Elevated microRNA-187 causes cardiac endothelial dysplasia to promote congenital heart disease through inhibition of NIPBL [Heart RNA-Seq]

Dysplasia of cardiac endothelial cells significantly contributes to congenital heart disease (CHD), the most common congenital disability. The regulatory role of miRNAs in this process remains elusive. This study identified elevated miR-187 expression in embryonic heart endothelial cells from CHD fetuses. Using a conditional knock-in model, we showed that increased miR-187 levels in embryonic endothelial cells induce CHD in homozygous fetal mice, closely mirroring human CHD. Mechanistically, miR-187 targets NIPBL, which is responsible for recruiting the cohesin complex and facilitating chromatin accessibility between enhancers and promoters. Consequently, the endothelial cell-specific upregulation of miR-187 inhibited NIPBL, leading to reduced chromatin accessibility and impaired gene expression, which hindered endothelial cell development and ultimately caused heart septal defects and reduced heart size both in vitro and in vivo. Importantly, exogenous miR-187 expression in human cardiac organoids mimicked developmental defects in the cardiac endothelial cells, reversible by NIPBL replenishment. Our findings establish the miR-187/NIPBL axis as a potent regulator that inhibits cardiac endothelial cell development by attenuating the transcription of numerous endothelial genes, with our mouse and human cardiac organoid models effectively replicating severe defects from minor perturbations. To investigate the effect of increased miR-187 expression on the transcriptome of mouse hearts, we performed RNA seq sequencing on the heart tissues of WT mice and miR-187 overexpressing mice during the P0 period.

心脏内皮细胞发育异常是先天性心脏病（Congenital Heart Disease, CHD）的重要致病因素，而先天性心脏病是最为常见的先天性残疾。微小RNA（microRNA, miRNA）在此过程中的调控作用仍不甚明确。本研究在先天性心脏病胎儿的胚胎心脏内皮细胞中，检测到miR-187的表达水平显著升高。本研究借助条件性敲入模型，证实胚胎内皮细胞中miR-187表达上调可诱导纯合子胎鼠罹患先天性心脏病，该表型与人类先天性心脏病高度相似。从机制层面分析，miR-187可靶向调控NIPBL，该蛋白负责招募黏连蛋白复合体并促进增强子与启动子之间的染色质可及性。因此，内皮细胞特异性的miR-187上调会抑制NIPBL的表达，进而降低染色质可及性、损伤基因表达程序，阻碍内皮细胞发育进程，最终在体外及体内实验中均引发心脏间隔缺损，并导致心脏体积缩小。值得注意的是，在人类心脏类器官中外源过表达miR-187，可模拟心脏内皮细胞的发育缺陷，且该缺陷可通过补充NIPBL得以逆转。本研究结果证实，miR-187/NIPBL信号轴是一类强效调控因子，可通过抑制众多内皮基因的转录来阻碍心脏内皮细胞发育；本研究构建的小鼠及人类心脏类器官模型，可有效复现由微小扰动引发的严重发育缺陷。为探究miR-187表达上调对小鼠心脏转录组的影响，本研究对出生后0天（postnatal day 0, P0）的野生型（Wild Type, WT）小鼠及miR-187过表达小鼠的心脏组织开展了RNA测序（RNA sequencing, RNA-seq）。