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

Purpose: To investigate the role of angiotensin II (Ang II) and beta adrenergic receptors (beta ARs) in autophagy regulation in human endothelial EA.hy926 cell line. Methods: The effect of pharmacological modulation of Ang II receptors and beta ARs 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 beta 1AR blocker propranolol). A selective beta 1AR agonist, dobutamine, reduced the expression of LC3B-II, and increased that of p62; the same was suppressed upon treatment with a selective MAR antagonist, metoprolol. A selective PAR agonist, salbutamol, resulted in increased expression of LC3B-II and reduced expression of p62. These effects were encountered upon treatment with selective beta 2AR 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. beta AR activation mediates isoproterenol-induced endothelial cell autophagy, which results from the balance of beta 1ARs-mediated suppression and beta 2AR-smediated upregulation of autophagy in the endothelial cells.