Circular RNAs (circRNAs) are covalently closed single-stranded RNAs with regulatory activity and regarded as new types of therapeutic targets in diseases such as cancers. By means of RNA-Seq technology, numerous cardiac circRNAs were discovered. Although some candidates were detected to involve in heart disease in murine model, relative low sequence conservation and expression level of their human homologs might result in an insignificant, even distinct effect in the human heart. Therefore, the therapeutic significance of circRNAs should be more strictly considered. It is also necessary to discuss which circRNA is suitable for being applied in heart disease treatment. Here, we are willing to introduce a ~ 1830 nt circular transcript generated from single exon of sodium/calcium exchanger 1 (ncx1) gene (also called solute carrier family 8 member A1, slc8a1), usually named circNCX1 or circSLC8A1, which is gradually coming into our view. circNCX1 is one of the most cardiac-enriched circRNAs. It is widely existent in vertebrate and relatively conserved, indicating its indispensability during the evolution of species. Indeed, circNCX1 was shown to involve in heart development by some expression analysis. It was further revealed that the dysregulation of circNCX1 is one of the key pathogeneses of heart diseases including ischemic cardiac injury and hypertrophic cardiomyopathy. To make the significance of circNCX1 in the heart clear, we comprehensively dissected circNCX1 in the aspects of its parental gene structure, conservation, biogenesis and expression profiles, function, molecular mechanisms, and clinical application in this review. New medicine or therapeutic schedules based on circNCX1 are expected in the future.

环状RNA（circRNAs）是共价闭合的单链RNA，具有调节活性，被视为癌症等疾病的新型治疗靶点。通过 RNA-Seq 技术，发现了许多心脏 circRNA。尽管在小鼠模型中检测到一些候选者与心脏病有关，但其人类同源物的序列保守性和表达水平相对较低，可能会导致对人类心脏的影响微不足道，甚至是明显的影响。因此，应该更严格地考虑circRNA的治疗意义。还需要讨论哪种circRNA适合应用于心脏病治疗。在这里，我们愿意介绍由钠/钙交换器 1 (ncx1) 基因（也称为溶质载体家族 8 成员 A1，slc8a1)，通常命名为 circNCX1 或 circSLC8A1，逐渐进入我们的视野。circNCX1 是心脏最丰富的 circRNA 之一。它广泛存在于脊椎动物中，相对保守，说明它在物种进化过程中不可或缺。事实上，通过一些表达分析表明，circNCX1 参与了心脏发育。进一步揭示了circNCX1的失调是包括缺血性心脏损伤和肥厚性心肌病在内的心脏病的关键发病机制之一。为了明确circNCX1在心脏中的意义，我们在本综述中从其亲本基因结构、保守性、生物发生和表达谱、功能、分子机制和临床应用等方面对circNCX1进行了全面剖析。