Vav1 and Rac control chemokine-promoted T lymphocyte adhesion mediated by the integrin alpha4beta1.
The chemokine CXCL12 promotes T lymphocyte adhesion mediated by the integrin alpha4beta1. CXCL12 activates the GTPase Rac, as well as Vav1, a guanine-nucleotide exchange factor for Rac, concomitant with up-regulation of alpha4beta1-dependent adhesion. Inhibition of CXCL12-promoted Rac and Vav1 activation by transfection of dominant negative Rac or Vav1 forms, or by transfection of their siRNA, remarkably impaired the increase in T lymphocyte attachment to alpha4beta1 ligands in response to this chemokine. Importantly, inhibition of Vav1 expression by RNA interference resulted in a blockade of Rac activation in response to CXCL12. Adhesions in flow chambers and soluble binding assays using these transfectants indicated that initial ligand binding and adhesion strengthening mediated by alpha4beta1 were dependent on Vav1 and Rac activation by CXCL12. Finally, CXCL12-promoted T-cell transendothelial migration involving alpha4beta1-mediated adhesion was notably inhibited by expression of dominant negative Vav1 and Rac. These results indicate that activation of Vav1-Rac signaling pathway by CXCL12 represents an important inside-out event controlling efficient up-regulation of alpha4beta1-dependent T lymphocyte adhesion.
García-Bernal
David
D
Department of Immunology, Centro de Investigaciones Biológicas, CSIC, 28006 Madrid, Spain.
Wright
Natalia
N
Sotillo-Mallo
Elena
E
Nombela-Arrieta
César
C
Stein
Jens V
JV
Bustelo
Xosé R
XR
Teixidó
Joaquin
J
D015153:Blotting, Western; D002448:Cell Adhesion; D002460:Cell Line; D002465:Cell Movement; D054377:Chemokine CXCL12; D018925:Chemokines / Q000378:metabolism; D019743:Chemokines, CXC / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000166:cytology; D020558:GTP Phosphohydrolases / Q000378:metabolism; D005799:Genes, Dominant; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D039041:Integrin alpha4beta1 / Q000378:metabolism*; D008024:Ligands; D008214:Lymphocytes / Q000166:cytology; D018613:Microscopy, Confocal; D051567:Proto-Oncogene Proteins c-vav / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation; D020744:rac GTP-Binding Proteins / Q000378:metabolism*
C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D018925:Chemokines; D019743:Chemokines, CXC; D039041:Integrin alpha4beta1; D008024:Ligands; D051567:Proto-Oncogene Proteins c-vav; D034741:RNA, Small Interfering; C496618:VAV1 protein, human; D049452:Green Fluorescent Proteins; D020558:GTP Phosphohydrolases; D020744:rac GTP-Binding Proteins