Centre for Vision and Vascular Science, Queen's University Belfast, Belfast, County Antrim, United Kingdom.
PLoS One. 2013 Jun 14;8(6):e65809. doi: 10.1371/journal.pone.0065809. Print 2013.
MicroRNAs (miRNAs) are single-stranded non-coding RNAs that negatively regulate target gene expression through mRNA cleavage or translational repression. There is mounting evidence that they play critical roles in heart disease. The expression of known miRNAs in the heart has been studied at length by microarray and quantitative PCR but it is becoming evident that microRNA isoforms (isomiRs) are potentially physiologically important. It is well known that left ventricular (patho)physiology is influenced by transmural heterogeneity of cardiomyocyte phenotype, and this likely reflects underlying heterogeneity of gene expression. Given the significant role of miRNAs in regulating gene expression, knowledge of how the miRNA profile varies across the ventricular wall will be crucial to better understand the mechanisms governing transmural physiological heterogeneity. To determinine miRNA/isomiR expression profiles in the rat heart we investigated tissue from different locations across the left ventricular wall using deep sequencing. We detected significant quantities of 145 known rat miRNAs and 68 potential novel orthologs of known miRNAs, in mature, mature* and isomiR formation. Many isomiRs were detected at a higher frequency than their canonical sequence in miRBase and have different predicted targets. The most common miR-133a isomiR was more effective at targeting a construct containing a sequence from the gelsolin gene than was canonical miR-133a, as determined by dual-fluorescence assay. We identified a novel rat miR-1 homolog from a second miR-1 gene; and a novel rat miRNA similar to miR-676. We also cloned and sequenced the rat miR-486 gene which is not in miRBase (v18). Signalling pathways predicted to be targeted by the most highly detected miRNAs include Ubiquitin-mediated Proteolysis, Mitogen-Activated Protein Kinase, Regulation of Actin Cytoskeleton, Wnt signalling, Calcium Signalling, Gap junctions and Arrhythmogenic Right Ventricular Cardiomyopathy. Most miRNAs are not expressed in a gradient across the ventricular wall, with exceptions including miR-10b, miR-21, miR-99b and miR-486.
微小 RNA（miRNAs）是单链非编码 RNA，通过 mRNA 切割或翻译抑制负调控靶基因表达。越来越多的证据表明，它们在心脏病中发挥着关键作用。通过微阵列和定量 PCR 对心脏中已知 miRNAs 的表达进行了广泛研究，但显然 miRNA 同工型（isomiRs）具有潜在的生理重要性。众所周知，左心室（病理）生理学受心肌细胞表型的穿壁异质性影响，这可能反映了基因表达的潜在异质性。鉴于 miRNAs 在调节基因表达方面的重要作用，了解 miRNA 谱在心室壁上的变化将对更好地理解调节穿壁生理异质性的机制至关重要。为了确定大鼠心脏中的 miRNA/isomiR 表达谱，我们使用深度测序研究了左心室壁不同位置的组织。我们在成熟、成熟*和 isomiR 形成中检测到 145 种已知大鼠 miRNAs 和 68 种潜在新的已知 miRNA 直系同源物，具有显著数量。许多 isomiRs 的检测频率高于 miRBase 中的其典型序列，并且具有不同的预测靶标。最常见的 miR-133a isomiR 比其在 miRBase 中的典型序列更有效地靶向包含凝溶胶基因序列的构建体，这通过双荧光测定确定。我们从第二个 miR-1 基因中鉴定出一种新型大鼠 miR-1 同源物；并鉴定出一种类似于 miR-676 的新型大鼠 miRNA。我们还克隆和测序了大鼠 miR-486 基因，该基因不在 miRBase（v18）中。预测被检测到的高度表达 miRNA 靶向的信号通路包括泛素介导的蛋白水解、丝裂原激活蛋白激酶、肌动蛋白细胞骨架调节、Wnt 信号、钙信号、间隙连接和致心律失常性右心室心肌病。大多数 miRNA 不在心室壁上呈梯度表达，miR-10b、miR-21、miR-99b 和 miR-486 除外。
