Wu Chao, Deng Chaofan, Zhang Jia-Xin, Pan Wei, Yang Liuyan, Pan Ke, Tan Qiao-Guo, Yue Tongtao, Miao Ai-Jun
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu Province 210023, China; Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong Province 518060, China.
Institute of Coastal Environmental Pollution Control, Key Laboratory of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao, Shandong Province 266100, China.
J Hazard Mater. 2024 Mar 15;466:133569. doi: 10.1016/j.jhazmat.2024.133569. Epub 2024 Jan 20.
The simultaneous presence of nanoparticles (NPs) and heavy metals in the environment may affect their mutual biological uptake. Although previous studies showed that NPs could alter the cellular uptake of heavy metals by their adsorption of heavy metals, whether they could affect metal uptake without the need for adsorption is unknown. This study examined the effects of silica (SiO) NPs on the uptake of Cd ion by the protozoan Tetrahymena thermophila. We found that, even with negligible levels of adsorption, SiO NPs at concentrations of 3 to 100 mg/L inhibited Cd uptake. This inhibitory effect decreased as the ambient Cd concentration increased from 1 to 100 μg/L, suggesting the involvement of at least two transporters with different affinities for Cd. The transporters were subsequently identified by the specific protein inhibitors amiloride and tariquidar as NCX and ABCB1, which are responsible for the uptake of Cd at low and high Cd levels, respectively. RT-qPCR and molecular dynamics simulation further showed that the inhibitory effects of SiO NPs were attributable to the down-regulated expression of the genes Ncx and Abcb1, steric hindrance of Cd uptake by NCX and ABCB1, and the shrinkage of the central channel pore of the transporters in the presence of SiO NPs. SiO NPs more strongly inhibited Cd transport by NCX than by ABCB1, due to the higher binding affinity of SiO NPs with NCX. Overall, our study sheds new light on a previously overlooked influence of NPs on metal uptake and the responsible mechanism.
环境中纳米颗粒（NPs）与重金属同时存在可能会影响它们的相互生物吸收。尽管先前的研究表明，NPs可通过吸附重金属来改变重金属的细胞摄取，但它们是否能在无需吸附的情况下影响金属摄取尚不清楚。本研究考察了二氧化硅（SiO）纳米颗粒对嗜热四膜虫摄取镉离子的影响。我们发现，即使吸附水平可忽略不计，浓度为3至100mg/L的SiO纳米颗粒也会抑制镉的摄取。随着环境镉浓度从1μg/L增加到100μg/L，这种抑制作用减弱，这表明至少有两种对镉具有不同亲和力的转运蛋白参与其中。随后，通过特异性蛋白抑制剂氨氯吡脒和他林洛尔将转运蛋白鉴定为NCX和ABCB1，它们分别在低镉水平和高镉水平下负责镉的摄取。RT-qPCR和分子动力学模拟进一步表明，SiO纳米颗粒的抑制作用归因于Ncx和Abcb1基因表达下调、NCX和ABCB1对镉摄取的空间位阻以及在存在SiO纳米颗粒的情况下转运蛋白中央通道孔的收缩。由于SiO纳米颗粒与NCX的结合亲和力更高，因此SiO纳米颗粒对NCX介导的镉转运的抑制作用比对ABCB1的抑制作用更强。总体而言，我们的研究揭示了NPs对金属摄取的影响及相关机制，这一影响此前被忽视。
