scholarly journals Regulation of thymocyte development through CD3. II. Expression of T cell receptor beta CD3 epsilon and maturation to the CD4+8+ stage are highly correlated in individual thymocytes.

1993 ◽  
Vol 178 (6) ◽  
pp. 1867-1875 ◽  
Author(s):  
C N Levelt ◽  
R Carsetti ◽  
K Eichmann

Recent studies have shown that maturation of CD4-8- double negative (DN) thymocytes to the CD4+8+ double positive (DP) stage is dependent on expression of the T cell receptor (TCR)-beta polypeptide. The exact mechanism by which the TCR-beta chain regulates this maturation step remains unknown. Previous experiments had suggested that in the presence of some TCR+ thymocytes, additional DN thymocytes not expressing a TCR-beta chain may be recruited to mature to the DP stage. The recent demonstration of an immature TCR-beta-CD3 complex on early thymocytes lead to the alternative hypothesis that signal transduction through an immature TCR-CD3 complex may induce maturation to the DP stage. In the latter case, maturation to the DP stage would depend on the expression of TCR-beta-CD3 in the same cell. We examined these two hypotheses by studying the expression of the intra- and extracellular CD3 epsilon, CD3 zeta, and TCR-beta polypeptides in intrathymic subpopulations during embryogenesis. CD3 epsilon and CD3 zeta were expressed intracellularly 2 and 1 d, respectively, before intracellular expression of the TCR-beta chain, potentially allowing immediate surface expression of an immature TCR-beta-CD3 complex as soon as functional rearrangement of a TCR-beta gene locus has been accomplished. Calcium mobilization could be induced by stimulation with anti-CD3 epsilon mAb as soon as intracellular TCR-beta was detectable, suggesting that a functional TCR-beta-CD3 complex is indeed expressed on the surface of early thymocytes. From day 17 on, most cells were in the DP stage, and over 95% of the DP cells expressed on the TCR-beta chain intracellularly. At day 19 of gestation, extremely low concentrations of TCR-beta chain and CD3 epsilon were detectable on the cell surface of nearly all thymocytes previously thought to be TCR-CD3 negative. These findings strongly support the hypothesis that maturation to the DP stage depends on surface expression of and subsequent signal transduction through an immature TCR-beta-CD3 complex and suggest that maturation to the DP stage by recruitment, if it occurs at all, is of minor relevance.

1993 ◽  
Vol 177 (4) ◽  
pp. 1079-1092 ◽  
Author(s):  
H R Rodewald ◽  
K Awad ◽  
P Moingeon ◽  
L D'Adamio ◽  
D Rabinowitz ◽  
...  

We have recently identified a dominant wave of CD4-CD8- (double-negative [DN]) thymocytes in early murine fetal development that express low affinity Fc gamma receptors (Fc gamma RII/III) and contain precursors for Ti alpha/beta lineage T cells. Here we show that Fc gamma RII/III is expressed in very immature CD4low single-positive (SP) thymocytes and that Fc gamma RII/III expression is downregulated within the DN subpopulation and before the CD3-CD8low SP stage in T cell receptor (TCR)-alpha/beta lineage-committed thymocytes. DN Fc gamma RII/III+ thymocytes also contain a small fraction of TCR-gamma/delta lineage cells in addition to TCR-alpha/beta progenitors. Fetal day 15.5 DN TCR-alpha/beta lineage progenitors can be subdivided into three major subpopulations as characterized by cell surface expression of Fc gamma RII/III vs. CD2 (Fc gamma RII/III+CD2-, Fc gamma RII/III+CD2+, Fc gamma RII/III-CD2+). Phenotypic analysis during fetal development as well as adoptive transfer of isolated fetal thymocyte subpopulations derived from C57B1/6 (Ly5.1) mice into normal, nonirradiated Ly5.2 congenic recipient mice identifies one early differentiation sequence (Fc gamma RII/III+CD2(-)-->Fc gamma RII/III+CD2(+)-->Fc gamma RII/III-CD2+) that precedes the entry of DN thymocytes into the CD4+CD8+ double-positive (DP) TCRlow/- stage. Unseparated day 15.5 fetal thymocytes develop into DP thymocytes within 2.5 d and remain at the DP stage for > 48 h before being selected into either CD4+ or CD8+ SP thymocytes. In contrast, Fc gamma RII/III+CD2- DN thymocytes follow this same developmental pathway but are delayed by approximately 24 h before entering the DP compartment, while Fc gamma RII/III-CD2+ display accelerated development by approximately 24 h compared with total day 15.5 thymocytes. Fc gamma RII/III-CD2+ are also more developmentally advanced than Fc gamma RII/III+CD2- fetal thymocytes with respect to their TCR beta chain V(D)J rearrangement. At day 15.5 in gestation, beta chain V(D)J rearrangement is mostly, if not entirely, restricted to the Fc gamma RII/III-CD2+ subset of DN fetal thymocytes. Consistent with this analysis in fetal thymocytes, > 90% of adult thymocytes derived from mice carrying a disrupting mutation at the recombination-activating gene 2 locus (RAG-2-/-) on both alleles are developmentally arrested at the DN CD2- stage. In addition, there is a fivefold increase in the relative percentage of thymocytes expressing Fc gamma RII/III in TCR and immunoglobulin gene rearrangement-incompetent homozygous RAG-2-/- mice (15% Fc gamma RII/III+) versus rearrangement-competent heterozygous RAG-2+/- mice (< 3% Fc gamma RII/III+). Thus, Fc gamma RII/III expression defines an early DN stage preceding V beta(D beta)I beta rearrangement, which in turn is followed by surface expression of CD2. Loss of Fc gamma RII/III and acquisition of CD2 expression characterize a late DN stage immediately before the conversion into DP thymocytes.


