National Reference Laboratory of Veterinary Drug Residues (HZAU) and MAO Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, Hubei 430070, China.
MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Hubei 430070, China.
Toxicology. 2019 Sep 1;425:152246. doi: 10.1016/j.tox.2019.152246. Epub 2019 Jul 29.
T-2 toxin is a secondary metabolite produced by Fusarium species and commonly contaminates food and animal feed. T-2 toxin can induce hepatotoxicity through apoptosis and oxidative stress; however, the underlying mechanism is not clear. Recent studies indicated that RASSF4, a member of the RASSF family, participates in cell apoptosis and some cancers due to its inactivation via DNA hypermethylation. However, its role in T-2 toxin-induced liver toxicity is poorly understood. Therefore, in this study, female Wistar rats were given a single dose of T-2 toxin at 2 mg/kg b.w. and were sacrificed at 1, 3 and 7 days post-exposure. A normal rat liver cell line (BRL) was exposed to different concentrations of T-2 toxin (10, 20, 40 nM) for 4, 8, 12 h, respectively. Histopathological analysis revealed with apoptosis in some liver cells and clear proliferation under T-2 toxin exposure. Expression analysis by immunohistochemical assays, quantitative real-time PCR (qPCR) and western blot demonstrated that T-2 toxin activated PI3K-Akt/Caspase/NF-κB signaling pathways. Additionally, DNA methylation assays revealed that the expression of RASSF4 was silenced by promoter hypermethylation after exposure to T-2 toxin for 1 and 3 days as compared to the control group. Moreover, joint treatment of 5-Aza-2'-deoxycytidine (DAC) (5 μM) and T-2 toxin (40 nM) increased expression of RASSF4 and PI3K-Akt/caspase/NF-κB signaling pathways-related genes, inducing cell apoptosis. These findings for the first time demonstrated that DNA methylation regulated the RASSF4 expression under T-2 toxin, along with the activation of its downstream pathways, resulting in apoptosis.
T-2 毒素是一种由镰刀菌属产生的次级代谢产物，通常污染食物和动物饲料。T-2 毒素可通过细胞凋亡和氧化应激诱导肝毒性；然而，其潜在机制尚不清楚。最近的研究表明，RASSF4 作为 RASSF 家族的一员，由于其 DNA 超甲基化失活，参与细胞凋亡和一些癌症。然而，其在 T-2 毒素诱导的肝毒性中的作用知之甚少。因此，在本研究中，雌性 Wistar 大鼠给予 2mg/kg b.w.的 T-2 毒素单次剂量，并在暴露后 1、3 和 7 天处死。正常大鼠肝细胞系（BRL）分别暴露于不同浓度的 T-2 毒素（10、20、40 nM）4、8、12 h。组织病理学分析显示，T-2 毒素暴露后部分肝细胞发生凋亡，细胞增殖明显。免疫组织化学检测、实时定量 PCR（qPCR）和 Western blot 分析表明，T-2 毒素激活了 PI3K-Akt/Caspase/NF-κB 信号通路。此外，DNA 甲基化分析显示，与对照组相比，T-2 毒素暴露 1 和 3 天后，RASSF4 的表达被启动子超甲基化沉默。此外，联合使用 5-Aza-2'-脱氧胞苷（DAC）（5 μM）和 T-2 毒素（40 nM）可增加 RASSF4 和 PI3K-Akt/caspase/NF-κB 信号通路相关基因的表达，诱导细胞凋亡。这些结果首次表明，T-2 毒素下的 DNA 甲基化调节 RASSF4 的表达，并激活其下游通路，导致细胞凋亡。
