ICAM-1 Clustering on Endothelial Cells Recruits VCAM-1

Abstract EN

In the initial stages of transendothelial migration, leukocytes use the endothelial integrin ligands ICAM-1 and VCAM-1 for strong adhesion.

Upon adhesion of the leukocyte to endothelial ICAM-1, ICAM-1 is clustered and recruited to the adhered leukocyte, promoting strong adhesion.

In this study, we provide evidence for the colocalization of VCAM-1 at sites of ICAM-1 clustering.

Anti-ICAM-1 antibody-coated beads were used to selectively cluster and recruit ICAM-1 on primary human endothelial cells.

In time, co-localization of ICAM-1 and VCAM-1 around the adherent beads was observed.

Biochemical pull-down assays showed that ICAM-1 clustering induced its association to VCAM-1, suggesting a physical link between these two adhesion molecules.

The association was partly dependent on lipid rafts as well as on F-actin and promoted adhesion.

These data show that VCAM-1 can be recruited, in an integrin-independent fashion, to clustered ICAM-1 which may serve to promote ICAM-1-mediated leukocyte adhesion.