ICAM-1-Coupled Cytoskeletal Rearrangements and Transendothelial Lymphocyte Migration Involve Intracellular Calcium Signaling in Brain Endothelial Cell Lines

Abstract

Endothelium of the cerebral blood vessels, which constitutes the blood-brain barrier, controls adhesion and trafficking of leukocytes into the brain. Investigating signaling pathways triggered by the engagement of adhesion molecules expressed on brain endothelial cells using two rat brain endothelial cell lines (RBE4 and GP8), we report in this paper that ICAM-1 cross-linking induces a sustained tyrosine phosphorylation of the phosphatidylinositol-phospholipase C (PLC)γ1, with a concomitant increase in both inositol phosphate production and intracellular calcium concentration. Our results suggest that PLC are responsible, via a calcium- and protein kinase C (PKC)-dependent pathway, for p60Src activation and tyrosine phosphorylation of the p60Src substrate, cortactin. PKCs are also required for tyrosine phosphorylation of the cytoskeleton-associated proteins, focal adhesion kinase and paxillin, but not for ICAM-1-coupled p130Cas phosphorylation. PKC’s activation is also necessary for stress fiber formation induced by ICAM-1 cross-linking. Finally, cell pretreatment with intracellular calcium chelator or PKC inhibitors significantly diminishes transmonolayer migration of activated T lymphocytes, without affecting their adhesion to brain endothelial cells. In summary, our data demonstrate that ICAM-1 cross-linking induces calcium signaling which, via PKCs, mediates phosphorylation of actin-associated proteins and cytoskeletal rearrangement in brain endothelial cell lines. Our results also indicate that these calcium-mediated intracellular events are essential for lymphocyte migration through the blood-brain barrier.

Estradiol Promotes Breast Cancer Cell Migration via Recruitment and Activation of Neutrophils

“…The nonmetastatic ER þ MCF-7 mammospheres showed high expression of ICAM-3 only. ICAM-1 molecules interact with the actincontaining cytoskeleton and a-actinin, inducing cytoskeletal rearrangement (42,43). This activity could explain the neutrophilindependent invasion and dissemination of MDA-MB-231 cancer cells because their high expression of ICAM molecules promotes their increased motility and invasion.…”

Neisseria meningitidis infection of human endothelial cells interferes with leukocyte transmigration by preventing the formation of endothelial docking structures

“…We and others have shown that endothelial adhesion molecules are involved in transducing leukocyte adhesion-mediated signaling responses to endothelium, leading to actin cytoskeletal reorganization (Etienne-Manneville et al, 2000;Cook-Mills et al, 2004). Moreover, recent studies have demonstrated that leukocyte adhesion promotes the remodeling of the apical endothelial plasma membrane into projections that surround adherent leukocytes (Carman and Springer, 2004;Shaw et al, 2004;Barreiro et al, 2005).…”

Activation of SRC Tyrosine Kinases in Response to ICAM-1 Ligation in Pulmonary Microvascular Endothelial Cells

“…Within the signaling pathways induced through ligation of ICAM-1, activation of SRC tyrosine kinases has been demonstrated in human umbilical vein ECs and rat brain microvascular ECs (5)(6)(7). In addition, ligation of ICAM-1 induces activation of LYN, a member of the SRC family tyrosine kinases, in a B cell lymphoma line (8).…”

“…The mechanisms underlying SRC activation in response to ICAM-1 cross-linking have been examined in rat brain microvascular ECs, where activation of SRC requires activation of phospholipase C (6). In these ECs and human umbilical vein ECs, activation of SRC in turn results in tyrosine phosphorylation of cortactin (5-7), an actin-binding protein that modulates the F-actin cytoskeleton as well as EC locomotion (14 -16).…”