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During the inflammatory response, endothelial cell (EC) functions and mechanics change dramatically. To understand these responses, the authors analyzed changes in EC gene expression in an in vitro model of inflammation using cDNA microarrays. After interleukin-1 beta (IL1beta) stimulation, over 2500 genes were differentially expressed, of which approximately 2000 had not been previously identified by microarray studies of IL1beta stimulation in human umbilical vein endothelial cells (HUVECs). Functional grouping of these genes according to gene ontologies revealed genes associated with apoptosis, cell cycle, nuclear factor (NF)-kappa B cascade, chemotaxis, and immune response. Interestingly, claudin-1, known to exist in endothelial cell-cell junctions was up-regulated, but claudin-5 and occludin, which also exist in EC junctions, were down-regulated. Pre-b-cell colony enhancing factor (PBEF), a cytokine which may play a role in regulating endothelial permeability, was also up-regulated following IL1beta stimulation. Neutrophil transmigration across IL1beta-stimulated ECs did not induce changes in EC gene expression as strongly as IL1beta stimulation alone. Nineteen genes after 1 h and 22 genes after 3 h of neutrophil application were differentially expressed. These results indicate that, in terms of transcriptional effects on ECs, neutrophil transmigration is a relatively small perturbation in comparison to the background of large scale changes induced in ECs by cytokine stimulation. Supplementary materials are available for this article. Go to the publisher's online edition of Endothelium for the following free supplementary resources: supplementary figures and tables.

This study addresses whether pathological levels of cyclic strain activate the c-Myc promoter, leading to c-Myc transcription and downstream gene induction in human umbilical vein endothelial cells (HUVEC) or human aortic endothelial cells (HAEC). mRNA and protein expression of c-Myc under physiological (6–10%) and pathological cyclic strain conditions (20%) were studied. Both c-Myc mRNA and protein expression increased 2–3-fold in HUVEC cyclically strained at 20%. c-Myc protein increased 4-fold in HAEC. In HUVEC, expression of mRNA peaked at 1.5–2 h. Subsequently, the effect of modulating c-Myc on potential downstream gene targets was determined. A small molecular weight compound that binds to and stabilizes the silencer element in the c-Myc promoter attenuates cyclic strain-induced c-Myc transcription by about 50%. This compound also modulates c-Myc downstream gene targets that may be instrumental in induction of vascular disease. Cyclic strain-induced gene expression of vascular endothelial growth factor, proliferating cell nuclear antigen and heat shock protein 60 are attenuated by this compound. These results offer a possible mechanism and promising clinical treatment for vascular diseases initiated by increased cyclic strain. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

CYP1A1 and CYP1B1 gene expression is dramatically upregulated by shear stress in human umbilical vein endothelial cells (HUVEC). CYP1A1 and 1B1 are capable of metabolizing arachidonic acid into epoxyeicosatrienoic acids (EETs). EETs are increased by shear stress in endothelial cells and mediate changes in gene transcription. We hypothesize that the increase in CYP1A1 or 1B1 regulates the expression of other shear stress responsive genes. We sought to 1) determine whether protein levels of CYP1A1 and 1B1 are also increased by shear stress, 2) examine the effect of siRNA knockdown of CYP1A1 or 1B1 on endothelin-1 (ET-1) expression, and 3) determine if CYP1A1 and 1B1 are expressed in human arteries. HUVEC (P3-5) were exposed to arterial levels of shear stress (25 dynes/cm2) for 24 hours. Densitometry of Western blots showed CYP1B1 protein significantly upregulated by flow. ET-1 is a potent vasoconstrictor which is downregulated by shear stress, siRNA knockdown of CYP1B1 resulted in a 2.7 fold increase in ET-1 mRNA, suggesting that a 1B1 metabolite mediates the shear stress down regulation of ET-1. CYP1A1 and 1B1 protein was observed in the endothelium of human coronary arteries. Although CYP1A1 and 1B1 are thought to be important in response to environmental toxins, these data suggest these genes have an important physiological function in the response of endothelial cells to mechanical forces. [ABSTRACT FROM AUTHOR]