title: The junctional adhesion molecule (JAM) family members JAM-2 and JAM-3 associate with the cell polarity protein PAR-3: a possible role for JAMs in endothelial cell polarity.
abstract: Tight junctions play a central role in the establishment of cell polarity in vertebrate endothelial and epithelial cells. A ternary protein complex consisting of the cell polarity proteins PAR-3 and PAR-6 and the atypical protein kinase C localizes at tight junctions and is crucial for tight junction formation. We have recently shown that PAR-3 directly associates with the junctional adhesion molecule (JAM), which suggests that the ternary complex is targeted to tight junctions of epithelial cells through PAR-3 binding to JAM. The expression of JAM-related proteins by endothelial cells prompted us to test whether recruitment of the ternary complex in endothelial cells can occur through binding to JAM-2, JAM-3, endothelial cell-selective adhesion molecule (ESAM) or coxsackie- and adenovirus receptor (CAR). Here we show that the two JAM-related proteins JAM-2 and JAM-3 directly associate with PAR-3. The association between PAR-3 and JAM-2/-3 is mediated through the first PDZ domain of PAR-3. In agreement with the predominant expression of JAM-2 and JAM-3 in endothelial cells, we found that PAR-3 is expressed by endothelial cells in vivo and is localized at cell contacts of cultured endothelial cells. PAR-3 associates with JAM-2/-3 but not with the JAM-related Ig-superfamily members ESAM or CAR. In addition, we show that the tight junction-associated protein ZO-1 associates with JAM-2/-3 in a PDZ domain-dependent manner. Using ectopic expression of JAM-2 in CHO cells, we show that the junctional localization of JAM-2 is regulated by serine phosphorylation and that its clustering at cell-cell contacts recruits endogenous PAR-3 and ZO-1. Our findings suggest that JAM-2 affects endothelial cell junctions by its regulated clustering at intercellular contacts, and they support a role for JAM-2, and possibly JAM-3, in tight junction formation of endothelial cells.
authors.affiliation: Institute of Cell Biology, ZMBE, University of Münster, Germany. ebnetk@uni-muenster.de
authors.forename: Klaus
authors.initials: K
authors.lastname: Ebnet
authors.forename: Michel
authors.initials: M
authors.lastname: Aurrand-Lions
authors.forename: Annegret
authors.initials: A
authors.lastname: Kuhn
authors.forename: Friedemann
authors.initials: F
authors.lastname: Kiefer
authors.forename: Stefan
authors.initials: S
authors.lastname: Butz
authors.forename: Kerstin
authors.initials: K
authors.lastname: Zander
authors.forename: Maria-Katharina
authors.initials: MK
authors.lastname: Meyer zu Brickwedde
authors.forename: Atsushi
authors.initials: A
authors.lastname: Suzuki
authors.forename: Beat A
authors.initials: BA
authors.lastname: Imhof
authors.forename: Dietmar
authors.initials: D
authors.lastname: Vestweber
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D002352:Carrier Proteins / Q000378:metabolism*; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D018797:Cell Cycle Proteins; D016764:Cell Polarity / Q000502:physiology*; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D006224:Cricetinae; D003412:Cricetulus; D042783:Endothelial Cells / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D007136:Immunoglobulins / Q000378:metabolism*; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012694:Serine / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D015815:Cell Adhesion Molecules; D018797:Cell Cycle Proteins; C428190:Esam protein, mouse; D007136:Immunoglobulins; C448000:JAM3 protein, human; C486723:Jam3 protein, mouse; D008565:Membrane Proteins; C115084:Pard3 protein, mouse; D012694:Serine