Objective-The transcription factor early growth response (EGR)-1 has been implicated as a key vascular phenotypic switch through its control of inducible transcription. EGR-1 autoregulation, and histone modification in the EGR-1 promoter, represent key mechanisms in EGR-1 control, but have not been explored. Methods and Results-We demonstrate that EGR-1 regulates its own transcription and that this involves histone H3 phosphorylation and acetylation. EGR-1 transactivates its promoter in smooth muscle cells exposed to interleukin (IL) 1 through a novel cis-acting element (Ϫ211/Ϫ203). PD98059, which inhibits mitogen-activated protein kinase kinase/extracellular regulated kinase (MEK/ERK) attenuates IL-1-inducible phosphorylation of extracellular signalregulated kinase 1/2 and mitogen and stress-activated protein kinases 1/2; and reduces levels of phosphorylated and acetylated histone H3. Histone deacetylase inhibition enhances EGR-1 transcription in response to cytokine. Conversely, suppression of histone modification with mitogen and stress-activated protein kinase 1/2 short interfering RNA, or the histone H3 acetyltransferase inhibitor Garcinol, inhibits IL-1-inducible EGR-1 transcription. EGR-1 interacts with the acetyltransferase p300. Acetylated H3 and phosphorylated H3 are enriched at the promoter of EGR-1; and EGR-1 is enriched at the promoters of tissue factor and plasminogen activator inhibitor 1 in response to IL-1, and attenuated by PD98059, Garcinol, and mitogen and stress-activated protein kinase 1/2 short interfering RNA. Key Words: histone modification Ⅲ immediate-early gene Ⅲ transcription E arly growth response 1 (human EGR-1 or mouse EGR-1, also known as NGFI-A, Zif268, Krox24, and Tis8) is an inducible zinc finger transcription factor that plays a critical role in controlling cell growth, proliferation, differentiation, and apoptosis. 1-5 EGR-1 belongs to a family of zinc finger transcription factors that also includes EGR-2, EGR-3, EGR-4, EGR-␣, and the Wilm tumor gene product. 6 EGR-1 contains a highly conserved DNA-binding domain (three zinc finger domains of the C2H2 subtype), an activation domain, a repression domain, and a nuclear localization signal. 7,8 Carman and Monroe 9 identified an activation domain between amino acids 174 and 270, a serine/threonine/prolinerich region that is critical for its activity. Mutants lacking this domain perturb wild-type EGR-1 function. 9 EGR-1 regulates the transcription of target genes by binding to GC-rich consensus DNA elements present in the regulatory regions in vascular pathophysiologically relevant genes, such as insulinlike growth factor II, platelet-derived growth factor A and B chains, tissue factor, fibroblast growth factor 2, transforming growth factor 1, urokinase plasminogen activator, and plasminogen activator inhibitor (PAI) 1. 5,7,10 -13 EGR-1 also regulates the expression of its corepressor nerve growth factor I-A binding protein-2. 11 Functional cis-acting elements within the human EGR-1 promoter have been identified in differen...