T cell factor 1 is a gatekeeper for T-cell specification in response to Notch signaling. Mus musculus

Although transcriptional programs associated with T-cell specification and commitment have been described, the functional hierarchy and the roles of key regulators in structuring/ orchestrating these programs remain unclear. Activation of Notch signaling in uncommitted precursors by the thymic stroma initiates the T-cell differentiation program. One regulator first induced in these precursors is the DNA binding protein Tcf-1, a T-cell specific mediator of Wnt signaling. Yet the specific contribution of Tcf-1 to early T-cell development and the signals inducing it in these cells remain unclear. Here we assign functional significance to Tcf-1 as a gatekeeper of T-cell fate. We show that Tcf-1 is directly activated by Notch signals. Tcf-1 is required at the earliest phase of Tcell determination for progression beyond the early thymic progenitor (ETP) stage. The global expression profile of Tcf-1 deficient progenitors indicates that basic processes of DNA metabolism are downregulated in its absence and the blocked T-cell progenitors become abortive and die by apoptosis. Our data thus add an important functional relationship to the roadmap of T-cell development. We used microarrays to detail the global programme of gene expression of mouse ETP thymocyte after Ikaros inactivation with dominant negative of Ik at different stage. Overall design: 6 samples (mouse ETP thymocytes from wt, and Tcf1 inactivation) are analyzed Mouse Microarray Expression platforms, Affymetrix Mouse 430 2.0,

尽管与T细胞特化及定型相关的转录调控程序已被阐明，但构建或协调此类程序的功能层级与关键调控因子的作用仍未明确。胸腺基质对未定型前体细胞的Notch信号通路激活，可启动T细胞分化程序。在这些前体细胞中首先被诱导的调控因子之一是DNA结合蛋白Tcf-1（Tcf-1），它是Wnt信号通路的T细胞特异性介导因子。然而，Tcf-1对早期T细胞发育的具体贡献，以及在这些细胞中诱导其表达的信号通路仍未明确。本研究明确了Tcf-1作为T细胞命运的关键守门因子。我们证实Tcf-1可被Notch信号直接激活。在T细胞定型的最早阶段，Tcf-1是细胞突破早期胸腺祖细胞（ETP）阶段以继续发育所必需的。Tcf-1缺陷型祖细胞的全局基因表达谱显示，在缺失Tcf-1的情况下，DNA代谢的基础过程被下调，而受阻的T细胞祖细胞会出现发育停滞并通过细胞凋亡发生死亡。因此，本研究的数据为T细胞发育的调控路线图补充了重要的功能关联信息。我们采用基因芯片技术，对经Ik显性负突变体介导Ikaros失活的不同发育阶段小鼠ETP胸腺细胞的全局基因表达程序进行了详细解析。实验整体设计：共分析6份样本（分别来自野生型（wt）小鼠与Tcf1失活小鼠的ETP胸腺细胞）。实验所用的小鼠基因芯片表达平台为Affymetrix Mouse 430 2.0。