RGS10 restricts upregulation by chemokines of T cell adhesion mediated by α4β1 and αLβ2 integrins

J Immunol. 2011 Aug 1;187(3):1264-72. doi: 10.4049/jimmunol.1002960. Epub 2011 Jun 24.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • CD11a Antigen / metabolism
  • CD11a Antigen / physiology*
  • CD18 Antigens / metabolism
  • CD18 Antigens / physiology*
  • Cell Adhesion / immunology
  • Cells, Cultured
  • Chemokines / antagonists & inhibitors*
  • Chemokines / physiology
  • Chemotaxis, Leukocyte / immunology
  • Down-Regulation / immunology*
  • Humans
  • Integrin alpha4 / metabolism
  • Integrin alpha4 / physiology*
  • Integrin beta1 / metabolism
  • Integrin beta1 / physiology*
  • Jurkat Cells
  • RGS Proteins / physiology*
  • Signal Transduction / immunology
  • T-Lymphocytes / cytology
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / metabolism
  • Up-Regulation / immunology

Substances

  • CD11a Antigen
  • CD18 Antigens
  • Chemokines
  • Integrin beta1
  • RGS Proteins
  • RGS10 protein, human
  • Integrin alpha4