CCL2 regulates angiogenesis via activation of Ets-1 transcription factor

Abstract

Although recent studies have suggested that CC chemokine CCL2 may directly affect the angiogenesis, the signaling events involved in such regulation remain to be determined. This study investigated a potential signal mechanism involved in CCL2-induced angiogenesis. Our in vitro and in vivo (hemangioma model of angiogenesis) experiments confirmed earlier findings that CCL2 can induce angiogenesis directly. Using a gene array analysis, CCL2 was found to induce expression of several angiogenic factors in brain endothelial cells. Among the most prominent was an up-regulation in Ets-1 transcription factor. CCL2 induced a significant increase in Ets-1 mRNA and protein expression as well as Ets-1 DNA-binding activity. Importantly, Ets-1 antisense oligonucleotide markedly abrogated in vitro CCL2-induced angiogenesis, suggesting that Ets-1 is critically involved in this process. Activation of Ets-1 by CCL2 further regulated some of Ets-1 target molecules including β3 integrins. CCL2 induced significant up-regulation of β3 mRNA and protein expression, and this effect of CCL2 was prevented by the Ets-1 antisense oligonucleotide. The functional regulation of Ets-1 activity by CCL2 was dependent on ERK-1/2 cascade. Inhibition of ERK1/2 activity by PD98509 prevented CCL2-induced increases in Ets-1 DNA-binding activity and Ets-1 mRNA expression. Based on these findings, we suggest that Ets-1 transcription factor plays a critical role in CCL2 actions on brain endothelial cells and CCL2-induced angiogenesis. Copyright © 2006 by The American Association of Immunologisis, Inc.