Endothelin-1 and endothelin-converting enzyme-1 gene regulation by shear stress and flow-induced pressure

Hemodynamic forces have been shown to modulate the expression of endothelin (ET-1) and endothelin-converting enzyme (ECE-1) in endothelial cells. We have subjected E.A. by 926 cells in culture to steady fluid shear stress with and without flow-induced pressure. The effect of combining these two mechanical forces on the expression of genes in the ET system was studied and the changes were compared to the mRNA levels in static culture. Analysis of total RNA by Nor-them blot analysis and RNAse protection showed that steady shear stress induced ET-1 gene expression three- to fourfold in this system. The same condition had little to no effect on altering expression of ECE-1 isoforms. A range of flow-induced pressure (80-160 mm Hg) was not able to further augment ET-1 or ECE-1 gene expression. Overall, with the mechanical environment studied, we have been able to detect a predominant contribution of shear stress to altering the ET-1 gene in our system. Furthermore, this induction was independent of an alteration in ECE-1 gene levels, suggesting that these two genes have a different pattern of regulation by the same stimuh in this cell type.