Cooperation of SRC-1 and p300 with NF-κB and CREB in angiotensin II-induced IL-6 expression in vascular smooth muscle cells

Objective - The purpose of this study was to evaluate the role of coactivator histone acetyltransferases ( HATs) p300 and SRC- 1 in angiotensin II ( Ang II) - induced interleukin- 6 ( IL- 6) gene expression in vascular smooth muscle cells ( VSMCs). Methods and Results - Ang II increased IL- 6 mRNA expression via NF-kappa B and CREB in an extracellular signal- regulated kinase ( ERK) - dependent manner in rat VSMCs. It was also significantly enhanced by the histone deacetylase inhibitor, Trichostatin A. Chromatin immunoprecipitation ( ChIP) assays showed that Ang II increased Histone H3 Lysine ( K9/14) acetylation on the IL- 6 promoter. Ang II - induced IL- 6 promoter transactivation was significantly enhanced by p300 and SRC- 1, with maximal activation in cells cotransfected with NF-kappa B ( p65) and SRC- 1. Nucleofection of VSMCs with either an ERK phosphorylation site mutant of SRC- 1 or p300/ CBP HAT deficient mutants significantly blocked Ang II - induced IL- 6 expression. ChIP assays revealed that Ang II enhanced coordinate occupancy of p65, CREB, p300, and SRC- 1 at the IL- 6 promoter. An ERK pathway inhibitor blocked Ang- induced IL- 6 promoter SRC- 1 occupancy and histone acetylation. Conclusions - Ang II - induced IL- 6 expression requires NF-kappa B and CREB as well as ERK- dependent histone acetylation mediated by p300 and SRC- 1. These results provide new insights into nuclear chromatin mechanisms by which Ang II regulates inflammatory gene expression.