Mutations in bone morphogenetic protein type II receptor (BMPR2) have been found in patients with congenital heart disease-associated pulmonary arterial hypertension (CHD-PAH). Our study aimed to clarify whether deficient BMPR2 signalling acts through downstream effectors, inhibitors of DNA-binding proteins (IDs), during heart development to contribute to the progress of PAH in CHD patients.
We found that Cardiomyocytes (CMs)-specific Id 1/3 knockout mice (Ids cDKO) developed mild PAH. Moreover, Ultrasound revealed that 33% of Ids cDKO mice had detectable defects in their ventricular septum. CMs differentiated from induced pluripotent stem cells (iPSCs) derived from CHD-PAH patients with BMPR mutations exhibited dysfunctional cardiac differentiation and reduced Ca2+ transients. Smad1/5 phosphorylation and ID1 and ID3 expression were reduced in CHD-PAH iPSCs and in Bmpr2 +/- rat right ventricles. Moreover, we generated ID1 and ID3 double-knockout (IDs KO) human embryonic stem cells. Single-cell RNA(scRNA)-seq analysis revealed impaired differentiation of CMPs and downregulated USP9X expression in IDs KO cells compared with wild-type (WT) cells.
We found that BMPR2 signals through IDs and USP9X to regulate cardiac differentiation, and the loss of ID1 and ID3 expression contributes to CM dysfunction in CHD-PAH patients with BMPR2 mutations.
