ICAM-1 signaling pathways associated with Rho activation in microvascular brain endothelial cells.
Endothelium of the cerebral blood vessels, which constitutes the blood-brain barrier, controls leukocyte adhesion and trafficking to the brain. Investigating signaling pathways triggered by the engagement of adhesion molecules expressed on brain endothelial cells, we report here that ICAM-1 cross-linking induces tyrosine phosphorylation of three cytoskeleton-associated proteins: focal adhesion kinase, paxillin, and p130Cas (Cas), which are found to associate as complexes. Tyrosine-phosphorylated Cas associates with the adaptor protein Crk and the GTP exchange factor C3G. In the same conditions the small G protein Rho was activated, as shown by the increase in its GTP loading. In addition, tyrosine phosphorylation of focal adhesion kinase, paxillin, and Cas as well as triggering of the Crk signaling pathway are blocked by pretreatment of the cells with the exoenzyme C3, a specific Rho inhibitor. C3-sensitive activation of the c-Jun N-terminal kinase in response to ICAM-1 cross-linking is also observed, whereas no significant activation of Ras or of the extracellular signal-regulated kinase was detected. In conclusion, these results suggest that through coupling to Rho activation and phosphorylation of cytoskeletal proteins and transcription factors, ICAM-1 cross-linking participates in the cell shape changes and gene regulation that may accompany lymphocyte migration through the blood-brain barrier.
Etienne
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S
Centre Nationale de la Recherche Scientifique, Unité Propre de Recherche 0415, Institut Cochin de Génétique Moléculaire, Paris, France. etienne@icgm.inserm.fr
Adamson
P
P
Greenwood
J
J
Strosberg
A D
AD
Cazaubon
S
S
Couraud
P O
PO
D000818:Animals; D001921:Brain / Q000098:blood supply*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002461:Cell Line, Transformed; D050719:Crk-Associated Substrate Protein; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D004789:Enzyme Activation / Q000276:immunology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D020558:GTP Phosphohydrolases / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D018799:Intercellular Adhesion Molecule-1 / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D048031:JNK Mitogen-Activated Protein Kinases; D008833:Microcirculation / Q000201:enzymology / Q000378:metabolism / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D050737:Proto-Oncogene Proteins c-crk; D051381:Rats; D050717:Retinoblastoma-Like Protein p130; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism; D020741:rho GTP-Binding Proteins
C493843:Bcar1 protein, rat; D015815:Cell Adhesion Molecules; C493872:Crk protein, rat; D050719:Crk-Associated Substrate Protein; D003598:Cytoskeletal Proteins; D051419:Paxillin; D010750:Phosphoproteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D050737:Proto-Oncogene Proteins c-crk; C496063:Pxn protein, rat; D050717:Retinoblastoma-Like Protein p130; D018799:Intercellular Adhesion Molecule-1; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020741:rho GTP-Binding Proteins