title: Heart of glass anchors Rasip1 at endothelial cell-cell junctions to support vascular integrity.
abstract: Heart of Glass (HEG1), a transmembrane receptor, and Rasip1, an endothelial-specific Rap1-binding protein, are both essential for cardiovascular development. Here we performed a proteomic screen for novel HEG1 interactors and report that HEG1 binds directly to Rasip1. Rasip1 localizes to forming endothelial cell (EC) cell-cell junctions and silencing HEG1 prevents this localization. Conversely, mitochondria-targeted HEG1 relocalizes Rasip1 to mitochondria in cells. The Rasip1-binding site in HEG1 contains a 9 residue sequence, deletion of which abrogates HEG1's ability to recruit Rasip1. HEG1 binds to a central region of Rasip1 and deletion of this domain eliminates Rasip1's ability to bind HEG1, to translocate to EC junctions, to inhibit ROCK activity, and to maintain EC junctional integrity. These studies establish that the binding of HEG1 to Rasip1 mediates Rap1-dependent recruitment of Rasip1 to and stabilization of EC cell-cell junctions.
authors.affiliation: Department of Medicine, University of California, San Diego, San Diego, United States.
authors.forename: Bart-Jan
authors.initials: BJ
authors.lastname: de Kreuk
authors.affiliation: Department of Medicine, University of California, San Diego, San Diego, United States.
authors.forename: Alexandre R
authors.initials: AR
authors.lastname: Gingras
authors.affiliation: Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada.
authors.forename: James Dr
authors.initials: JD
authors.lastname: Knight
authors.affiliation: Department of Medicine, University of California, San Diego, San Diego, United States.
authors.forename: Jian J
authors.initials: JJ
authors.lastname: Liu
authors.affiliation: Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada.|Department of Molecular Genetics, University of Toronto, Toronto, Canada.
authors.forename: Anne-Claude
authors.initials: AC
authors.lastname: Gingras
authors.affiliation: Department of Medicine, University of California, San Diego, San Diego, United States.
authors.forename: Mark H
authors.identifier: http://orcid.org/0000-0002-5685-5417
authors.initials: MH
authors.lastname: Ginsberg
mesh_terms: D002460:Cell Line; D042783:Endothelial Cells / Q000502:physiology*; D006801:Humans; D007365:Intercellular Junctions / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D011485:Protein Binding
chemical_list: C584441:HEG1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C487329:RASIP1 protein, human
keywords: Heart of Glass; Rap1; Rasip1; Rho Kinase; cell biology; developmental biology; endothelial cells; human; stem cells