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

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 chromatin openness in mouse heart, we performed ATAC seq sequencing on the heart tissues of WT mice in P0 phase and miR-187 overexpressing mice.