title: Ablation of SLP-76 signaling after T cell priming generates memory CD4 T cells impaired in steady-state and cytokine-driven homeostasis.
abstract: The intracellular signaling mechanisms regulating the generation and long-term persistence of memory T cells in vivo remain unclear. In this study, we used mouse models with conditional deletion of the key T cell receptor (TCR)-coupled adaptor molecule SH2-domain-containing phosphoprotein of 76 kDa (SLP-76), to analyze signaling mechanisms for memory CD4 T cell generation, maintenance, and homeostasis. We found that ablation of SLP-76 expression after T cell priming did not inhibit generation of phenotypic effector or memory CD4 T cells; however, the resultant SLP-76-deficient memory CD4 T cells could not produce recall cytokines in response to TCR-mediated stimulation and showed decreased persistence in vivo. In addition, SLP-76-deficient memory CD4 T cells exhibited reduced steady-state homeostasis and were impaired in their ability to homeostatically expand in vivo in response to the gamma(c) cytokine IL-7, despite intact proximal signaling through the IL-7R-coupled JAK3/STAT5 pathway. Direct in vivo deletion of SLP-76 in polyclonal memory CD4 T cells likewise led to impaired steady-state homeostasis as well as impaired homeostatic responses to IL-7. Our findings demonstrate a dominant role for SLP-76-dependent TCR signals in regulating turnover and perpetuation of memory CD4 T cells and their responses to homeostatic cytokines, with implications for the selective survival of memory CD4 T cells following pathogen exposure, vaccination, and aging.
authors.affiliation: Department of Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Bushar
authors.forename: Evann
authors.initials: E
authors.lastname: Corbo
authors.forename: Michelle
authors.initials: M
authors.lastname: Schmidt
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Maltzman
authors.forename: Donna L
authors.initials: DL
authors.lastname: Farber
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D016207:Cytokines / Q000502:physiology*; D015536:Down-Regulation; D018014:Gene Transfer Techniques; D017930:Genes, Reporter; D006706:Homeostasis / Q000235:genetics / Q000276:immunology; D007156:Immunologic Memory; D015851:Interleukin-7 / Q000494:pharmacology; D008164:Luminescent Proteins / Q000235:genetics; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D010750:Phosphoproteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D016207:Cytokines; D015851:Interleukin-7; D008164:Luminescent Proteins; D010750:Phosphoproteins; C092947:SLP-76 signal Transducing adaptor proteins