Department of Bioscience and Biotechnology and Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung 202301, Taiwan.
Graduate Institute of Food Safety and Risk Management, National Taiwan Ocean University, Keelung, 202301, Taiwan.
Ecotoxicol Environ Saf. 2022 Sep 1;242:113902. doi: 10.1016/j.ecoenv.2022.113902. Epub 2022 Jul 19.
Aluminum (Al) is extensively used for making cooking utensils and its presence in the aquatic environment may occur through acid mine drainage and wastewater discharge. Al is known to induce genotoxicity in human cells, rodents, and fish. Nucleotide excision repair (NER) eliminates helix-twisting DNA lesions such as UV-induced dipyrimidine photoproducts. Because our earlier investigation revealed the operation of NER in zebrafish (Danio rerio) embryos, this study explored if inhibition of NER could be a mechanism of Al-induced genotoxicity using zebrafish embryo as a model system. An acute fish embryo toxicity test indicated that Al (as aluminum sulfate) at 2-15 mg/L were nonlethal to zebrafish embryos, yet exposure of embryos at 1 h post fertilization (hpf) to Al at 10-15 mg/L for 71 h significantly repressed their NER capacity monitored by a transcription-based DNA repair assay. Band shift analysis indicated a higher sensitivity of (6-4) photoproduct (6-4PP) than cyclobutane pyrimidine dimer (CPD) detecting activities to Al, reflecting the preferential influence of Al on the detection of strongly distorted DNA lesions. Time-course experiments showed a delayed response of NER to Al as repair machinery was unaffected by Al at 15 mg/L following a 35-h exposure, while Al treatment for the same period obviously inhibited 6-4PP binding activities although the gene expression of damage recognition factors remained active. Inhibition of 6-4PP detection blocked downstream lesion incision/excision detected by a terminal deoxy transferase-mediated end labeling assay. As the disturbance of damage sensing preceded that of the overall repair process, Al exposure was believed to downregulate NER capacity by inhibiting the activities of lesion detection proteins. Our results revealed the ability of Al to enhance its genotoxicity by suppressing NER capacity.
铝（Al）被广泛用于制造炊具，其在水环境中的存在可能是通过酸性矿山排水和废水排放产生的。已知铝会在人类细胞、啮齿动物和鱼类中引起遗传毒性。核苷酸切除修复（NER）可消除 DNA 损伤，如紫外线诱导的嘧啶二聚体光产物引起的螺旋扭曲。由于我们之前的研究揭示了 NER 在斑马鱼（Danio rerio）胚胎中的作用，因此本研究探讨了抑制 NER 是否可以成为铝诱导遗传毒性的机制，使用斑马鱼胚胎作为模型系统。急性鱼类胚胎毒性试验表明，铝（以硫酸铝形式）在 2-15mg/L 时对斑马鱼胚胎无致死作用，但在受精后 1 小时（hpf）将胚胎暴露于 10-15mg/L 的 Al 中 71 小时，会显著抑制其 NER 能力，通过基于转录的 DNA 修复测定进行监测。带迁移分析表明，（6-4）光产物（6-4PP）比环丁烷嘧啶二聚体（CPD）检测活性对铝的敏感性更高，反映了铝对强扭曲 DNA 损伤检测的优先影响。时程实验表明，NER 对铝的反应延迟，因为在 35 小时暴露后，铝对修复机制没有影响，而在相同时间段内，铝处理明显抑制了 6-4PP 结合活性，尽管损伤识别因子的基因表达仍然活跃。6-4PP 检测的抑制阻止了末端脱氧转移酶介导的末端标记测定检测到的下游损伤切口/切除。由于损伤感应的干扰先于整个修复过程，因此铝暴露被认为通过抑制损伤检测蛋白的活性来下调 NER 能力。我们的结果表明，铝通过抑制 NER 能力增强其遗传毒性的能力。
