title: The VEGFR2 receptor tyrosine kinase undergoes constitutive endosome-to-plasma membrane recycling.
abstract: The VEGFR2 receptor tyrosine kinase regulates vascular physiology and animal development. The mechanism underlying VEGFR2 membrane trafficking is not well understood. Herein, we show that VEGFR2 undergoes membrane recycling in both vascular and non-vascular cells. In primary human endothelial cells, VEGFR2 normally distributes between the plasma membrane and early endosomes undergoing endocytosis and recycling. This pathway is independent of VEGFR tyrosine kinase activity and occurs constitutively, similar to other integral membrane proteins such as the transferrin receptor and β1 integrin. Expression of a VEGFR2-EGFP hybrid protein in non-vascular cells revealed plasma membrane and endosome distribution. The VEGF-A ligand stimulated phosphorylation of residue Y1175 on VEGFR2-EGFP which is a key hallmark of receptor activation. Live cell imaging and quantitative analysis showed that activated VEGFR2-EGFP displayed reduced mobility linked to endocytosis and recycling between the plasma membrane and endosomes. Total internal reflection microscopy and kinetics indicates that VEGFR2 undergoes recycling between the plasma membrane and peripheral endosomes proximal to the membrane bilayer. We thus provide evidence that the VEGFR2 receptor tyrosine kinase undertakes a constitutive recycling pathway between the peripheral endosomes and cell surface and this exists in both vascular and non-vascular cells.
authors.affiliation: Endothelial Cell Biology Unit, Institute of Molecular and Cellular Biology, University of Leeds, LIGHT Laboratories, Clarendon Way, Leeds LS2 9JT, UK.
authors.forename: Helen M
authors.initials: HM
authors.lastname: Jopling
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Howell
authors.forename: Nikita
authors.initials: N
authors.lastname: Gamper
authors.forename: Sreenivasan
authors.initials: S
authors.lastname: Ponnambalam
mesh_terms: D002462:Cell Membrane / Q000201:enzymology*; D002478:Cells, Cultured; D004705:Endocytosis; D011992:Endosomes / Q000201:enzymology*; D042783:Endothelial Cells / Q000201:enzymology; D004730:Endothelium, Vascular / Q000201:enzymology; D057809:HEK293 Cells; D006801:Humans; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism*
chemical_list: D040301:Vascular Endothelial Growth Factor Receptor-2