LFA-1 binding destabilizes the JAM-A homophilic interaction during leukocyte transmigration.
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.
Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, Florida 33136, USA. ewojcikiewicz@med.miami.edu
Ewa P
EP
Wojcikiewicz
Rory R
RR
Koenen
Line
L
Fraemohs
Julia
J
Minkiewicz
Hashem
H
Azad
Christian
C
Weber
Vincent T
VT
Moy
D000818:Animals; D001667:Binding, Competitive; D016466:CHO Cells; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002465:Cell Movement / Q000502:physiology*; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D007136:Immunoglobulins / Q000235:genetics / Q000378:metabolism*; D019169:Jurkat Cells; D036904:Leukocyte Rolling / Q000502:physiology*; D007962:Leukocytes / Q000502:physiology*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D011485:Protein Binding / Q000502:physiology; D011956:Receptors, Cell Surface; D017384:Sequence Deletion
D015815:Cell Adhesion Molecules; C407243:F11R protein, human; D007136:Immunoglobulins; D016169:Lymphocyte Function-Associated Antigen-1; D011956:Receptors, Cell Surface