ROLE OF THE PRE-T CELL RECEPTOR IN LINEAGE COMMITMENT

胸腺中Alphabeta T细胞的发育在第一个检查点由前T细胞受体(TCR)控制，TCR由TCRbeta链与Pre-TCRpha(PTalpha)链共价配对，并与信号转导CD3分子结合。在pTalpha缺陷小鼠中，Alphabeta T细胞谱系的发育严重受损，而Gammadelta T细胞数量增加。然而，基于对Gammadelta T细胞Vbeta重排的分析，有人认为，由于高达70%的重排似乎是在框架内，前TCR在Gammadelta T细胞的TCRbeta选择中发挥了作用。我们用单细胞聚合酶链式反应(PCR)重新分析了来自正常和pTalpha缺陷小鼠的Gammadelta T细胞中的Vbeta重排，发现来自pTalpha-/-的Gammadelta T细胞的Vbeta重排比来自正常小鼠的T细胞进行得更远。此外，我们在后一种细胞中观察到了针对基础重排的选择，但在前一种细胞中没有观察到这种选择。基于这些结果，我们建议研究Pre-TCR和Gammadelta TCR是否会产生不同的信号，从而导致不同的血统承诺。为此，我们将构建PRO-T细胞系以及表达可诱导的TCRbeta、TCRGamma和Delta转基因的小鼠，以便在仅表达其中一种受体的细胞中分析谱系承诺和由不同受体传递的假定的不同信号，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.