Fine-tuning of T-cell development by the CD3γ di-leucine-based TCR-sorting motif.
The CD3γ di-leucine-based (diL) receptor-sorting motif plays a central role in TCR down-regulation and in clonal expansion of virus-specific T cells. However, the role of the CD3γ diL motif in T-cell development is not known. In this study, we show that protein kinase C-induced TCR down-regulation is abolished in thymocytes from CD3γLLAA mice with a mutated CD3γ diL motif, and that CD3γLLAA mice have reduced numbers of thymocytes compared with aged-matched wild-type mice. We found that early thymocyte development at the β-selection checkpoint is impaired resulting in reduced numbers of double negative (DN) 4 cells in CD3γLLAA mice. This was not caused by reduced proliferation but most probably by increased down-regulation of the antiapoptotic molecule Bcl-2 causing enhanced apoptosis during the transition from the DN3 to the DN4 stage. In contrast, proliferation of immature CD8 single positive (ISP) thymocytes was increased resulting in normal numbers of ISP in CD3γLLAA mice. Despite the normal numbers of ISP, CD3γLLAA mice had reduced numbers of double positive and SP thymocytes indicating that the CD3γ diL motif also affected later stages of T-cell development. In accordance, we found that positive and negative selection, differentiation toward CD4 and CD8 SP T cells and the development of nonconventional T cells were affected in CD3γLLAA mice. In conclusion, our study identifies an important role of the CD3γ diL motif in T-cell development most probably mediated by its fine-tuning of pre-TCR and TCR expression, down-regulation and signaling.
Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark.
Jens Peter H
JP
Lauritsen
Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark.
Lasse
L
Boding
Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark.
Terkild B
TB
Buus
Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark.
Martin
M
Kongsbak
Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark.
Trine B
TB
Levring
Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark.
Anna K O
AK
Rode
Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark.
Charlotte Menné
CM
Bonefeld
Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark cge@sund.ku.dk.
Carsten
C
Geisler
D000409:Alanine / Q000276:immunology / Q000378:metabolism*; D020816:Amino Acid Motifs; D019943:Amino Acid Substitution; D000818:Animals; D017209:Apoptosis; D017252:CD3 Complex / Q000235:genetics* / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D016827:CD8 Antigens / Q000235:genetics / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D002454:Cell Differentiation; D049109:Cell Proliferation; D002999:Clone Cells; D005786:Gene Expression Regulation; D016130:Immunophenotyping; D007930:Leucine / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction; D060168:Thymocytes / Q000166:cytology / Q000276:immunology*
D017252:CD3 Complex; C452842:CD3 antigen, gamma chain; D016827:CD8 Antigens; D019253:Proto-Oncogene Proteins c-bcl-2; C052617:Bcl2 protein, mouse; D007930:Leucine; D000409:Alanine
T-cell receptor; development; down-regulation; thymocyte