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目的 了解燃煤污染型地方性砷中毒患者组蛋白H4第20位赖氨酸一甲基化(H4K20me1)修饰水平与碱基切除修复基因mRNA的转录水平,并分析其与DNA损伤的关系,为深入揭示砷致DNA损伤修复机制提供科学依据.方法 收集贵州省兴仁县交乐村2014年自愿手术治疗的47例燃煤污染型砷中毒患者(一般病变组15例、癌前病变组14例、癌变组18例)及12例对照组的皮肤组织标本、头发样本和外周血样.电感耦合等离子质谱(ICP-MS)法测定发砷含量;免疫组化法检测皮肤组织中组蛋白H4 K20me1修饰水平;实时荧光定量PCR检测外周血聚腺苷酸二磷酸核糖聚合酶-1(PARP1)、N-甲基化嘌呤-DNA-糖基化酶(MPG)、X射线修复交叉互补基因1(XRCC1)基因mRNA转录水平;单细胞凝胶电泳法检测外周血DNA损伤;酶联免疫吸附试验法检测外周血H4K20me1总体修饰水平.结果 与对照组[中位数(第25 ～ 75百分位数):0.15(0.07 ～0.23)μg/L]比较,砷中毒患者发砷含量[0.34(0.17 ～ 0.51)μg/L]明显升高(Z=6.037,P＜0.05);与对照组(0.32±0.13、0.17±0.12)比较,癌变组患者外周血H4K20me1修饰水平(0.62±0.11)、癌前病变组和癌变组患者皮肤组织中H4K20me1修饰水平(0.54±0.20、0.83±0.10)明显增加(P＜0.05);与对照组[0.95 (0.50～1.49)、1.12(0.98～1.48)、0.96(0.67 ～ 1.17)]比较,癌变组PARP1、MPG基因mRNA表达[0.37 (0.30～0.44)、0.38(0.15～0.48)]、癌前病变组和癌变组XRCC1基因mRNA表达[0.48(0.38 ～ 0.89)、0.32(0.20～ 0.55)]明显降低(P＜0.05);与对照组(1.19±0.55、1.27±0.51)比较,一般病变组(6.49±0.98、6.60±1.11)、癌前病变组(11.22±1.40、10.07±1.11)和癌变组(20.38±1.72、27.01±1.78)彗星尾部DNA百分含量(TailDNA％)和彗星尾矩(OTM)明显升高(P＜0.05);砷中毒患者皮肤组织H4K20me1修饰水平、外周血H4K20me1修饰水平、DNA损伤水平(TailDNA％、OTM)与其皮肤病变程度呈正相关关系(r=0.885、0.855、0.806、0.883,P均＜0.05);外周血中H4K20me1修饰水平与DNA损伤水平(TailDNA％、OTM)、皮肤H4K20me1修饰水平均呈正相关关系(r=0.535、0.804、0.754,P均＜0.05),与MPG、XRCC1、PARP1基因mRNA表达水平呈负相关关系(r=-0.563、-0.514、-0.550,P均＜0.05);皮肤H4K20me1修饰水平与DNA损伤水平(TailDNA％、OTM)呈正相关关系(r=0.602、0.875,P均＜0.05),与MPG、XRCC1、PARP1基因mRNA表达水平呈负相关关系(r=-0.492、-0.502、-0.552,P均＜0.05).结论 燃煤污染型砷中毒可能通过影响H4K20me1修饰水平,抑制碱基切除PARP1、MPG、XRCC1基因mRNA的转录表达,致DNA损伤加重,参与砷中毒皮肤病变的发生发展.“,”Objective To investigate the global level of histone 4 lysine 20 monomethylation (H4K20me1) and expression of base excision repair related mRNA in coal-burning-borne endemic arsenism patients and to analyze its relationship with DNA damage,in order to provide a scientific basis in deepening the interpretation of the role of arsenic in inhibiting repair of DNA damage.Methods In 2014,47 hair samples,blood samples and skin tissue samples of the cases in Xingren County Guizhou Province were collected from the voluntary surgical treatment patients with endemic arsenism (15 general pathological change cases,14 precancerous cases and 18 cancerous cases) and 12 controls.The hair arsenic content was tested via the inductively coupled plasma-mass spectrometry method.The expression of histone H4K20me1 in skin tissues was detected via the immunohistochemistry method;quantitative real-time polymerase chain reaction was used to detect the mRNA levels of poly (ADP-ribose) polymerase (PARP1),N-methylation of purine-DNA-glycosylation (MPG) and X-ray repair cross complementary gene 1 (XRCC1);and DNA damage in peripheral blood was detected by single cell gel electrophoresis test,the level of H4K20me1 in peripheral blood cells was detected by using a sandwich enzyme-linked immunosorbent assay.Results Compared with the control group [median (25 ～ 75 percentile):0.15 (0.07-0.23) μg/L],the hair arsenic content in the case group [0.34 (0.17-0.51) μg/L] was significantly increased (Z =6.037,P ＜ 0.05).Compared with the control group (0.32 ± 0.13,0.17 ± 0.12),the modification level of H4K20me1 in peripheral blood with cancerous group (0.62 ± 0.11) was significantly increased,the modification levels of H4K20me1 (0.54 ± 0.20,0.83 ± 0.10) in skin tissues were increased in the precancerous group and cancerous group (P ＜ 0.05).Compared with the control group [0.95 (0.50-1.49),1.12 (0.98-1.48),0.96 (0.67-1.17)],the mRNA expression levels of PARP1 and MPG in cancerous group [0.37 (0.30-0.44),0.38 (0.15-0.48)] were significantly decreased;the mRNA expression levels of XRCC1 [0.48 (0.38-0.89),0.32 (0.20-0.55)] were significantly decreased in the precancerous group and cancerous group (P ＜ 0.05).Compared with the control group (1.19 ± 0.55,1.27 ± 0.51),Tail DNA％ and Tail moment were significantly increased in the general pathological change group (6.49 ± 0.98,6.60 ± 1.11),the precancerous lesion group (11.22 ± 1.40,10.07 ± 1.11),and the cancerous group (20.38 ± 1.72,27.01 ± 1.78,P ＜ 0.05).There was a positive correlation between the degree of skin lesion and modification level of H4K20me1 in peripheral blood and skin tissues and DNA damage levels (TailDNA％,OTM,r =0.885,0.855,0.806,0.883,P ＜ 0.05).There was a positive correlation between modification level of H4K20me1 in peripheral blood and level of DNA damage (TailDNA％,OTM),the level of H4K20me1 protein expression in skin (r =0.535,0.804,0.754,P ＜ 0.05),and a negative correlation with mRNA expression of MPG,XRCC1 and PARP1 (r =-0.563,-0.514,-0.550,P ＜ 0.05).There was a positive correlation between the modification level of H4K20me1 in skin and DNA damage levels (TailDNA％,OTM,r =0.602,0.875,P ＜ 0.05),and a negative correlation with mRNA expression of MPG,XRCC1 and PARP1 (r =-0.492,-0.502,-0.552,P ＜ 0.05).Conclusion The arsenic pollution of coal burning may affect the level of H4K20me1 modification,inhibit mRNA transcriptional expression of PARP1,MPG and XRCC1 genes related with base excision repair,which may lead to increased DNA damage and participate in the occurrence and development of arsenic poisoning skin lesions.