Exposed to ubiquitously perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) has been associated with non-alcoholic fatty liver disease (NAFLD), yet the underlying molecular mechanism remains elusive. The extrapolation of empirical studies correlating per- and polyfluoroalkyl substance (PFAS) exposure with NAFLD occurrence to real-life exposure was hindered by the limited availability of mechanistic data at environmentally relevant concentrations. Herein, a novel pathway mediating hepatocyte lipid accumulation by PFOA and PFOS at human-relevant dose (<10 μM) was identified by integrating CRISPR-Cas9 genome screening, concentration-dependent transcriptional assay in HepG2 cell and epidemiological data mining. 1) At genetic level, nudt7 showed the highest enriched potency among 569 NAFLD-related genes, and the transcription of nudt7 was significantly downregulated by PFOA and PFOS exposure (<7 μM). 2) At molecular pathway, upon exposure to ≤10−4 μM PFOA and PFOS, the downregulation of nudt7 transcriptional expression triggered the reduction of Ace-CoA hydrolase activity. 3) At cellular level, increased lipids were measured in HepG2 cells with PFOA and PFOS (<2 μM). Overall, we identified a novel mechanism mediated by transcriptional downregulation of nudt7 gene in hepatocellular lipid increase treated with PFOA and PFOS, which could potentially explain the NAFLD occurrence associated with exposure to PFASs in humans.

中文翻译：

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PFOA 和 PFOS 引起人肝细胞脂质积累的新分子途径


接触普遍存在的全氟辛酸 (PFOA) 和全氟辛烷磺酸 (PFOS) 与非酒精性脂肪肝 (NAFLD) 相关，但潜在的分子机制仍然难以捉摸。由于环境相关浓度的机械数据有限，将全氟烷基物质和多氟烷基物质 (PFAS) 暴露与 NAFLD 发生相关的实证研究外推到现实生活中的暴露受到阻碍。在此，通过整合 CRISPR-Cas9 基因组筛选、HepG2 细胞浓度依赖性转录测定和流行病学数据挖掘，确定了人类相关剂量 (<10 μM) 的 PFOA 和 PFOS 介导肝细胞脂质积累的新途径。 1）在基因水平上，nudt7在569个NAFLD相关基因中表现出最高的富集效力，并且PFOA和PFOS暴露（<7 μM）显着下调nudt7的转录。 2）在分子途径上，暴露于≤10−4 μM PFOA和PFOS后，nudt7转录表达的下调触发了Ace-CoA水解酶活性的降低。 3) 在细胞水平上，在使用 PFOA 和 PFOS (<2 μM) 的 HepG2 细胞中测量到脂质增加。总体而言，我们发现了一种由 nudt7 基因转录下调介导的 PFOA 和 PFOS 处理肝细胞脂质增加的新机制，这可能解释与人类接触 PFAS 相关的 NAFLD 发生。