Cardiovascular Research Institute, National University Health System, Singapore; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Interdisciplinary Stem Cell Institute, Department of Pediatrics, Division of Cardiology, University of Miami Miller School of Medicine, Miami, FL, USA.
Cardiovascular Research Institute, National University Health System, Singapore; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
J Mol Cell Cardiol. 2017 Nov;112:27-39. doi: 10.1016/j.yjmcc.2017.08.013. Epub 2017 Sep 1.
Myocardial infarction (MI) triggers a dynamic microRNA response with the potential of yielding therapeutic targets.
We aimed to identify novel aberrantly expressed cardiac microRNAs post-MI with potential roles in adverse remodeling in a rat model, and to provide post-ischemic therapeutic inhibition of a candidate pathological microRNA in vivo.
Following microRNA array profiling in rat hearts 2 and 14days post-MI, we identified a time-dependent up-regulation of miR-31 compared to sham-operated rats. A progressive increase of miR-31 (up to 91.4±11.3 fold) was detected in the infarcted myocardium by quantitative real-time PCR. Following target prediction analysis, reporter gene assays confirmed that miR-31 targets the 3´UTR of cardiac troponin-T (Tnnt2), E2F transcription factor 6 (E2f6), mineralocorticoid receptor (Nr3c2) and metalloproteinase inhibitor 4 (Timp4) mRNAs. In vitro, hypoxia and oxidative stress up-regulated miR-31 and suppressed target genes in cardiac cell cultures, whereas LNA-based oligonucleotide inhibition of miR-31 (miR-31i) reversed its repressive effect on target mRNAs. Therapeutic post-ischemic administration of miR-31i in rats silenced cardiac miR-31 and enhanced expression of target genes, while preserving cardiac structure and function at 2 and 4weeks post-MI. Left ventricular ejection fraction (EF) improved by 10% (from day 2 to 30 post-MI) in miR-31i-treated rats, whereas controls receiving scrambled LNA inhibitor or placebo incurred a 17% deterioration in EF. miR-31i decreased end-diastolic pressure and infarct size; attenuated interstitial fibrosis in the remote myocardium and enhanced cardiac output.
miR-31 induction after MI is deleterious to cardiac function while its therapeutic inhibition in vivo ameliorates cardiac dysfunction and prevents the development of post-ischemic adverse remodeling.
心肌梗死（MI）引发动态 microRNA 反应，具有产生治疗靶点的潜力。
我们旨在识别 MI 后大鼠模型中潜在的心脏 microRNA 异常表达，这些 microRNA 可能在不良重构中发挥作用，并在体内对候选病理性 microRNA 进行缺血后治疗抑制。
在 MI 后 2 天和 14 天的大鼠心脏进行 microRNA 芯片分析后，我们发现与假手术大鼠相比，miR-31 的表达呈时间依赖性上调。通过定量实时 PCR 检测到梗死心肌中 miR-31 的逐渐增加（高达 91.4±11.3 倍）。通过靶标预测分析，报告基因检测证实 miR-31 靶向心脏肌钙蛋白-T（Tnnt2）、E2F 转录因子 6（E2f6）、盐皮质激素受体（Nr3c2）和金属蛋白酶抑制剂 4（Timp4）mRNA 的 3´UTR。在体外，低氧和氧化应激上调 miR-31 并抑制心脏细胞培养物中的靶基因，而基于 LNA 的寡核苷酸抑制 miR-31（miR-31i）逆转其对靶 mRNA 的抑制作用。在大鼠中进行缺血后治疗性 miR-31i 给药可沉默心脏 miR-31 并增强靶基因的表达，同时在 MI 后 2 周和 4 周时保持心脏结构和功能。在 miR-31i 治疗的大鼠中，左心室射血分数（EF）提高了 10%（从第 2 天到第 30 天），而接受 scrambled LNA 抑制剂或安慰剂的对照组 EF 恶化了 17%。miR-31i 降低了舒张末期压和梗死面积；减轻了远程心肌的间质纤维化并增加了心输出量。
MI 后 miR-31 的诱导对心脏功能有害，而体内的治疗性抑制可改善心脏功能障碍并防止缺血后不良重构的发展。
