MicroRNA-214 protects the mouse heart from ischemic injury by controlling Ca2+ overload and cell death
Arin B. Aurora, … , Hesham A. Sadek, Eric N. Olson
Arin B. Aurora, … , Hesham A. Sadek, Eric N. Olson
Published March 19, 2012
Citation Information: J Clin Invest. 2012;122(4):1222-1232. https://doi.org/10.1172/JCI59327.
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Research Article Cardiology

MicroRNA-214 protects the mouse heart from ischemic injury by controlling Ca2+ overload and cell death

Abstract

Early reperfusion of ischemic cardiac tissue remains the most effective intervention for improving clinical outcome following myocardial infarction. However, abnormal increases in intracellular Ca2+ during myocardial reperfusion can cause cardiomyocyte death and consequent loss of cardiac function, referred to as ischemia/reperfusion (IR) injury. Therapeutic modulation of Ca2+ handling provides some cardioprotection against the paradoxical effects of restoring blood flow to the heart, highlighting the significance of Ca2+ overload to IR injury. Cardiac IR is also accompanied by dynamic changes in the expression of microRNAs (miRNAs); for example, miR-214 is upregulated during ischemic injury and heart failure, but its potential role in these processes is unknown. Here, we show that genetic deletion of miR-214 in mice causes loss of cardiac contractility, increased apoptosis, and excessive fibrosis in response to IR injury. The cardioprotective roles of miR-214 during IR injury were attributed to repression of the mRNA encoding sodium/calcium exchanger 1 (Ncx1), a key regulator of Ca2+ influx; and to repression of several downstream effectors of Ca2+ signaling that mediate cell death. These findings reveal a pivotal role for miR-214 as a regulator of cardiomyocyte Ca2+ homeostasis and survival during cardiac injury.

Authors

Arin B. Aurora, Ahmed I. Mahmoud, Xiang Luo, Brett A. Johnson, Eva van Rooij, Satoshi Matsuzaki, Kenneth M. Humphries, Joseph A. Hill, Rhonda Bassel-Duby, Hesham A. Sadek, Eric N. Olson

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Figure 4

miR-214 regulates NCX1.

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miR-214 regulates NCX1. (A) Predicted miR-214 binding sites in the 3′-UT...
(A) Predicted miR-214 binding sites in the 3′-UTR of Ncx1 mRNA. Ncx1 contains 3 conserved sites. Site position relative to beginning of the 3′-UTR is indicated above. Seed and target sequences are highlighted in red, and base pairing between miR-214 and target site marked by vertical lines. (B) Ability of miR-214 to directly repress activity of the luciferase reporter construct that contains the portion of the Ncx1 3′-UTR that includes site 3 (pmiR-Ncx1 site 3). WT and mutant Ncx1 3′-UTR sequences were tested. Black triangles indicate increasing amounts of transfected miR-214 expression plasmid (0, 50, 100, and 200 ng). Luciferase activity was normalized to β-galactosidase activity and compared with empty vector measurements (pmiR empty). Luciferase assays were performed in triplicate and are representative of 2–3 independent experiments. Data are mean ± SEM. **P < 0.01, #P < 0.001. (C) NCX1 protein levels measured by immunoblotting in whole heart lysates from miR-214 KO mice compared with WT at baseline and after IR (24 hours and 7 days). Quantification was normalized to tubulin as a loading control and then compared with WT. Data are representative of 2 independent experiments. Mean ± SEM; n = 3. *P < 0.04, **P < 0.01.