Cross-linking of brain endothelial intercellular adhesion molecule (ICAM)-1 induces association of ICAM-1 with detergent-insoluble cytoskeletal fraction

Intercellular adhesion molecule (ICAM)-1 plays a vital role in the process of leukocyte transmigration through endothelial cell (EC) barriers and has been shown to mediate signal transduction events in ECs induced either by i ts cross-linking or by the binding of T lymphocytes. Immunoblotting of ICAM -1 of Triton X-100 detergent fractions demonstrated that the majority of IC AM-1 was contained within the detergent-soluble fraction (noncytoskeletal a ssociated) under basal conditions. After cross-linking of endothelial ICAM- 1 with monoclonal antibody or coculture with T lymphocytes, EC ICAM-1 was o bserved to partition with a Triton X-100-insoluble (cytoskeletal associated ) fraction in a dose- and time-dependent manner. Redistribution of ICAM-1 w as specific, inasmuch as no association with the Triton X-100-insoluble fra ction was observed after cross-linking of vascular cell adhesion molecule-1 , nor did cross-linking of ICAM-1 result in a redistribution of the platele t and EC adhesion molecule. ICAM-1 association with the endothelial cytoske leton after cross-linking was unaffected after treatment of the cells with cytochalasin D, C3-transferase, removal of extracellular calcium ions, or c helation of intracellular calcium ions. These data show that ICAM-1 colocal izes with the endothelial cytoskeleton and associates with a detergent-inso luble fraction after cross-linking.