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 3

miR-214 protects the heart against MI and IR.

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miR-214 protects the heart against MI and IR. (A) Survival curve followi...
(A) Survival curve following MI (permanent LAD ligation) in miR-214 KO mice or WT littermates. n = 13–15, data represent mice from 3 different experiments. *P < 0.05. (B) Northern blotting and quantification of miR-214 expression in WT hearts at baseline and following IR. miR-214 levels were normalized to U6 loading control and expressed relative to baseline. *P = 0.04, **P < 0.01. (C) Cardiac function in WT and miR-214 KO mice before and after IR (7 days reperfusion). Quantification of left ventricular internal diameter in systole or diastole (LVIDs or LVIDd), fractional shortening (FS) and ejection fraction (EF), is shown. n = 6; data represent mean ± SEM of 3 independent experiments. **P < 0.01, ***P < 0.001. (D) TUNEL staining in heart sections following IR. Representative images at 24 hours and 7 days of reperfusion are shown. Scale bar: 200 μm. The percentage of TUNEL-positive nuclei was calculated. For each mouse, sections at 3 different levels (6–8 fields per section) were counted. Bottom: Simultaneous TUNEL (green) and desmin staining (red) from miR-214 KO heart sections following IR. Scale bar: 40 μm. (E) Masson’s trichrome staining on transverse heart sections after 7 days of reperfusion. Representative images shown at two different magnifications. Scale bars: 2 mm (top), 100 μM (bottom). The area of blue staining was quantified (3 section levels per heart) and expressed as a percentage of total area. For D and E, mean ± SEM; n = 3; *P < 0.05.