Gads‐deficient thymocytes are blocked at the transitional single positive CD4⁺ stage

Abstract

Positive selection of T-cell precursors is the process by which a diverse T-cell repertoire is established. Positive selection begins at the CD4 1 CD8 1 double positive (DP) stage of development and involves at least two steps. First, DP thymocytes down-regulate CD8 to become transitional single positive (TSP) CD4 1 thymocytes. Then, cells are selected to become either mature single positive CD4 1 or mature single positive CD8 1 thymocytes. We sought to define the function of Gads during the two steps of positive selection by analyzing a Gads-deficient mouse line. In Gads 1/1 mice, most TSP CD4 1 thymocytes are TCR hi Bcl-2 hi CD69 1 , suggesting that essential steps in positive selection occurred in the DP stage. Despite that Gads À/À mice could readily generate TSP CD4 1 thymocytes, many Gads À/À TSP CD4 1 cells were TCR lo Bcl-2 lo CD69 À , suggesting that Gads À/À cells proceeded to the TSP CD4 1 stage prior to being positively selected. These data suggest that positive selection is not a prerequisite for the differentiation of DP thymocytes into TSP CD4 1 thymocytes. We propose a model in which positive selection and differentiation into the TSP CD4 1 stage are separable events and Gads is only required for positive selection.

Depletion and recovery of lymphoid subsets following morphine administration

“…+ and SP CD8 + thymocytes (Lundberg et al, 1995;Suzuki et al, 1995;Lucas and Germain, 1996;Dalheimer et al, 2009). Previous analyses of the thymocyte populations in morphinetreated mice demonstrated that DP thymocytes are highly susceptible to morphine treatment (Sei et al, 1991;Freier and Fuchs, 1993).…”

Gads Regulates the Expansion Phase of CD8+ T Cell-Mediated Immunity

“…C57BL/6 Gads −/− mice and Gads −/− OT-I mice were described previously (16, 18) and backcrossed onto the CD45.1 + C57BL/6 genetic background. To generate CD45.1 + CD45.2 + OT-I mice, CD45.1 + OT-I mice were bred with CD45.2 + wild-type C57BL/6 mice.…”

“…Surface labeling of cells was performed as described previous (18). Briefly, single cell suspensions were prepared and labeled in staining buffer (PBS containing 2% FetalClone I bovine serum product (HyClone Laboratories, Inc., Logan, UT)) before fixing with 1% paraformaldehyde in PBS overnight or at least one hour at room temperature.…”

“…During the CD4 − CD8 − double negative (DN) stage of T cell development, Gads is required for the survival of thymocytes expressing TCRβ (17). Later, when TCRα is expressed, Gads is required for positive and negative selection of CD4 + CD8 + double positive (DP) thymocytes (18). While the locations of these blocks are consistent with a role for Gads in regulating TCR-mediated signal transduction, the fact that the blocks are not complete indicates that Gads expression is not an absolute requirement for TCR-mediated signal transduction.…”

“…During our analysis of the function of Gads in T cell development, we found that crossing Gads −/− mice with mice expressing an MHC class I-restricted transgenic TCR could rescue the production of naïve CD8 + T cells (18). These transgenic TCR-expressing Gads −/− mouse lines enable us to examine the function of Gads during the activation of naïve CD8 + T cells.…”