School of Public Health, The key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, China.
Department of Orthopedics, Guizhou Province Orthopedics Hospital, Guiyang, China.
Environ Toxicol. 2021 Sep;36(9):1817-1828. doi: 10.1002/tox.23302. Epub 2021 Jun 3.
Fluoride is a persistent environmental pollutant, and its excessive intake contributes to skeletal and dental fluorosis. The mechanisms underlying fluoride-induced abnormal osteoblast proliferation and activation, which are related to skeletal fluorosis, have not yet been fully clarified. As important epigenetic regulators, microRNAs (miRNAs) participate in bone metabolism. On the basis of our previous miRNA-seq results and bioinformatics analysis, this study investigated the role and specific molecular mechanism of miR-486-3p in fluoride-induced osteoblast proliferation and activation via CyclinD1. Herein, in the fluoride-challenged population, we observed that miR-486-3p expression decreased while CyclinD1 and transforming growth factor (TGF)-β1 increased, and miR-486-3p level correlated negatively with the expression of CyclinD1 and TGF-β1 genes. Further, we verified that sodium fluoride (NaF) decreases miR-486-3p expression in human osteoblasts and overexpression of miR-486-3p reduces fluoride-induced osteoblast proliferation and activation. Meanwhile, we demonstrated that miR-486-3p regulates NaF-induced upregulation of CyclinD1 by directly targeting its 3'-untranslated region (3'-UTR). In addition, we observed that NaF activates the TGF-β1/Smad2/3/CyclinD1 axis and miR-486-3p mediates transcriptional regulation of CyclinD1 by TGF-β1/Smad2/3 signaling pathway via targeting TGF-β1 3'-UTR in vitro. This study, thus, contributes significantly in revealing the mechanism of miR-486-3p-mediated CyclinD1 upregulation in skeletal fluorosis and sheds new light on endemic fluorosis treatment.
氟化物是一种持久性的环境污染物，其摄入过量会导致骨骼和牙齿氟中毒。氟化物诱导的异常成骨细胞增殖和激活的机制与骨骼氟中毒有关，但尚未完全阐明。作为重要的表观遗传调控因子，microRNAs（miRNAs）参与骨代谢。基于我们之前的 miRNA-seq 结果和生物信息学分析，本研究通过 CyclinD1 探讨了 miR-486-3p 在氟化物诱导的成骨细胞增殖和激活中的作用及其特定的分子机制。在此，在氟化物暴露人群中，我们观察到 miR-486-3p 表达降低，而 CyclinD1 和转化生长因子（TGF）-β1 增加，miR-486-3p 水平与 CyclinD1 和 TGF-β1 基因的表达呈负相关。此外，我们验证了氟化钠（NaF）降低人成骨细胞中 miR-486-3p 的表达，并且过表达 miR-486-3p 可减少氟化物诱导的成骨细胞增殖和激活。同时，我们证明 miR-486-3p 通过直接靶向其 3'-非翻译区（3'-UTR）来调节 NaF 诱导的 CyclinD1 上调。此外，我们观察到 NaF 激活 TGF-β1/Smad2/3/CyclinD1 轴，并且 miR-486-3p 通过靶向 TGF-β1 3'-UTR 介导 TGF-β1/Smad2/3 信号通路对 CyclinD1 进行转录调节。因此，本研究揭示了 miR-486-3p 介导的 CyclinD1 在骨骼氟中毒中的上调机制，并为地方性氟中毒的治疗提供了新的思路。
