title: VEGF induces signalling and angiogenesis by directing VEGFR2 internalisation through macropinocytosis.
abstract: Endocytosis plays a crucial role in receptor signalling. VEGFR2 (also known as KDR) and its ligand VEGFA are fundamental in neovascularisation. However, our understanding of the role of endocytosis in VEGFR2 signalling remains limited. Despite the existence of diverse internalisation routes, the only known endocytic pathway for VEGFR2 is the clathrin-mediated pathway. Here, we show that this pathway is the predominant internalisation route for VEGFR2 only in the absence of ligand. Intriguingly, VEGFA induces a new internalisation itinerary for VEGFR2, the pathway of macropinocytosis, which becomes the prevalent endocytic route for the receptor in the presence of ligand, whereas the contribution of the clathrin-mediated route becomes minor. Macropinocytic internalisation of VEGFR2, which mechanistically is mediated through the small GTPase CDC42, takes place through macropinosomes generated at ruffling areas of the membrane. Interestingly, macropinocytosis plays a crucial role in VEGFA-induced signalling, endothelial cell functions in vitro and angiogenesis in vivo, whereas clathrin-mediated endocytosis is not essential for VEGFA signalling. These findings expand our knowledge on the endocytic pathways of VEGFR2 and suggest that VEGFA-driven internalisation of VEGFR2 through macropinocytosis is essential for endothelial cell signalling and angiogenesis.
authors.affiliation: Institute of Molecular Biology and Biotechnology-Biomedical Research, Foundation for Research and Technology, Ioannina 45110, Greece.|Laboratory of Biological Chemistry, Department of Medicine, School of Health Sciences, University of Ioannina, Ioannina 45110, Greece.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Basagiannis
authors.affiliation: Institute of Molecular Biology and Biotechnology-Biomedical Research, Foundation for Research and Technology, Ioannina 45110, Greece.
authors.forename: Sofia
authors.initials: S
authors.lastname: Zografou
authors.affiliation: Institute of Molecular Biology and Biotechnology-Biomedical Research, Foundation for Research and Technology, Ioannina 45110, Greece.|School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Carol
authors.initials: C
authors.lastname: Murphy
authors.affiliation: Institute of Molecular Biology and Biotechnology-Biomedical Research, Foundation for Research and Technology, Ioannina 45110, Greece.|Laboratory of Biological Chemistry, Department of Medicine, School of Health Sciences, University of Ioannina, Ioannina 45110, Greece.
authors.forename: Theodore
authors.initials: T
authors.lastname: Fotsis
authors.affiliation: Department of Life Sciences, University of Siena, Via Aldo Moro 2, Siena 53100, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Morbidelli
authors.affiliation: Department of Life Sciences, University of Siena, Via Aldo Moro 2, Siena 53100, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Ziche
authors.affiliation: Institute of Biochemistry, ETH, Zurich 8093, Switzerland.
authors.forename: Christopher
authors.initials: C
authors.lastname: Bleck
authors.affiliation: Institute of Biochemistry, ETH, Zurich 8093, Switzerland.|MRC-Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Jason
authors.initials: J
authors.lastname: Mercer
authors.affiliation: Institute of Molecular Biology and Biotechnology-Biomedical Research, Foundation for Research and Technology, Ioannina 45110, Greece savvas_christoforidis@imbb.forth.gr schristo@uoi.gr.|Laboratory of Biological Chemistry, Department of Medicine, School of Health Sciences, University of Ioannina, Ioannina 45110, Greece.
authors.forename: Savvas
authors.identifier: 0000-0002-0210-0713
authors.initials: S
authors.lastname: Christoforidis
mesh_terms: D002966:Clathrin / Q000378:metabolism; D034281:Dynamins / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D008954:Models, Biological; D018919:Neovascularization, Physiologic; D010873:Pinocytosis; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism
chemical_list: D002966:Clathrin; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2; D020764:cdc42 GTP-Binding Protein; D034281:Dynamins
keywords: Endocytosis; Macropinocytosis; Membrane trafficking; Signalling; VEGF; VEGFR2