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Swamy M, Siegers GM, Fiala GJ, Molnar E, Dopfer EP, Fisch P, Schraven B, Schamel WWA. Stoichiometry and intracellular fate of TRIM-containing TCR complexes. Cell Commun Signal 2010; 8:5. [PMID: 20298603 PMCID: PMC2848047 DOI: 10.1186/1478-811x-8-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Accepted: 03/18/2010] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Studying the stoichiometry and intracellular trafficking of the T cell antigen receptor (TCR) is pivotal in understanding its mechanisms of activation. The alphabetaTCR includes the antigen-binding TCRalphabeta heterodimer as well as the signal transducing CD3epsilongamma, CD3epsilondelta and zeta2 subunits. Although the TCR-interacting molecule (TRIM) is also part of the alphabetaTCR complex, it has not been included in most reports so far. RESULTS We used the native antibody-based mobility shift (NAMOS) assay in a first dimension (1D) blue native (BN)-PAGE and a 2D BN-/BN-PAGE to demonstrate that the stoichiometry of the digitonin-solublized TRIM-containing alphabetaTCR is TCRalphabetaCD3epsilon2gammadeltazeta2TRIM2. Smaller alphabetaTCR complexes possess a TCRalphabeta CD3epsilon2gammadeltazeta2 stoichiometry. Complexes of these sizes were detected in T cell lines as well as in primary human and mouse T cells. Stimulating the alphabetaTCR with anti-CD3 antibodies, we demonstrate by confocal laser scanning microscopy that CD3epsilon colocalizes with zeta and both are degraded upon prolonged stimulation, possibly within the lysosomal compartment. In contrast, a substantial fraction of TRIM does not colocalize with zeta. Furthermore, TRIM neither moves to lysosomes nor is degraded. Immunoprecipitation studies and BN-PAGE indicate that TRIM also associates with the gammadeltaTCR. CONCLUSIONS Small alphabetaTCR complexes have a TCRalphabeta CD3epsilon2gammadeltazeta2 stoichiometry; whereas those associated with one TRIM dimer are TCRalphabeta CD3epsilon2gammadeltazeta2TRIM2. TRIM is differentially processed compared to CD3 and zeta subunits after T cell activation and is not degraded. The gammadeltaTCR also associates with TRIM.
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Affiliation(s)
- Mahima Swamy
- Department of Molecular Immunology, Max Planck-Institute of Immunobiology and Institute for Biology III, Albert Ludwigs University Freiburg, Stübeweg 51, 79108 Freiburg, Germany
| | - Gabrielle M Siegers
- Department of Molecular Immunology, Max Planck-Institute of Immunobiology and Institute for Biology III, Albert Ludwigs University Freiburg, Stübeweg 51, 79108 Freiburg, Germany
- Cell Therapy Program, Princess Margaret Hospital/Ontario Cancer Institute, 610 University Ave., Toronto, Ontario, M5G 2M9, Canada
| | - Gina J Fiala
- Department of Molecular Immunology, Max Planck-Institute of Immunobiology and Institute for Biology III, Albert Ludwigs University Freiburg, Stübeweg 51, 79108 Freiburg, Germany
- Spemann Graduate School of Biology and Medicine (SGBM), Albert Ludwigs University Freiburg, Albertstraße 19A, 79104 Freiburg, Germany
| | - Eszter Molnar
- Department of Molecular Immunology, Max Planck-Institute of Immunobiology and Institute for Biology III, Albert Ludwigs University Freiburg, Stübeweg 51, 79108 Freiburg, Germany
| | - Elaine P Dopfer
- Department of Molecular Immunology, Max Planck-Institute of Immunobiology and Institute for Biology III, Albert Ludwigs University Freiburg, Stübeweg 51, 79108 Freiburg, Germany
| | - Paul Fisch
- Department of Pathology, University of Freiburg Medical Center, 79110 Freiburg, Germany
| | - Burkhart Schraven
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke-Universität Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany
| | - Wolfgang WA Schamel
- Department of Molecular Immunology, Max Planck-Institute of Immunobiology and Institute for Biology III, Albert Ludwigs University Freiburg, Stübeweg 51, 79108 Freiburg, Germany
