MicroRNA-214 protects the mouse heart from ischemic injury by controlling Ca2+ overload and cell death
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
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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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 5

miR-214 regulation of Ca2+ signaling and cell death genes.

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miR-214 regulation of Ca2+ signaling and cell death genes. (A) Predi...
(A) Predicted miR-214 binding sites in the 3′-UTR of Bim, CamkIId, and Ppif mRNA. Bim contains 4 predicted sites, while CamkIId and Ppif each contain one. Site position relative to beginning of the 3′-UTR is indicated above each panel. Seed and target sequences are highlighted in red and base pairing between miR-214 and target site marked by vertical lines. (B and C) Target protein levels measured by immunoblotting in whole heart lysates from miR-214 KO mice compared with control at baseline (B) and after IR (7 days) (C). Quantification is normalized to indicated loading control and then compared with WT. Data are representative of 2 independent experiments. Mean ± SEM; n = 3. *P < 0.05, **P < 0.01. (D) Ability of miR-214 to directly repress the activity of luciferase reporter constructs that contain the 3′-UTR for CamkIId and Ppif as indicated. Transfection with or without miR-214 expression plasmid is indicated. Luciferase activity was normalized to β-galactosidase activity and compared with empty vector measurements. Luciferase assays were performed in triplicate and are representative of 2–3 independent experiments. Data are mean ± SEM. *P < 0.05.