title: Pertussis toxin utilizes proximal components of the T-cell receptor complex to initiate signal transduction events in T cells.
abstract: Pertussis toxin (PTx) is an AB(5) toxin produced by the human pathogen Bordetella pertussis. Previous work demonstrates that the five binding (B) subunits of PTx can have profound effects on T lymphocytes independent of the enzymatic activity of the A subunit. Stimulation of T cells with holotoxin (PTx) or the B subunit alone (PTxB) rapidly induces signaling events resulting in inositol phosphate accumulation, Ca(2+) mobilization, interleukin-2 (IL-2) production, and mitogenic cell growth. Although previous reports suggest the presence of PTx signaling receptors expressed on T cells, to date, the receptor(s) and membrane proximal signaling events utilized by PTx remain unknown. Here we genetically and biochemically define the membrane proximal components utilized by PTx to initiate signal transduction in T cells. Using mutants of the Jurkat T-cell line deficient for key components of the T-cell receptor (TCR) pathway, we have compared stimulation with PTx to that of anti-CD3 monoclonal antibody (MAb), which directly interacts with and activates the TCR complex. Our genetic data in combination with biochemical analysis show that PTx (via the B subunit) activates TCR signaling similar to that of anti-CD3 MAb, including activation of key signaling intermediates such as Lck, ZAP-70, and phospholipase C-gamma1. Moreover, the data indicate that costimulatory activity, as provided by CD28 ligation, is required for PTx to fully stimulate downstream indicators of T-cell activation such as IL-2 gene expression. By illuminating the signaling pathways that PTx activates in T cells, we provide a mechanistic understanding for how these signals deregulate immune system functions during B. pertussis infection.
authors.affiliation: Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, 2256 Medical Science Building, 231 Albert Sabin Way, Cincinnati, OH 45267-0524, USA.
authors.forename: Olivia D
authors.initials: OD
authors.lastname: Schneider
authors.forename: Alison A
authors.initials: AA
authors.lastname: Weiss
authors.forename: William E
authors.initials: WE
authors.lastname: Miller
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D001886:Bordetella pertussis / Q000276:immunology; D018106:CD28 Antigens / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D007376:Interleukin-2 / Q000096:biosynthesis; D007527:Isoenzymes / Q000032:analysis; D019169:Jurkat Cells; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000032:analysis; D008954:Models, Biological; D037342:Pertussis Toxin / Q000276:immunology* / Q000378:metabolism*; D054799:Phospholipase C beta; D051966:Phospholipase C gamma / Q000378:metabolism; D011485:Protein Binding; D011948:Receptors, Antigen, T-Cell / Q000172:deficiency / Q000276:immunology* / Q000378:metabolism*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D010738:Type C Phospholipases / Q000032:analysis; D051746:ZAP-70 Protein-Tyrosine Kinase / Q000032:analysis
chemical_list: D000911:Antibodies, Monoclonal; D018106:CD28 Antigens; D017252:CD3 Complex; D007295:Inositol Phosphates; D007376:Interleukin-2; D007527:Isoenzymes; D011948:Receptors, Antigen, T-Cell; D037342:Pertussis Toxin; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051746:ZAP-70 Protein-Tyrosine Kinase; D010738:Type C Phospholipases; D054799:Phospholipase C beta; D051966:Phospholipase C gamma; D002118:Calcium