Watanabe Mayuki, Terasawa Masao, Miyano Kei, Yanagihara Toyoshi, Uruno Takehito, Sanematsu Fumiyuki, Nishikimi Akihiko, Côté Jean-François, Sumimoto Hideki, Fukui Yoshinori
Division of Immunogenetics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan;
Department of Biochemistry, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan;
J Immunol. 2014 Dec 1;193(11):5660-7. doi: 10.4049/jimmunol.1400885. Epub 2014 Oct 22.
Neutrophils are highly motile leukocytes that play important roles in the innate immune response to invading pathogens. Neutrophils rapidly migrate to the site of infections and kill pathogens by producing reactive oxygen species (ROS). Neutrophil chemotaxis and ROS production require activation of Rac small GTPase. DOCK2, an atypical guanine nucleotide exchange factor (GEF), is one of the major regulators of Rac in neutrophils. However, because DOCK2 deficiency does not completely abolish fMLF-induced Rac activation, other Rac GEFs may also participate in this process. In this study, we show that DOCK5 acts with DOCK2 in neutrophils to regulate multiple cellular functions. We found that fMLF- and PMA-induced Rac activation were almost completely lost in mouse neutrophils lacking both DOCK2 and DOCK5. Although β2 integrin-mediated adhesion occurred normally even in the absence of DOCK2 and DOCK5, mouse neutrophils lacking DOCK2 and DOCK5 exhibited a severe defect in chemotaxis and ROS production. Similar results were obtained when human neutrophils were treated with CPYPP, a small-molecule inhibitor of these DOCK GEFs. Additionally, we found that DOCK2 and DOCK5 regulate formation of neutrophil extracellular traps (NETs). Because NETs are involved in vascular inflammation and autoimmune responses, DOCK2 and DOCK5 would be a therapeutic target for controlling NET-mediated inflammatory disorders.
中性粒细胞是高度可移动的白细胞，在对入侵病原体的固有免疫反应中发挥重要作用。中性粒细胞迅速迁移到感染部位，并通过产生活性氧（ROS）杀死病原体。中性粒细胞的趋化作用和ROS产生需要Rac小GTP酶的激活。DOCK2是一种非典型鸟嘌呤核苷酸交换因子（GEF），是中性粒细胞中Rac的主要调节因子之一。然而，由于DOCK2缺陷并没有完全消除fMLF诱导的Rac激活，其他Rac GEF也可能参与这一过程。在本研究中，我们表明DOCK5在中性粒细胞中与DOCK2共同作用，调节多种细胞功能。我们发现，在同时缺乏DOCK2和DOCK5的小鼠中性粒细胞中，fMLF和PMA诱导的Rac激活几乎完全丧失。尽管即使在没有DOCK2和DOCK5的情况下，β2整合素介导的黏附也能正常发生，但缺乏DOCK2和DOCK5的小鼠中性粒细胞在趋化作用和ROS产生方面表现出严重缺陷。当用人中性粒细胞用这些DOCK GEF的小分子抑制剂CPYPP处理时，也得到了类似的结果。此外，我们发现DOCK2和DOCK5调节中性粒细胞胞外陷阱（NETs）的形成。由于NETs参与血管炎症和自身免疫反应，DOCK2和DOCK5可能是控制NET介导的炎症性疾病的治疗靶点。
