title: A Rac/Cdc42 exchange factor complex promotes formation of lateral filopodia and blood vessel lumen morphogenesis.
abstract: During angiogenesis, Rho-GTPases influence endothelial cell migration and cell-cell adhesion; however it is not known whether they control formation of vessel lumens, which are essential for blood flow. Here, using an organotypic system that recapitulates distinct stages of VEGF-dependent angiogenesis, we show that lumen formation requires early cytoskeletal remodelling and lateral cell-cell contacts, mediated through the RAC1 guanine nucleotide exchange factor (GEF) DOCK4 (dedicator of cytokinesis 4). DOCK4 signalling is necessary for lateral filopodial protrusions and tubule remodelling prior to lumen formation, whereas proximal, tip filopodia persist in the absence of DOCK4. VEGF-dependent Rac activation via DOCK4 is necessary for CDC42 activation to signal filopodia formation and depends on the activation of RHOG through the RHOG GEF, SGEF. VEGF promotes interaction of DOCK4 with the CDC42 GEF DOCK9. These studies identify a novel Rho-family GTPase activation cascade for the formation of endothelial cell filopodial protrusions necessary for tubule remodelling, thereby influencing subsequent stages of lumen morphogenesis.
authors.affiliation: Institute of Cancer Research, Division of Cancer Biology, 237 Fulham Road, London SW3 6JB, UK.
authors.forename: Sabu
authors.initials: S
authors.lastname: Abraham
authors.affiliation: Leeds Institute of Cancer and Pathology, University of Leeds, St James' University Hospital, Beckett Street, Leeds LS9 7TF, UK.
authors.forename: Margherita
authors.initials: M
authors.lastname: Scarcia
authors.affiliation: Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, M5G 1X5 Ontario, Canada.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Bagshaw
authors.affiliation: Leeds Institute of Cancer and Pathology, University of Leeds, St James' University Hospital, Beckett Street, Leeds LS9 7TF, UK.
authors.forename: Kathryn
authors.initials: K
authors.lastname: McMahon
authors.affiliation: Leeds Institute of Cancer and Pathology, University of Leeds, St James' University Hospital, Beckett Street, Leeds LS9 7TF, UK.
authors.forename: Gary
authors.initials: G
authors.lastname: Grant
authors.affiliation: Leeds Institute of Cancer and Pathology, University of Leeds, St James' University Hospital, Beckett Street, Leeds LS9 7TF, UK.
authors.forename: Tracey
authors.initials: T
authors.lastname: Harvey
authors.affiliation: Institute of Cancer Research, Division of Cancer Biology, 237 Fulham Road, London SW3 6JB, UK.
authors.forename: Maggie
authors.initials: M
authors.lastname: Yeo
authors.affiliation: Leeds Institute of Cancer and Pathology, University of Leeds, St James' University Hospital, Beckett Street, Leeds LS9 7TF, UK.
authors.forename: Filomena O G
authors.initials: FOG
authors.lastname: Esteves
authors.affiliation: Leeds Institute of Cancer and Pathology, University of Leeds, St James' University Hospital, Beckett Street, Leeds LS9 7TF, UK.
authors.forename: Helene H
authors.initials: HH
authors.lastname: Thygesen
authors.affiliation: Leeds Institutes of Molecular Medicine, University of Leeds, St James' University Hospital, Beckett Street, Leeds LS9 7TF, UK.
authors.forename: Pamela F
authors.initials: PF
authors.lastname: Jones
authors.affiliation: Leeds Institute of Cancer and Pathology, University of Leeds, St James' University Hospital, Beckett Street, Leeds LS9 7TF, UK.
authors.forename: Valerie
authors.initials: V
authors.lastname: Speirs
authors.affiliation: Leeds Institute of Cancer and Pathology, University of Leeds, St James' University Hospital, Beckett Street, Leeds LS9 7TF, UK.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Hanby
authors.affiliation: Leeds Institute of Cancer and Pathology, University of Leeds, St James' University Hospital, Beckett Street, Leeds LS9 7TF, UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Selby
authors.affiliation: Leeds Institute of Cancer and Pathology, University of Leeds, St James' University Hospital, Beckett Street, Leeds LS9 7TF, UK.
authors.forename: Mihaela
authors.initials: M
authors.lastname: Lorger
authors.affiliation: Leeds Institutes of Molecular Medicine, University of Leeds, St James' University Hospital, Beckett Street, Leeds LS9 7TF, UK.
authors.forename: T Neil
authors.initials: TN
authors.lastname: Dear
authors.affiliation: Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, M5G 1X5 Ontario, Canada.
authors.forename: Tony
authors.initials: T
authors.lastname: Pawson
authors.affiliation: Institute of Cancer Research, Division of Cancer Biology, 237 Fulham Road, London SW3 6JB, UK.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Marshall
authors.affiliation: Leeds Institute of Cancer and Pathology, University of Leeds, St James' University Hospital, Beckett Street, Leeds LS9 7TF, UK.
authors.forename: Georgia
authors.initials: G
authors.lastname: Mavria
mesh_terms: D000818:Animals; D003599:Cytoskeleton / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000502:physiology*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009389:Neovascularization, Pathologic; D018919:Neovascularization, Physiologic; D011554:Pseudopodia / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism
chemical_list: C510122:DOCK4 protein, human; C466321:DOCK9 protein, human; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D042461:Vascular Endothelial Growth Factor A; C075397:RHOG protein, human; D020764:cdc42 GTP-Binding Protein; D020741:rho GTP-Binding Proteins