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，前T细胞受体（TCR）由与前TCR α（pT α）链共价配对的TCR β链组成，与信号转导CD 3分子缔合。 在ρ Τ α缺陷小鼠中，T细胞的α谱系的发育严重受损，而γ δ T细胞在数值上升高。 然而，基于对γ δ T细胞中V β重排的分析，有人认为，由于高达70%的这种重排似乎是符合读码框的，因此前TCR在γ δ T细胞的TCR β选择中起作用。 我们通过单细胞聚合酶链反应（PCR）重新分析了正常和pTa缺陷小鼠的γ δ T细胞中的V β重排，发现与正常小鼠相比，来自pTa-/-的γ δ T细胞中的V β重排进一步进行。 此外，我们观察到选择对框内重排在后者，而不是前者的细胞。 在这些结果的基础上，我们提出研究一方面的前TCR和另一方面的γ δ TCR是否产生导致不同谱系承诺的不同信号。 为此，我们将构建前T细胞系以及表达诱导型TCR β、TCR γ和δ转基因的小鼠，以便在刚刚表达一种或另一种受体的细胞中分析谱系定型和由不同受体传递的推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.