Expression and selection of productively rearranged TCR beta VDJ genes are sequentially regulated by CD3 signaling in the development of NK1.1(+) alpha beta T cells.
The generation of thymic NK1.1(+)alpha beta T (NKT) cells involves positive selection of cells enriched for V(alpha)14/V(beta)8 TCR by CD1d MHC class I molecules. However, it has not been determined whether positive selection is preceded by pre-TCR-dependent beta selection. Here we studied NKT cell development in CD3 signaling-deficient mice (CD3 zeta/eta(-/-) and/or p56(lck-/-)) and TCR alpha-deficient mice. In contrast to wild-type mice, NK1.1(+) thymocytes in CD3 signaling-deficient mice are approximately 10-fold reduced in number, do not exhibit V(alpha)14-J(alpha)281 rearrangements and fail to express alpha beta TCR at the cell surface. However, they exhibit TCR beta VDJ rearrangements and pre-T alpha mRNA, suggesting that they contain pre-NKT cells. Strikingly, pre-NKT cells of CD3 zeta/Lck double-deficient mice fail to express TCR beta mRNA and protein. Whereas in wild-type NKT cells TCR beta VDJ junctions are selected for productive V(beta)8 and against productive V(beta)5 rearrangements, V(beta)8 and V(beta)5 rearrangements are non-selected in pre-NKT cells of CD3 signaling-deficient mice. Thus, pre-NKT cell development in CD3 signaling-deficient mice is blocked after rearrangement of TCR beta VDJ genes but before expression of TCR beta proteins. Most NKT cells of TCR alpha-deficient mice exhibit cell surface gamma delta TCR. In contrast to pre-NKT cells of CD3 signaling-deficient mice, approximately 25% of NKT cells of TCR alpha-deficient mice exhibit intracellular TCR beta polypeptide chains. Moreover, both V(beta)8 and V(beta)5 families are selected for in-frame VDJ joints in the TCR beta(+) NKT cell subset of TCR alpha-deficient mice. The data suggest that CD3 signals regulate initial TCR beta VDJ gene expression prior to beta selection in developing pre-NKT cells.
Baur
N
N
Max-Planck-Institut für Immunbiologie, Stübeweg 51, 79108 Freiburg, Germany.
Nerz
G
G
Nil
A
A
Eichmann
K
K
D000818:Animals; D005434:Flow Cytometry; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor; D018960:Hyaluronan Receptors / Q000378:metabolism; D007694:Killer Cells, Natural / Q000378:metabolism*; D051379:Mice; D020297:Mice, Congenic; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D012322:RNA Precursors / Q000378:metabolism; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000096:biosynthesis / Q000172:deficiency / Q000502:physiology*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics* / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000378:metabolism*
D018960:Hyaluronan Receptors; D012322:RNA Precursors; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta