Department of Genetics, University of Seville, Sevilla, Spain.
Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Sevilla, Spain.
PLoS Genet. 2020 May 11;16(5):e1008787. doi: 10.1371/journal.pgen.1008787. eCollection 2020 May.
During repair of DNA double-strand breaks, resection of DNA ends influences how these lesions will be repaired. If resection is activated, the break will be channeled through homologous recombination; if not, it will be simply ligated using the non-homologous end-joining machinery. Regulation of resection relies greatly on modulating CtIP, which can be done by modifying: i) its interaction partners, ii) its post-translational modifications, or iii) its cellular levels, by regulating transcription, splicing and/or protein stability/degradation. Here, we have analyzed the role of ALC1, a chromatin remodeler previously described as an integral part of the DNA damage response, in resection. Strikingly, we found that ALC1 affects resection independently of chromatin remodeling activity or its ability to bind damaged chromatin. In fact, it cooperates with the RNA-helicase eIF4A1 to help stabilize the most abundant splicing form of CtIP mRNA. This function relies on the presence of a specific RNA sequence in the 5' UTR of CtIP. Therefore, we describe an additional layer of regulation of CtIP-at the level of mRNA stability through ALC1 and eIF4A1.
在 DNA 双链断裂的修复过程中，DNA 末端的切除会影响这些损伤的修复方式。如果激活了切除，断裂将通过同源重组进行修复；如果没有，它将通过非同源末端连接机制简单地连接。切除的调节在很大程度上依赖于 CtIP 的调节，这可以通过修饰：i）其相互作用伙伴，ii）其翻译后修饰，或 iii）通过调节转录、剪接和/或蛋白稳定性/降解来调节其细胞水平。在这里，我们分析了先前被描述为 DNA 损伤反应的组成部分的染色质重塑因子 ALC1 在切除中的作用。令人惊讶的是，我们发现 ALC1 独立于染色质重塑活性或其结合受损染色质的能力影响切除。事实上，它与 RNA 解旋酶 eIF4A1 合作，帮助稳定 CtIP mRNA 中最丰富的剪接形式。该功能依赖于 CtIP 5'UTR 中存在特定的 RNA 序列。因此，我们通过 ALC1 和 eIF4A1 描述了 CtIP 稳定性的另一个调节层次。
