Essential role of Rap signal in pre-TCR-mediated β-selection checkpoint in αβ T-cell development
Essential role of Rap signal in pre-TCR-mediated β-selection checkpoint in αβ T-cell development
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DOI：
10.1182/blood-2008-06-164517
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发表时间：
2008-12-01
期刊：
影响因子：
20.3
通讯作者：
Minato, Nagahiro
中科院分区：
文献类型：
--
作者：
Kometani, Kohei;Moriyama, Masaki;Minato, Nagahiro
我们证明，lck启动子驱动的转基因SPA-1（一种Rap GTP酶激活蛋白）的条件表达，由于增强的细胞死亡而不影响γ δ T细胞发育，导致在CD 4/CD 8双阴性（DN）阶段α β T细胞发育的严重缺陷。这种效应是DN阶段特有的，因为CD 4启动子驱动的SPA-1表达几乎不影响T细胞发育。Rap 1A 17是一种显性负性Rap突变体，在体外抗CD 3 γ抗体和Notch配体存在下，可干扰Rag 2（-/-）胎儿胸腺细胞产生双阳性（DP）细胞。在DN细胞系中，Rap GTP酶通过自身寡聚化CD 3（CD 8：CD 3嵌合体）的表达而被激活，其取代自主前T细胞受体（TCR）信号，诱导CD 69表达和CD 25下调。相反，C3 G，一种Rap鸟嘌呤核苷酸交换因子，在正常和Rag 2（-/-）DN细胞中的表达显著增强了Notch依赖的DP细胞的产生和扩增，而没有额外的抗CD 3 β抗体，从而绕过了前TCR。通过引入p53（-/-）突变，条件SPA-1转基因小鼠中缺陷的α β T细胞发育完全恢复。这些结果表明，前TCR下游的内源性Rap GTP酶在将前T细胞从p53介导的检查点应答中拯救出来方面发挥重要作用，从而允许Notch介导的扩增和分化。（血。2008; 112：4565-4573）
We demonstrate that lck promoter-driven conditional expression of transgenic SPA-1, a Rap GTPase-activation protein, causes a profound defect of alpha beta T-cell development at the CD4/CD8 double-negative (DN) stage due to enhanced cell death without affecting gamma delta T-cell development. The effect was specific to the DN stage, because CD4 promoter-driven SPA-1 expression hardly affected T-cell development. Rap1A17, a dominant-negative Rap mutant, interfered with the generation of double-positive (DP) cells from Rag2(-/-) fetal thymocytes in vitro in the presence of anti-CD3 epsilon antibody and Notch ligand. Rap GTPases were activated in a DN cell line by the expression of self-oligomerizing CD3 (CD8:CD3 epsilon chimera), which substituted autonomous pre-T-cell receptor (TCR) signal, inducing CD69 expression and CD25 down-regulation. Reciprocally, expression of C3G, a Rap guanine nucleotide exchange factor, in both normal and Rag2(-/-) DN cells markedly enhanced Notch-dependent generation and expansion of DP cells without additional anti-CD3 epsilon antibody, thus bypassing pre-TCR. Defective alpha beta T-cell development in the conditional SPA-1-transgenic mice was restored completely by introducing a p53(-/-) mutation. These results suggest that endogenous Rap GTPases downstream of pre-TCR play an essential role in rescuing pre-T cells from the p53-mediated checkpoint response, thus allowing Notch-mediated expansion and differentiation. (Blood. 2008; 112: 4565-4573)