Identification of a cis -Element Regulating Transcriptional Activity in Response to Fluid Shear Stress in Bovine Aortic Endothelial Cells

Abstract

Fluid shear stress exerts numerous effects on gene expression in endothelial cells. To investigate the regulatory mechanisms involved, we designed oligonucleotides composed of a 20-bp core containing the classical shear stress response element (SSRE+) or of a 20-bp core, in which base pairs flanking the SSRE were mutated (SSRE-). Hexamers of the oligonucleotides were cloned in front of reporter genes, transfected in bovine aortic endothelial cells (BAECs), and subjected to either a continuous low shear stress (3 dynes cm(-2)) or to a stepwise increase in shear stress from 3 dynes cm(-2) to 12 dynes cm(-2) (16/4 h). Shear stress increased reporter gene activity in cells transfected with pSSRE-, but not with pSSRE+. Cyclic strain (6%, 1 Hz, 4 h) did not significantly affect reporter gene activity. In gel retardation assays, more proteins bound to SSRE- than to SSRE+ in response to high shear stress. In competition experiments, a cAMP response element-binding (CREB) protein-specific oligonucleotide suppressed protein binding to the SSRE-; however, an antibody directed against CREB itself did not affect protein binding to the SSRE+. Our results indicate that the sequence ACC(G)/(T)AGACCAG represents a novel SSRE and that a protein that binds a CREB-specific oligonucleotide is part of the complex implicated in response to shear stress.

The Assembly and Application of 'Shear Rings': A Novel Endothelial Model for Orbital, Unidirectional and Periodic Fluid Flow and Shear Stress

“…Fluid shear stress has been shown to modulate endothelial gene programs [1][2][3][4][5] through activation of cis-regulatory elements 6 , histone acetyltransferase activity 7 and shear stress response elements (SSRE) 8 . Shear stress influences endothelial contributions towards coagulation by modulating tissue factor 9 and tissue plasminogen activator (tPA) 10 expression.…”