Blood ◽  
2005 ◽  
Vol 106 (4) ◽  
pp. 1296-1304 ◽  
Author(s):  
Ariadne L. Hager-Theodorides ◽  
Johannes T. Dessens ◽  
Susan V. Outram ◽  
Tessa Crompton

AbstractGlioblastoma 3 (Gli3) is a transcription factor involved in patterning and oncogenesis. Here, we demonstrate a role for Gli3 in thymocyte development. Gli3 is differentially expressed in fetal CD4–CD8– double-negative (DN) thymocytes and is most highly expressed at the CD44+ CD25– DN (DN1) and CD44–CD25– (DN4) stages of development but was not detected in adult thymocytes. Analysis of null mutants showed that Gli3 is involved at the transitions from DN1 to CD44+ CD25+ DN (DN2) cell and from DN to CD4+CD8+ double-positive (DP) cell. Gli3 is required for differentiation from DN to DP thymocyte, after pre–T-cell receptor (TCR) signaling but is not necessary for pre-TCR–induced proliferation or survival. The effect of Gli3 was dose dependent, suggesting its direct involvement in the transcriptional regulation of genes controlling T-cell differentiation during fetal development.


1996 ◽  
Vol 184 (2) ◽  
pp. 519-530 ◽  
Author(s):  
A R Ramiro ◽  
C Trigueros ◽  
C Márquez ◽  
J L San Millán ◽  
M L Toribio

In murine T cell development, early thymocytes that productively rearrange the T cell receptor (TCR) beta locus are selected to continue maturation, before TCR alpha expression, by means of a pre-TCR alpha- (pT alpha-) TCR beta heterodimer (pre-TCR). The aim of this study was to identify equivalent stages in human thymocyte development. We show here that variable-diversity-joining region TCR beta rearrangement and the expression of full-length TCR beta transcripts have been initiated in some immature thymocytes at the TCR alpha/beta- CD4+CD8- stage, and become common in a downstream subset of TCR alpha/beta- CD4+CD8+ thymocytes that is highly enriched in large cycling cells. TCR beta chain expression was hardly detected in TCR alpha/beta- CD4+CD8- thymocytes, whereas cytoplasmic TCR beta chain was found in virtually all TCR alpha/beta- CD4+CD8+ blasts. In addition, a TCR beta complex distinct from the mature TCR alpha/beta heterodimer was immunoprecipitated only from the latter subset. cDNA derived from TCR alpha/beta- CD4+CD8+ blasts allowed us to identify and clone the gene encoding the human pT alpha chain, and to examine its expression at different stages of thymocyte development. Our results show that high pT alpha transcription occurs only in CD4+CD8- and CD4+CD8+ TCR alpha/beta- thymocytes, whereas it is weaker in earlier and later stages of development. Based on these results, we propose that the transition from TCR alpha/beta- CD4+CD8- to TCR alpha/beta- CD4+CD8+ thymocytes represents a critical developmental stage at which the successful expression of TCR beta promotes the clonal expansion and further maturation of human thymocytes, independent of TCR alpha.


