Relocalization of junctional adhesion molecule A during inflammatory stimulation of brain endothelial cells.
Junctional adhesion molecule A (JAM-A) is a unique tight junction (TJ) transmembrane protein that under basal conditions maintains endothelial cell-cell interactions but under inflammatory conditions acts as a leukocyte adhesion molecule. This study investigates the fate of JAM-A during inflammatory TJ complex remodeling and paracellular route formation in brain endothelial cells. The chemokine (C-C motif) ligand 2 (CCL2) induced JAM-A redistribution from the interendothelial cell area to the apical surface, where JAM-A played a role as a leukocyte adhesion molecule participating in transendothelial cell migration of neutrophils and monocytes. JAM-A redistribution was associated with internalization via macropinocytosis during paracellular route opening. A tracer study with dextran-Texas Red indicated that internalization occurred within a short time period (~10 min) by dextran-positive vesicles and then became sorted to dextran-positive/Rab34-positive/Rab5-positive vesicles and then Rab4-positive endosomes. By ~20 min, most internalized JAM-A moved to the brain endothelial cell apical membrane. Treatment with a macropinocytosis inhibitor, 5-(N-ethyl-N-isopropyl)amiloride, or Rab5/Rab4 depletion with small interfering RNA oligonucleotides prevented JAM-A relocalization, suggesting that macropinocytosis and recycling to the membrane surface occur during JAM-A redistribution. Analysis of the signaling pathways indicated involvement of RhoA and Rho kinase in JAM-A relocalization. These data provide new insights into the molecular and cellular mechanisms involved in blood-brain barrier remodeling during inflammation.
Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA.
Svetlana M
SM
Stamatovic
Nikola
N
Sladojevic
Richard F
RF
Keep
Anuska V
AV
Andjelkovic
D000818:Animals; D001921:Brain / Q000098:blood supply / Q000166:cytology*; D015815:Cell Adhesion Molecules / Q000032:analysis* / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000276:immunology; D042783:Endothelial Cells / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D021381:Protein Transport; D011956:Receptors, Cell Surface / Q000032:analysis* / Q000276:immunology* / Q000378:metabolism; D015398:Signal Transduction; D019108:Tight Junctions / Q000276:immunology* / Q000378:metabolism / Q000648:ultrastructure
D015815:Cell Adhesion Molecules; D018932:Chemokine CCL2; C498686:F11r protein, mouse; D011956:Receptors, Cell Surface