Liu Honglei, Zhang Hongqiao, Iles Karen E, Rinna Alessandra, Merrill Gary, Yodoi Junji, Torres Martine, Forman Henry Jay
School of Natural Sciences, University of California Merced, Merced, CA 95340, USA.
Free Radic Res. 2006 Aug;40(8):865-74. doi: 10.1080/10715760600758514.
The role of H2O2 as a second messenger in signal transduction pathways is well established. We show here that the NADPH oxidase-dependent production of O2*(-) and H2O2 or respiratory burst in alveolar macrophages (AM) (NR8383 cells) is required for ADP-stimulated c-Jun phosphorylation and the activation of JNK1/2, MKK4 (but not MKK7) and apoptosis signal-regulating kinase-1 (ASK1). ASK1 binds only to the reduced form of thioredoxin (Trx). ADP induced the dissociation of ASK1/Trx complex and thus resulted in ASK1 activation, as assessed by phosphorylation at Thr845, which was enhanced after treatment with aurothioglucose (ATG), an inhibitor of Trx reductase. While dissociation of the complex implies Trx oxidation, protein electrophoretic mobility shift assay detected oxidation of Trx only after bolus H2O2 but not after ADP stimulation. These results demonstrate that the ADP-stimulated respiratory burst activated the ASK1-MKK4-JNK1/c-Jun signaling pathway in AM and suggest that transient and localized oxidation of Trx by the NADPH oxidase-mediated generation of H2O2 may play a critical role in ASK1 activation and the inflammatory response.
H2O2作为信号转导途径中的第二信使的作用已得到充分证实。我们在此表明，肺泡巨噬细胞（AM，NR8383细胞）中依赖NADPH氧化酶产生O2*(-)和H2O2或呼吸爆发，是ADP刺激的c-Jun磷酸化以及JNK1/2、MKK4（而非MKK7）和凋亡信号调节激酶-1（ASK1）激活所必需的。ASK1仅与还原型硫氧还蛋白（Trx）结合。ADP诱导ASK1/Trx复合物解离，从而导致ASK1激活，通过Thr845位点的磷酸化评估，在用硫氧还蛋白还原酶抑制剂金硫葡萄糖（ATG）处理后这种激活增强。虽然复合物的解离意味着Trx氧化，但蛋白质电泳迁移率变动分析仅在注射H2O2后而非ADP刺激后检测到Trx氧化。这些结果表明，ADP刺激的呼吸爆发激活了AM中的ASK1-MKK4-JNK1/c-Jun信号通路，并提示NADPH氧化酶介导的H2O2生成导致的Trx瞬时和局部氧化可能在ASK1激活和炎症反应中起关键作用。
