title: Rasip1 regulates vertebrate vascular endothelial junction stability through Epac1-Rap1 signaling.
abstract: Establishment and stabilization of endothelial tubes with patent lumens is vital during vertebrate development. Ras-interacting protein 1 (RASIP1) has been described as an essential regulator of de novo lumenogenesis through modulation of endothelial cell (EC) adhesion to the extracellular matrix (ECM). Here, we show that in mouse and zebrafish embryos, Rasip1-deficient vessels transition from an angioblast cord to a hollow tube, permit circulation of primitive erythrocytes, but ultimately collapse, leading to hemorrhage and embryonic lethality. Knockdown of RASIP1 does not alter EC-ECM adhesion, but causes cell-cell detachment and increases permeability of EC monolayers in vitro. We also found that endogenous RASIP1 in ECs binds Ras-related protein 1 (RAP1), but not Ras homolog gene family member A or cell division control protein 42 homolog. Using an exchange protein directly activated by cyclic adenosine monophosphate 1 (EPAC1)-RAP1-dependent model of nascent junction formation, we demonstrate that a fraction of the RASIP1 protein pool localizes to cell-cell contacts. Loss of RASIP1 phenocopies loss of RAP1 or EPAC1 in ECs by altering junctional actin organization, localization of the actin-bundling protein nonmuscle myosin heavy chain IIB, and junction remodeling. Our data show that RASIP1 regulates the integrity of newly formed blood vessels as an effector of EPAC1-RAP1 signaling.
authors.affiliation: Department of Molecular Biology, Genentech, Inc., South San Francisco, CA;
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Wilson
authors.forename: Leon H
authors.initials: LH
authors.lastname: Parker
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Hall
authors.forename: Tanya
authors.initials: T
authors.lastname: Smyczek
authors.forename: Judy
authors.initials: J
authors.lastname: Mak
authors.forename: Ailey
authors.initials: A
authors.lastname: Crow
authors.forename: George
authors.initials: G
authors.lastname: Posthuma
authors.forename: Ann
authors.initials: A
authors.lastname: De Mazière
authors.forename: Meredith
authors.initials: M
authors.lastname: Sagolla
authors.forename: Cecile
authors.initials: C
authors.lastname: Chalouni
authors.forename: Philip
authors.initials: P
authors.lastname: Vitorino
authors.forename: Merone
authors.initials: M
authors.lastname: Roose-Girma
authors.forename: Søren
authors.initials: S
authors.lastname: Warming
authors.forename: Judith
authors.initials: J
authors.lastname: Klumperman
authors.forename: Philip S
authors.initials: PS
authors.lastname: Crosier
authors.forename: Weilan
authors.initials: W
authors.lastname: Ye
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D030801:Animals, Genetically Modified; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D004730:Endothelium, Vascular / Q000196:embryology* / Q000502:physiology*; D005260:Female; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D007365:Intercellular Junctions / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D018345:Mice, Knockout; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism; D018919:Neovascularization, Physiologic; D011247:Pregnancy; D034622:RNA Interference; D015398:Signal Transduction; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D000199:Actins; D002352:Carrier Proteins; C482601:Epac protein, mouse; D020662:Guanine Nucleotide Exchange Factors; D047908:Intracellular Signaling Peptides and Proteins; C541054:Rasip1 protein, mouse; D029961:Zebrafish Proteins; D020559:Monomeric GTP-Binding Proteins; D020827:rap1 GTP-Binding Proteins; C581234:terf2ip protein, zebrafish