Abstract 333: Histone Deacetylase 5 Interacts With and Regulates Kruppel-like Factor 2 (KLF2) Transcriptional Activation and its Downstream Target eNOS Gene Expression
Vascular endothelial dysfunction and inflammation are hallmarks of atherosclerosis. It is important to understand the detailed mechanisms for regulation of endothelial function and inflammation. Emerging evidence suggests that the transcription factor Kruppel-like Factor 2 (KLF2) is a key mediator of the anti-inflammatory and anti-thrombotic properties of the endothelium. KLF2 also mediates laminar blood flow-dependent endothelial atheroprotective functions. Despite intense investigation of KLF2 function, little is known of the molecular mechanisms for regulation of KLF2 transcriptional activation. Histone deacetylase 5 (HDAC5) HDAC5 is a transcriptional repressor, and we have previously shown that HDAC5 inhibits flow-mediated endothelial nitric oxide synthase (eNOS) gene expression (Wang & Jin, Blood 2010). Here, we demonstrate that HDAC5 physically associates with KLF2 and negatively regulates KLF2 transcriptional activation. Using co-transfected cell line and GST-fusion protein pull-down assays, we found that HDAC5 directly interacts with KLF2. We also detected the association of endogenous HDAC5 and KFL2 in endothelial cells. To understand the nature of this interaction, we further mapped the HDAC5 and KLF2 interaction domains. Using luciferase reporter assay, we observed that HDAC5, through association with KLF2, repressed KLF2 transcriptional activation. Moreover, HDAC5 inhibited KLF2-dependent eNOS promoter activity and eNOS expression in endothelial cells, which reveals epigenetic mechanism whereby flow mediates eNOS expression through stimulating nuclear export of HDAC5. Collectively, these results define a novel transcriptional pathway that regulates KLF2-dependent gene expression and suggest a new molecular target to prevent vascular inflammation and endothelial dysfunction associated with cardiovascular disease.
- © 2013 by American Heart Association, Inc.