Zhejiang Provincial Key Laboratory of Medical Genetics, Key Laboratory of Laboratory Medicine, Ministry of Education, China, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China; Department of Laboratory Medicine, Shanghai Tenth People's Hospital of Tongji University, Shanghai 200072, China.
National and Local Joint Engineering Laboratory of Municipal Sewage Resource Utilization Technology, School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China.
Sci Total Environ. 2021 May 20;770:145285. doi: 10.1016/j.scitotenv.2021.145285. Epub 2021 Jan 22.
Chronic exposure of triclosan (TCS) to zebrafish triggers high incidence of fatty liver and hepatitis; however, the underlying molecular mechanisms remain unclear. Herein, we identified miR-30b as a sensitive biomarker to TCS stress, reflecting in that its decreased expression caused metabolic toxicity, abnormal development and behavior, and lipid-metabolism disorder. By microinjecting the inhibitor and mimic experiments, miR-30b was proved to regulate lipid metabolism by its main target gene fto. Over-expression of FTO resulted in fat accumulation, elevation of the TG and TC levels and up-regulation of the PPARγ and CEBPα, as well as decrease of the global mA level in larvae. On the contrary, the knock-down of FTO using MO caused the anti-lipogenic effect, decrease of the TG and T-CHO levels, and abnormal changes of cebpɑ, acsl5, fasn, ppap2c and pparγ etc. Further fortification tests of cycloleucine and betaine evidenced that the toxic effect was strongly dependent on regulation of the mA level. The toxicity effects in the treatments of methylated donors and receptors were consistent with the changes in physiological functions of FTO knockdown and overexpression. The effects of cycloleucine on mA level and lipid metabolism generally consisted with those of FTO, but this was not the case for betaine, reflecting in increased mA level and lipid accumulation in larval liver. Consequently, we posit that TCS exposure caused zebrafish lipid-metabolism disorder by decreasing miR-30b expression to regulate fto-mediated mA methylation level. These findings contribute to our deep understanding of the underlying molecular mechanisms regarding contaminant-originating fatty liver and hepatocellular carcinoma, and also have practical significance in pollution warning and target therapy for related diseases.
三氯生（TCS）慢性暴露于斑马鱼会引发脂肪肝和肝炎的高发病率；然而，其潜在的分子机制尚不清楚。在此，我们将 miR-30b 鉴定为 TCS 应激的敏感生物标志物，其表达下调导致代谢毒性、异常发育和行为以及脂质代谢紊乱。通过微注射抑制剂和模拟实验，证明 miR-30b 通过其主要靶基因 fto 来调节脂质代谢。FTO 的过表达导致脂肪积累、TG 和 TC 水平升高以及 PPARγ 和 CEBPα 的上调，以及幼虫全局 mA 水平的降低。相反，使用 MO 敲低 FTO 会导致抗脂生成作用、TG 和 T-CHO 水平降低以及 cebpɑ、acsl5、fasn、ppap2c 和 pparγ 等异常变化。进一步强化环亮氨酸和甜菜碱的实验证实，毒性作用强烈依赖于 mA 水平的调节。甲基供体和受体处理的毒性作用与 FTO 敲低和过表达的生理功能变化一致。环亮氨酸对 mA 水平和脂质代谢的影响一般与 FTO 的变化一致，但甜菜碱并非如此，反映出幼虫肝中 mA 水平和脂质积累增加。因此，我们假设 TCS 暴露通过降低 miR-30b 的表达来调节 fto 介导的 mA 甲基化水平，导致斑马鱼脂质代谢紊乱。这些发现有助于我们深入了解污染物引起的脂肪肝和肝细胞癌的潜在分子机制，并且在污染预警和相关疾病的靶向治疗方面具有实际意义。
