JAM-L-mediated leukocyte adhesion to endothelial cells is regulated in cis by alpha4beta1 integrin activation.
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Luissint AC, Lutz PG, Calderwood DA, Couraud PO, Bourdoulous S
JAM-L-mediated leukocyte adhesion to endothelial cells is regulated in cis by alpha4beta1 integrin activation.
J Cell Biol. 2008 Dec 15;183(6):1159-73. doi: 10.1083/jcb.200805061. Epub 2008 Dec 8.
- PubMed ID
- 19064666 [ View in PubMed]
- Abstract
Junctional adhesion molecules (JAMs) are endothelial and epithelial adhesion molecules involved in the recruitment of circulating leukocytes to inflammatory sites. We show here that JAM-L, a protein related to the JAM family, is restricted to leukocytes and promotes their adhesion to endothelial cells. Cis dimerization of JAM-L is required to engage in heterophilic interactions with its cognate counter-receptor CAR (coxsackie and adenovirus receptor). Interestingly, JAM-L expressed on neutrophils binds CAR independently of integrin activation. However, on resting monocytes and T lymphocytes, which express the integrin VLA-4, JAM-L molecules engage in complexes with VLA-4 and mainly accumulate in their monomeric form. Integrin activation is required for the dissociation of JAM-L-VLA-4 complexes and the accumulation of functional JAM-L dimers, which indicates that the leukocyte integrin VLA-4 controls JAM-L function in cis by controlling its dimerization state. This provides a mechanism through which VLA-4 and JAM-L functions are coordinately regulated, allowing JAM-L to strengthen integrin-dependent adhesion of leukocytes to endothelial cells.