Heterogeneity of endothelial junctions is reflected by differential expression and specific subcellular localization of the three JAM family members.
Endothelial cells are linked to each other through intercellular junctional complexes that regulate the barrier and fence function of the vascular wall. The nature of these intercellular contacts varies with the need for permeability: For example, in brain the impervious blood-brain barrier is maintained by "tight" contacts between endothelial cells. By contrast, in high endothelial venules (HEVs), where lymphocytes continuously exit the bloodstream, the contacts are generally leaky. The precise molecular components that define the type of junction remain to be characterized. An immunoglobulin superfamily molecule named JAM-2, specifically expressed in lymphatic endothelial cells and HEVs, was recently identified. JAM-3 was cloned and characterized in the current study, and JAM-1, -2, and -3 were shown to form a novel protein family belonging to the larger cortical thymocyte Xenopus (CTX) molecular family. Using antibodies specific for each of the 3 family members, their specific participation in different types of cell-cell contact in vivo and their specific and differential localization in lateral contacts or tight junctions were demonstrated. Furthermore, it was shown that JAM-1 and JAM-2 differentially regulate paracellular permeability, suggesting that the presence of JAM-1, -2, or -3 in vascular junctions may play a role in regulating vascular function in vivo.
Aurrand-Lions
M
M
Department of Pathology, Centre Medical Universitaire, Geneva, Switzerland. michel.aurrand-lions@medecine.unige.ch
Johnson-Leger
C
C
Wong
C
C
Du Pasquier
L
L
Imhof
B A
BA
D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity; D015152:Blotting, Northern; D001923:Brain Chemistry; D015815:Cell Adhesion Molecules; D002460:Cell Line; D002463:Cell Membrane Permeability; D004622:Embryo, Mammalian; D004730:Endothelium, Vascular / Q000737:chemistry / Q000648:ultrastructure*; D015870:Gene Expression; D049452:Green Fluorescent Proteins; D007136:Immunoglobulins / Q000032:analysis / Q000235:genetics* / Q000502:physiology; D007150:Immunohistochemistry; D007365:Intercellular Junctions / Q000502:physiology*; D007668:Kidney / Q000737:chemistry; D008164:Luminescent Proteins / Q000235:genetics; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics* / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D010802:Phylogeny; D012333:RNA, Messenger / Q000032:analysis; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014018:Tissue Distribution; D014162:Transfection; D062765:Junctional Adhesion Molecule B
D015815:Cell Adhesion Molecules; D049452:Green Fluorescent Proteins; D007136:Immunoglobulins; D008164:Luminescent Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; C498686:F11r protein, mouse; C498781:Jam2 protein, mouse; D062765:Junctional Adhesion Molecule B; C486723:Jam3 protein, mouse