ICAM-1-mediated endothelial nitric oxide synthase activation via calcium and AMP-activated protein kinase is required for transendothelial lymphocyte migration.
As a gatekeeper of leukocyte trafficking the vasculature fulfills an essential immune function. We have recently shown that paracellular transendothelial lymphocyte migration is controlled by intercellular adhesion molecule 1 (ICAM-1)-mediated vascular endothelial cadherin (VEC) phosphorylation [Turowski et al., J. Cell Sci. 121, 29-37 (2008)]. Here we show that endothelial nitric oxide synthase (eNOS) is a critical regulator of this pathway. ICAM-1 stimulated eNOS by a mechanism that was clearly distinct from that utilized by insulin. In particular, phosphorylation of eNOS on S1177 in response to ICAM-1 activation was regulated by src family protein kinase, rho GTPase, Ca(2+), CaMKK, and AMPK, but not Akt/PI3K. Functional neutralization of any component of this pathway or its downstream effector guanylyl cyclase significantly reduced lymphocyte diapedesis across the endothelial monolayer. In turn, activation of NO signaling promoted lymphocyte transmigration. The eNOS signaling pathway was required for T-cell transmigration across primary rat and human microvascular endothelial cells and also when shear flow was applied, suggesting that this pathway is ubiquitously used. These data reveal a novel and essential role of eNOS in basic immune function and provide a key link in the molecular network governing endothelial cell compliance to diapedesis.
Martinelli
Roberta
R
Division of Cell Biology, Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom.
Gegg
Matthew
M
Longbottom
Rebecca
R
Adamson
Peter
P
Turowski
Patric
P
Greenwood
John
J
D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D008214:Lymphocytes / Q000166:cytology* / Q000187:drug effects; D051379:Mice; D008954:Models, Biological; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects
D007328:Insulin; D018799:Intercellular Adhesion Molecule-1; D052250:Nitric Oxide Synthase Type III; D051057:Proto-Oncogene Proteins c-akt; D055372:AMP-Activated Protein Kinases; D002118:Calcium