Intrinsic GATA4 expression sensitizes the aortic root to dilation in a Loeys–Dietz syndrome mouse model

Loeys–Dietz syndrome (LDS) is a connective tissue disorder caused by mutations that decrease transforming growth factor-β signaling. LDS-causing mutations increase the risk of aneurysm throughout the arterial tree, yet the aortic root is a site of heightened susceptibility. Here we investigate the heterogeneity of vascular smooth muscle cells (VSMCs) in the aorta of Tgfbr1M318R/+ LDS mice by single-cell transcriptomics to identify molecular determinants of this vulnerability. Reduced expression of components of the extracellular matrix–receptor apparatus and upregulation of stress and inflammatory pathways were observed in all LDS VSMCs. However, regardless of genotype, a subset of Gata4-expressing VSMCs predominantly located in the aortic root intrinsically displayed a less differentiated, proinflammatory profile. A similar population was also identified among aortic VSMCs in a human single-cell RNA sequencing dataset. Postnatal VSMC-specific Gata4 deletion reduced aortic root dilation in LDS mice, suggesting that this factor sensitizes the aortic root to the effects of impaired transforming growth factor-β signaling. Bramel et al. identify a population of GATA4+ vascular smooth muscle cells enriched in the human and mouse aortic root that is intrinsically more susceptible to Loeys–Dietz-syndrome-causing mutations and demonstrate that postnatal deletion of Gata4 in vascular smooth muscle cells reduces aortic root dilation in a mouse model of Loeys–Dietz syndrome.