Endoglin Mediates Vascular Maturation by Promoting Vascular Smooth Muscle Cell Migration and Spreading

Objective—Endoglin, a transforming growth factor-β superfamily coreceptor, is predominantly expressed in endothelial cells and has essential roles in vascular development. However, whether endoglin is also expressed in vascular smooth muscle cells (VSMCs), especially in vivo, remains controversial. Furthermore, the roles of endoglin in VSMC biology remain largely unknown. Our objective was to examine the expression and determine the function of endoglin in VSMCs during angiogenesis. Approach and Results—Here, we determine that endoglin is robustly expressed in VSMCs. Using CRISPR/CAS9 knockout and short hairpin RNA knockdown in the VSMC/endothelial coculture model system, we determine that endoglin in VSMCs, but not in endothelial cells, promotes VSMCs recruitment by the endothelial cells both in vitro and in vivo. Using an unbiased bioinformatics analysis of RNA sequencing data and further study, we determine that, mechanistically, endoglin mediates VSMC recruitment by promoting VSMC migration and spread...