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. 1995 Jan 1;181(1):193–202. doi: 10.1084/jem.181.1.193

Early molecular events induced by T cell receptor (TCR) signaling in immature CD4+ CD8+ thymocytes: increased synthesis of TCR-alpha protein is an early response to TCR signaling that compensates for TCR-alpha instability, improves TCR assembly, and parallels other indicators of positive selection

PMCID: PMC2191831  PMID: 7528767

Abstract

Differentiation of immature CD4+ CD8+ thymocytes into mature CD4+ or CD8+ T cells occurs within the thymus and is dependent upon expression of antigen receptor complexes (T cell receptor [TCR]) containing clonotypic alpha/beta proteins. We have recently found that CD4+ CD8+ thymocytes express low levels of surface TCR because of limitations placed on TCR assembly by the instability of nascent TCR-alpha proteins within the endoplasmic reticulum (ER) of immature thymocytes. Because TCR-alpha/beta expression increases during development, a molecular mechanism must exist for increasing the number of assembled TCR complexes present in immature CD4+ CD8+ thymocytes that have been signaled to differentiate into mature T cells, although no such mechanism has yet been described. In the current report we have examined the molecular consequences of intracellular signals generated by engagement of surface TCR complexes on immature CD4+ CD8+ thymocytes. Isolated TCR engagement generated signals that increased TCR-alpha RNA levels and increased synthesis of TCR-alpha proteins, which, in turn, significantly increased assembly of complete TCR- alpha/beta complexes in CD4+ CD8+ thymocytes. Increased TCR-alpha protein levels in TCR-signaled CD4+ CD8+ thymocytes was the result of increased synthesis and not increased stability of TCR-alpha proteins, indicating that TCR engagement compensates for, but does not correct, the inherent instability of TCR-alpha proteins in the ER of immature thymocytes. Consistent with the delivery by TCR engagement of a positive selection signal, TCR engagement also increased CD5 expression, decreased RAG-1 expression, and decreased CD4/CD8 coreceptor expression in immature CD4+ CD8+ thymocytes. These data identify amplified TCR-alpha expression as an initial response of immature CD4+ CD8+ thymocytes to TCR-mediated positive selection signals and provide a molecular basis for increased surface TCR density on developing thymocytes undergoing selection events within the thymus.

