Mutation of LRP1 in cardiac neural crest cells causes congenital heart defects by perturbing outflow lengthening

Abstract

The recent recovery of mutations in vesicular trafficking genes causing congenital heart disease (CHD) revealed an unexpected role for the endocytic pathway. We now show that mice with a C4232R missense mutation in Low density lipoprotein receptor related protein 1 (LRP1) exhibit atrioventricular septal defects with double outlet right ventricle. Lrp1^m/m mice exhibit shortened outflow tracts (OFT) and dysmorphic hypocellular cushions with reduced proliferation and increased apoptosis. Lrp1^m/m embryonic fibroblasts show decreased cell motility and focal adhesion turnover associated with retention of mutant LRP1 in endoplasmic reticulum and reduced LRP1 expression. Conditional deletion of Lrp1 in cardiac neural crest cells (CNC) replicates the full CHD phenotype. Cushion explants showed defective cell migration, with gene expression analysis indicating perturbation of Wnt and other signaling pathways. Thus, LRP1 function in CNCs is required for normal OFT development with other cell lineages along the CNC migratory path playing a supporting role.

Lin et al. find that mutation in endocytic trafficking protein Lrp1 causes congenital heart defects in mice due to a requirement for Lrp1 in the neural crest lineage, where it regulates outflow tract lengthening. This study provides insights into how Lrp1 and the neural crest contribute to heart development.