Positive and negative regulation by SLP-76/ADAP and Pyk2 of chemokine-stimulated T-lymphocyte adhesion mediated by integrin α4β1

• Published in: Molecular biology of the cell 2015-09, Vol.26 (18), p.3215-3228
• Main Authors: Dios-Esponera, Ana, Isern de Val, Soledad, Sevilla-Movilla, Silvia, García-Verdugo, Rosa, García-Bernal, David, Arellano-Sánchez, Nohemí, Cabañas, Carlos, Teixidó, Joaquin
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Signal Transducing - metabolism; Cell Adhesion - physiology; Cell Line; Chemokine CXCL12 - metabolism; Focal Adhesion Kinase 2 - metabolism; Humans; Integrin alpha4beta1 - metabolism; Jurkat Cells; Ligands; Phosphoproteins - metabolism; Protein Transport; Proto-Oncogene Proteins c-vav - metabolism; rac1 GTP-Binding Protein - metabolism; Signal Transduction; T-Lymphocytes - cytology; T-Lymphocytes - metabolism; Vascular Cell Adhesion Molecule-1 - metabolism
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.E14-07-1246

Stimulation by chemokines of integrin α4β1-dependent T-lymphocyte adhesion is a crucial step for lymphocyte trafficking. The adaptor Vav1 is required for chemokine-activated T-cell adhesion mediated by α4β1. Conceivably, proteins associating with Vav1 could potentially modulate this adhesion. Correlating with activation by the chemokine CXCL12 of T-lymphocyte attachment to α4β1 ligands, a transient stimulation in the association of Vav1 with SLP-76, Pyk2, and ADAP was observed. Using T-cells depleted for SLP-76, ADAP, or Pyk2, or expressing Pyk2 kinase-inactive forms, we show that SLP-76 and ADAP stimulate chemokine-activated, α4β1-mediated adhesion, whereas Pyk2 opposes T-cell attachment. While CXCL12-promoted generation of high-affinity α4β1 is independent of SLP-76, ADAP, and Pyk2, the strength of α4β1-VCAM-1 interaction and cell spreading on VCAM-1 are targets of regulation by these three proteins. GTPase assays, expression of activated or dominant-negative Rac1, or combined ADAP and Pyk2 silencing indicated that Rac1 activation by CXCL12 is a common mediator response in SLP-76-, ADAP-, and Pyk2-regulated cell adhesion involving α4β1. Our data strongly suggest that chemokine-stimulated associations between Vav1, SLP-76, and ADAP facilitate Rac1 activation and α4β1-mediated adhesion, whereas Pyk2 opposes this adhesion by limiting Rac1 activation.