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Selected References

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  1. Becker M. L., Near R., Mudgett-Hunter M., Margolies M. N., Kubo R. T., Kaye J., Hedrick S. M. Expression of a hybrid immunoglobulin-T cell receptor protein in transgenic mice. Cell. 1989 Sep 8;58(5):911–921. doi: 10.1016/0092-8674(89)90943-4. [DOI] [PubMed] [Google Scholar]
  2. Blackman M., Kappler J., Marrack P. The role of the T cell receptor in positive and negative selection of developing T cells. Science. 1990 Jun 15;248(4961):1335–1341. doi: 10.1126/science.1972592. [DOI] [PubMed] [Google Scholar]
  3. Bonifacino J. S., Cosson P., Klausner R. D. Colocalized transmembrane determinants for ER degradation and subunit assembly explain the intracellular fate of TCR chains. Cell. 1990 Nov 2;63(3):503–513. doi: 10.1016/0092-8674(90)90447-m. [DOI] [PubMed] [Google Scholar]
  4. Bonifacino J. S., McCarthy S. A., Maguire J. E., Nakayama T., Singer D. S., Klausner R. D., Singer A. Novel post-translational regulation of TCR expression in CD4+CD8+ thymocytes influenced by CD4. Nature. 1990 Mar 15;344(6263):247–251. doi: 10.1038/344247a0. [DOI] [PubMed] [Google Scholar]
  5. Bruce J., Symington F. W., McKearn T. J., Sprent J. A monoclonal antibody discriminating between subsets of T and B cells. J Immunol. 1981 Dec;127(6):2496–2501. [PubMed] [Google Scholar]
  6. Cenciarelli C., Hou D., Hsu K. C., Rellahan B. L., Wiest D. L., Smith H. T., Fried V. A., Weissman A. M. Activation-induced ubiquitination of the T cell antigen receptor. Science. 1992 Aug 7;257(5071):795–797. doi: 10.1126/science.1323144. [DOI] [PubMed] [Google Scholar]
  7. Clipstone N. A., Crabtree G. R. Identification of calcineurin as a key signalling enzyme in T-lymphocyte activation. Nature. 1992 Jun 25;357(6380):695–697. doi: 10.1038/357695a0. [DOI] [PubMed] [Google Scholar]
  8. Dialynas D. P., Wilde D. B., Marrack P., Pierres A., Wall K. A., Havran W., Otten G., Loken M. R., Pierres M., Kappler J. Characterization of the murine antigenic determinant, designated L3T4a, recognized by monoclonal antibody GK1.5: expression of L3T4a by functional T cell clones appears to correlate primarily with class II MHC antigen-reactivity. Immunol Rev. 1983;74:29–56. doi: 10.1111/j.1600-065x.1983.tb01083.x. [DOI] [PubMed] [Google Scholar]
  9. Fowlkes B. J., Pardoll D. M. Molecular and cellular events of T cell development. Adv Immunol. 1989;44:207–264. doi: 10.1016/s0065-2776(08)60643-4. [DOI] [PubMed] [Google Scholar]
  10. Groettrup M., Ungewiss K., Azogui O., Palacios R., Owen M. J., Hayday A. C., von Boehmer H. A novel disulfide-linked heterodimer on pre-T cells consists of the T cell receptor beta chain and a 33 kd glycoprotein. Cell. 1993 Oct 22;75(2):283–294. doi: 10.1016/0092-8674(93)80070-u. [DOI] [PubMed] [Google Scholar]
  11. Iwabuchi K., Nakayama K., McCoy R. L., Wang F., Nishimura T., Habu S., Murphy K. M., Loh D. Y. Cellular and peptide requirements for in vitro clonal deletion of immature thymocytes. Proc Natl Acad Sci U S A. 1992 Oct 1;89(19):9000–9004. doi: 10.1073/pnas.89.19.9000. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Jenkins M. K., Schwartz R. H., Pardoll D. M. Effects of cyclosporine A on T cell development and clonal deletion. Science. 1988 Sep 23;241(4873):1655–1658. doi: 10.1126/science.241.4873.1655. [DOI] [PubMed] [Google Scholar]
  13. Kearse K. P., Roberts J. L., Munitz T. I., Wiest D. L., Nakayama T., Singer A. Developmental regulation of alpha beta T cell antigen receptor expression results from differential stability of nascent TCR alpha proteins within the endoplasmic reticulum of immature and mature T cells. EMBO J. 1994 Oct 3;13(19):4504–4514. doi: 10.1002/j.1460-2075.1994.tb06772.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Kearse K. P., Williams D. B., Singer A. Persistence of glucose residues on core oligosaccharides prevents association of TCR alpha and TCR beta proteins with calnexin and results specifically in accelerated degradation of nascent TCR alpha proteins within the endoplasmic reticulum. EMBO J. 1994 Aug 15;13(16):3678–3686. doi: 10.1002/j.1460-2075.1994.tb06677.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Klausner R. D., Lippincott-Schwartz J., Bonifacino J. S. The T cell antigen receptor: insights into organelle biology. Annu Rev Cell Biol. 1990;6:403–431. doi: 10.1146/annurev.cb.06.110190.002155. [DOI] [PubMed] [Google Scholar]
