Experimental Cardiology Unit, Division of Cardiology, Department of Cardiovascular Medicine, University of Lausanne Medical School, Switzerland (P.A., I.P., R.B., M.N., T.P.).
Institute of Cardiovascular Sciences, University College London, United Kingdom (T.A.T.).
Circulation. 2023 Aug 29;148(9):778-797. doi: 10.1161/CIRCULATIONAHA.122.062601. Epub 2023 Jul 10.
Cardiac fibroblasts have crucial roles in the heart. In particular, fibroblasts differentiate into myofibroblasts in the damaged myocardium, contributing to scar formation and interstitial fibrosis. Fibrosis is associated with heart dysfunction and failure. Myofibroblasts therefore represent attractive therapeutic targets. However, the lack of myofibroblast-specific markers has precluded the development of targeted therapies. In this context, most of the noncoding genome is transcribed into long noncoding RNAs (lncRNAs). A number of lncRNAs have pivotal functions in the cardiovascular system. lncRNAs are globally more cell-specific than protein-coding genes, supporting their importance as key determinants of cell identity.
In this study, we evaluated the value of the lncRNA transcriptome in very deep single-cell RNA sequencing. We profiled the lncRNA transcriptome in cardiac nonmyocyte cells after infarction and probed heterogeneity in the fibroblast and myofibroblast populations. In addition, we searched for subpopulation-specific markers that can constitute novel targets in therapy for heart disease.
We demonstrated that cardiac cell identity can be defined by the sole expression of lncRNAs in single-cell experiments. In this analysis, we identified lncRNAs enriched in relevant myofibroblast subpopulations. Selecting 1 candidate we named (fibrogenic -locus enhancer RNA), we showed that its silencing limits fibrosis and improves heart function after infarction. Mechanitically, interacts with CBX4, an E3 SUMO protein ligase and transcription factor, guiding CBX4 to the promoter of the transcription factor RUNX1 to control its expression and, consequently, the expression of a fibrogenic gene program.. is conserved in humans, supporting its translational value.
Our results demonstrated that lncRNA expression is sufficient to identify the various cell types composing the mammalian heart. Focusing on cardiac fibroblasts and their derivatives, we identified lncRNAs uniquely expressed in myofibroblasts. In particular, the lncRNA represents a novel therapeutic target for cardiac fibrosis.
心肌成纤维细胞在心脏中具有重要作用。特别是，成纤维细胞在受损的心肌中分化为肌成纤维细胞，有助于形成瘢痕和间质纤维化。纤维化与心脏功能障碍和衰竭有关。因此，肌成纤维细胞是有吸引力的治疗靶点。然而，缺乏肌成纤维细胞特异性标志物使得靶向治疗的发展受到阻碍。在这种情况下，大部分非编码基因组被转录为长非编码 RNA（lncRNA）。许多 lncRNA 在心血管系统中具有关键功能。lncRNA 在细胞中的特异性普遍高于蛋白质编码基因，支持它们作为细胞身份关键决定因素的重要性。
在这项研究中，我们评估了 lncRNA 转录组在非常深的单细胞 RNA 测序中的价值。我们在梗塞后对心脏非心肌细胞中的 lncRNA 转录组进行了分析，并探讨了成纤维细胞和肌成纤维细胞群体中的异质性。此外，我们还寻找了可以构成心脏病治疗新靶点的亚群特异性标志物。
我们证明了在单细胞实验中，lncRNA 的单独表达可以定义心脏细胞的身份。在这个分析中，我们确定了在相关肌成纤维细胞亚群中富集的 lncRNA。选择 1 个候选者，我们将其命名为（纤维化 - 基因座增强 RNA），我们发现其沉默限制了梗塞后纤维化并改善了心脏功能。机制上，与 CBX4（一种 E3 SUMO 蛋白连接酶和转录因子）相互作用，指导 CBX4 到转录因子 RUNX1 的启动子，控制其表达，进而控制纤维化基因程序的表达。在人类中 是保守的，支持其翻译价值。
我们的研究结果表明，lncRNA 的表达足以识别构成哺乳动物心脏的各种细胞类型。我们专注于心脏成纤维细胞及其衍生物，鉴定了在肌成纤维细胞中特异性表达的 lncRNA。特别是，lncRNA 代表了心脏纤维化的一个新的治疗靶点。
