Environmental Toxicology Graduate Program.
Department of Biological Sciences, Clemson University, Clemson, South Carolina 29634.
Toxicol Sci. 2018 Mar 1;162(1):64-78. doi: 10.1093/toxsci/kfx241.
Chronic arsenic exposure can result in adverse development effects including decreased intellectual function, reduced birth weight, and altered locomotor activity. Previous in vitro studies have shown that arsenic inhibits stem cell differentiation. MicroRNAs (miRNAs) are small noncoding RNAs that regulate multiple cellular processes including embryonic development and cell differentiation. The purpose of this study was to examine whether altered miRNA expression was a mechanism by which arsenic inhibited cellular differentiation. The pluripotent P19 mouse embryonal carcinoma cells were exposed to 0 or 0.5 μM sodium arsenite for 9 days during cell differentiation, and changes in miRNA expression was analyzed using microarrays. We found that the expression of several miRNAs important in cellular differentiation, such as miR-9 and miR-199 were decreased by 1.9- and 1.6-fold, respectively, following arsenic exposure, while miR-92a, miR-291a, and miR-709 were increased by 3-, 3.7-, and 1.6-fold, respectively. The members of the miR-466-669 cluster and its host gene, Scm-like with 4 Mbt domains 2 (Sfmbt2), were significantly induced by arsenic from 1.5- to 4-fold in a time-dependent manner. Multiple miRNA target prediction programs revealed that several neurogenic transcription factors appear to be targets of the cluster. When consensus anti-miRNAs targeting the miR-466-669 cluster were transfected into P19 cells, arsenic-exposed cells were able to more effectively differentiate. The consensus anti-miRNAs appeared to rescue the inhibitory effects of arsenic on cell differentiation due to an increased expression of NeuroD1. Taken together, we conclude that arsenic induces the miR-466-669 cluster, and that this induction acts to inhibit cellular differentiation in part due to a repression of NeuroD1.
慢性砷暴露可导致不良发育影响，包括智力下降、出生体重降低和运动活动改变。先前的体外研究表明，砷抑制干细胞分化。microRNAs (miRNAs) 是调节包括胚胎发育和细胞分化在内的多种细胞过程的小非编码 RNA。本研究旨在研究 miRNA 表达的改变是否是砷抑制细胞分化的机制。将多能 P19 小鼠胚胎癌细胞在细胞分化期间暴露于 0 或 0.5 μM 亚砷酸钠 9 天，并使用微阵列分析 miRNA 表达的变化。我们发现，几种在细胞分化中重要的 miRNA 的表达，如 miR-9 和 miR-199，分别下降了 1.9 倍和 1.6 倍，而 miR-92a、miR-291a 和 miR-709 分别增加了 3 倍、3.7 倍和 1.6 倍。miR-466-669 簇及其宿主基因 Scm-like with 4 Mbt domains 2 (Sfmbt2) 的成员在时间依赖性方式下，砷诱导增加了 1.5-4 倍。多个 miRNA 靶标预测程序表明，几种神经发生转录因子似乎是该簇的靶标。当靶向 miR-466-669 簇的共识抗 miRNA 转染到 P19 细胞中时，暴露于砷的细胞能够更有效地分化。由于 NeuroD1 的表达增加，共识抗 miRNA 似乎挽救了砷对细胞分化的抑制作用。总之，我们得出结论，砷诱导 miR-466-669 簇，这种诱导作用部分通过抑制 NeuroD1 的表达来抑制细胞分化。
