Zu Y L, Qi J, Gilchrist A, Fernandez G A, Vazquez-Abad D, Kreutzer D L, Huang C K, Sha'afi R I
Department of Physiology, University of Connecticut Health Center, Farmington 06030, USA.
J Immunol. 1998 Feb 15;160(4):1982-9.
Mitogen-activated protein (MAP) kinase-mediated signal-transduction pathways convert extracellular stimulation into a variety of cellular functions. However, the roles of MAP kinases in neutrophils are not well understood yet. Protein phosphorylation analysis of cellular MAP kinases indicates that exposure of human neutrophils to chemotactic factor FMLP as well as granulocyte-macrophage CSF, PMA, or ionomycin rapidly induced the activation of p38 and p44/42 MAP kinases, but stimulation with inflammatory cytokine TNF-alpha triggered the activation of p38 MAP kinase only. To study the cellular functions of these MAP kinases, the inhibitor SB20358, which specifically inhibited enzymatic activity of cellular p38 MAP kinase, and the inhibitor PD98059, which specifically blocked the induced protein phosphorylation and activation of p44/42 MAP kinase in intact neutrophils, were utilized. Inhibition of the cellular p38 MAP kinase activation almost completely abolished the TNF-alpha-stimulated IL-8 production and superoxide generation of human neutrophils. In addition, the FMLP-induced neutrophil chemotaxis as well as superoxide generation were suppressed markedly by inhibiting the activation of cellular p38 MAP kinase, but not p44/42 MAP kinase. Moreover, RIA indicates that the activation of cellular p38 MAP kinase was required for the neutrophil IL-8 production stimulated by granulocyte-macrophage CSF or LPS as well as TNF-alpha, but not for that induced by PMA or ionomycin. These results demonstrate that the activation of cellular p38 MAP kinase is indispensable for the TNF-alpha- or FMLP-mediated cellular functions in human neutrophils, and suggest that p38 MAP kinase may play a different role in response to distinct stimulation.
丝裂原活化蛋白（MAP）激酶介导的信号转导通路可将细胞外刺激转化为多种细胞功能。然而，MAP激酶在中性粒细胞中的作用尚未完全明确。对细胞MAP激酶的蛋白质磷酸化分析表明，人类中性粒细胞暴露于趋化因子FMLP以及粒细胞-巨噬细胞集落刺激因子、佛波酯或离子霉素后，可迅速诱导p38和p44/42 MAP激酶的激活，但炎性细胞因子TNF-α刺激仅能触发p38 MAP激酶的激活。为研究这些MAP激酶的细胞功能，使用了特异性抑制细胞p38 MAP激酶酶活性的抑制剂SB20358，以及特异性阻断完整中性粒细胞中p44/42 MAP激酶诱导的蛋白质磷酸化和激活的抑制剂PD98059。抑制细胞p38 MAP激酶的激活几乎完全消除了TNF-α刺激的人类中性粒细胞IL-8产生和超氧化物生成。此外，抑制细胞p38 MAP激酶的激活可显著抑制FMLP诱导的中性粒细胞趋化以及超氧化物生成，但对p44/42 MAP激酶无此作用。而且，放射免疫分析表明，粒细胞-巨噬细胞集落刺激因子、脂多糖或TNF-α刺激的中性粒细胞IL-8产生需要细胞p38 MAP激酶的激活，但佛波酯或离子霉素诱导的IL-8产生则不需要。这些结果表明，细胞p38 MAP激酶的激活对于TNF-α或FMLP介导的人类中性粒细胞细胞功能是不可或缺的，提示p38 MAP激酶在对不同刺激的反应中可能发挥不同作用。
