Cross-talk between Chk1 and Chk2 in double-mutant thymocytes
Cross-talk between Chk1 and Chk2 in double-mutant thymocytes
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DOI：
10.1073/pnas.0611584104
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发表时间：
2007-03-06
影响因子：
11.1
通讯作者：
Mak, Tak W.
中科院分区：
文献类型：
--
作者：
Zaugg, Kathrin;Su, Yu-Wen;Mak, Tak W.
Chk1是一种检查点激酶，是哺乳动物细胞分裂的重要调节因子。由于小鼠Chk1的零突变是胚胎致死的，我们使用Cre-loxP系统和Lck启动子来产生条件突变小鼠，其中Chk1仅在T谱系中被删除。在缺乏Chk1的情况下，由于DN2和DN3阶段凋亡的增加，CD4(-)CD8（-）双阴性（DN）胸腺细胞向CD4(+)CD8（+）双阳性（DP）细胞的转变被阻断。引人注目的是，Chk1的缺失激活了这些胸腺细胞中的检查点激酶Chk2以及肿瘤抑制因子p53。然而，Chk1缺失引起的发育缺陷并不能通过p53失活来挽救。值得注意的是，尽管Chk1缺失在增殖组织中是高度致命的，但我们成功地使用体内方法产生了Chk1/Chk2双敲除T细胞。对这些T细胞的分析揭示了Chk1和Chk2功能之间有趣的相互作用，这种相互作用部分地挽救了双突变细胞的凋亡。因此，Chk1对增殖细胞的存活至关重要，并与Chk2检查点激酶通路相互作用。这些因素对靶向Chk1作为抗癌治疗具有重要意义。
Chk1 is a checkpoint kinase and an important regulator of mammalian cell division. Because null mutation of Chk1 in mice is embryonic lethal, we used the Cre-loxP system and the Lck promoter to generate conditional mutant mice in which Chk1 was deleted only in the T lineage. In the absence of Chk1, the transition of CD4(-)CD8(-) double-negative (DN) thymocytes to CD4(+)CD8(+) double-positive (DP) cells was blocked due to an increase in apoptosis at the DN2 and DN3 stages. Strikingly, loss of Chk1 activated the checkpoint kinase Chk2 as well as the tumor suppressor p53 in these thymocytes. However, the developmental defects caused by Chk1 deletion were not rescued by p53 inactivation. Significantly, even though Chk1 deletion is highly lethal in proliferating tissues, we succeeded in using in vivo methods to generate Chk1/Chk2 double-knockout T cells. Analysis of these T cells revealed an interesting interaction between Chk1 and Chk2 functions that partially rescued the apoptosis of the double-mutant cells. Thus, Chk1 is both critical for the survival of proliferating cells and engages in cross-talk with the Chk2 checkpoint kinase pathway. These factors have implications for the targeting of Chk1 as an anticancer therapy.