摘要目的:探究SUMO E3连接酶(zinc finger protein 451，ZNF451)介导非小细胞肺癌A549细胞和宫颈癌HeLa细胞DNA损伤修复的功能及机制。方法:采用γ射线或依托泊苷处理A549细胞和HeLa细胞，CCK-8法检测细胞增殖活力，蛋白免疫印迹法检测蛋白表达量。DR-GFP质粒系统检测DNA损伤修复水平，免疫荧光法检测蛋白的空间定位。结果:依托泊苷抑制了ZNF451的表达并呈剂量及时间依赖性。30、50、80 μmol/L依托泊苷处理，敲低ZNF451后的A549和HeLa细胞增殖活力显著降低(A549： t ＝ 27.62、25.61、5.32, P<0.01；HeLa： t ＝ 30.77、21.28、4.18， P<0.01)。ZNF451在DNA损伤位点处募集并与γ-H2AX存在胞内共定位和内源性的相互作用，且在30、50、80 μmol/L依托泊苷处理的ZNF451敲低细胞中，γ-H2AX的表达水平显著增加(A549： t ＝ 6.12、10.67、4.68， P<0.01；HeLa： t ＝ 7.94、9.81、15.12， P<0.01)。敲低ZNF451的细胞非同源末端连接(NHEJ)修复效率降低( t ＝ 18.60， P<0.05)。在辐射和依托泊苷处理后，ZNF451与P53结合蛋白1(53BP1)和DNA损伤检查点介质1(MDC1)有明显的共定位。 结论:敲低ZNF451抑制A549和HeLa细胞增殖并诱导DNA损伤水平加剧。ZNF451可以募集至DNA损伤位点，通过与DNA损伤修复因子53BP1/MDC1共定位参与NHEJ修复。

abstractsObjective:To investigate the role of SUMO E3 ligase ZNF451 in DNA damage repair and explore the underlying mechanism in non-small cell lung cancer A549 cells and cervical cancer HeLa cells.Methods:A549 cells and HeLa cells were irradiated with γ-ray irradiation or treated with etoposide. Cell proliferation viability was detected by the cell counting kit-8 assay. Protein expression was detected by Western blot assay. DNA damage repair level was detected by DR-GFP plasmid system, and the spatial positioning was detected by immunofluorescence.Results:Etoposide decreased the expression level of ZNF451 in a dose- and time- dependent manner. After treatment with 30, 50, 80 μmol/L etoposide, the cell viability were reduced after the knockdown of ZNF451 in A549 and HeLa cells(A549: t = 27.62, 25.61, 5.32, P<0.01; HeLa: t = 30.77, 21.28, 4.18, P<0.01). Furthermore, ZNF451 was recruited at DNA damage sites. A co-localization and endogenous interaction were found between ZNF451 and γ-H2AX after the treatment of irradiation or etoposide. Moreover, the expression level of γ-H2AX was significantly increased after treatment with 30, 50, 80 μmol/L etoposide(A549: t = 6.12, 10.67, 4.68, P<0.01; HeLa: t = 7.94, 9.81, 15.12, P<0.01)and the repair efficiency of NHEJ was reduced in ZNF451 knockdown cells( t = 18.60, P<0.05). Finally, the immunofluorescence assay showed that ZNF451 was co-localizated with 53BP1 and MDC1 after irradiation or etoposide treatment. Conclusions:Knockdown of ZNF451 inhibits cell proliferation and increases the level of DNA damage in A549 and HeLa cells. ZNF451 was recruited to DNA damage sites after DSBs and participated in NHEJ repair by co-localizing with DNA damage repair factor 53BP1/MDC1.