Coronary arterial development is regulated by a Dll4-Jag1-EphrinB2 signaling cascade

Coronaries are essential for myocardial growth and heart function. Notch is crucial for mouse embryonic angiogenesis, but its role in coronary development remains uncertain. We show Jag1, Dll4 and activated Notch1 receptor expression in sinus venosus (SV) endocardium. Endocardial Jag1 removal blocks SV capillary sprouting, while Dll4 inactivation stimulates excessive capillary growth, suggesting that ligand antagonism regulates coronary primary plexus formation. Later endothelial ligand removal, or forced expression of Dll4 or the glycosyltransferase Mfng, blocks coronary plexus remodeling, arterial differentiation, and perivascular cell maturation. Endocardial deletion of Efnb2 phenocopies the coronary arterial defects of Notch mutants. Angiogenic rescue experiments in ventricular explants, or in primary human endothelial cells, indicate that EphrinB2 is a critical effector of antagonistic Dll4 and Jag1 functions in arterial morphogenesis. Thus, coronary arterial precursors are specified in the SV prior to primary coronary plexus formation and subsequent arterial differentiation depends on a Dll4-Jag1-EphrinB2 signaling cascade. This study was supported by grants SAF2016-78370-R, CB16/11/00399 (CIBER CV), and RD16/0011/0021 (TERCEL) from the Spanish Ministry of Science, Innovation and Universities (MCIU) and grants from the Fundacion BBVA (Ref.: BIO14_298) and Fundacion La Marato (Ref.: 20153431) to JLDLP. JG-B is funded by Atraccion de Talento Program from the Comunidad de Madrid. The cost of this publication was supported in part with funds from the ERDF. The CNIC is supported by the MCIU and the Pro-CNIC Foundation and is a Severo Ochoa Center of Excellence (SEV-2015–0505). Sí