Foxc2 in pharyngeal arch mesenchyme is important for aortic arch artery remodelling and ventricular septum formation

Abstract

The forkhead box C2 (Foxc2) protein is a member of the forkhead/winged helix transcription factor family and plays an essential role in cardiovascular development. Previous studies showed that Foxc2 null mouse embryos die during midgestation or just after birth with severe cardiovascular defects, including interruption, coarctation of the aortic arch and ventricular septal defects. These are also seen in human congenital heart disease. However, the tissue specific role of Foxc2 in aortic arch remodelling is not yet fully understood. Here we show that Foxc2 is expressed in a restricted pattern in several cell populations, including the mesenchyme and endothelium of pharyngeal arch arteries, which are important for cardiovascular development. In this study, we use a conditional knockout approach to examine the tissue specific role of Foxc2 in aortic arch remodelling. We demonstrate that mouse embryos lacking Foxc2 in Mx2.5-expressing mesenchyme and endothelium of pharyngeal arch arteries display aortic arch interruption type B and ventricular septal defects. In contrast, conditional deletion of Foxc2 in 7z'e2-expressing endothelial cells does not result in aortic arch or ventricular septal defects, but does result in embryonic lethality due to peripheral oedema. Our data therefore provide for a detailed understanding of the role of mesen-chymal Foxc2 in aortic arch remodelling and in the development of ventricular septum.