Adenosine diphosphate (ADP)-ribosylation of the guanosine triphosphatase (GTPase) rho in resting peripheral blood human T lymphocytes results in pseudopodial extension and the inhibition of T cell activation.
Scrape loading Clostridium botulinum C3 exoenzyme into primary peripheral blood human T lymphocytes (PB T cells) efficiently adenosine diphosphate (ADP)-ribosylates and thus inactivates the guanosine triphosphatase (GTPase) Rho. Basal adhesion of PB T cells to the beta1 integrin substrate fibronectin (Fn) was not inhibited by inactivation of Rho, nor was upregulation of adhesion using phorbol myristate acetate (PMA; 10 ng/ml) or Mn++ (1 mM) affected. Whereas untreated PB T cells adherent to Fn remain spherical, C3-treated PB T cells extend F-actin-containing pseudopodia. Inactivation of Rho delayed the kinetics of PMA-dependent PB T cell homotypic aggregation, a process involving integrin alphaLbeta2. Although C3 treatment of PB T cells did not prevent adhesion to the beta1 integrin substrate Fn, it did inhibit beta1 integrin/CD3-mediated costimulation of proliferation. Analysis of intracellular cytokine production at the single cell level demonstrated that ADP-ribosylation of Rho inhibited beta1 integrin/ CD3 and CD28/CD3 costimulation of IL-2 production within 6 h of activation. Strikingly, IL-2 production induced by PMA and ionomycin was unaffected by C3 treatment. Thus, the GTPase Rho is a novel regulator of T lymphocyte cytoarchitecture, and functional Rho is required for very early events regulating costimulation of IL-2 production in PB T cells.
Department of Immunology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
D G
DG
Woodside
D K
DK
Wooten
B W
BW
McIntyre
D036002:ADP Ribose Transferases / Q000494:pharmacology; D000199:Actins / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000378:metabolism*; D001905:Botulinum Toxins; D018821:CD18 Antigens / Q000378:metabolism; D018106:CD28 Antigens / Q000378:metabolism; D017252:CD3 Complex / Q000378:metabolism; D002448:Cell Adhesion; D002455:Cell Division; D002460:Cell Line; D002478:Cells, Cultured; D015536:Down-Regulation; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism; D012266:Ribose / Q000378:metabolism*; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein
D000199:Actins; D018821:CD18 Antigens; D018106:CD28 Antigens; D017252:CD3 Complex; D019012:Integrin beta1; D007376:Interleukin-2; D016693:Receptors, Antigen, T-Cell, alpha-beta; D000244:Adenosine Diphosphate; D012266:Ribose; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001905:Botulinum Toxins; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein