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Updated: Aug 8, 2026
Characterization of Thymic Settling Progenitors in the Mouse Embryo Using In Vivo and In Vitro Assays
Published on: June 9, 2015
T cell development in mice lacking all T cell receptor zeta family members (Zeta, eta, and FcepsilonRIgamma)
1Division of Hematologic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892. shoresew@helix.nih.gov
Abstract:
The zeta family includes zeta, eta, and FcepsilonRIgamma (Fcgamma). Dimers of the zeta family proteins function as signal transducing subunits of the T cell antigen receptor (TCR), the pre-TCR, and a subset of Fc receptors. In mice lacking zeta/eta chains, T cell development is impaired, yet low numbers of CD4+ and CD8+ T cells develop. This finding suggests either that pre-TCR and TCR complexes lacking a zeta family dimer can promote T cell maturation, or that in the absence of zeta/eta, Fcgamma serves as a subunit in TCR complexes. To elucidate the role of zeta family dimers in T cell development, we generated mice lacking expression of all of these proteins and compared their phenotype to mice lacking only zeta/eta or Fcgamma. The data reveal that surface complexes that are expressed in the absence of zeta family dimers are capable of transducing signals required for alpha/beta-T cell development. Strikingly, T cells generated in both zeta/eta-/- and zeta/eta-/--Fcgamma-/- mice exhibit a memory phenotype and elaborate interferon gamma. Finally, examination of different T cell populations reveals that zeta/eta and Fcgamma have distinct expression patterns that correlate with their thymus dependency. A possible function for the differential expression of zeta family proteins may be to impart distinctive signaling properties to TCR complexes expressed on specific T cell populations.
Insights
T cell development relies on zeta family proteins like zeta, eta, and Fcgamma. Even without these, T cells mature, suggesting alternative signaling pathways are involved in T cell immunity.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- The zeta (ζ) family, including zeta, eta, and FcεRIγ (Fcγ), comprises crucial signaling subunits for T cell receptors (TCRs) and Fc receptors.
- Deficiencies in zeta/eta chains impair T cell development, yet some T cells still mature, indicating potential alternative signaling mechanisms or roles for Fcγ in TCR complexes.
Purpose of the Study:
- To investigate the precise roles of zeta family dimers in T cell development.
- To compare the T cell development and function in mice lacking zeta/eta, Fcγ, or all zeta family proteins.
Main Methods:
- Generation of genetically modified mice lacking specific zeta family protein expression (zeta/eta-/-, Fcγ-/-, and zeta/eta-/--Fcγ-/-).
- Phenotypic analysis of T cell populations in these mouse models.
- Assessment of T cell signaling and function, including interferon-gamma production and memory phenotype.
Main Results:
- T cell development (specifically alpha/beta T cells) can proceed even in the absence of zeta family dimers, indicating functional surface complexes exist.
- T cells developed in mice lacking zeta/eta or all zeta family proteins exhibit a memory phenotype and produce interferon-gamma.
- Distinct expression patterns of zeta/eta and Fcγ correlate with thymus dependency, suggesting specialized roles in different T cell populations.
Conclusions:
- Zeta family dimers are not absolutely essential for T cell maturation, as alternative signaling pathways can support T cell development.
- The differential expression of zeta family proteins may fine-tune the signaling capabilities of TCR complexes in specific T cell subsets.
- Fcγ may play a compensatory or distinct role in TCR signaling in the absence of zeta/eta.
