Synergistic Induction of Endothelin-1 by Tumor Necrosis Factor α and Interferon γ Is due to Enhanced NF-κB Binding and Histone Acetylation at Specific κB Sites

Endothelin-1 (ET-1) is a potent vasoconstrictor and co-mitogen for vascular smooth muscle and is implicated in pulmonary vascular remodeling and the development of pulmonary arterial hypertension. Vascular smooth muscle is an important source of ET-1. Here we demonstrate synergistic induction of preproET-1 message RNA and release of mature peptide by a combination of tumor necrosis factor alpha(TNF alpha) and interferon gamma(IFN gamma) in primary human pulmonary artery smooth muscle cells. This induction was prevented by pretreatment with the histone acetyltransferase inhibitor anacardic acid. TNF alpha induced a rapid and prolonged pattern of nuclear factor (NF)-kappa B p65 subunit activation and binding to the native preproET-1 promoter. In contrast, IFN gamma induced a delayed activation of interferon regulatory factor-1 without any effect on NF-kappa B p65 nuclear localization or consensus DNA binding. However, we found cooperative p65 binding and histone H4 acetylation at distinct kappa B sites in the preproET-1 promoter after stimulation with both TNF alpha and IFN gamma. This was associated with enhanced recruitment of RNA polymerase II to the ATG start site and read-through of the ET-1 coding region. Understanding such mechanisms is crucial in determining the key control points in ET-1 release. This has particular relevance to developing novel treatments targeted at the inflammatory component of pulmonary vascular remodeling.