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The CD3-gammadeltaepsilon and CD3-zeta/eta modules are each essential for allelic exclusion at the T cell receptor beta locus but are both dispensable for the initiation of V to (D)J recombination at the T cell receptor-beta, -gamma, and -delta loci.

Ardouin L, Ismaili J, Malissen B, Malissen M - J. Exp. Med. (1998)

Bottom Line: The pre-T cell receptor (TCR) associates with CD3-transducing subunits and triggers the selective expansion and maturation of T cell precursors expressing a TCR-beta chain.Furthermore, using mutant mice lacking both the CD3-epsilon and CD3-zeta/eta genes, we established that the CD3 gene products are dispensable for the onset of V to (D)J recombination (V, variable; D, diversity; J, joining) at the TCR-beta, TCR-gamma, and TCR-delta loci.Thus, the CD3 components are differentially involved in the sequential events that make the TCR-beta locus first accessible to, and later insulated from, the action of the V(D)J recombinase.

View Article: PubMed Central - PubMed

Affiliation: Centre d'Immunologie Institut National de la Santé et de la Recherche Médicale-Centre National de la Recherche Scientifique de Marseille-Luminy, Case 906, 13288 Marseille Cedex 9, France.

ABSTRACT
The pre-T cell receptor (TCR) associates with CD3-transducing subunits and triggers the selective expansion and maturation of T cell precursors expressing a TCR-beta chain. Recent experiments in pre-Talpha chain-deficient mice have suggested that the pre-TCR may not be required for signaling allelic exclusion at the TCR-beta locus. Using CD3-epsilon- and CD3-zeta/eta-deficient mice harboring a productively rearranged TCR-beta transgene, we showed that the CD3-gammadeltaepsilon and CD3-zeta/eta modules, and by inference the pre-TCR/CD3 complex, are each essential for the establishment of allelic exclusion at the endogenous TCR-beta locus. Furthermore, using mutant mice lacking both the CD3-epsilon and CD3-zeta/eta genes, we established that the CD3 gene products are dispensable for the onset of V to (D)J recombination (V, variable; D, diversity; J, joining) at the TCR-beta, TCR-gamma, and TCR-delta loci. Thus, the CD3 components are differentially involved in the sequential events that make the TCR-beta locus first accessible to, and later insulated from, the action of the V(D)J recombinase.

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Expression of a transgenic TCR-β chain does not inhibit endogenous Vβ to DβJβ  rearrangements in the absence of  CD3-ζ/η polypeptide. The relative levels of TCR-β rearrangements found in CD3-ζ/η+/+  (WT), CD3-ζ/η+/+ TCR-β  (TCRβ), and CD3-ζ/η−/−  TCR-β thymocytes were determined as described in the legend  of Fig. 4.
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Figure 5: Expression of a transgenic TCR-β chain does not inhibit endogenous Vβ to DβJβ rearrangements in the absence of CD3-ζ/η polypeptide. The relative levels of TCR-β rearrangements found in CD3-ζ/η+/+ (WT), CD3-ζ/η+/+ TCR-β (TCRβ), and CD3-ζ/η−/− TCR-β thymocytes were determined as described in the legend of Fig. 4.

Mentions: Disruption of the CD3-ζ/η gene incompletely blocks the DN to DP transition and plausibly corresponds to a leaky mutation of the pre-TCR sensor (see review in reference 31). Accordingly, CD3-ζ/η−/− mice have small thymuses that contain from 2–30-fold less DP cells than wild-type littermates. These DP cells appear to have been generated via TCR-β selection since almost all of them express intracellular TCR-β chains, a situation that contrasts with that observed in pTα−/− mice (20) and is consistent with the complete absence of γ/δ T cells in CD3-ζ/η−/− mice. However, the DP cells found in CD3-ζ/η−/− thymuses can be distinguished from bona fide wild-type DP cells because they have a limited content of rearranged TCR-α gene segments (32), exhibit a reduced sensitivity to dexamethasone-induced apoptosis (15), and part of them still express CD25 (9). The split pattern of phenotypic changes elicited by the pre-TCR in the absence of CD3-ζ/η subunit is likely to reflect the fact that different cellular responses have different activation thresholds (e.g., the strength of stimulation required for the induction of the CD4 and CD8 genes being lower than that required for triggering efficient Vα→ Jα recombination). Along that line, it was interesting to analyze whether the CD3-ζ/η subunit of the pre-TCR was required for the establishment of allelic exclusion at the TCR-β locus. To this end, CD3-ζ/η−/− mice were crossed with the P14 TCR-β transgenic mice and the effect of the β transgene on endogenous β locus determined with the DNA-PCR assay described in the above paragraph. Note that the levels of TCR-β gene rearrangement found in CD3-ζ/η–deficient thymocytes are similar to those found in wild-type littermates (12), and that the introduction of the P14 TCR-β transgene in CD3-ζ/η−/− mice did not lead to any change in thymocyte cellularity and surface phenotype (data not shown). As shown in Fig. 5, the level of Dβ2 to Jβ2 rearrangement was similar in DNA extracted from wild-type (WT), TCR-β wild-type (TCRβ), and TCR-β CD3-ζ/η−/− mice. As previously documented for CD3-ε–deficient mice (see above), allelic exclusion of the endogenous TCR-β locus was severely compromised in the absence of CD3-ζ/η polypeptide (Fig. 5, compare V to DJ rearrangements in lanes TCRβ and TCRβ CD3-ζ/η−/−). Thus, these data suggest that the signals conveyed by the partial pre-TCR/CD3 complexes found in CD3-ζ/η–deficient mice are unable to trigger TCR-β allelic exclusion.


