Single-cell RNA sequencing reveals that BMPR2 mutation regulates right ventricular function via ID genes

Area of Science:

• Cardiovascular Biology
• Developmental Biology
• Molecular Genetics

Background:

• Mutations in bone morphogenetic protein type II receptor (BMPR2) are linked to congenital heart disease-associated pulmonary arterial hypertension (CHD-PAH).
• The role of BMPR2 signaling downstream effectors, specifically inhibitors of DNA-binding proteins (ID), in CHD-PAH pathogenesis during heart development requires clarification.

Purpose of the Study:

• To investigate whether deficient BMPR2 signaling, acting through ID proteins, contributes to pulmonary arterial hypertension (PAH) in patients with congenital heart disease (CHD).
• To elucidate the molecular mechanisms by which BMPR2-ID signaling impacts cardiac development and function in the context of CHD-PAH.

Main Methods:

• Generated cardiomyocyte-specific Id1/Id3 double knockout (Ids cDKO) mice and ID1/ID3 double-knockout (IDs KO) human embryonic stem cells.
• Utilized induced pluripotent stem cells (iPSCs) from CHD-PAH patients with BMPR2 mutations for comparative analysis.
• Performed in vivo (ultrasound, hemodynamic assessment) and in vitro (confocal microscopy, single-cell RNA sequencing) experiments to assess cardiac function and differentiation.

Main Results:

• Ids cDKO mice exhibited mild pulmonary arterial hypertension (PAH) with altered hemodynamics and pulmonary vascular remodeling.
• Cardiomyocytes derived from CHD-PAH patient iPSCs showed impaired differentiation, reduced calcium transients, and decreased Smad1/5 phosphorylation and ID1/ID3 expression.
• IDs KO cells displayed impaired cardiac mesoderm progenitor (CMP) differentiation and downregulated USP9X expression, indicating a role for BMPR2-ID signaling in cardiac development.

Conclusions:

• BMPR2 signaling regulates cardiac differentiation through downstream effectors ID1, ID3, and USP9X.
• Loss of ID1 and ID3 expression contributes to cardiomyocyte dysfunction observed in CHD-PAH patients with BMPR2 mutations.
• This study identifies a critical BMPR2-ID signaling pathway involved in the pathogenesis of CHD-PAH.