Abstract：
MicroRNAs (miRs) are non-coding small RNA containing 18 to 22 nucleotides, that post-transcriptionally regulates mRNA expression. Chronic injection of β stimulator is known to induce cardiac injury and change of miRs expression level in the heart with some pathological changes such as fibrosis, heart failure, myocardial infarction. We investigated the changes in the expression level of miRs in the rat heart one hour after isoproterenol (a β stimulator) injection. Male Sprague-Dawley rats were assigned into three groups and received subcutaneous injection of normal sarin (NS) or 0.1 mg/kg isoproterenol (ISO-0.1) or 10 mg/kg isoproterenol (ISO-10). After one hour, we collected their heart and plasma. Total RNA was extracted from the left ventricle and used for deep miRNA sequencing. Based on the results of miRNA sequencing, we performed real-time polymerase chain reaction (RT-PCR) using 8 miR primers. Cardiac injury was evaluated by hematoxylin and eosin, and phosphotungstic acid-hematoxylin staining and measuring troponin-I levels in plasma. Troponin-I was significantly increased in ISO-0.1 and ISO-10 groups, but histological observation did not show any cardiac necrosis. miRNA sequencing identified 14 upregulated miRs and 12 downregulated miRs. Of the 26 miRs, RT-PCR confirmed miR-144-3p/5p and miR-451-5p were decreased, and that 5 miRs (miR-27a-5p, miR-30b-3p, miR-92a-1-5p, miR-132-5p, miR-582-3p) were upregulated. This study showed that β stimulus causes downregulation of miR-144/451 cluster and increases expression of five 5 miRs in the heart, especially 6.5-fold upregulation of miR-27a-5p as early as one hour after isoproterenol injection. Therefore, these miRs might be good biomarkers for cardiac injury.
摘要：
microRNAs(miRs)是含有18至22个核苷酸的非编码小RNA,转录后调节mRNA表达。已知慢性注射β刺激因子会引起心脏损伤和心脏miRs表达水平的改变，并伴有纤维化等病理变化。心力衰竭,心肌梗塞。我们研究了注射异丙肾上腺素（β刺激剂）一小时后大鼠心脏miRs表达水平的变化。雄性Sprague-Dawley大鼠分为三组，皮下注射正常沙林蛋白（NS）或0.1mg/kg异丙肾上腺素（ISO-0.1）或10mg/kg异丙肾上腺素（ISO-10）。一小时后,我们收集了他们的心脏和血浆.从左心室提取总RNA并用于深度miRNA测序。根据miRNA测序结果,我们使用8个miR引物进行了实时聚合酶链反应(RT-PCR).心脏损伤通过苏木精和伊红进行评估，和磷钨酸-苏木精染色并测量血浆中的肌钙蛋白-I水平。肌钙蛋白-I在ISO-0.1和ISO-10组中显著增加,但组织学观察未显示任何心脏坏死。miRNA测序鉴定出14个上调的miR和12个下调的miR。在26个miRs中,RT-PCR证实miR-144-3p/5p和miR-451-5p均降低,和5miRs（miR-27a-5p，miR-30b-3p,miR-92a-1-5p,miR-132-5p,miR-582-3p）上调。这项研究表明，β刺激引起miR-144/451簇的下调，并增加心脏中5个5miRs的表达，特别是miR-27a-5p的6.5倍上调早在异丙肾上腺素注射后一小时。因此,这些miR可能是心脏损伤的良好生物标志物.
