Vascular endothelium forms a dynamic interface between blood elements and peripheral tissues. Endothelial cells can undergo changes in function that are critical to normal physiological processes, and nonadaptive alterations that are important in the pathogenesis of vascular disease. The working hypothesis for these studies has been that inducible gene expression plays a critical role in endothellial dysfunction. Analysis of the E-slectin promoter reveals a small cytokine response region with four positive regulatory domains (PDIIV) consisting of three NfkappaB elements and a CRE/ATF-like site. These elements can bind p50/p65 and a cJUN/ATF-2 heterodimer, in association with the architectural protein, HMGI (Y). The transcription factors that recognize these elements are targets of signaling events leading to induced gene expression. Phosphorylation of nuclear c-JUN and ATF-2 by constitutively associated JNK and p38 kinases may be an important signal transduction pathway parallel to that of NF-kappaB activation. The signaling events may lead to the recruitment of transcriptional coactivators from the CBP/p300 family. Evidence is presented that p65 and CBP can directly interact and that the coactivator stimulates p65-dependent transcription. We propose that cytokine-induced transcriptional enhancers consist of a specific spatial arrangement of transcription factors, in association with architectural proteins and kinases. Signaling events which activate these enhancers are intergrated by specific transcriptional coactivators into a stimulus to increase transcription. This model driven hypothesis will be explored with three approaches: first, we will fully defne the transcriptional activators which interact with the positive regulatory regions of the E-selectin promoter and utilize transgenic models to determine their in vivo relevance; second, we will analyze the architecture and composition of the enhancer; and third, we will determine the requirements of the cytokine-induced enhancer for coactivators. By characterizing the cytokine-induced enhancer in the E- selectin promoter, it may be possible to elucidate the transcriptional control processes that activate other inducible genes and concert the quiescent endothelium into dysfunctional vascualr element. Such information may provide novel strategies for therapeutic approaches to the important problem of vascualr disease.
