Cardiovascular Research Advance Access originally published online on July 6, 2009
Cardiovascular Research 2009 84(3):434-441; doi:10.1093/cvr/cvp232
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MicroRNA-1 downregulation by propranolol in a rat model of myocardial infarction: a new mechanism for ischaemic cardioprotection



1 Department of Pharmacology (State-Province Key Laboratories of Biomedicine and Pharmaceutics), Harbin Medical University, Harbin, Heilongjiang 150081, People's Republic of China
2 Institute of Cardiovascular Research, Harbin Medical University, Harbin, Heilongjiang 150081, People's Republic of China
* Corresponding author. Tel: +86 451 8667 1 354; fax: +86 451 8667 5 769. E-mail address: yangbf{at}ems.hrbmu.edu.cn
Aims: The present study was designed to investigate whether the beneficial effects of β-blocker propranolol are related to regulation of microRNA miR-1.
Methods and results: We demonstrated that propranolol reduced the incidence of arrhythmias in a rat model of myocardial infarction by coronary artery occlusion. Overexpression of miR-1 was observed in ischaemic myocardium and strikingly, administration of propranolol reversed the up-regulation of miR-1 nearly back to the control level. In agreement with its miR-1-reducing effect, propranolol relieved myocardial injuries during ischaemia, restored the membrane depolarization and cardiac conduction slowing, by rescuing the expression of inward rectifying K+ channel subunit Kir2.1 and gap junction channel connexin 43. Our results further revealed that the β-adrenoceptor–cAMP–Protein Kinase A (PKA) signalling pathway contributed to the expression of miR-1, and serum response factor (SRF), which is known as one of the transcriptional enhancers of miR-1, was up-regulated in ischaemic myocardium. Moreover, propranolol inhibited the β-adrenoceptor–cAMP–PKA signalling pathway and suppressed SRF expression.
Conclusion: We conclude that the β-adrenergic pathway can stimulate expression of arrhythmogenic miR-1, contributing to ischaemic arrhythmogenesis, and β-blockers produce their beneficial effects partially by down-regulating miR-1, which might be a novel strategy for ischaemic cardioprotection.
KEYWORDS Propranolol; Arrhythmia; MicroRNA; Ion channels; Myocardial infarction
Time for primary review: 38 days
Y.L., Y.Z., and H.S. contributed equally to this work.