title: Trans-dimerization of JAM-A regulates Rap2 and is mediated by a domain that is distinct from the cis-dimerization interface.
abstract: Junctional adhesion molecule-A (JAM-A) is a tight junction-associated signaling protein that regulates epithelial cell proliferation, migration, and barrier function. JAM-A dimerization on a common cell surface (in cis) has been shown to regulate cell migration, and evidence suggests that JAM-A may form homodimers between cells (in trans). Indeed, transfection experiments revealed accumulation of JAM-A at sites between transfected cells, which was lost in cells expressing cis- or predicted trans-dimerization null mutants. Of importance, microspheres coated with JAM-A containing alanine substitutions to residues 43NNP45 (NNP-JAM-A) within the predicted trans-dimerization site did not aggregate. In contrast, beads coated with cis-null JAM-A demonstrated enhanced clustering similar to that observed with wild-type (WT) JAM-A. In addition, atomic force microscopy revealed decreased association forces in NNP-JAM-A compared with WT and cis-null JAM-A. Assessment of effects of JAM-A dimerization on cell signaling revealed that expression of trans- but not cis-null JAM-A mutants decreased Rap2 activity. Furthermore, confluent cells, which enable trans-dimerization, had enhanced Rap2 activity. Taken together, these results suggest that trans-dimerization of JAM-A occurs at a unique site and with different affinity compared with dimerization in cis. Trans-dimerization of JAM-A may thus act as a barrier-inducing molecular switch that is activated when cells become confluent.
authors.affiliation: Epithelial Pathobiology and Mucosal Inflammation Research Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322.
authors.forename: Ana C
authors.initials: AC
authors.lastname: Monteiro
authors.affiliation: Epithelial Pathobiology and Mucosal Inflammation Research Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322.
authors.forename: Anny-Claude
authors.initials: AC
authors.lastname: Luissint
authors.affiliation: Epithelial Pathobiology and Mucosal Inflammation Research Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322.
authors.forename: Ronen
authors.initials: R
authors.lastname: Sumagin
authors.affiliation: Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University School of Medicine, Nashville, TN 37232.
authors.forename: Caroline
authors.initials: C
authors.lastname: Lai
authors.affiliation: Institute of Anatomy and Cell Biology, Ludwig-Maximilians University, 80336 Munich, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Vielmuth
authors.affiliation: Epithelial Pathobiology and Mucosal Inflammation Research Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322.
authors.forename: Mattie F
authors.initials: MF
authors.lastname: Wolf
authors.affiliation: Epithelial Pathobiology and Mucosal Inflammation Research Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322.
authors.forename: Oskar
authors.initials: O
authors.lastname: Laur
authors.affiliation: Interfaculty Institute of Biochemistry, University of Tübingen, D-72076 Tübingen, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Reiss
authors.affiliation: Institute of Anatomy and Cell Biology, Ludwig-Maximilians University, 80336 Munich, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Spindler
authors.affiliation: Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University School of Medicine, Nashville, TN 37232Interfaculty Institute of Biochemistry, University of Tübingen, D-72076 Tübingen, Germany.
authors.forename: Thilo
authors.initials: T
authors.lastname: Stehle
authors.affiliation: Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University School of Medicine, Nashville, TN 37232Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232.
authors.forename: Terence S
authors.initials: TS
authors.lastname: Dermody
authors.affiliation: Epithelial Pathobiology and Mucosal Inflammation Research Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322.
authors.forename: Asma
authors.initials: A
authors.lastname: Nusrat
authors.affiliation: Epithelial Pathobiology and Mucosal Inflammation Research Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322 cparkos@emory.edu.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Parkos
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D016466:CHO Cells; D002448:Cell Adhesion / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002449:Cell Aggregation / Q000502:physiology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D003412:Cricetulus; D057809:HEK293 Cells; D006801:Humans; D007365:Intercellular Junctions / Q000378:metabolism; D018625:Microscopy, Atomic Force; D009154:Mutation; D055503:Protein Multimerization / Q000502:physiology*; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D034741:RNA, Small Interfering; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D019108:Tight Junctions / Q000235:genetics / Q000502:physiology*; D020668:rap GTP-Binding Proteins / Q000096:biosynthesis*
chemical_list: D015815:Cell Adhesion Molecules; C407243:F11R protein, human; D034741:RNA, Small Interfering; D011956:Receptors, Cell Surface; C116756:RAP2A protein, human; D020668:rap GTP-Binding Proteins