DCBLD1 Modulates Angiogenesis by Regulation of the VEGFR-2 Endocytosis in Endothelial Cells

BACKGROUND: Unwanted angiogenesis is involved in the progression of various malignant tumors and cardiovascular diseases, and the factors that regulate angiogenesis are potential therapeutic targets. We tested the hypothesis that DCBLD1 (discoidin, CUB, and LCCL domain-containing protein 1) is a coreceptor of VEGFR-2 (vascular endothelial growth factor receptor-2) and modulates angiogenesis in endothelial cells. METHODS: A carotid artery ligation model and retinal angiogenesis assay were used to study angiogenesis using globe knockout or endothelial cell–specific conditional Dcbld1 knockout mice in vivo. Immunoblotting, immunofluorescence staining, plasma membrane subfraction isolation, Coimmunoprecipitation, and mass spectrum assay were performed to clarify the molecular mechanisms. RESULTS: Loss of Dcbld1 impaired VEGF (vascular endothelial growth factor) response and inhibited VEGF-induced endothelial cell proliferation and migration. Dcbld1 deletion interfered with adult and developmental angiogenesis. Mechanistically, DCBLD1 bound to VEGFR-2 and regulated the formation of VEGFR-2 complex with negative regulators: protein tyrosine phosphatases, E3 ubiquitin ligases (neuronal precursor cell-expressed developmentally downregulated gene 4, Nedd4 and c-Casitas B-lineage lymphoma, c-Cbl), and also Dcbld1 knockdown promoted lysosome-mediated VEGFR-2 degradation in endothelial cells. CONCLUSION: These findings demonstrated the essential role of endothelial DCBLD1 in regulating VEGF signaling and provided evidence that DCBLD1 promotes VEGF-induced angiogenesis by limiting the dephosphorylation, ubiquitination, and lysosome degradation after VEGFR-2 endocytosis. We proposed that endothelial DCBLD1 is a potential therapeutic target for ischemic cardiovascular diseases by the modulation of angiogenesis through regulation of the VEGFR-2 endocytosis.