The CD3-gammadeltaepsilon and CD3-zeta/eta modules are each essential for allelic exclusion at the T cell receptor beta locus but are both dispensable for the initiation of V to (D)J recombination at the T cell receptor-beta, -gamma, and -delta loci.

Ardouin L, Ismaili J, Malissen B, Malissen M - J. Exp. Med. (1998)

Expression of a transgenic TCR-β chain does not inhibit endogenous Vβ to DβJβ  rearrangements in the absence of  CD3-ζ/η polypeptide. The relative levels of TCR-β rearrangements found in CD3-ζ/η+/+  (WT), CD3-ζ/η+/+ TCR-β  (TCRβ), and CD3-ζ/η−/−  TCR-β thymocytes were determined as described in the legend  of Fig. 4.
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Related In: Results  -  Collection

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Figure 5: Expression of a transgenic TCR-β chain does not inhibit endogenous Vβ to DβJβ rearrangements in the absence of CD3-ζ/η polypeptide. The relative levels of TCR-β rearrangements found in CD3-ζ/η+/+ (WT), CD3-ζ/η+/+ TCR-β (TCRβ), and CD3-ζ/η−/− TCR-β thymocytes were determined as described in the legend of Fig. 4.
Mentions: Disruption of the CD3-ζ/η gene incompletely blocks the DN to DP transition and plausibly corresponds to a leaky mutation of the pre-TCR sensor (see review in reference 31). Accordingly, CD3-ζ/η−/− mice have small thymuses that contain from 2–30-fold less DP cells than wild-type littermates. These DP cells appear to have been generated via TCR-β selection since almost all of them express intracellular TCR-β chains, a situation that contrasts with that observed in pTα−/− mice (20) and is consistent with the complete absence of γ/δ T cells in CD3-ζ/η−/− mice. However, the DP cells found in CD3-ζ/η−/− thymuses can be distinguished from bona fide wild-type DP cells because they have a limited content of rearranged TCR-α gene segments (32), exhibit a reduced sensitivity to dexamethasone-induced apoptosis (15), and part of them still express CD25 (9). The split pattern of phenotypic changes elicited by the pre-TCR in the absence of CD3-ζ/η subunit is likely to reflect the fact that different cellular responses have different activation thresholds (e.g., the strength of stimulation required for the induction of the CD4 and CD8 genes being lower than that required for triggering efficient Vα→ Jα recombination). Along that line, it was interesting to analyze whether the CD3-ζ/η subunit of the pre-TCR was required for the establishment of allelic exclusion at the TCR-β locus. To this end, CD3-ζ/η−/− mice were crossed with the P14 TCR-β transgenic mice and the effect of the β transgene on endogenous β locus determined with the DNA-PCR assay described in the above paragraph. Note that the levels of TCR-β gene rearrangement found in CD3-ζ/η–deficient thymocytes are similar to those found in wild-type littermates (12), and that the introduction of the P14 TCR-β transgene in CD3-ζ/η−/− mice did not lead to any change in thymocyte cellularity and surface phenotype (data not shown). As shown in Fig. 5, the level of Dβ2 to Jβ2 rearrangement was similar in DNA extracted from wild-type (WT), TCR-β wild-type (TCRβ), and TCR-β CD3-ζ/η−/− mice. As previously documented for CD3-ε–deficient mice (see above), allelic exclusion of the endogenous TCR-β locus was severely compromised in the absence of CD3-ζ/η polypeptide (Fig. 5, compare V to DJ rearrangements in lanes TCRβ and TCRβ CD3-ζ/η−/−). Thus, these data suggest that the signals conveyed by the partial pre-TCR/CD3 complexes found in CD3-ζ/η–deficient mice are unable to trigger TCR-β allelic exclusion.

Bottom Line: The pre-T cell receptor (TCR) associates with CD3-transducing subunits and triggers the selective expansion and maturation of T cell precursors expressing a TCR-beta chain.Furthermore, using mutant mice lacking both the CD3-epsilon and CD3-zeta/eta genes, we established that the CD3 gene products are dispensable for the onset of V to (D)J recombination (V, variable; D, diversity; J, joining) at the TCR-beta, TCR-gamma, and TCR-delta loci.Thus, the CD3 components are differentially involved in the sequential events that make the TCR-beta locus first accessible to, and later insulated from, the action of the V(D)J recombinase.

View Article: PubMed Central - PubMed

Affiliation: Centre d'Immunologie Institut National de la Santé et de la Recherche Médicale-Centre National de la Recherche Scientifique de Marseille-Luminy, Case 906, 13288 Marseille Cedex 9, France.

ABSTRACT
The pre-T cell receptor (TCR) associates with CD3-transducing subunits and triggers the selective expansion and maturation of T cell precursors expressing a TCR-beta chain. Recent experiments in pre-Talpha chain-deficient mice have suggested that the pre-TCR may not be required for signaling allelic exclusion at the TCR-beta locus. Using CD3-epsilon- and CD3-zeta/eta-deficient mice harboring a productively rearranged TCR-beta transgene, we showed that the CD3-gammadeltaepsilon and CD3-zeta/eta modules, and by inference the pre-TCR/CD3 complex, are each essential for the establishment of allelic exclusion at the endogenous TCR-beta locus. Furthermore, using mutant mice lacking both the CD3-epsilon and CD3-zeta/eta genes, we established that the CD3 gene products are dispensable for the onset of V to (D)J recombination (V, variable; D, diversity; J, joining) at the TCR-beta, TCR-gamma, and TCR-delta loci. Thus, the CD3 components are differentially involved in the sequential events that make the TCR-beta locus first accessible to, and later insulated from, the action of the V(D)J recombinase.

Show MeSH
Related in: MedlinePlus