Identification of the main barriers to Ku accumulation in chromatin.
Identification of the main barriers to Ku accumulation in chromatin.
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识别染色质中 Ku 积累的主要障碍。
DOI：
10.1101/2024.01.03.574002
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发表时间：
2024
期刊：
影响因子：
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通讯作者：
Britton,Sébastien
中科院分区：
文献类型：
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作者：
Bossaert,Madeleine;Moreno,Andrew;Peixoto,Antonio;Pillaire,Marie-Jeanne;Chanut,Pauline;Frit,Philippe;Calsou,Patrick;Loparo,JosephJohn;Britton,Sébastien
非同源末端连接途径对DNA双链断裂的修复是通过Ku与DNA末端结合而启动的。体外将多个Ku蛋白负载到线形DNA上。然而，在细胞中，Ku的负载量仅限于每个∼末端的DNA1-2分子。执行这一限制的机制目前尚不清楚。在这里，我们表明，DNA依赖的蛋白激酶催化亚单位(DNA-PKcs)，而不是其蛋白激酶活性，是必需的，以防止过量的Ku进入染色质。Ku的积累进一步受到两种机制的限制：一种是依赖于脱氧核糖核酸/FbxL12的过程，它在整个细胞周期中主动地移除负载的Ku分子；另一种是依赖于CtIP/ATM的机制，它运行在S期。最后，我们证明了Ku负载的错误调节导致DNA末端附近的转录受损。总之，我们的数据揭示了防止Ku入侵染色质和干扰其他DNA交易的多种机制。
Repair of DNA double-strand breaks by the non-homologous end-joining pathway is initiated by the binding of Ku to DNA ends. Multiple Ku proteins load onto linear DNAsin vitro. However, in cells, Ku loading is limited to ∼1–2 molecules per DNA end. The mechanisms enforcing this limit are currently unclear. Here, we show that the catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs), but not its protein kinase activity, is required to prevent excessive Ku entry into chromatin. Ku accumulation is further restricted by two mechanisms: a neddylation/FBXL12-dependent process that actively removes loaded Ku molecules throughout the cell cycle and a CtIP/ATM-dependent mechanism that operates in S phase. Finally, we demonstrate that the misregulation of Ku loading leads to impaired transcription in the vicinity of DNA ends. Together, our data shed light on the multiple mechanisms operating to prevent Ku from invading chromatin and interfering with other DNA transactions.