title: Transactivation of vascular endothelial growth factor receptor-2 by interleukin-8 (IL-8/CXCL8) is required for IL-8/CXCL8-induced endothelial permeability.
abstract: Interleukin-8 (IL-8/CXCL8) is a chemokine that increases endothelial permeability during early stages of angiogenesis. However, the mechanisms involved in IL-8/CXCL8-induced permeability are poorly understood. Here, we show that permeability induced by this chemokine requires the activation of vascular endothelial growth factor receptor-2 (VEGFR2/fetal liver kinase 1/KDR). IL-8/CXCL8 stimulates VEGFR2 phosphorylation in a VEGF-independent manner, suggesting VEGFR2 transactivation. We investigated the possible contribution of physical interactions between VEGFR2 and the IL-8/CXCL8 receptors leading to VEGFR2 transactivation. Both IL-8 receptors interact with VEGFR2 after IL-8/CXCL8 treatment, and the time course of complex formation is comparable with that of VEGFR2 phosphorylation. Src kinases are involved upstream of receptor complex formation and VEGFR2 transactivation during IL-8/CXCL8-induced permeability. An inhibitor of Src kinases blocked IL-8/CXCL8-induced VEGFR2 phosphorylation, receptor complex formation, and endothelial permeability. Furthermore, inhibition of the VEGFR abolishes RhoA activation by IL-8/CXCL8, and gap formation, suggesting a mechanism whereby VEGFR2 transactivation mediates IL-8/CXCL8-induced permeability. This study points to VEGFR2 transactivation as an important signaling pathway used by chemokines such as IL-8/CXCL8, and it may lead to the development of new therapies that can be used in conditions involving increases in endothelial permeability or angiogenesis, particularly in pathological situations associated with both IL-8/CXCL8 and VEGF.
authors.affiliation: Graduate Program in Cell, Molecular, and Developmental Biology, Department of Cell Biology and Neuroscience, and Division of Biomedical Sciences, University of California, Riverside, Riverside, CA 92521, USA.
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Petreaca
authors.forename: Min
authors.initials: M
authors.lastname: Yao
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Kathryn
authors.initials: K
authors.lastname: Defea
authors.forename: Manuela
authors.initials: M
authors.lastname: Martins-Green
mesh_terms: D000818:Animals; D002463:Cell Membrane Permeability / Q000187:drug effects*; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D016209:Interleukin-8 / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008833:Microcirculation / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D053700:Receptors, Interleukin-8 / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics* / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D016209:Interleukin-8; D053700:Receptors, Interleukin-8; D040301:Vascular Endothelial Growth Factor Receptor-2; D019061:src-Family Kinases; D020742:rhoA GTP-Binding Protein