title: The myosin motor Myo1c is required for VEGFR2 delivery to the cell surface and for angiogenic signaling.
abstract: Vascular endothelial growth factor receptor-2 (VEGFR2) is a receptor tyrosine kinase that is expressed in endothelial cells and regulates angiogenic signal transduction under both physiological and pathological conditions. VEGFR2 turnover at the plasma membrane (PM) is regulated by its transport through endocytic and secretory transport pathways. Short-range cargo trafficking along actin filaments is commonly regulated by motor proteins of myosin superfamily. In the current study, performed in primary human endothelial cells, we demonstrate that unconventional myosin 1c (Myo1c; class I family member) regulates the localization of VEGFR2 at the PM. We further demonstrate that the recruitment of VEGFR2 to the PM and its colocalization with Myo1c and caveolin-1 occur in response to VEGF-A (VEGF) stimulation. In addition, VEGF-induced delivery of VEGFR2 to the cell surface requires Myo1c; surface VEGFR2 levels are reduced in the absence of Myo1c and, more importantly, are restored by the overexpression of wild-type but not mutant Myo1c. Subcellular density gradient fractionation revealed that partitioning of VEGFR2 into caveolin-1- and Myo1c-enriched membrane fractions is dependent on VEGF stimulation. Myo1c depletion resulted in increased VEGF-induced VEGFR2 transport to the lysosomes for degradation and was rescued by applying either brefeldin A, which blocks trafficking between the endoplasmic reticulum and the Golgi complex, or dynasore, an inhibitor of dynamin-mediated endocytosis. Myo1c depletion also reduced VEGF-induced VEGFR2 phosphorylation at Y1175 and phosphorylation-dependent activation of ERK1/2 and c-Src kinase, leading to reduced cell proliferation and cell migration. This is the first report demonstrating that Myo1c is an important mediator of VEGF-induced VEGFR2 delivery to the cell surface and plays a role in angiogenic signaling.
authors.affiliation: Department of Anatomy and Cell Biology, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Ajit
authors.initials: A
authors.lastname: Tiwari
authors.forename: Jae-Joon
authors.initials: JJ
authors.lastname: Jung
authors.forename: Shivangi M
authors.initials: SM
authors.lastname: Inamdar
authors.forename: Deepak
authors.initials: D
authors.lastname: Nihalani
authors.forename: Amit
authors.initials: A
authors.lastname: Choudhury
mesh_terms: D000962:Antimalarials / Q000494:pharmacology; D020126:Brefeldin A / Q000494:pharmacology; D051242:Caveolin 1 / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement / Q000502:physiology; D049109:Cell Proliferation; D002738:Chloroquine / Q000494:pharmacology; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D006835:Hydrazones / Q000494:pharmacology; D021962:Membrane Microdomains / Q000378:metabolism; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism*; D024461:Myosin Type I / Q000235:genetics / Q000378:metabolism*; D018919:Neovascularization, Physiologic / Q000502:physiology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D055571:Secretory Pathway / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
chemical_list: D000962:Antimalarials; C495540:CAV1 protein, human; D051242:Caveolin 1; D006835:Hydrazones; D020409:Molecular Motor Proteins; C511794:N'-(3,4-dihydroxybenzylidene)-3-hydroxy-2-naphthahydrazide; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D020126:Brefeldin A; D002738:Chloroquine; D040301:Vascular Endothelial Growth Factor Receptor-2; D024461:Myosin Type I; C460367:MYO1C protein, human