Immune Defense: The Role of NKG2D/DAP10

NK细胞提供针对已被病毒感染的细胞或经历病毒感染的细胞的第一线监测。 肿瘤性转化在众多介导NK细胞识别的细胞表面受体中， 作为靶细胞，NKG2D的独特之处在于它识别各种I类相关分子，这些分子充当"标志" 感染或异常的细胞。体外研究表明，NKG2D仅依赖于跨膜 适配器DAP 10用于信令。DAP 10含有募集磷脂酰肌醇-3激酶的YxxM基序。 已经在CD28中报道了相同的对接基序，其介导naTve T细胞中的共刺激信号。 因此，NKG2D/DAP 10目前被认为是所有NK细胞上的共刺激复合物， 激活细胞毒性T细胞。NKG2D/DAP 10和CD28之间的这种功能平行性提出了几个问题。 重要问题：NK细胞是否需要共刺激信号来杀死其靶细胞和/或在体内增殖？是 NKG2D/DAP 10参与外周淋巴器官中CD8 * T细胞的引发和扩增，类似于 CD28？或者，NKG2D/DAP 10是否主要增强针对表达NKG2D的细胞的CTL效应子应答 外周组织中的配体 为了解决这些关键问题，我们通过基因靶向产生了DAP 10缺陷小鼠。我们 初步结果表明，在NK细胞中，NKG2D不仅能够与DAP 10结合， 也与适配体DAP 12，其通过不同的细胞内信号传导途径介导直接激活。 相反，在T细胞中，NKG2D仅与DAP 10结合，因此仅限于YxxM "共刺激"途径。在这些结果的基础上，我们建议剖析NKG2D/DAP 10的作用， 在NK细胞生物学中的"共刺激"和NKG2D/DAP 12 "激活"途径， DAP10~#小鼠与DAP12~#小鼠及正常小鼠的体内、体外实验结果表明，此外，我们建议澄清 NKG2D/DAP 10 "共刺激"通路在抗病毒和抗肿瘤CD8 <$T细胞应答中的作用 vivo.为此，我们将分析DAP 10-#的激活、扩增和效应子功能的获得。 病毒感染和肿瘤移植小鼠模型中的CD8~+ T细胞。此外，我们会研究 DAP10对建立和维持初级记忆后的长期记忆CTL的要求 感染和肿瘤疫苗接种。 虽然先前的研究表明NKG2D配体在病毒感染和肿瘤中的表达 细胞对于产生保护性免疫反应很重要，但目前尚不清楚NKG 2D的原因和位置 在响应期间需要信令。因此，详细了解NKG2D/DAP 10的体内功能 基于对DAP 10-/-小鼠的分析，特别是考虑到可能的开发， NKG2D-NKG2D-配体相互作用在肿瘤治疗和疫苗设计中的应用。

NK cells provide first line surveillance against cells that have been infected by viruses or undergo neoplastic transformation. Among the numerous cell surface receptors mediating NK cell recognition of target cells, NKG2D is unique in that it recognizes a variety of class I-related molecules that serve as "flags" for infected or abnormal cells. In vitro studies indicate that NKG2D depends solely on the transmembrane adapter DAP10 for signaling. DAP10 contains an YxxM motif that recruits Phosphatidyl Inositol-3 Kinase. The same docking motif has been reported in CD28, which mediates a costimulatory signal in naTve T cells. Therefore, NKG2D/DAP10 is currently considered a costimulatory complex on all NK cells as well as on activated cytotoxic T cells. This functional parallel between NKG2D/DAP10 and CD28 raises several important issues: Do NK cells require a costimulatory signal to kill their targets and/or proliferate in vivo? Is NKG2D/DAP10 involved in priming and expansion of CD8*T cells in peripheral lymphoid organs, similar to CD28? Or, does NKG2D/DAP10 mainly enhance CTL effector responses against cells expressing NKG2D ligands in peripheral tissues? To address these crucial questions we have generated DAP10-deficient mice by gene targeting. Our preliminary results indicate that in NK cells, NKG2D has the capacity to associate not only with DAP10 but also with the adapter DAP12, which mediates direct activation via a distinct intracellular signaling pathway. In contrast, in T cells, NKG2D associates only with DAP10 and therefore is limited to the YxxM "costimulatory" pathway. On the basis of these results, we propose to dissect the role of NKG2D/DAP10 "costimulatory" and NKG2D/DAP12 "activating" pathways in NK cell biology by comparing NK cell function in DAP10 # mice with that of DAP12 _ and normal mice in vitro and in vivo. In addition, we propose to clarify the role of the NKG2D/DAP10 "costimulatory" pathway in anti-viral and anti-tumor CD8¿T cell responses in vivo. For this purpose, we will analyse activation, expansion and acquisition of effector function of DAP10 -# CD8¿T cell in mouse models of viral infection and tumor engraftment. In addition, we will study the requirement of DAP10 for establishment and maintenance of long-term memory CTLs following primary infections and tumor vaccination. While previous studies have indicated that expression of NKG2D ligands on virally infected and tumor cells is important for generating a protective immune response, it is not understood why and where NKG2D signaling is required during the response. Therefore, detailed knowledge of NKG2D/DAP10 function in vivo based on the analysis of DAP10-/- mice will be of great value, particularly in view of the possible exploitation of NKG2D-NKG2D-ligands interactions in tumor therapy and vaccine design.