As key regulators of gene expression, microRNAs (miRNAs) have emerged as targets in basic experimentation and therapy. Administration of DNA-encoded RNA molecules, targeting miRNAs through base pairing, is one viable strategy for inhibiting specific miRNAs. A naturally occurring circular RNA (circRNA), ciRS-7, serving as a miRNA-7 (miR-7) sponge was recently identified. This has sparked tremendous interest in adapting circRNAs for suppressing miRNA function. In parallel, we and others have demonstrated efficacy of expressed anti-miRNA Tough Decoy (TuD) hairpins. To compare properties of such inhibitors, we express ciRS-7 and TuD-containing miRNA suppressor transcripts from identical vector formats adapted from RNA polymerase II-directed expression plasmids previously used for production of ciRS-7. In general, markedly higher levels of miR-7 suppression with TuD transcripts relative to ciRS-7 are observed, leading to superior miRNA sponge effects using expressed TuD hairpins. Notably however, we find that individual ciRS-7 transcripts are more potent inhibitors of miR-7 activity than individual TuD7-containing transcripts, although each miR-7 seed match target site in ciRS-7 is, on average, less potent than the perfectly matched target sites in the TuD motif. All together, our studies call for improved means of designing and producing circRNAs for customized miRNA targeting to match TuD hairpins for tailored miRNA suppression.

作为基因表达的关键调节剂，微小RNA（miRNA）已成为基础实验和治疗的靶标。通过碱基配对靶向miRNA的DNA编码RNA分子的给药是抑制特定miRNA的一种可行策略。最近鉴定出一种天然的环状RNA（circRNA）ciRS-7，可作为miRNA-7（miR-7）海绵。这引起了人们对适应circRNA抑制miRNA功能的巨大兴趣。同时，我们和其他人证明了表达的抗miRNA强韧诱饵（TuD）发夹的功效。为了比较这类抑制剂的特性，我们从相同的载体形式表达了ciRS-7和含TuD的miRNA抑制子转录物，这些载体形式适用于先前用于生产ciRS-7的RNA聚合酶II定向表达质粒。一般来说，观察到，相对于ciRS-7，使用TuD转录本抑制miR-7的水平明显更高，从而导致使用表达的TuD发夹产生出众的miRNA海绵效应。但是，值得注意的是，尽管平均而言，ciRS-7中每个miR-7种子匹配目标位点的效力均不如完全理想，但我们发现，单独的ciRS-7转录物比单独的包含TuD7的转录物更有效地抑制miR-7活性。在TuD主题中匹配了目标位点。总之，我们的研究要求改进设计和生产用于定制miRNA靶向的circRNA的方法，以匹配TuD发夹以定制miRNA的抑制作用。我们发现，单独的ciRS-7转录本比单独的包含TuD7的转录本更有效地抑制miR-7活性，尽管ciRS-7中的每个miR-7种子匹配目标位点平均而言都比完全匹配的目标位点要弱在TuD主题中。总之，我们的研究要求改进设计和生产用于定制miRNA靶向的circRNA的方法，以匹配TuD发夹以定制miRNA的抑制作用。我们发现，单独的ciRS-7转录本比单独的包含TuD7的转录本更有效地抑制miR-7活性，尽管ciRS-7中的每个miR-7种子匹配目标位点平均而言都比完全匹配的目标位点要弱在TuD主题中。总之，我们的研究要求改进设计和生产用于定制miRNA靶向的circRNA的方法，以匹配TuD发夹以定制miRNA的抑制作用。