title: Regulation of CXCR4 by the Notch ligand delta-like 4 in endothelial cells.
abstract: Gene-targeting studies have shown that Delta-like 4 (Dll4) is required for normal embryonic vascular remodeling, but the mechanisms underlying Dll4 regulatory functions are not well defined. We generated primary human umbilical vascular endothelial cells that express Dll4 protein to study Dll4 function and previously showed that Dll4 down-regulates vascular endothelial growth factor (VEGF) receptor 2 and NRP1 expression and inhibits VEGF function. We now report that expression of Dll4 in endothelial cells inhibited attachment and migration to stromal-derived growth factor 1 (SDF1) chemokine. Cell surface, total protein, and mRNA levels of CXCR4, principal signaling receptor for SDF1, were significantly decreased in Dll4-transduced endothelial cells, attributable to a significant reduction of CXCR4 promoter activity. An immobilized recombinant extracellular portion of Dll4 (rhDLL4) was sufficient to down-regulate CXCR4 mRNA and protein, whereas protein levels of SDF1, VEGF, and RDC1 were unchanged. The gamma-secretase inhibitor L-685,458 significantly reconstituted CXCR4 mRNA in rhDLL4-stimulated endothelial cells. CXCR4 mRNA levels were significantly reduced in mouse xenografts of Dll4-transduced human gliomas compared with control gliomas, and vascular CXCR4 was not detected by immunohistochemistry in the enlarged vessels within the Dll4 gliomas. Thus, Dll4 may contribute to vascular differentiation and inhibition of the angiogenic response by regulating multiple receptor pathways.
authors.affiliation: Molecular Oncology Laboratories, Cancer Research UK, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom.
authors.forename: Cassin Kimmel
authors.initials: CK
authors.lastname: Williams
authors.forename: Marta
authors.initials: M
authors.lastname: Segarra
authors.forename: Maria De La Luz
authors.initials: Mde L
authors.lastname: Sierra
authors.forename: Richard C A
authors.initials: RC
authors.lastname: Sainson
authors.forename: Giovanna
authors.initials: G
authors.lastname: Tosato
authors.forename: Adrian L
authors.initials: AL
authors.lastname: Harris
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002135:Calcium-Binding Proteins; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D054377:Chemokine CXCL12 / Q000378:metabolism / Q000494:pharmacology; D015536:Down-Regulation; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D005909:Glioblastoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D019718:Receptors, CXCR4 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C527276:CXCR4 protein, human; D002135:Calcium-Binding Proteins; D054377:Chemokine CXCL12; C424126:DLL4 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D019718:Receptors, CXCR4; D051880:Receptors, Notch