Cyclic strain-induced monocyte chemotactic protein-1 gene expression in endothelial cells involves reactive oxygen species activation of activator protein 1
Wung, B.S.; Cheng, J.J.; Hsieh, H.J.; Shyy, Y.J.; Wang, D.L.
Circulation Research 81(1): 1-7
1997
ISSN/ISBN: 0009-7330 PMID: 9201021 Document Number: 480264
Endothelial cells (ECs) are constantly exposed to blood pressure-induced mechanical strain. We have previously demonstrated that cyclic strain can induce gene expression of monocyte chemotactic protein-1 (MCP-1). The molecular mechanisms of gene induction by strain, however, remain unclear. Recent evidence indicates that intracellular reactive oxygen species (ROS) can act as a second messenger for signal transduction and thus affect gene expression. The potential role of ROS in strain-induced MCP-1 expression was investigated. ECs under cyclic strain induced a sustained elevated production of intracellular superoxide. ECs under strain or pretreated with either H-2O-2 or xanthine oxidase/hypoxanthine induced MCP-1 expression. Strain- or oxidant-induced MCP-1 mRNA levels could be inhibited by treating ECs with catalase or antioxidant N-acetyl-cysteine (NAC). Functional analysis of MCP-1 promoter and site-specific mutations indicates that the proximal tissue plasminogen activator-responsive element (TRE) in the -60-bp promoter region is sufficient for strain or H-2O-2 inducibility. Electrophoretic mobility shift assays demonstrated an increase of nuclear proteins binding to TRE sequences from ECs subsequent to strain or H-2O-2 treatment. NAC or catalase pretreatment of ECs inhibited the strain- or H-2O-2-induced AP-1 binding. These results clearly indicate that cyclic strain inducibility of MCP-1 in ECs uses the interaction of AP-1 proteins with TRE sites via the elevation of intracellular ROS levels in strained ECs. These findings emphasize the importance of intracellular ROS in the modulation of hemodynamic force-induced gene expression in vascular ECs.