Cyclic Strain–Induced Monocyte Chemotactic Protein-1 Gene Expression in Endothelial Cells Involves Reactive Oxygen Species Activation of Activator Protein 1

Abstract

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 H2O2 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 H2O2 inducibility. Electrophoretic mobility shift assays demonstrated an increase of nuclear proteins binding to TRE sequences from ECs subsequent to strain or H2O2 treatment. NAC or catalase pretreatment of ECs inhibited the strain- or H2O2-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.

Temporal Gradient in Shear But Not Steady Shear Stress Induces PDGF-A and MCP-1 Expression in Endothelial Cells

“…48 Although eNOS can produce NO as well as O 2 Ϫ , NOS inhibitors may only block NO production, 49,50 leading to excess O 2 Ϫ . Superoxide, in turn, can activate the transcription factors AP-1, 51 NFB, 52 and egr-1, 53 and therefore induce expression of MCP-1 and PDGF-A. Another source of O 2 Ϫ is activated Ras.…”

Reactive Oxygen Intermediates Induce Monocyte Chemotactic Protein-1 in Vascular Endothelium after Brief Ischemia

“…ROI scavenger experiments by Bolli and colleagues 12 used a glucose/glucose oxidase reaction to generate H 2 O 2 and measured its rate of production to be 11 mol/L/min. Experiments by Wung and colleagues 31 induced MCP-1 expression in bovine artery endothelial cells with exogenous H 2 O 2 at a concentration of 100 mol/L. Therefore, we stimulated CJVECs with equivalent concentrations of H 2 O 2 .…”

“…Because of the oxy-sensitive nature of the transcription factors AP-1 and NF-B 28 and their potential role in mediating the induction of MCP-1 by oxidant stress, 31 we investigated the effects of anti-oxidants NAC and PDTC on oxidant-induced AP-1 and NF-B DNA binding ( Figure 8). Nuclear proteins isolated from CJVECs pretreated with NAC (5 and 10 mmol/L) or PDTC (1 and 10 mmol/L) for 1 hour before stimulation with H 2 O 2 (100 mol/L) were incubated with consensus oligonucleotides against AP-1 ( Figure 8A) and NF-B ( Figure 8B).…”

Blood Pressure Parameters and Carotid Intraplaque Hemorrhage as Measured by Magnetic Resonance Imaging

“…2,7 That cyclic hemodynamic factors affect atherosclerosis progression and plaque instability is supported by several experimental models in which pulsatile strain was shown to affect the endothelium, vascular smooth muscle cells, and the production of elastin, collagen, and glycosaminoglycans, resulting in increased atherosclerotic plaque volume. [27][28][29][30] However, rupture of a plaque occurs when the stresses within the plaque exceed the strength of the plaque. Accordingly one would expect a greater contribution of SBP than PP causing rupture of the neovessels.…”