Ding M, Shi X, Lu Y, Huang C, Leonard S, Roberts J, Antonini J, Castranova V, Vallyathan V
Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, West Virginia 26505, USA.
J Biol Chem. 2001 Mar 23;276(12):9108-14. doi: 10.1074/jbc.M007666200. Epub 2000 Nov 28.
We reported previously that freshly fractured silica (FFSi) induces activator protein-1 (AP-1) activation through extracellular signal-regulated protein kinases (ERKs) and p38 kinase pathways. In the present study, the biologic activities of FFSi and aged silica (ASi) were compared by measuring their effects on the AP-1 activation and phosphorylation of ERKs and p38 kinase. The roles of reactive oxygen species (ROS) in this silica-induced AP-1 activation were also investigated. We found that FFSi-induced AP-1 activation was four times higher than that of ASi in JB6 cells. FFSi also caused greater phosphorylation of ERKs and p38 kinase than ASi. FFSi generated more ROS than ASi when incubated with the cells as measured by electron spin resonance (ESR). Studies using ROS-sensitive dyes and oxygen consumption support the conclusion that ROS are generated by silica-treated cells. N-Acetylcysteine (an antioxidant) and polyvinyl pyridine-N-oxide (an agent that binds to Si-OH groups on silica surfaces) decreased AP-1 activation and phosphorylation of ERKs and p38 kinase. Catalase inhibited phosphorylation of ERKs and p38 kinase, as well as AP-1 activation induced by FFSi, suggesting the involvement of H(2)O(2) in the mechanism of silica-induced AP-1 activation. Sodium formate (an ( small middle dot)OH scavenger) had no influence on silica-induced MAPKs or AP-1 activation. Superoxide dismutase enhanced both AP-1 and MAPKs activation, indicating that H(2)O(2), but not O(2), may play a critical role in silica-induced AP-1 activation. These studies indicate that freshly ground silica is more biologically active than aged silica and that ROS, in particular H(2)O(2), play a significant role in silica-induced AP-1 activation.
我们之前报道过，新鲜破碎的二氧化硅（FFSi）通过细胞外信号调节蛋白激酶（ERK）和p38激酶途径诱导活化蛋白-1（AP-1）激活。在本研究中，通过测量FFSi和老化二氧化硅（ASi）对AP-1激活以及ERK和p38激酶磷酸化的影响，比较了它们的生物学活性。还研究了活性氧（ROS）在这种二氧化硅诱导的AP-1激活中的作用。我们发现，在JB6细胞中，FFSi诱导的AP-1激活比ASi高四倍。FFSi还比ASi引起更高程度的ERK和p38激酶磷酸化。通过电子自旋共振（ESR）测量，与细胞孵育时，FFSi产生的ROS比ASi更多。使用ROS敏感染料和耗氧量的研究支持了二氧化硅处理的细胞产生ROS的结论。N-乙酰半胱氨酸（一种抗氧化剂）和聚乙烯吡啶-N-氧化物（一种与二氧化硅表面的Si-OH基团结合的试剂）降低了AP-1激活以及ERK和p38激酶的磷酸化。过氧化氢酶抑制了ERK和p38激酶的磷酸化以及FFSi诱导的AP-1激活，表明H2O2参与了二氧化硅诱导的AP-1激活机制。甲酸钠（一种·OH清除剂）对二氧化硅诱导的丝裂原活化蛋白激酶（MAPK）或AP-1激活没有影响。超氧化物歧化酶增强了AP-1和MAPK的激活，表明H2O2而非O2可能在二氧化硅诱导的AP-1激活中起关键作用。这些研究表明，新鲜研磨的二氧化硅比老化的二氧化硅具有更高的生物活性，并且ROS，特别是H2O2，在二氧化硅诱导的AP-1激活中起重要作用。
