Mechanisms Regulating Human NK Cell Cytotoxicity

NK细胞是淋巴细胞的一个亚群，其独特的受体有助于检测感染病毒， 转化的，或“受压力的”细胞。这种免疫识别随后导致了NK细胞的发展-- 介导的细胞毒性或产生的细胞因子和趋化因子，激活细胞的其他成分 免疫系统。高IgE综合征(HIEs)患者存在免疫调节失调，可受 顽固性皮肤疱疹病毒和乳头瘤病毒感染。在这些基因中发现的一种主要的基因异常 患者是编码胞质分裂因子8(DOCK8)基因的缺失或功能丧失突变，a Cdc42的鸟嘌呤核苷酸交换因子。复发性皮肤病毒的高发病率 DOCK8缺陷患者的感染提示自然杀伤(NK)细胞功能缺陷。事实上，其他人 我们最近发现，DOCK8缺乏的NK细胞的裂解功能降低， 黏附，F-肌动蛋白在细胞毒性突触聚集，以及无法将溶解颗粒极化到 目标单元格。然而，DOCK8是如何调控NK细胞杀伤发展中的许多关键步骤的 不知道。我们的中心假设是DOCK8-相互作用体协调肌动蛋白的调节 微管细胞骨架促进NK细胞极化，影响NK细胞的细胞毒作用。 根据该提案中包含的初步数据，我们假设：(A)CDC42的DOCK8激活 对NK细胞杀伤的发展至关重要；(B)DOCK8与WASP的相互作用是其定位的关键 并在NKIS产生F-肌动蛋白；(C)DOCK8募集Talin介导NK细胞与靶细胞的黏附；(D) HkRP3是一种造血表达的蛋白，与DOCK8相互作用，参与MTOC极化和 溶解颗粒聚集及其与微管蛋白和动力蛋白相互作用对溶解颗粒聚集的影响 运动复合体；(E)Septins是DOCK8相互作用的蛋白质，调节NK细胞的杀伤；(F)Borg稳定 为了调节NK细胞的杀伤，活性的CDC42损伤了间隔蛋白细丝的活性。为了测试这些 假设我们将：(1)确定DOCK8调节F-肌动蛋白动力学和细胞的机制 (2)确定HkRP3调节溶解颗粒聚集和MTOC的机制 极化；(3)确定Septins在调节NK细胞杀伤活性中的作用。选举的结果是 拟议的实验将为理解以下分子事件提供实验基础 参与调节NK细胞效应器的功能，在更广泛的背景下，将促进我们的 了解细胞激活导致F-肌动蛋白调节、MTOC极化的基本过程 颗粒胞吐。此外，通过这些研究获得的信息可能会指导如何 DOCK8在其他免疫细胞中发挥作用。

NK cells are a subpopulation of lymphocytes whose unique receptors facilitate the detection of infected, transformed, or `stressed' cells. This immune recognition subsequently leads to the development of NK cell- mediated cytotoxicity or the generation of cytokines and chemokines that activate other components of the immune system. Patients with hyper-IgE syndrome (HIES) have immune dysregulation and can be affected by recalcitrant cutaneous herpes virus and papillomavirus infections. A major genetic abnormality found in these patients is deletion or loss-of-function mutations in the gene encoding Dedicator of Cytokinesis 8 (DOCK8), a guanine nucleotide exchange factor (GEF) for Cdc42. The high incidence of recurrent cutaneous viral infections in DOCK8-deficient patients is suggestive of defects in natural killer (NK) cell function. In fact, others and we have recently shown that NK cells deficient in DOCK8 have reduced lytic function, decreased adhesion, F-actin accumulation at the cytotoxic synapse and an inability to polarize lytic granules toward the target cell. However, how DOCK8 can regulate so many critical steps in the development of NK cell killing is not known. It is our central hypothesis that the DOCK8-interactome coordinates the regulation of the actin and microtubule cytoskeletons to facilitate NK cell polarization and effect NK cellular cytotoxicity. Based on the preliminary data included in this proposal, we hypothesize that: (a) DOCK8 activation of CDC42 is critical to the development of NK cell killing; (b) DOCK8 interaction with WASP is critical for its localization and F-actin generation at the NKIS; (c) talin recruitment by DOCK8 mediates NK cell – target adhesion; (d) HkRP3, a hematopoietically expressed protein that interacts with DOCK8 is involved in MTOC polarization and lytic granule clustering and affects lytic granule clustering through its interactions with tubulin and the dynein motor complex; (e) septins are DOCK8 interacting proteins that regulate NK cell killing; (f) BORG stabilization of septin filaments is impaired by active Cdc42 in order to regulate NK cell killing. In order to test these hypotheses we will: (1) Determine the mechanism by which DOCK8 regulates F-actin dynamics and cell adhesion; (2) Define the mechanism by which HkRP3 regulates lytic granule convergence and MTOC polarization; (3) Determine the role of septins in the regulation of the NK cell cytotoxicity. The outcome of the proposed experiments will provide an experimental basis for understanding the molecular events that are involved in the regulation of NK cell effector functions, and will, in a broader context, advance our understanding of fundamental processes in cellular activation leading to F-actin regulation, MTOC polarization and granule exocytosis. Moreover, the information obtained through these studies will likely instruct how DOCK8 is functioning in other immune cells.