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Kölsch U, Arndt B, Reinhold D, Lindquist JA, Jüling N, Kliche S, Pfeffer K, Bruyns E, Schraven B, Simeoni L. Normal T-cell development and immune functions in TRIM-deficient mice. Mol Cell Biol 2006; 26:3639-48. [PMID: 16612002 PMCID: PMC1447406 DOI: 10.1128/mcb.26.9.3639-3648.2006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The transmembrane adaptor molecule TRIM is strongly expressed within thymus and in peripheral CD4(+) T cells. Previous studies suggested that TRIM is an integral component of the T-cell receptor (TCR)/CD3 complex and might be involved in regulating TCR cycling. To elucidate the in vivo function of TRIM, we generated TRIM-deficient mice by homologous recombination. TRIM(-/-) mice develop normally and are healthy and fertile. However, the animals show a mild reduction in body weight that appears to be due to a decrease in the size and/or cellularity of many organs. The morphology and anatomy of nonlymphoid as well as primary and secondary lymphoid organs is normal. The frequency of thymocyte and peripheral T-cell subsets does not differ from control littermates. In addition, a detailed analysis of lymphocyte development revealed that TRIM is not required for either positive or negative selection. Although TRIM(-/-) CD4(+) T cells showed an augmented phosphorylation of the serine/threonine kinase Akt, the in vitro characterization of peripheral T cells indicated that proliferation, survival, activation-induced cell death, migration, adhesion, TCR internalization and recycling, TCR-mediated calcium fluxes, tyrosine phosphorylation, and mitogen-activated protein family kinase activation are not affected in the absence of TRIM. Similarly, the in vivo immune response to T-dependent and T-independent antigens as well as the clinical course of experimental autoimmune encephalomyelitis, a complex Th1-mediated autoimmune model, is comparable to that of wild-type animals. Collectively, these results demonstrate that TRIM is dispensable for T-cell development and peripheral immune functions. The lack of an evident phenotype could indicate that TRIM shares redundant functions with other transmembrane adaptors involved in regulating the immune response.
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Affiliation(s)
- Uwe Kölsch
- Institute of Immunology, Otto von Guericke University, Leipziger Str. 44, 39120 Magdeburg, Germany
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Abstract
Transmembrane adapter proteins (TRAPs) represent a relatively new and unique group of signalling molecules in hematopoetic cells. They differ from other signalling proteins as they lack any enzymatic or transcriptional activity, instead they possesses multiple tyrosine-based signalling motifs (TBSMs). Triggering of immunoreceptors induces tyrosine phosphorylation of these motifs by members of the Src-, Syk- or Tec-family of protein tyrosine kinases thus enabling the TRAPs to recruit cytosolic adapter and/or effector molecules via their SH2-domains into close proximity to the immunoreceptors, a position from which they can coordinate and modulate signal transduction pathways important for lymphocyte function.
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Affiliation(s)
- Stefanie Kliche
- Institute of Immunology, Otto-von Guericke-University, Leipziger Strasse 44, 39120 Magdeburg, Germany
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Abstract
Transmembrane adapter proteins (TRAPs) are a relatively new and growing family of proteins that include linker for activation of T cells (LAT), phosphoprotein associated with glycosphingolipid-enriched micro domains (PAG)/C-terminal Src kinase (Csk) binding protein (Cbp), SHP2-interacting transmembrane adapter protein (SIT), T cell receptor interacting molecule (TRIM), and the recently identified non-T cell activation linker (NTAL) and pp30. TRAPs share several common structural features, but more importantly they possess multiple sites of tyrosine phosphorylation, by which they act as scaffolds for recruiting cytosolic adapter and/or effector proteins. The membrane association of TRAPs places them near to the immunoreceptors, a position from which they coordinate and modulate the signals they receive to produce an appropriate cellular response.
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