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.

中文翻译：

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miR-486-3p 调节 CyclinD1 并促进氟化物诱导的成骨细胞增殖和活化

氟化物是一种持久性环境污染物，其过量摄入会导致骨骼和牙齿氟中毒。氟诱导的异常成骨细胞增殖和激活与氟骨症相关的机制尚未完全阐明。作为重要的表观遗传调控因子，微小RNA（miRNA）参与骨代谢。在我们之前的miRNA-seq结果和生物信息学分析的基础上，本研究通过CyclinD1研究了miR-486-3p在氟化物诱导的成骨细胞增殖和活化中的作用和具体分子机制。在此，在氟化物挑战的人群中，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，和miR-486-3p水平的表达呈负相关细胞周期蛋白D1和TGF-β1基因。此外，我们证实氟化钠 (NaF) 会降低人成骨细胞中 miR-486-3p 的表达，并且 miR-486-3p 的过表达会降低氟化物诱导的成骨细胞增殖和活化。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，miR-486-3p通过靶向TGF-β1介导TGF-β1/Smad2/3 信号通路介导CyclinD1的转录调控3'-UTR 体外。因此，这项研究有助于揭示 miR-486-3p 介导的CyclinD1上调在氟骨症中的机制，并为地方性氟中毒治疗提供了新的思路。