Expression and endocytosis of VEGF and its receptors in human colonic vascular endothelial cells.
Normal human colonic microvascular endothelial cells (HUCMEC) have been isolated from surgical specimens by their adherence to Ulex europaeus agglutinin bound to magnetic dynabeads that bind alpha-L-fucosyl residues on the endothelial cell membrane. Immunocytochemistry demonstrated the presence of a range of endothelial-specific markers on HUCMEC, including the von Willebrand factor, Ulex europaeus agglutinin, and platelet endothelial cell adhesion molecule-1. The growing cells form monolayers with the characteristic cobblestone morphology of endothelial cells and eventually form tube-like structures. HUCMEC produce vascular endothelial growth factor (VEGF) and express the receptors, kinase insert domain-containing receptor (KDR) and fms-like tyrosine kinase, through which VEGF mediates its actions in the endothelium. VEGF induces the tyrosine phosphorylation of KDR and a proliferative response from HUCMEC comparable to that elicited from human umbilical vein endothelial cells (HUVEC). On binding to HUCMEC or HUVEC, (125)I-labeled VEGF internalizes or dissociates to the medium. Once internalized, (125)I-labeled VEGF is degraded and no evidence of ligand recycling was observed. However, significantly less VEGF is internalized, and more is released to the medium from HUCMEC than HUVEC. Angiogenesis results from the proliferation and migration of microvascular, not large-vessel, endothelial cells. The demonstration that microvascular endothelial cells degrade less and release more VEGF to the medium than large-vessel endothelial cells identifies a mechanism permissive of the role of microvascular cells in angiogenesis.
Wang
Dongfang
D
Department of Surgery, School of Medicine, University of California, San Francisco, California 94143-0790, USA.
Lehman
Richard E
RE
Donner
David B
DB
Matli
Mary R
MR
Warren
Robert S
RS
Welton
Mark L
ML
D019898:Autocrine Communication / Q000502:physiology; D002478:Cells, Cultured; D003106:Colon / Q000098:blood supply*; D004705:Endocytosis / Q000502:physiology*; D016228:Endothelial Growth Factors / Q000235:genetics / Q000493:pharmacokinetics*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D007457:Iodine Radioisotopes; D008222:Lymphokines / Q000235:genetics / Q000493:pharmacokinetics*; D008833:Microcirculation / Q000502:physiology; D018919:Neovascularization, Physiologic / Q000502:physiology; D019899:Paracrine Communication / Q000502:physiology; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000235:genetics / Q000378:metabolism*; D040262:Receptors, Vascular Endothelial Growth Factor; D014471:Umbilical Veins / Q000166:cytology; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D007457:Iodine Radioisotopes; D008222:Lymphokines; D017978:Receptors, Growth Factor; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor