Arsenic suppresses GDF1 expression via ROS-dependent downregulation of specificity protein 1
Arsenic suppresses GDF1 expression via ROS-dependent downregulation of specificity protein 1
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DOI：
10.1016/j.envpol.2020.116302
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发表时间：
2021-02-15
影响因子：
8.9
通讯作者：
Lu, Cailing
中科院分区：
文献类型：
--
作者：
Gao, Xiaobo;Zhang, Chen;Lu, Cailing
无机砷是一种环境污染物，具有不良的健康后果。我们以前的研究表明，砷通过下调Dvr1/GDF1的表达而导致斑马鱼胚胎心脏的异常发育，而叶酸可以保护这些作用。然而，砷抑制Dvr1/GDF1表达的机制尚不清楚。在这里，我们证明了特异性蛋白1(Sp1)作为GDF1的转录激活剂。砷处理使SPL在mRNA和蛋白水平均下调，并下调其下游靶基因GDF1和SIRT1。染色质免疫沉淀分析表明，亚砷酸盐使Sp1在GDF1或SIRT1启动子上的占有率显著降低。进一步的研究表明，Sp1的过表达抑制了砷诱导的GDF1和SIRT1的减少，而Sp1的过表达则起到了相反的作用。我们发现氧化接头p66shc的表达与SIRT1的表达呈负相关，并且SIRT1与p66shc启动子的结合被亚砷酸盐处理后显著减弱。SIRT1过表达使p66shc表达减弱，而GDF1蛋白表达增强，而SIRT1缺失则起相反作用。抗氧化剂N-乙酰半胱氨酸和叶酸均能逆转砷对Sp1、GDF1和SIRT1的抑制作用。此外，野生型p66shc的过表达增强了砷对Sp1、GDF1和SIRT1的抑制，并伴随着细胞内活性氧水平的增加，而显性负向突变体p66shcSer36Ala的过表达和p66shc的缺失都逆转了这些作用。综上所述，我们的结果表明，砷通过依赖ROS下调Sp1/SIRT1轴，与p66shc形成负反馈环来调节氧化应激，从而抑制GDF1的表达。我们的发现揭示了砷毒性的一个新的分子机制，并为叶酸在砷介导的毒性中的保护作用提供了新的见解。(C)2020年由爱思唯尔有限公司出版。
Inorganic arsenic, an environmental contaminant, has adverse health outcomes. Our previous studies showed that arsenic causes abnormal cardiac development in zebrafish embryos by downregulating Dvr1/GDF1 expression and that folic acid protects against these effects. However, the mechanism by which arsenic represses Dvr1/GDF1 expression remains unknown. Herein, we demonstrate that specificity protein 1 (Sp1) acts as a transcriptional activator of GDF1. Arsenic treatment downregulated Spl at both the mRNA and protein level and its downstream targets GDF1 and SIRT1. Chromatin immunoprecipitation analysis showed that the occupancy of Sp1 on the GDF1 or SIRT1 promoter was significantly reduced in response to arsenite. Further investigation showed that Sp1 overexpression inhibited the arsenic-mediated decrease in GDF1 and SIRT1, while Spl knockdown had the opposite effect. We found that expression of the oxidative adaptor p66shc was inversely related to that of SIRT1 and that the binding of SIRT1 to the p66shc promoter was sharply attenuated by arsenite treatment. SIRT1 overexpression attenuated p66shc expression but enhanced GDF1 protein expression, while SIRT1 depletion exerted the opposite effect. Both the antioxidants N-acetylcysteine and folic acid reversed the arsenic-mediated repression of Sp1, GDF1 and SIRT1. Moreover, wild-type p66shc overexpression enhanced the arsenic-mediated repression of Sp1, GDF1 and SIRT1, which was accompanied by an increase in intracellular reactive oxygen species (ROS) levels, while both overexpression of a dominant negative p66shcSer36Ala mutant and deficiency in p66shc reversed these effects. Taken together, our results revealed that arsenic suppresses GDF1 expression via the ROS-dependent downregulation of the Sp1/ SIRT1 axis, which forms a negative feedback loop with p66shc to regulate oxidative stress. Our findings reveal a novel molecular mechanism underlying arsenic toxicity and provide new insight into the protective effect of folic acid in arsenic-mediated toxicity. (C) 2020 Published by Elsevier Ltd.