WRN helicase and mismatch repair complexes independently and synergistically disrupt cruciform DNA structures.
WRN helicase and mismatch repair complexes independently and synergistically disrupt cruciform DNA structures.
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DOI：
10.15252/embj.2022111998
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发表时间：
2023-02-01
期刊：
影响因子：
--
通讯作者：
中科院分区：
文献类型：
--
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Werner综合征解旋酶，WRN，是治疗微卫星不稳定性(MSI)癌症的一个有前途的靶点。长期的MSI导致TA核苷酸重复序列的扩张，形成十字形DNA结构，从而在WRN下调时导致DNA断裂和细胞死亡。在这里，我们使用生化分析来证明WRN解旋酶可以有效地和直接地展开十字形结构，从而阻止它们被SLX1-SLX4结构特异性内切酶切割。TA重复序列特别容易形成十字形结构，这解释了为什么在WRN下调时，这些DNA序列在MSI细胞中优先被破坏。我们进一步证明，错配修复复合体MutSα(Msh2-MsH6)、MutSβ(Msh2-MsH3)和MutLα(MLH1-PMS2)的活性类似地降低了DNA十字架的水平，尽管机制与WRN所采用的不同。当WRN和MutLα在体外十字形加工中表现出更高的相加效应时，表明WRN和MMR蛋白可能是协同作用的。我们的数据解释了WRN和MMR缺陷如何导致带有扩展TA重复序列的MSI细胞的基因组不稳定，并为最近发现的合成致死相互作用在精确癌症治疗中的应用提供了机制基础。生化分析确定了在微卫星不稳定的癌症中，由于Werner综合征解旋酶和MMR的丢失而导致合成致命性的分子基础。
The Werner Syndrome helicase, WRN, is a promising therapeutic target in cancers with microsatellite instability (MSI). Long‐term MSI leads to the expansion of TA nucleotide repeats proposed to form cruciform DNA structures, which in turn cause DNA breaks and cell lethality upon WRN downregulation. Here we employed biochemical assays to show that WRN helicase can efficiently and directly unfold cruciform structures, thereby preventing their cleavage by the SLX1‐SLX4 structure‐specific endonuclease. TA repeats are particularly prone to form cruciform structures, explaining why these DNA sequences are preferentially broken in MSI cells upon WRN downregulation. We further demonstrate that the activity of the DNA mismatch repair (MMR) complexes MutSα (MSH2‐MSH6), MutSβ (MSH2‐MSH3), and MutLα (MLH1‐PMS2) similarly decreases the level of DNA cruciforms, although the mechanism is different from that employed by WRN. When combined, WRN and MutLα exhibited higher than additive effects in in vitro cruciform processing, suggesting that WRN and the MMR proteins may cooperate. Our data explain how WRN and MMR defects cause genome instability in MSI cells with expanded TA repeats, and provide a mechanistic basis for their recently discovered synthetic‐lethal interaction with promising applications in precision cancer therapy. Biochemical assays define the molecular basis of synthetic lethality caused by loss of both Werner Syndrome helicase and MMR in cancers with microsatellite instability.
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DOI：
10.1016/j.cub.2021.02.001
发表时间：
2021-03-22
期刊：
Current biology : CB
影响因子：
--
作者：
Fishel R
通讯作者：
Fishel R
影响因子：
29.4
作者：
Boland CR;Goel A
通讯作者：
Goel A
影响因子：
16.6
作者：
Datta A;Biswas K;Sommers JA;Thompson H;Awate S;Nicolae CM;Thakar T;Moldovan GL;Shoemaker RH;Sharan SK;Brosh RM Jr
通讯作者：
Brosh RM Jr
影响因子：
64.5
作者：
Fekairi S;Scaglione S;Chahwan C;Taylor ER;Tissier A;Coulon S;Dong MQ;Ruse C;Yates JR 3rd;Russell P;Fuchs RP;McGowan CH;Gaillard PHL
通讯作者：
Gaillard PHL
影响因子：
3.7
作者：
Kitano K
通讯作者：
Kitano K