The relationship of T cell receptor assembly, expression, and signaling to T cell development in the thymus has been elucidated by a variety of in vitro and in vivo experiments. We have demonstrated that the major route of TCR assembly in immature thymocytes is the association and subsequent disulfide bonding of two trimeric complexes: one consisting of TCRalpha, CD3gamma, and CD3epsilons proteins; and the other consisting of TCRbeta,CD3delta, and CD3 epsilon proteins. However, we discovered that in immature thymocytes assembly of complete TCR complexes was not necessary for surface expression as immature thymocytes expressed on their cell surfaces partial receptor complexes, referred to as clonotype- independent complexes, that consisted of CD3 components associated with a surface form of the molecular chaperon calnexin and that were able to transduce signals regulating early T cell development. Interestingly, we found that retention of nascent proteins within the endoplasmic reticulum (ER) was generally inefficient in immature thymocytes and in that a variety of different molecular chaperones are expressed on the surface of immature thymocytes that normally are completely retained within the ER. With regard to repertoire selection events in the thymus, we found a marked asymmetry in the signals required for CD4 versus CD8 commitment, in that CD8-commitment was strictly dependent upon MHC class I instructional signals whereas CD4-commitment appeared to occur by default. We developed an assay, referred to as the coreceptor reexpression assay, that was capable of detecting lineage commitment at a molecular level immediately upon termination of either CD4 or CD8 synthesis. Interestingly, we identified a specific subpopulation of TCRhiBcl2hi immature thymocytes as the earliest cells to have undergone lineage commitment. Significantly, we have developed an in vitro system in which immature DP thymocytes can be signaled to differentiated into CD4+ T cells in the absence of thymic epithelium. This in vitro system has the potential to identify receptor-ligand interactions between immature thymocytes and thymic epithelium that generate intracellular signals resulting in positive selection.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Intramural Research (Z01)
Project #
1Z01BC009273-09
Application #
2463768
Study Section
Special Emphasis Panel (EIB)
Project Start
Project End
Budget Start
Budget End
Support Year
9
Fiscal Year
1996
Total Cost
Indirect Cost
Name
National Cancer Institute Division of Basic Sciences
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Tai, Xuguang; Van Laethem, Francois; Sharpe, Arlene H et al. (2007) Induction of autoimmune disease in CTLA-4-/- mice depends on a specific CD28 motif that is required for in vivo costimulation. Proc Natl Acad Sci U S A 104:13756-61
Yu, Qing; Park, Jung-Hyun; Doan, Loretta L et al. (2006) Cytokine signal transduction is suppressed in preselection double-positive thymocytes and restored by positive selection. J Exp Med 203:165-75
Graham, Daniel B; Bell, Michael P; Huntoon, Catherine J et al. (2006) CD28 ligation costimulates cell death but not maturation of double-positive thymocytes due to defective ERK MAPK signaling. J Immunol 177:6098-107
Tai, Xuguang; Cowan, Michelle; Feigenbaum, Lionel et al. (2005) CD28 costimulation of developing thymocytes induces Foxp3 expression and regulatory T cell differentiation independently of interleukin 2. Nat Immunol 6:152-62
Sarafova, Sophia D; Erman, Batu; Yu, Qing et al. (2005) Modulation of coreceptor transcription during positive selection dictates lineage fate independently of TCR/coreceptor specificity. Immunity 23:75-87
Yu, Qing; Erman, Batu; Park, Jung-Hyun et al. (2004) IL-7 receptor signals inhibit expression of transcription factors TCF-1, LEF-1, and RORgammat: impact on thymocyte development. J Exp Med 200:797-803
Erman, Batu; Guinter, Terry I; Singer, Alfred (2004) Defined alphabeta T cell receptors with distinct ligand specificities do not require those ligands to signal double negative thymocyte differentiation. J Exp Med 199:1719-24
Park, Jung-Hyun; Yu, Qing; Erman, Batu et al. (2004) Suppression of IL7Ralpha transcription by IL-7 and other prosurvival cytokines: a novel mechanism for maximizing IL-7-dependent T cell survival. Immunity 21:289-302
Singer, Alfred; Bosselut, Remy (2004) CD4/CD8 coreceptors in thymocyte development, selection, and lineage commitment: analysis of the CD4/CD8 lineage decision. Adv Immunol 83:91-131
Bosselut, Remy; Guinter, Terry I; Sharrow, Susan O et al. (2003) Unraveling a revealing paradox: Why major histocompatibility complex I-signaled thymocytes ""paradoxically"" appear as CD4+8lo transitional cells during positive selection of CD8+ T cells. J Exp Med 197:1709-19

Showing the most recent 10 out of 19 publications