Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, School of Public Health, Guizhou Medical University, Guiyang 550025, Guizhou, China.
Guiyang Centers for Diseases Control and Prevention, Guiyang 550001, Guizhou, China.
Bone. 2019 Jun;123:196-203. doi: 10.1016/j.bone.2019.03.016. Epub 2019 Mar 16.
Chronic exposure to combined fluoride (F) and arsenic (As) continues to be a major public health problem worldwide, attracting the attention of an increasing number of researchers. While bone is the main target organ of syndrome of endemic arsenic poisoning and fluorosis (SEAF), the specific mechanism and targeted intervention remains uncertain. The first question in this study sought to determine the interaction of F and As on the Wnt signaling pathway and its role in osteogenic differentiation in the SEAF population. As can be seen from the data, with the increase in exposure to F, the content of Wnt signaling inhibitor Dickkopf-related protein 1 (DKK1) gradually decreased, but the expression of glycogen synthase kinase-3β (GSK3β), β-catenin and the osteogenic differentiation indicators pro-collagen I alpha 1 (COL1A1) and bone alkaline phosphatase (BALP) were increased. Next, we grouped the SEAF population according to urinary As and found that As can upregulate the GSK3β, β-catenin level and the bone formation bio-marker BALP in serum. But the experiments did not detect any evidence that As can change the content of DKK1 in serum. To better understand the combined effects of F and As on the Wnt signaling pathway, we performed further interaction analysis. These results suggest that the interaction of F and As can inhibit the GSK3β, β-catenin, COL1A1 and BALP. And DKK1 is mainly manifested by the independent effect of F. To further study the role of DKK1 and GSK3β in fluoride-arsenic pollution combined with osteogenic differentiation, we attempted to silence the DKK1 and GSK3β gene in hFOB 1.19 cells. The results show that F, As alone and in combination exposure can up-regulate GSK catenin transcription and protein expression levels and down-regulate DKK1, and COL1A1 and ALP are significantly increased, after silenced the DKK1. The same results did not appear after silenced the GSK3β. F and As alone and in combination exposure did not reverse the inhibition of GSK3β and β-catenin by GSK3β silencing, and COL1A1 and ALP are significantly decreased. The results indicate that silencing GSK3β instead of DKK1 can inhibit osteogenic differentiation caused by co-exposure to fluoride and arsenic. This study can provide a scientific basis for further understanding the causes of bone formation caused by F and As and the improvement of targeted intervention strategies.
慢性氟砷联合暴露仍然是全球范围内一个主要的公共卫生问题，引起了越来越多研究人员的关注。虽然骨骼是地方性砷中毒和氟中毒综合征（SEAF）的主要靶器官，但具体机制和靶向干预仍不确定。本研究的首要问题是确定 F 和 As 对 Wnt 信号通路的相互作用及其在 SEAF 人群成骨分化中的作用。从数据可以看出，随着 F 暴露的增加，Wnt 信号抑制剂 Dickkopf 相关蛋白 1（DKK1）的含量逐渐降低，但糖原合酶激酶-3β（GSK3β）、β-连环蛋白和骨形成标志物Ⅰ型前胶原α1（COL1A1）和骨碱性磷酸酶（BALP）的表达增加。接下来，我们根据尿砷将 SEAF 人群进行分组，发现砷可以上调血清中 GSK3β、β-连环蛋白水平和骨形成生物标志物 BALP。但实验并未检测到任何证据表明砷可以改变血清中 DKK1 的含量。为了更好地了解 F 和 As 对 Wnt 信号通路的联合作用，我们进行了进一步的相互作用分析。这些结果表明，F 和 As 的相互作用可以抑制 GSK3β、β-连环蛋白、COL1A1 和 BALP。而 DKK1 主要表现为 F 的独立作用。为了进一步研究 DKK1 和 GSK3β 在氟砷污染联合成骨分化中的作用，我们试图在 hFOB 1.19 细胞中沉默 DKK1 和 GSK3β 基因。结果表明，F、As 单独和联合暴露均可上调 GSK catenin 转录和蛋白表达水平，下调 DKK1，COL1A1 和 ALP 显著增加，沉默 DKK1 后。沉默 GSK3β 后并未出现相同的结果。F、As 单独和联合暴露并不能逆转 GSK3β 沉默对 GSK3β 和 β-连环蛋白的抑制作用，COL1A1 和 ALP 显著降低。结果表明，沉默 GSK3β 而不是 DKK1 可以抑制氟砷联合暴露引起的成骨分化。本研究可为进一步了解 F 和 As 引起的骨形成原因及改善靶向干预策略提供科学依据。
