Suppression of Tousled-like kinase activity after DNA damage or replication block requires ATM, NBS1 and Chk1
Suppression of Tousled-like kinase activity after DNA damage or replication block requires ATM, NBS1 and Chk1
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DOI：
10.1038/sj.onc.1206691
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发表时间：
2003-09-04
期刊：
影响因子：
8
通讯作者：
Khanna, K
中科院分区：
文献类型：
--
作者：
Krause, DR;Jonnalagadda, JC;Khanna, K
人类凌乱样激酶1和2 （TLK）已被证明在细胞周期的S期具有活性。DNA损伤和复制抑制剂可迅速抑制TLK活性。在这里，我们报道了在DNA双链断裂（DSBs）诱导后导致TLK活性短暂抑制的信号转导途径依赖于功能性失调性毛细血管扩张突变激酶（ATM）的存在。有趣的是，我们发现在低剂量紫外线照射或阿菲霉素诱导的复制阻断后，TLK活性的快速抑制也是依赖于atm的。在UVC和复制阻断后触发TLK活性atm依赖性下调的信号的性质尚不清楚，但它并不完全是由于DNA中的dsb。我们还证明，TLK的抑制依赖于一种功能性奈梅根断裂综合征蛋白（NBS1）的存在。ATM依赖性的NBS1磷酸化是抑制TLK活性所必需的，这表明NBS1在ATM/TLK通路中作为接头或支架发挥作用。ATM不直接磷酸化TLK来调节其活性，但Chk1可以在体外磷酸化TLK1 gst融合蛋白。通过使用Chk1 sirna，我们发现Chk1对于抑制复制阻断后的TLK活性至关重要，而ATR、Chk2和BRCA1对于抑制TLK是必不可少的。总的来说，我们认为ATM激活并不仅仅与dsb相关，并且ATM参与启动响应复制阻断和紫外线诱导的DNA损伤的信号通路。
The human Tousled-like kinases 1 and 2 (TLK) have been shown to be active during S phase of the cell cycle. TLK activity is rapidly suppressed by DNA damage and by inhibitors of replication. Here we report that the signal transduction pathway, which leads to transient suppression of TLK activity after the induction of double-strand breaks (DSBs) in the DNA, is dependent on the presence of a functional ataxia-telangiectasia-mutated kinase (ATM). Interestingly, we have discovered that rapid suppression of TLK activity after low doses of ultraviolet (UV) irradiation or aphidicolin-induced replication block is also ATM-dependent. The nature of the signal that triggers ATM-dependent downregulation of TLK activity after UVC and replication block remains unknown, but it is not due exclusively to DSBs in the DNA. We also demonstrate that TLK suppression is dependent on the presence of a functional Nijmegan Breakage Syndrome protein (NBS1). ATM-dependent phosphorylation of NBS1 is required for the suppression of TLK activity, indicating a role for NBS1 as an adaptor or scaffold in the ATM/TLK pathway. ATM does not phosphorylate TLK directly to regulate its activity, but Chk1 does phosphorylate TLK1 GST-fusion proteins in vitro. Using Chk1 siRNAs, we show that Chk1 is essential for the suppression of TLK activity after replication block, but that ATR, Chk2 and BRCA1 are dispensable for TLK suppression. Overall, we propose that ATM activation is not linked solely to DSBs and that ATM participates in initiating signaling pathways in response to replication block and UV-induced DNA damage.