Boots Agnes W, Hristova Milena, Kasahara David I, Haenen Guido R M M, Bast Aalt, van der Vliet Albert
Department of Pathology, University of Vermont, Burlington, Vermont 05405, USA.
J Biol Chem. 2009 Jun 26;284(26):17858-67. doi: 10.1074/jbc.M809761200. Epub 2009 Apr 21.
Activation of the NADPH oxidase homolog dual oxidase 1 (DUOX1) within the airway epithelium represents a key mechanism of innate airway host defense, through enhanced production of H2O2, which mediates cellular signaling pathways that regulate the production of various inflammatory mediators. Production of the CXC chemokine interleukin (IL)-8/CXCL8 forms a common epithelial response to many diverse stimuli, including bacterial and viral triggers, environmental oxidants, and other biological mediators, suggesting the potential involvement of a common signaling pathway that may involve DUOX1-dependent H2O2 production. Following previous reports showing that DUOX1 is activated by extracellular ATP and purinergic receptor stimulation, this study demonstrates that airway epithelial IL-8 production in response to several bacterial stimuli involves ATP release and DUOX1 activation. ATP-mediated DUOX1 activation resulted in the activation of ERK1/2 and NF-kappaB pathways, which was associated with epidermal growth factor receptor (EGFR) ligand shedding by ADAM17 (a disintegrin and metalloproteinase-17). Although ATP-mediated ADAM17 activation and IL-8 release were not prevented by extracellular H2O2 scavenging by catalase, these responses were attenuated by intracellular scavengers of H2O2 or related oxidants, suggesting an intracellular redox signaling mechanism. Both ADAM17 activation and IL-8 release were suppressed by inhibitors of EGFR/ERK1/2 signaling, which can regulate ADAM17 activity by serine/threonine phosphorylation. Collectively, our results indicate that ATP-mediated DUOX1 activation represents a common response mechanism to several environmental stimuli, involving H2O2-dependent EGFR/ERK activation, ADAM17 activation, and EGFR ligand shedding, leading to amplified epithelial EGFR activation and IL-8 production.
气道上皮细胞内烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶同系物双氧化酶1（DUOX1）的激活是先天性气道宿主防御的关键机制，其通过增强过氧化氢（H2O2）的生成来介导细胞信号通路，从而调节各种炎症介质的产生。CXC趋化因子白细胞介素（IL）-8/CXCL8的产生是上皮细胞对多种不同刺激的常见反应，这些刺激包括细菌和病毒触发因素、环境氧化剂及其他生物介质，这表明可能存在一条涉及DUOX1依赖性H2O2生成的共同信号通路。此前有报道显示DUOX1可被细胞外ATP和嘌呤能受体刺激激活，本研究表明气道上皮细胞对几种细菌刺激产生的IL-8涉及ATP释放和DUOX1激活。ATP介导的DUOX1激活导致细胞外信号调节激酶1/2（ERK1/2）和核因子κB（NF-κB）信号通路激活，这与去整合素和金属蛋白酶17（ADAM17）介导的表皮生长因子受体（EGFR）配体脱落有关。尽管过氧化氢酶清除细胞外H2O2并不能阻止ATP介导的ADAM17激活和IL-8释放，但H2O2或相关氧化剂的细胞内清除剂可减弱这些反应，提示存在一种细胞内氧化还原信号机制。EGFR/ERK1/2信号通路抑制剂可抑制ADAM17激活和IL-8释放，该信号通路可通过丝氨酸/苏氨酸磷酸化调节ADAM17活性。总之，我们的结果表明ATP介导的DUOX1激活是对几种环境刺激的常见反应机制，涉及H2O2依赖性EGFR/ERK激活、ADAM17激活和EGFR配体脱落，从而导致上皮细胞EGFR激活和IL-8生成增加。
