent studies have also implicated Vav1 in natural killer (NK) cell-mediated cytotoxicity of tumor cells. However, whether Vav1 effects all NK cell activating pathways is not known, and it is possible that other Vav family molecules are involved in NK cell triggering. NK cells recognize tumor or virally-infected cells through multiple activating receptors with diverse structures, specificities and signaling adaptors. The activating NK cell receptor NKG2D recognizes endogenous major histocompatibility complex (MHC) class I-related molecules expressed at high levels primarily in virally infected and tumor cells while Ly49H mediates selective recognition of m157, a murine cytomegalovirus (MCMV)-encoded class I-like molecule that is expressed on infected cells. Both NKG2D and Ly49H deliver stimulatory signals which trigger secretion of IFN-? and release of cytotoxic granules that contain perforin and granzymes. However, it is not know exactly how such stimulatory signals are transduced inside the NK cells. NKG2D and Ly49D/H lack cytoplasmic signaling elements and can deliver stimulatory signals only by associating with transmembrane adaptor proteins. Ly49D and Ly49H signal through DAP12 (also called KARAP) which contains immunoreceptor tyrosine-based activation motifs (ITAM) that are phosphorylated and function as docking sites for Syk and ZAP70 protein tyrosine kinases. In contrast, NKG2D signals through DAP10, a unique adapter that contains a YxNM motif which recruits phosphatidyl inositol 3-kinase (PI3-K) and Grb-2. As part of our preliminary studies for this proposal we generated mice lacking the individual, or all, Vavfamily proteins and began to examine the potential contribution of these proteins to NK cell cytotoxicity. Intriguingly, these data indicate that Vav is essential for DAP10- but not for DAP12-mediated natural cytotoxicity. Thus, these data suggest a new paradigm regarding the utilization of Vav in activation of natural cytotoxicity downstream of NK cell surface receptors associated with non-ITAM- vs. ITAM-containing adaptors. Here, we propose to use several in vitro and in vivo approaches to determine Vav mechanism in NK cell function and development of natural cytotoxicity against virally-infected and tumor cells.

描述（申请人提供）：Vav蛋白是鸟嘌呤核苷酸交换因子和分子接头，在淋巴细胞抗原受体的信号转导中发挥关键作用。最近的几项研究还表明 Vav1 与自然杀伤 (NK) 细胞介导的肿瘤细胞细胞毒性有关。然而，Vav1是否影响所有NK细胞激活途径尚不清楚，其他Vav家族分子可能参与NK细胞触发。 NK 细胞通过具有不同结构、特异性和信号适配器的多种激活受体来识别肿瘤或病毒感染的细胞。激活的 NK 细胞受体 NKG2D 识别主要在病毒感染细胞和肿瘤细胞中高水平表达的内源性主要组织相容性复合体 (MHC) I 类相关分子，而 Ly49H 介导选择性识别 m157，m157 是一种鼠巨细胞病毒 (MCMV) 编码的 I 类样分子在受感染细胞上表达的分子。 NKG2D 和 Ly49H 均传递刺激信号，触发 IFN-α 的分泌。并释放含有穿孔素和颗粒酶的细胞毒性颗粒。然而，目前尚不清楚此类刺激信号是如何在 NK 细胞内转导的。 NKG2D 和 Ly49D/H 缺乏细胞质信号元件，只能通过与跨膜接头蛋白结合来传递刺激信号。 Ly49D 和 Ly49H 通过 DAP12（也称为 KARAP）发出信号，DAP12 包含基于免疫受体酪氨酸的激活基序 (ITAM)，这些基序被磷酸化并充当 Syk 和 ZAP70 蛋白酪氨酸激酶的对接位点。相比之下，NKG2D 通过 DAP10 发出信号，DAP10 是一种独特的接头，包含 YxNM 基序，可招募磷脂酰肌醇 3 激酶 (PI3-K) 和 Grb-2。 作为该提案初步研究的一部分，我们培育了缺乏单个或全部 Vav 家族蛋白的小鼠，并开始研究这些蛋白对 NK 细胞毒性的潜在贡献。有趣的是，这些数据表明 Vav 对于 DAP10 介导的天然细胞毒性至关重要，但对于 DAP12 介导的天然细胞毒性则不然。因此，这些数据提出了关于利用 Vav 激活与非 ITAM 与含 ITAM 接头相关的 NK 细胞表面受体下游天然细胞毒性的新范例。在这里，我们建议使用几种体外和体内方法来确定 NK 细胞功能中的 Vav 机制以及针对病毒感染和肿瘤细胞的天然细胞毒性的发展。