Rat angiotensin-converting enzyme promoter regulation by beta-adrenergics and cAMP in endothelium

To shed light on mechanisms of angiotensin-converting enzyme (ACE) upregula tion, we used a rabbit endothelial cell model to characterize intracellular pathways of beta-adrenergic stimulation. In these cells, ACE activity is i ncreased by isoproterenol (ISO). The stably transfected 1273-bp ACE promote r is stimulated by ISO in the presence of isobutyl methylxanthine. This eff ect is abolished by propranolol. Promoter stimulation is mimicked by choler a toxin, forskolin, and 8BrcAMP, but not by 8BrcGMP. Promoter stimulation b y ISO and isobutyl methylxanthine is blocked by protein kinase A inhibitors , indicating that beta-adrenergic stimulation of the ACE gene depends on ph osphorylation of protein kinase A targets. Activation by cAMP, resistance t o phorbol ester, and lack of synergism between cAMP and phorbol ester sugge st that promoter regulation is due to cAMP responsive element rather than t o activating protein-2 sequences. Okadaic acid potentiation of 8BrcAMP indu ction indicated that promoter activation by cAMP is regulated by phosphatas es controlling activation of typical cAMP responsive element regulated gene s. In summary, beta-adrenergic activation of rat ACE promoter is specific; uses G(s) proteins, adenylyl cyclase, protein kinase A; and probably includ es cAMP responsive element-like sequences.