Submitted April 22, 2008
Accepted February 13, 2009
Regulated release and functional modulation of junctional adhesion molecule A by disintegrin metalloproteinases
Rory R. Koenen, Jessica Pruessmeyer, Oliver Soehnlein, Line Fraemohs, Alma Zernecke, Nicole Schwarz, Karina Reiss, Alisina Sarabi, Lennart Lindbom, Tilman M. Hackeng, Christian Weber, and Andreas Ludwig*
Institute for Molecular Cardiovascular Research, RWTH Aachen University, Aachen, Germany
Institute for Pharmacology and Toxicology, RWTH Aachen University, Aachen, Germany
Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
Institute for Biochemistry, Christian-Albrechts-University (CAU), Kiel, Germany
Cardiovascular Research Institute Maastricht (CARIM), University Maastricht, Maastricht, Netherlands
Interdisciplinary Center for Clinical Research Biomat., RWTH Aachen University, Aachen, Germany
* Corresponding author; email: aludwig{at}ukaachen.de.
Junctional adhesion molecule-A (JAM-A) is a transmembrane adhesive glycoprotein that participates in the organization of endothelial tight junctions and contributes to leukocyte transendothelial migration. We here demonstrate that cultured endothelial cells not only express a cellular 43 kDa-variant of JAM-A but also release considerable amounts of a 33 kDa soluble JAM-A variant. This release is enhanced by treatment with proinflammatory cytokines and is associated with the downregulation of surface JAM-A. Inhibition experiments, loss/gain of function experiments and cleavage experiments with recombinant proteases indicated that cleavage of JAM-A is predominantly mediated by the disintegrin and metalloproteinase (ADAM) 17 and to a lesser extent by ADAM10. Cytokine-treatment of mice increased JAM-A serum level and in excised murine aortas increased ADAM10/17 activity correlated with enhanced JAM-A release. Functionally, soluble JAM-A blocked migration of cultured endothelial cells, reduced transendothelial migration of isolated neutrophils in vitro and decreased neutrophil infiltration in a murine air pouch model by LFA-1- and JAM-A-dependent mechanisms. Therefore, shedding of JAM-A by inflamed vascular endothelium via ADAM17 and ADAM10 may not only generate a biomarker for vascular inflammation but could also be instrumental in controlling JAM-A functions in the molecular zipper guiding transendothelial diapedesis of leukocytes.
