Tian Hongyu, Ketova Tatiana, Hardy Duriel, Xu Xiaojiang, Gao Xia, Zijlstra Andries, Blobe Gerard C
From the Division of Medical Oncology, Department of Medicine (H.T., D.H., G.C.B.) and Department of Pharmacology and Cancer Biology (G.C.B.), Duke University Medical Center, Durham, NC; Department of Pathology, Microbiology, and Immunology (T.K., A.Z.) and Department of Cancer Biology (A.Z.), Vanderbilt University, Nashville, TN; Integrative Bioinformatics, National Institute of Environmental Health Sciences, Research Triangle Park, NC (X.X.); Department of Cell Biology, Duke University School of Medicine, Durham, NC (X.G.); and Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN (A.Z.);
From the Division of Medical Oncology, Department of Medicine (H.T., D.H., G.C.B.) and Department of Pharmacology and Cancer Biology (G.C.B.), Duke University Medical Center, Durham, NC; Department of Pathology, Microbiology, and Immunology (T.K., A.Z.) and Department of Cancer Biology (A.Z.), Vanderbilt University, Nashville, TN; Integrative Bioinformatics, National Institute of Environmental Health Sciences, Research Triangle Park, NC (X.X.); Department of Cell Biology, Duke University School of Medicine, Durham, NC (X.G.); and Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN (A.Z.).
Arterioscler Thromb Vasc Biol. 2017 Jun;37(6):1115-1126. doi: 10.1161/ATVBAHA.116.308859. Epub 2017 Apr 27.
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.
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 spreading on endothelial cells via increasing integrin/FAK pathway signaling, whereas endoglin has minimal effects on VSMC adhesion to endothelial cells. In addition, we further determine that loss of endoglin in VSMCs inhibits VSMC recruitment in vivo.
These studies demonstrate that endoglin has an important role in VSMC recruitment and blood vessel maturation during angiogenesis and also provide novel insights into how discordant endoglin function in endothelial and VSMCs may regulate vascular maturation and angiogenesis.
内皮糖蛋白是一种转化生长因子-β超家族共受体，主要在内皮细胞中表达，在血管发育中起重要作用。然而，内皮糖蛋白是否也在血管平滑肌细胞（VSMC）中表达，尤其是在体内表达，仍存在争议。此外，内皮糖蛋白在VSMC生物学中的作用仍 largely未知。我们的目的是研究内皮糖蛋白在血管生成过程中在VSMC中的表达并确定其功能。
在此，我们确定内皮糖蛋白在VSMC中大量表达。在VSMC/内皮细胞共培养模型系统中使用CRISPR/CAS9基因敲除和短发夹RNA敲低技术，我们确定VSMC中的内皮糖蛋白而非内皮细胞中的内皮糖蛋白在体外和体内均促进内皮细胞对VSMC的募集。通过对RNA测序数据进行无偏倚的生物信息学分析及进一步研究，我们确定，从机制上讲，内皮糖蛋白通过增加整合素/黏着斑激酶（FAK）信号通路促进VSMC在内皮细胞上的迁移和铺展，从而介导VSMC的募集，而内皮糖蛋白对VSMC与内皮细胞的黏附影响极小。此外，我们进一步确定VSMC中内皮糖蛋白的缺失在体内抑制VSMC的募集。
这些研究表明，内皮糖蛋白在血管生成过程中的VSMC募集和血管成熟中起重要作用，也为内皮细胞和VSMC中内皮糖蛋白功能的差异如何调节血管成熟和血管生成提供了新的见解。
