Trans-dimerization of JAM-A regulates Rap2 and is mediated by a domain that is distinct from the cis-dimerization interface

• Type of Material: Article
• Authors: Ana C. Monteiro, Emory University; Anny-Claude Luissint, Emory University; Ronen Sumagin, Emory University; Caroline Lai, Vanderbilt University School of Medicine; Franziska Vielmuth, Ludwig-Maximilians University; Mattie F. Wolf, Emory University; Oskar Laur, Emory University; Kerstin Reiss, University of Tübingen; Volker Spindler, Ludwig-Maximilians University; Thilo Stehle, Vanderbilt University School of Medicine; Terence S. Dermody, Vanderbilt University School of Medicine; Asma Nusrat, Emory University; Charles Parkos, Emory University
• Language: English
• Date: 2014-05-15
• Publisher: American Society for Cell Biology
• Publication Version: Final Published Version
• Copyright Statement: © 2014 Monteiro et al.
• License: Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported
• Final Published Version (URL): http://www.molbiolcell.org/content/25/10/1574
• Title of Journal or Parent Work: Molecular Biology of the Cell
• ISSN: 1059-1524
• Volume: 25
• Issue: 10
• Start Page: 1574
• End Page: 1585
• Grant/Funding Information: Public Health Service Awards T32 GM007347 to C.M.L., F31 NS074596 to C.M.L.; R01 AI76983 and German Research Foundation grant KFO-274 to T.S. and T.S.D. and R37 AI38296 to T.S.D.; and the Elizabeth B.; Lamb Center for Pediatric Research. Additional support was provided by the Vanderbilt-Ingram Cancer Center (CA68485), the Vanderbilt Flow Cytometry Shared Resource (DK058404), and the Vanderbilt Cell Imaging Shared Resource (DK20593).; This research was supported by National Institutes of Health grants DK061379, DK072564, and DK079392 to C.A.P., DK59888 and DK55679 to A.N., and DK064399 to C.A.P. and A.N.
• Research Categories: Health Sciences, Pathology

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.