ROLE OF THE PRE-T CELL RECEPTOR IN LINEAGE COMMITMENT

胸腺中α -T细胞的发育在第一个检查点由前T细胞受体（TCR）控制，其由tcrβ链与前tcrα (pTalpha)链共价配对组成，与CD3分子的信号转导有关。在α - T细胞缺陷小鼠中，α - T细胞谱系的发育严重受损，而γ - T细胞数量增加。然而，基于对γ - δ T细胞中vβ重排的分析，有人认为，由于高达70%的这种重排似乎在框架中，因此前tcr在γ - δ T细胞的tcrβ选择中起作用。我们用单细胞聚合酶链反应（PCR）重新分析了来自正常和pTalpha缺陷小鼠的γ - T细胞中的vβ重排，发现来自pTalpha-/-的γ - T细胞中的vβ重排比来自正常小鼠的γ - T细胞中的vβ重排进行得更远。此外，我们观察到在后者而不是前者细胞中存在针对框内重排的选择。在这些结果的基础上，我们建议研究是否一方面是前TCR，另一方面是γ - δ TCR产生不同的信号，导致不同的谱系承诺。为此，我们将构建表达可诱导的TCRbeta、TCRgamma和delta转基因的前t细胞系和小鼠，以便在仅表达一种或另一种受体的细胞中分析谱系承诺和不同受体传递的假定不同信号，以及信号转导的后果。

The development of alphabeta T cells in the thymus is controlled at the first checkpoint by the pre-T cell receptor (TCR), that consists of the TCRbeta chain covalently paired with the pre- TCRalpha (pTalpha) chain, in association with the signal transducing CD3 molecules. In pTalpha deficient mice development of the alphabeta lineage of T cells is severely compromised, while gammadelta T cells are numerically elevated. Nevertheless, on the basis of the analysis of Vbeta rearrangement in gammadelta T cells it has been argued that, since up to 70 percent of such rearrangements appear to be in frame, the pre-TCR has a role in TCRbeta selection of gammadelta T cells. We have re-analyzed Vbeta rearrangement in gammadelta T cells from normal and pTalpha-deficient mice by single cell polymerase chain reaction (PCR), and found that Vbeta-rearrangement proceeds further in gammadelta T cells derived from pTalpha-/- than those derived from normal mice. Furthermore, we observed selection against inframe rearrangement in the latter but not the former cells. On the basis of these results we propose to study whether the pre- TCR on the one hand and the gammadelta TCR on the other hand generate distinct signals that result in different lineage committments. To this end we will construct pro-Tcell lines as well as mice that express inducible TCRbeta TCRgamma and delta transgenes, so that lineage commitment and putative distinct signals transmitted by the different receptors, as well as the consequences of signal transduction, can be analyzed in cells that have just expressed one or the other receptor.