  16. Kosugi A., Weissman A. M., Ogata M., Hamaoka T., Fujiwara H. Instability of assembled T-cell receptor complex that is associated with rapid degradation of zeta chains in immature CD4+CD8+ thymocytes. Proc Natl Acad Sci U S A. 1992 Oct 15;89(20):9494–9498. doi: 10.1073/pnas.89.20.9494. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Kubo R. T., Born W., Kappler J. W., Marrack P., Pigeon M. Characterization of a monoclonal antibody which detects all murine alpha beta T cell receptors. J Immunol. 1989 Apr 15;142(8):2736–2742. [PubMed] [Google Scholar]
  18. Leo O., Foo M., Sachs D. H., Samelson L. E., Bluestone J. A. Identification of a monoclonal antibody specific for a murine T3 polypeptide. Proc Natl Acad Sci U S A. 1987 Mar;84(5):1374–1378. doi: 10.1073/pnas.84.5.1374. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Maguire J. E., McCarthy S. A., Singer A., Singer D. S. Inverse correlation between steady-state RNA and cell surface T cell receptor levels. FASEB J. 1990 Oct;4(13):3131–3134. doi: 10.1096/fasebj.4.13.1698681. [DOI] [PubMed] [Google Scholar]
  20. Nakayama T., June C. H., Munitz T. I., Sheard M., McCarthy S. A., Sharrow S. O., Samelson L. E., Singer A. Inhibition of T cell receptor expression and function in immature CD4+CD8+ cells by CD4. Science. 1990 Sep 28;249(4976):1558–1561. doi: 10.1126/science.2120773. [DOI] [PubMed] [Google Scholar]
  21. Nakayama T., Samelson L. E., Nakayama Y., Munitz T. I., Sheard M., June C. H., Singer A. Ligand-stimulated signaling events in immature CD4+CD8+ thymocytes expressing competent T-cell receptor complexes. Proc Natl Acad Sci U S A. 1991 Nov 15;88(22):9949–9953. doi: 10.1073/pnas.88.22.9949. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Ohashi P. S., Pircher H., Bürki K., Zinkernagel R. M., Hengartner H. Distinct sequence of negative or positive selection implied by thymocyte T-cell receptor densities. Nature. 1990 Aug 30;346(6287):861–863. doi: 10.1038/346861a0. [DOI] [PubMed] [Google Scholar]
  23. Page D. M., Kane L. P., Allison J. P., Hedrick S. M. Two signals are required for negative selection of CD4+CD8+ thymocytes. J Immunol. 1993 Aug 15;151(4):1868–1880. [PubMed] [Google Scholar]
  24. Punt J. A., Osborne B. A., Takahama Y., Sharrow S. O., Singer A. Negative selection of CD4+CD8+ thymocytes by T cell receptor-induced apoptosis requires a costimulatory signal that can be provided by CD28. J Exp Med. 1994 Feb 1;179(2):709–713. doi: 10.1084/jem.179.2.709. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Shi Y. F., Sahai B. M., Green D. R. Cyclosporin A inhibits activation-induced cell death in T-cell hybridomas and thymocytes. Nature. 1989 Jun 22;339(6226):625–626. doi: 10.1038/339625a0. [DOI] [PubMed] [Google Scholar]
  26. Shin J., Lee S., Strominger J. L. Translocation of TCR alpha chains into the lumen of the endoplasmic reticulum and their degradation. Science. 1993 Mar 26;259(5103):1901–1904. doi: 10.1126/science.8456316. [DOI] [PubMed] [Google Scholar]
  27. Swat W., Ignatowicz L., von Boehmer H., Kisielow P. Clonal deletion of immature CD4+8+ thymocytes in suspension culture by extrathymic antigen-presenting cells. Nature. 1991 May 9;351(6322):150–153. doi: 10.1038/351150a0. [DOI] [PubMed] [Google Scholar]
  28. Weissman I. L. Developmental switches in the immune system. Cell. 1994 Jan 28;76(2):207–218. doi: 10.1016/0092-8674(94)90329-8. [DOI] [PubMed] [Google Scholar]
  29. von Boehmer H. Positive selection of lymphocytes. Cell. 1994 Jan 28;76(2):219–228. doi: 10.1016/0092-8674(94)90330-1. [DOI] [PubMed] [Google Scholar]

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