Charting vascular development Junctional landscapes guiding endothelial migration and signaling routes to capillary malformations

This thesis dissects how endothelial cells build, remodel, and sometimes corrupt the vascular network, linking vascular morphogenesis to human vascular disease.
First, it interrogates asymmetric adherens junctions (AAJs), an adhesive molecular structure that forms at leader-follower interfaces in migrating endothelial collectives. Using live fluorescence imaging, focused ion beam scanning electron microscopy, proteomics and we uncover the ultrastructural landscape of AAJs. Secondly, we use live imaging of endothelial migration in the developing zebrafish common cardinal vein to establish the functional relevance of AAJs in vivo. We describe AAJs as highly curved, engulfed membrane folds packed with the adhesion molecule VE-cadherin, and a substantial number of membrane curvature sensing BAR proteins, endocytic and cytoskeletal regulators. Systematic tracking of AAJ lifecycles shows that sequential BAR protein recruitment sculpts junctional membranes, controls VE-cadherin trafficking, and tunes junction plasticity. We discover that AAJ internalization emerges as a key bottleneck for maintaining collective migration in vitro and in vivo.
The second arm of the thesis confronts GNAQ-driven capillary malformations, including Sturge-Weber Syndrome, by combining patient-derived endothelial cultures, CRISPR engineered cells, and SILAC-based phosphoproteomics. These approaches reveal that the GNAQ p.R183Q mutation rewires calcineurin NFATC and PTEN signaling, offering molecular hypotheses for aberrant endothelial behavior and pinpointing candidate targets for pathway-specific intervention. Together, the two objectives establish AAJs as transient spatially restricted adhesive platforms that steer vascular morphogenesis, while mapping pathogenic signaling circuits in GNAQ-mutant endothelium. As such, this thesis delivers foundational insights into how junctional dynamics and G protein signaling shape vascular form and function, opening new conceptual and therapeutic avenues in cardiovascular medicine.