National Food Institute, Technical University of Denmark, Denmark; Department for Biotechnology and Biomedicine, Technical University of Denmark, Denmark.
Department of Health Technology, Technical University of Denmark, Denmark.
Chemosphere. 2021 Dec;284:131225. doi: 10.1016/j.chemosphere.2021.131225. Epub 2021 Jun 18.
Conazole fungicides such as epoxiconazole are mostly used on cereals of crops to inhibit fungal growth through direct inhibition of sterol 14α-demethylase (CYP51A1). However, this enzyme is highly conserved and in humans it is part of the steroid hormone biosynthesis pathway. Endocrine disrupting effects of epoxiconazole have been shown in rodents and have been substantiated by in vitro data, however, the underlying molecular mechanisms are not clear. We took advantage of a human stem cell based in vitro model for developmental toxicity to study the molecular effects of epoxiconazole. This model is based on 3D cultures of embryoid bodies and differentiation into cardiomyocytes, which mimics the early stages of embryonic development. We have previously shown that epoxiconazole impairs differentiation of these embryoid bodies and therefore has the potential to affect human embryonic development. We employed global transcriptome analysis using RNA sequencing and found that the steroid biosynthesis pathway including CYP51A1, the human sterol 14α-demethylase, was highly deregulated by epoxiconazole in our model. We confirmed that most genes of the steroid biosynthesis pathway were upregulated, including CYP51A1, suggesting a compensatory mechanism at the gene expression level. Our data suggest that epoxiconazole acts mainly by decreasing cholesterol biosynthesis in the cells. We conclude that epoxiconazole bears the potential to harm human embryonic development through inhibition of the steroid biosynthesis pathway. As this may be a common feature of compounds that target sterol 14α-demethylase, we add evidence to the assumption that conazole fungicides may be human developmental toxicants.
唑类杀菌剂，如环氧康唑，主要用于谷物作物，通过直接抑制固醇 14α-脱甲基酶（CYP51A1）来抑制真菌生长。然而，这种酶高度保守，在人类中它是甾体激素生物合成途径的一部分。环氧康唑对啮齿动物具有内分泌干扰作用，并得到体外数据的证实，然而，其潜在的分子机制尚不清楚。我们利用基于人类干细胞的体外发育毒性模型来研究环氧康唑的分子效应。该模型基于胚状体的 3D 培养和向心肌细胞分化，模拟胚胎发育的早期阶段。我们之前已经表明，环氧康唑会损害这些胚状体的分化，因此有可能影响人类胚胎发育。我们采用 RNA 测序进行全转录组分析，发现环氧康唑在我们的模型中高度调控了类固醇生物合成途径，包括 CYP51A1，即人类固醇 14α-脱甲基酶。我们证实，类固醇生物合成途径的大多数基因都被上调，包括 CYP51A1，表明在基因表达水平上存在代偿机制。我们的数据表明，环氧康唑主要通过降低细胞内胆固醇的生物合成来发挥作用。我们得出结论，环氧康唑通过抑制类固醇生物合成途径有损害人类胚胎发育的潜力。由于这可能是靶向固醇 14α-脱甲基酶的化合物的共同特征，我们为唑类杀菌剂可能是人类发育毒物的假设提供了证据。
