Involvement of angiotensin II and beta-adrenergic receptors in the regulation of autophagy in human endothelial EA.hy926 cell line

Abstract

Purpose: To investigate the role of angiotensin II (Ang II) and β adrenergic receptors (βARs) in autophagy regulation in human endothelial EA.hy926 cell line.Methods: The effect of pharmacological modulation of Ang II receptors and βARs on the expression of LC3B-II and p62 proteins (autophagosome formation marker and autophagic flux marker, respectively) in the human endothelial EA.hy926 cell line were investigated by immunoblotting technique.Results: Ang II-induced autophagy was characterized by increased LC3B-II and reduced p62 expressions. Candesartan, an AT1R agonist,  significantly suppressed the effects of Ang II, while a selective AT2R antagonist, PD123319, inhibited the effect of candesartan. An AT2R agonist, CGP-42112A, also suppressed the Ang II-induced autophagy. Treatment with isoproterenol enhanced the expression of LC3B-II and reduced that of p62; these effects were suppressed upon cotreatment with propranolol (non-selective βAR blocker propranolol). A selective β1AR agonist, dobutamine, reduced the expression of LC3B-II, and increased that of p62; the same was suppressed upon treatment with a selective β1AR antagonist, metoprolol. A selective β2AR agonist, salbutamol, resulted in increased expression of LC3B-II and reduced expression of p62. These effects were encountered upon treatment with selective β2AR antagonist, ICI-118,551.Conclusion: Based on the foregoing, it is evident that AT1Rs mediates Ang II-induced endothelial cell autophagy, while AT2Rs antagonizes the mechanism. βAR activation mediates isoproterenol-induced endothelial cell autophagy, which results from the balance of β1ARs-mediated suppression and β2ARsmediated upregulation of autophagy in the endothelial cells. Keywords: Autophagy, Angiotensin II type 1 receptors, Angiotensin II type 2 receptors β adrenergic type 1 receptors, β adrenergic type 2 receptors endothelial cells