title: Expression of junctional adhesion molecule-A prevents spontaneous and random motility.
abstract: Junctional adhesion molecule-A (JAM-A) is a cell-surface glycoprotein that localizes to intercellular junctions and associates with intracellular proteins via PSD95-Dlg-ZO1-binding residues. To define the functional consequences of JAM-A expression, we have produced endothelial cells from JAM-A-deficient mice. We report here that the absence of JAM-A enhanced spontaneous and random motility. In turn, the enhanced motility of JAM-A-negative cells was abrogated either on transfection of exogenous JAM-A or on treatment with inhibitors of glycogen synthase kinase-3beta (GSK-3beta). In addition, in JAM-A-positive cells, motility was enhanced on inactivation of protein kinase Czeta (PKCzeta), which is an inhibitor of GSK-3beta. Although these findings suggested that JAM-A might inhibit GSK-3beta, we found that expression per se of JAM-A did not change the levels of inactive GSK-3beta. Thus, JAM-A expression may regulate effectors of motility that are also downstream of the PKCzeta/GSK-3beta axis. In support of this view, we found that JAM-A absence increased the number of actin-containing protrusions, reduced the stability of microtubules and impaired the formation of focal adhesions. Notably, all the functional consequences of JAM-A absence were reversed either on treatment with GSK-3beta inhibitors or on transfection of full-length JAM-A, but not on transfection of a JAM-A deletion mutant devoid of the PSD95-Dlg-ZO1-binding residues. Thus, by regulating cytoskeletal and adhesive structures, JAM-A expression prevents cell motility, probably in a PSD95-Dlg-ZO1-dependent manner.
authors.affiliation: Laboratory of Systems Biology, Department of Immunology and Cell Biology, Istituto di Ricerche Farmacologiche Mario Negri, 20157 Milano, Italy. bazzoni@marionegri.it
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Bazzoni
authors.forename: Paolo
authors.initials: P
authors.lastname: Tonetti
authors.forename: Luca
authors.initials: L
authors.lastname: Manzi
authors.forename: Maria R
authors.initials: MR
authors.lastname: Cera
authors.forename: Giovanna
authors.initials: G
authors.lastname: Balconi
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Dejana
mesh_terms: D000818:Animals; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002450:Cell Communication / Q000502:physiology; D002461:Cell Line, Transformed; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D022081:Cell Surface Extensions / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D022001:Focal Adhesions / Q000378:metabolism; D015870:Gene Expression; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D007211:Indoles / Q000494:pharmacology; D008094:Lithium / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008870:Microtubules / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000099221:Protein Kinase C zeta
chemical_list: D015815:Cell Adhesion Molecules; D004791:Enzyme Inhibitors; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D007211:Indoles; D008094:Lithium; D008301:Maleimides; D008565:Membrane Proteins; D011493:Protein Kinase C; D011956:Receptors, Cell Surface; D000099221:Protein Kinase C zeta; C498686:F11r protein, mouse; C417521:SB 216763; C000605507:Gsk3b protein, mouse