title: RGS10 restricts upregulation by chemokines of T cell adhesion mediated by α4β1 and αLβ2 integrins.
abstract: Chemokines rapidly and transiently upregulate α4β1 and αLβ2 integrin-mediated adhesion during T lymphocyte extravasation by activating Gα-dependent inside-out signaling. To limit and terminate Gα-mediated signaling, cells can use several mechanisms, including the action of regulator of G protein signaling (RGS) proteins, which accelerate the GTPase activity of Gα subunits. Using human T cells silenced for or overexpressing RGS10, we show in this article that RGS10 functions as an inhibitor of Gα(i)-dependent, chemokine-upregulated T cell adhesion mediated by α4β1 and αLβ2. Shear stress-dependent detachment and cell spreading analyses revealed that RGS10 action mainly targets the adhesion strengthening and spreading phases of α4β1-mediated cell attachment. Associated with these observations, chemokine-stimulated Vav1-Rac1 activation was longer sustained and of higher intensity in RGS10-silenced T cells, or inhibited in cells overexpressing RGS10. Of importance, expression of constitutively activated Rac1 forms in cells overexpressing RGS10 led to the rescue of CXCL12-stimulated adhesion to VCAM-1 to levels similar to those in control transfectants. Instead, adhesion under flow conditions, soluble binding experiment, flow cytometry, and biochemical analyses revealed that the earlier chemokine-triggered integrin activation step was mostly independent of RGS10 actions. The data strongly suggest that RGS10 opposes activation by chemokines of the Vav1-Rac1 pathway in T cells, leading to repression of adhesion strengthening mediated by α4β1. In addition to control chemokine-upregulated T cell attachment, RGS10 also limited adhesion-independent cell chemotaxis and activation of cdc42. These results identify RGS10 as a key molecule that contributes to the termination of Gα-dependent signaling during chemokine-activated α4β1- and αLβ2-dependent T cell adhesion.
authors.affiliation: Departamento de Medicina Celular y Molecular, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
authors.forename: David
authors.initials: D
authors.lastname: García-Bernal
authors.forename: Ana
authors.initials: A
authors.lastname: Dios-Esponera
authors.forename: Elena
authors.initials: E
authors.lastname: Sotillo-Mallo
authors.forename: Rosa
authors.initials: R
authors.lastname: García-Verdugo
authors.forename: Nohemí
authors.initials: N
authors.lastname: Arellano-Sánchez
authors.forename: Joaquin
authors.initials: J
authors.lastname: Teixidó
mesh_terms: D040881:CD11a Antigen / Q000378:metabolism / Q000502:physiology*; D018821:CD18 Antigens / Q000378:metabolism / Q000502:physiology*; D002448:Cell Adhesion / Q000276:immunology; D002478:Cells, Cultured; D018925:Chemokines / Q000037:antagonists & inhibitors* / Q000502:physiology; D002634:Chemotaxis, Leukocyte / Q000276:immunology; D015536:Down-Regulation / Q000276:immunology*; D006801:Humans; D039441:Integrin alpha4 / Q000378:metabolism / Q000502:physiology*; D019012:Integrin beta1 / Q000378:metabolism / Q000502:physiology*; D019169:Jurkat Cells; D020710:RGS Proteins / Q000502:physiology*; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D015854:Up-Regulation / Q000276:immunology
chemical_list: D040881:CD11a Antigen; D018821:CD18 Antigens; D018925:Chemokines; D019012:Integrin beta1; D020710:RGS Proteins; C101113:RGS10 protein, human; D039441:Integrin alpha4