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Endothelin-1 is a key regulator of vascular tone and blood pressure in health and disease. We have recently found that ET-1 production in human microvascular endothelial cells (HMECs) can be promoted by angiotensin II (Ang II) through a novel mechanism involving octamer-binding transcription factor-1 (Oct-1), NADPH oxidase-2 (NOX2), and superoxide anions. As the formation of bioactive ET-1 also depends on endothelin-converting enzyme-1 (ECE-1), we investigated the transcriptional regulation of the <i>ECE1</i> gene. We found that exposure of HMECs to Ang II resulted in a concentration- and time-dependent increase in <i>ECE1</i> mRNA expression. Pharmacological inhibition of ECE-1 reduced Ang II-stimulated ET-1 release to baseline values. The effect of Ang II on <i>ECE1</i> mRNA expression was associated with Oct-1 binding to the <i>ECE1</i> promoter, resulting in its increased activity. Consequently, the Ang II-stimulated increase in <i>ECE1</i> mRNA expression could be prevented by siRNA-mediated Oct-1 inhibition. It could also be abolished by silencing the <i>NOX2</i> gene and neutralizing superoxide anions with superoxide dismutase. In mice fed a high-fat diet, cardiac expression of <i>Ece1</i> mRNA increased in wild-type mice but not in <i>Nox2</i>-deficient animals. It can be concluded that Ang II engages Oct-1, NOX2, and superoxide anions to stimulate <i>ECE1</i> expression in the endothelium.