title: Colocalization of the VEGF-R2 and the common IL-3/GM-CSF receptor beta chain to lipid rafts leads to enhanced p38 activation.
abstract: Previous studies suggested an important role for vascular endothelial growth factor (VEGF) and its receptors in postnatal haemopoiesis. However, it is unclear how VEGF receptor (VEGFR) signalling could interact with that issued from the activation of haematopoietic growth factor receptors. To elucidate this point we explored VEGF-R2 and granulocyte-macrophage colony-stimulating factor receptor (GM-CSFR) membrane localization and cell signalling in TF1-KDR cells (TF1 leukaemic cells that overexpress VEGF-R2/KDR). Activation of either GM-CSFR or VEGF-R2 was shown to determine the migration of both receptor elements (VEGF-R2 and the common beta-chain of the GM-CSFR) to lipid rafts. The study of receptor phosphorylation showed that GM-CSF induced the phosphorylation of its own receptor and the transphosphorylation of VEGF-R2; on the other hand, VEGF triggered the phosphorylation of its receptor and transphosphorylated the beta-chain of the GM-CSFR. Co-stimulation of TF1-KDR cells with both GM-CSF and VEGF-A resulted in massive migration of both the common GM-CSFR beta-chain and VEGF-R2 to lipid rafts and sustained p38 mitogen-activated protein kinase activation. Disruption of lipid rafts inhibited the capacity of both GM-CSF and VEGF-A to activate p38. Experiments with specific p38 inhibitors showed that p38 activation was required to sustain the VEGF- and GM-CSF-dependent proliferation of TF1-KDR and the survival of primary acute myeloid leukaemia blasts.
authors.affiliation: Department of Haematology, Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Ernestina
authors.initials: E
authors.lastname: Saulle
authors.forename: Roberta
authors.initials: R
authors.lastname: Riccioni
authors.forename: Simona
authors.initials: S
authors.lastname: Coppola
authors.forename: Isabella
authors.initials: I
authors.lastname: Parolini
authors.forename: Daniela
authors.initials: D
authors.lastname: Diverio
authors.forename: Viviana
authors.initials: V
authors.lastname: Riti
authors.forename: Gualtiero
authors.initials: G
authors.lastname: Mariani
authors.forename: Stefan
authors.initials: S
authors.lastname: Laufer
authors.forename: Massimo
authors.initials: M
authors.lastname: Sargiacomo
authors.forename: Ugo
authors.initials: U
authors.lastname: Testa
mesh_terms: D017209:Apoptosis; D001692:Biological Transport; D015153:Blotting, Western / Q000379:methods; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival; D053648:Cytokine Receptor Common beta Subunit / Q000378:metabolism*; D004789:Enzyme Activation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D016130:Immunophenotyping; D047468:Immunoprecipitation; D007377:Interleukin-3 / Q000378:metabolism*; D015470:Leukemia, Myeloid, Acute / Q000378:metabolism* / Q000473:pathology; D021962:Membrane Microdomains / Q000378:metabolism*; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: C522498:(4-(5-(4-fluorophenyl)-2-methylsulfanyl-3H-imidazol-4-yl)pyridin-2-yl)-(1-phenylethyl)amine; D053648:Cytokine Receptor Common beta Subunit; D007093:Imidazoles; D007377:Interleukin-3; D011725:Pyridines; D042461:Vascular Endothelial Growth Factor A; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D040301:Vascular Endothelial Growth Factor Receptor-2; D048051:p38 Mitogen-Activated Protein Kinases