Relocalization of Junctional Adhesion Molecule A during Inflammatory Stimulation of Brain Endothelial Cells

Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA.
Molecular and Cellular Biology (Impact Factor: 4.78). 06/2012; 32(17):3414-27. DOI: 10.1128/MCB.06678-11
Source: PubMed


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.

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Available from: Anuska V Andjelkovic
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    • "In vitro, the total amount of JAM-A protein was not changed by OGD/reoxygenation injury and adding an inhibitor of matrix metalloproteinase (GM-6001) as well as an inhibitor of protein synthesis, cycloheximide, which can modulate the TJ protein levels during ischemic injury (Yang et al., 2013), did not affect JAM-A expression (Fig. 2B). Thus, during OGD/reoxygenation injury, JAM-A has a redistribution pattern similar to that found in inflammatory conditions (treatment with CCL2 or lipopolysaccharide) (Stamatovic et al., 2012) which could, based on the observed time, be linked to the proinflammatory response at brain endothelial cells during OGD/reoxygenation injury. "
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    • "JAM-A is a homophilic adhesion receptor present at tight junctions of epithelial and endothelial cells as well as on surfaces of some blood cells and functions in barrier function and cell migration [117] [118]. RhoA signaling was shown to be important for the relocalization of JAM-A on the surface of epithelial cells [119] and brain endothelial cells [120] during inflammation. Another group showed that JAM-A homophilic interactions within tight junctions of endothelial cells could be disassociated through a higher affinity interaction with LFA-1 on leukocytes, thus promoting transendothelial migration [121]. "
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