title: Transforming growth factor beta 1 down-regulates vascular endothelial growth factor receptor 2/flk-1 expression in vascular endothelial cells.
abstract: Although the importance of the vascular endothelial growth factor (VEGF)/VEGF tyrosine kinase receptor (VEGFR) system in angiogenesis is well established, very little is known about the regulation of VEGFR expression in vascular endothelial cells. We have cloned partial cDNAs encoding bovine VEGFR-1 (flt) and -2 (flk-1) and used them to study VEGFR expression by bovine microvascular- and large vessel-derived endothelial cells. Both cell lines express flk-1, but not flt. Transforming growth factor beta 1 (TGF-beta 1) reduced the high affinity 125I-VEGF binding capacity of both cell types in a dose-dependent manner, with a 2.0-2.7-fold decrease at 1-10 ng/ml. Cross-linking experiments revealed a decrease in 125I-VEGF binding to a cell surface monomeric protein corresponding to Flk-1 on the basis of its affinity for VEGF, molecular mass (185-190 kDa), and apparent internalization after VEGF binding. Immunoprecipitation and Western blot experiments demonstrated a decrease in Flk-1 protein expression, and TGF-beta 1 reduced flk-1 mRNA levels in a dose-dependent manner. These results imply that TGF-beta 1 is a major regulator of the VEGF/Flk-1 signal transduction pathway in endothelial cells.
authors.affiliation: Department of Morphology, University Medical Center, Geneva, Switzerland.
authors.forename: S J
authors.initials: SJ
authors.lastname: Mandriota
authors.forename: P A
authors.initials: PA
authors.lastname: Menoud
authors.forename: M S
authors.initials: MS
authors.lastname: Pepper
mesh_terms: D000302:Adrenal Cortex / Q000098:blood supply; D000595:Amino Acid Sequence; D000818:Animals; D001011:Aorta; D001483:Base Sequence; D002417:Cattle; D002460:Cell Line; D017124:Conserved Sequence; D017931:DNA Primers; D015536:Down-Regulation / Q000187:drug effects; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008833:Microcirculation; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000096:biosynthesis*; D017978:Receptors, Growth Factor / Q000096:biosynthesis*; D040262:Receptors, Vascular Endothelial Growth Factor; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger; D017978:Receptors, Growth Factor; D016212:Transforming Growth Factor beta; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor