Pro-Inflammatory Stimuli Engage Brahma Related Gene 1 (Brg1) and Brahma (Brm) in Endothelial Injury
Rationale: Endothelial dysfunction inflicted by inflammation is found in a host of cardiovascular pathologies. One hallmark event in this process is the aggregation and adhesion of leukocyte to the vessel wall mediated by the up-regulation of adhesion molecules (CAM) in endothelial cells at the transcriptional level. The epigenetic modulator(s) of CAM transactivation and its underlying pathophysiological relevance remain poorly defined.
Objective: Our goal was to determine the involvement of Brg1 and Brm in CAM transactivation and its relevance in the pathogenesis of atherosclerosis.
Methods and Results: In the present study, we report that pro-inflammatory stimuli augmented the expression of Brg1 and Brm in vitro in cultured endothelial cells and in vivo in arteries isolated from rodents. Over-expression of Brg1 and Brm promoted whereas knockdown of Brg1 and Brm abrogated transactivation of adhesion molecules and leukocyte adhesion induced by inflammatory signals. Brg1 and Brm interacted with and were recruited to the CAM promoters by NF-κB/p65. Conversely, depletion of Brg1 and Brm disrupted the kinetics of p65 binding on CAM promoters and crippled CAM activation. Silencing of Brg1 and Brm also altered key epigenetic changes associated with CAM transactivation. Of intrigue, 17β-estradiol antagonized both the expression and activity of Brg1/Brm. Most importantly, endothelial-targeted elimination of Brg1/Brm conferred atheroprotective effects to Apoe-/- mice on a Western diet.
Conclusions: Therefore, our data suggest that Brg1 and Brm integrate various pro-inflammatory cues into CAM transactivation and endothelial malfunction and as such may serve as potential therapeutic targets in treating inflammation related cardiovascular diseases.
- Received March 5, 2013.
- Revision received August 12, 2013.
- Accepted August 20, 2013.