Down-regulation of CREB-binding protein expression blocks thrombin-mediated endothelial activation by inhibiting acetylation of NF-κB

Abstract

Objectives: CREB-binding protein (CBP) belongs to a unique class of transcription co-activators possessing histone acetyltransferase (HAT) activity. The aim of the present study was to evaluate the role of CBP in thrombin-induced endothelial activation, and also explore the underlying mechanism.

Methods: Leukocyte-endothelial adhesion was calculated as the proportion of the labeled-neutrophils that adhered to ECs relative to all neutrophils applied. Levels of adhesion molecules were analyzed by real-time RT-PCR and western blot. Electrophoretic mobility shift assay and NF-κB reporter assay were performed to evaluate NF-κB activation. Acetylation of NF-κB was measured with immunoprecipitation and western blot assay. To detect the CBP-HAT activity, acetyl residues on an acetylated histone H4 was analyzed.

Results: Leukocyte-endothelial adhesion induced by thrombin was markedly attenuated in endothelial cells with CBP knockdown. The decreased adhesion was paralleled by the reduction of vascular cell adhesion molecule-1, intercellular adhesion molecule-1 and E-selectin. Furthermore, CBP silencing suppressed thrombin-mediated NF-κB activation, and this inhibitory effect was associated with decreased acetylation of NF-κB and CBP-HAT activity.

Conclusions: Our results indicate that CBP is involved in the regulation of endothelial activation via NF-κB-dependent pathway. Down-regulation of CBP may play a role in returning ECs from a pre-inflammatory status to a quiescent state in the pathogenesis of atherosclerosis.