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 7

miR-214 protection of cardiomyocytes and regulation of target genes in vitro.

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miR-214 protection of cardiomyocytes and regulation of target genes in v...
(A) RNA isolated from neonatal rat cardiomyocytes transfected with antimiR-214 or 15-mer control (100 nM) was analyzed by miR-214–specific RT-PCR and qPCR to assess levels of miR-214 suppression. **P < 0.01. (B and C) TUNEL staining of neonatal rat cardiomyocytes transfected with control or antimiR-214 and then subjected to in vitro simulation of IR. (B) Representative images of total nuclei (blue) and apoptotic nuclei (red) from normoxic and both IR conditions are shown for control and antimiR-214 transfected samples. Scale bar: 100 μm. (C) Quantification of percent TUNEL-positive nuclei. Samples were assayed in triplicate, and results are representative of 2–3 independent experiments. Data are mean ± SEM; **P < 0.01. (D) Levels of miR-214 target mRNAs in cardiomyocytes transfected with antimiR-214 or control antimiR as indicated. Data were normalized to ribosomal 18S and expressed relative to control. Samples were run in triplicate, and results are representative of 2 independent experiments. All data are mean ± SEM; *P = 0.02, **P < 0.01.