1991 ◽  
Vol 173 (5) ◽  
pp. 1247-1256 ◽  
Author(s):  
L Tan ◽  
J Turner ◽  
A Weiss

The T cell antigen receptor consists of the Ti alpha/beta heterodimer which recognizes antigen, and the associated CD3 chains, thought to be involved in signal transduction. To understand the nature of the interaction between Ti and CD3, chimeric molecules which included the COOH-terminal segments of Ti alpha or beta linked to the extracellular segment of CD8, were transfected into a mutant T cell deficient in Ti beta chain expression and cell surface CD3. Both chimeric chains were required to express the chimeric Ti and to restore CD3 surface expression. CD8/Ti and CD3 cointernalized and coimmunoprecipitated. Stimulation of the chimeric receptor induced transmembrane signaling events and cell activation. These results demonstrate that the Ti alpha and beta COOH termini containing the transmembrane domains are sufficient for structural and functional coupling of Ti to CD3.


1997 ◽  
Vol 186 (5) ◽  
pp. 767-775 ◽  
Author(s):  
Anna Krotkova ◽  
Harald von Boehmer ◽  
Hans Jörg Fehling

Although individual T lymphocytes have the potential to generate two distinct T cell receptor (TCR)-β chains, they usually express only one allele, a phenomenon termed allelic exclusion. Expression of a functional TCR-β chain during early T cell development leads to the formation of a pre-T cell receptor (pre-TCR) complex and, at the same developmental stage, arrest of further TCR-β rearrangements, suggesting a role of the pre-TCR in mediating allelic exclusion. To investigate the potential link between pre-TCR formation and inhibition of further TCR-β rearrangements, we have studied the efficiency of allelic exclusion in mice lacking the pre-TCR-α (pTα) chain, a core component of the pre-TCR. Staining of CD3+ thymocytes and lymph node cells with antibodies specific for Vβ6 or Vβ8 and a pool of antibodies specific for most other Vβ elements, did not reveal any violation of allelic exclusion at the level of cell surface expression. This was also true for pTα-deficient mice expressing a functionally rearranged TCR-β transgene. Interestingly, although the transgenic TCR-β chain significantly influenced thymocyte development even in the absence of pTα, it was not able to inhibit fully endogeneous TCR-β rearrangements either in total thymocytes or in sorted CD25+ pre-T cells of pTα−/− mice, clearly indicating an involvement of the pre-TCR in allelic exclusion.


1993 ◽  
Vol 177 (2) ◽  
pp. 541-546 ◽  
Author(s):  
J H Park ◽  
R Mitnacht ◽  
N Torres-Nagel ◽  
T Hünig

The role of interleukin (IL)2 in intrathymic T cell development is highly controversial, and nothing is known about IL-2R expression on thymocytes of the T cell receptor (TCR) alpha/beta lineage undergoing TCR-driven differentiation events. We analyze here IL-2R alpha and beta mRNA expression in an in vitro system where newly generated rat CD4,8 double positive (DP) thymocytes respond to TCR ligation plus IL-2 (but not to either stimulus alone) with rapid differentiation to functional CD8 single positive T cells (Hünig, T., and R. Mitnacht. 1991. J. Exp. Med. 173:561). TCR ligation induced expression of IL-2R beta (but not alpha) chain mRNA in DP thymocytes. Addition of IL-2 then lead to functional maturation and expression of the IL-2R alpha chain. To investigate if the CD8 T cells generated via this IL-2R beta-driven pathway in vitro correspond to the bulk of CD8 T cells seeding peripheral lymphoid organs in vivo, we compared their phenotype to that of lymph node CD8 T cells. Surprisingly, analysis of CD8 cell surface expression using a novel anti-CD8 monoclonal antibody specific for the alpha/beta heterodimeric isoform, and of CD8 alpha and beta chain mRNA revealed that T cells generated by TCR ligation plus IL-2 resemble thymus-independent rather than thymus-derived CD8 cells in that they express CD8 alpha without beta chains. These findings demonstrate that TCR crosslinking induces functional IL-2R on immature DP rat thymocytes. In addition, they show that at least in vitro, CD8 alpha/alpha T cells are generated from TCR-stimulated DP thymocytes (which express the CD8 alpha/beta in the heterodimeric isoform) along an IL-2-driven pathway of T cell differentiation.


