[HTML][HTML] LFA-1 binding destabilizes the JAM-A homophilic interaction during leukocyte transmigration

EP Wojcikiewicz, RR Koenen, L Fraemohs… - Biophysical journal, 2009 - cell.com
EP Wojcikiewicz, RR Koenen, L Fraemohs, J Minkiewicz, H Azad, C Weber, VT Moy
Biophysical journal, 2009cell.com
Leukocyte transendothelial migration into inflamed areas is regulated by the integrity of
endothelial cell junctions and is stabilized by adhesion molecules including junctional
adhesion molecule-A (JAM-A). JAM-A has been shown to participate in homophilic
interactions with itself and in heterophilic interactions with leukocyte function-associated
antigen-1 (LFA-1) via its first and second immunoglobulin domains, respectively. Using
competitive binding assays in conjunction with atomic force microscopy adhesion …
Abstract
Leukocyte transendothelial migration into inflamed areas is regulated by the integrity of endothelial cell junctions and is stabilized by adhesion molecules including junctional adhesion molecule-A (JAM-A). JAM-A has been shown to participate in homophilic interactions with itself and in heterophilic interactions with leukocyte function-associated antigen-1 (LFA-1) via its first and second immunoglobulin domains, respectively. Using competitive binding assays in conjunction with atomic force microscopy adhesion measurements, we provide compelling evidence that the second domain of JAM-A stabilizes the homophilic interaction because its deletion suppresses the dynamic strength of the JAM-A homophilic interaction. Moreover, binding of the LFA-1 inserted domain to the second domain of JAM-A reduces the dynamic strength of the JAM-A homophilic interaction to the level measured with the JAM-A domain 2 deletion mutant. This finding suggests that LFA-1 binding cancels the stabilizing effects of the second immunoglobulin domain of JAM-A. Finally, our atomic force microscopy measurements reveal that the interaction of JAM-A with LFA-1 is stronger than the JAM-A homophilic interaction. Taken together, these results suggest that LFA-1 binding to JAM-A destabilizes the JAM-A homophilic interaction. In turn, the greater strength of the LFA-1/JAM-A complex permits it to support the tension needed to disrupt the JAM-A homophilic interaction, thus allowing transendothelial migration to proceed.
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