Department of Occupational and Environmental Health, Key Laboratory of Environment and Health, Ministry of Education, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China.
Department of Occupational and Environmental Health, Key Laboratory of Environment and Health, Ministry of Education, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China.
Toxicol Appl Pharmacol. 2018 May 15;347:60-69. doi: 10.1016/j.taap.2018.03.030. Epub 2018 Mar 30.
There has been a great concern about the neurotoxicity of fluoride since it can pass through the blood-brain barrier and accumulate in the brain. It has been suggested that apoptosis plays a vital role in neurotoxicity of fluoride. However, whether p53-mediated apoptotic pathway is involved is still unclear. Our results showed that apoptosis was induced after treatment with 40 and 60 mg/L of NaF for 24 h in human neuroblastoma SH-SY5Y cells. Exposure to 60 mg/L of NaF for 24 h significantly upregulated the levels of p53 and apoptosis-related proteins including PUMA, cytochrome c (cyto c), cleaved caspase-3 and cleaved PARP, whereas downregulated Bcl-2 in SH-SY5Y cells. Meanwhile, fluoride increased p53 nuclear translocation, cyto c release from mitochondria to cytoplasm and mitochondrial translocation of Bax in SH-SY5Y cells. Fluoride-induced increases of apoptotic rates and apoptosis-related protein levels were significantly attenuated by inhibiting p53 transcriptional activity with pifithrin-α. In addition, fluoride inhibited the deacetylase activity of SIRT1 and increased p53 (acetyl K382) level in SH-SY5Y cells. Apoptosis and upregulation of cleaved caspase-3, cleaved PARP and p53 (acetyl K382) induced by fluoride could be ameliorated by SIRT1 overexpression or its activator resveratrol in SH-SY5Y cells. Taken together, our study demonstrates that fluoride induces apoptosis by inhibiting the deacetylase activity of SIRT1 to activate mitochondrial p53 pathway in SH-SY5Y cells, which depends on p53 transcriptional activity. Thus, SIRT1 may be a promising target to protect against neurotoxicity induced by fluoride.
自氟化物可以穿透血脑屏障并在大脑中积累以来，人们一直对其神经毒性感到担忧。有研究表明，细胞凋亡在氟化物的神经毒性中起着至关重要的作用。然而，p53 介导的凋亡途径是否参与其中尚不清楚。我们的研究结果表明，在人神经母细胞瘤 SH-SY5Y 细胞中，用 40 和 60mg/L 的 NaF 处理 24 小时后会诱导细胞凋亡。暴露于 60mg/L 的 NaF 24 小时会显著上调 p53 和凋亡相关蛋白的水平，包括 PUMA、细胞色素 c（cyto c）、裂解 caspase-3 和裂解 PARP，而 Bcl-2 的水平则下调。同时，氟化物增加了 p53 的核转位、细胞色素 c 从线粒体释放到细胞质以及 Bax 的线粒体易位。用 pifithrin-α抑制 p53 转录活性可显著减弱氟化物诱导的细胞凋亡率和凋亡相关蛋白水平的增加。此外，氟化物抑制了 SIRT1 的去乙酰化酶活性，并增加了 SH-SY5Y 细胞中 p53（乙酰化 K382）的水平。在 SH-SY5Y 细胞中，氟化物诱导的细胞凋亡以及裂解 caspase-3、裂解 PARP 和 p53（乙酰化 K382）的上调，可通过 SIRT1 过表达或其激活剂白藜芦醇得到改善。总之，我们的研究表明，氟化物通过抑制 SIRT1 的去乙酰化酶活性来激活线粒体 p53 途径，从而诱导 SH-SY5Y 细胞凋亡，这取决于 p53 的转录活性。因此，SIRT1 可能是预防氟化物诱导的神经毒性的一个有前途的靶点。