1998 ◽  
Vol 188 (9) ◽  
pp. 1669-1678 ◽  
Author(s):  
Andreas Würch ◽  
Judit Biro ◽  
Alexandre J. Potocnik ◽  
Ingrid Falk ◽  
Horst Mossmann ◽  
...  

During αβ thymocyte development, the clonotypic αβ–T cell receptor (TCR) is preceded by sequentially expressed immature versions of the TCR–CD3 complex: the pre-TCR, containing a clonotypic TCR-β chain and invariant pre-Tα, is expressed on pre-T cells before rearrangement of the TCR-α locus. Moreover, clonotype-independent CD3 complexes (CIC) appear on pro-T cells before VDJ rearrangements of TCR-β genes. The pre-TCR is known to mediate TCR-β selection, the prerequisite for maturation of CD4−8− double negative (DN) thymocytes to the CD4+8+ double positive stage. A developmental function of CIC has so far not been delineated. In mice single deficient and double deficient for CD3ζ/η and/or p56lck, we observe a pronounced reduction in the proportions of CD25+ DN thymocytes that express intracellular TCR-β chains. TCR-β transcripts are reduced in parallel with TCR-β polypeptide chains whereas no reduction in TCR-β locus rearrangements could be detected. Wild-type levels of TCR-β transcripts and of cells expressing TCR-β polypeptide chains are induced by treatment with anti-CD3ε mAb. The data suggest that the initial expression of rearranged TCR-β VDJ genes in pro-T cell to pre-T cell progression is dependent on CD3 complex signaling, and thus define a putative developmental function for CIC.


2006 ◽  
Vol 203 (1) ◽  
pp. 165-175 ◽  
Author(s):  
Qing Yu ◽  
Jung-Hyun Park ◽  
Loretta L. Doan ◽  
Batu Erman ◽  
Lionel Feigenbaum ◽  
...  

Death by neglect requires that CD4+8+ double-positive (DP) thymocytes avoid cytokine-mediated survival signals, which is presumably why DP thymocytes normally extinguish IL-7R gene expression. We report that DP thymocytes before positive selection (preselection DP thymocytes) fail to transduce IL-7 signals even when they express high levels of transgenic IL-7R on their surface, because IL-7R signal transduction is actively suppressed in preselection DP thymocytes by suppressor of cytokine signaling (SOCS)–1. SOCS-1 is highly expressed in preselection DP thymocytes, but it is down-regulated by T cell receptor–mediated positive selection signals. Interestingly, we found that the uniquely small cell volume of DP thymocytes is largely the result of absent IL-7 signaling in preselection DP thymocytes. We also report that, contrary to current concepts, preselection DP thymocytes express high levels of endogenously encoded IL-4Rs. However, their ability to transduce cytokine signals is similarly suppressed by SOCS-1. Thus, despite high surface expression of transgenic or endogenous cytokine receptors, cytokine signal transduction is actively suppressed in preselection DP thymocytes until it is restored by positive selection.


1996 ◽  
Vol 183 (4) ◽  
pp. 1923-1928 ◽  
Author(s):  
D Jiang ◽  
M J Lenardo ◽  
J C Zúñiga-Pflücker

Rearrangement of the immunoglobulin (Ig) and T cell receptor (TCR) gene loci allows for the generation of B and T lymphocytes with antigen-specific receptors. Complete rearrangement and expression of the TCR-beta chain enables immature thymocytes to differentiate from the CD4-CD8- to the CD4+CD8+ stage mice in which rearrangement is impaired, such as severe combined immunodeficient (SCID) mice or recombinase activating gene-deficient (RAG-/-) mice, lack mature B and T lymphocytes. Thymocytes from these mice are arrested at the CD4-CD8- stage of T cell development. We previously observed that thymocytes from RAG-2-/- mice exposed to gamma radiation differentiate from CD4-CD8- into CD4+CD8+ without TCR-beta chain rearrangement. We now report that irradiated RAG-2-/- thymocytes undergo direct somatic mutations at the p53 gene locus, and that p53 inactivation is associated with maturation of RAG2-/- thymocytes to the CD4+CD8+ stage. Generation of RAG2-/- and p53-/- double-deficient mice revealed that, in the absence of TCR-beta chain rearrangement, loss of p53 function is sufficient for CD4-CD8- thymocytes to differentiate into the CD4+CD8+ stage of T cell development. Our data provide evidence for a novel p53 mediated checkpoint in early thymocyte development that regulates the transition of CD4-CD8- into CD4+CD8+ thymocytes.


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