Department of Environmental Health and Center for Environmental Genetics.
Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267.
Toxicol Sci. 2020 Dec 1;178(2):325-337. doi: 10.1093/toxsci/kfaa153.
Congenital heart disease (CHD), the leading birth defect worldwide, has a largely unknown etiology, likely to result from complex interactions between genetic and environmental factors during heart development, at a time when the heart adapts to diverse physiological and pathophysiological conditions. Crucial among these is the regulation of cardiomyocyte development and postnatal maturation, governed by dynamic changes in DNA methylation. Previous work from our laboratory has shown that exposure to the environmental toxicant tetrachlorodibenzo-p-dioxin (TCDD) disrupts several molecular networks responsible for heart development and function. To test the hypothesis that the disruption caused by TCDD in the heart results from changes in DNA methylation and gene expression patterns of cardiomyocytes, we established a stable mouse embryonic stem cell line expressing a puromycin resistance selectable marker under control of the cardiomyocyte-specific Nkx2-5 promoter. Differentiation of these cells in the presence of puromycin induces the expression of a large suite of cardiomyocyte-specific markers. To assess the consequences of TCDD treatment on gene expression and DNA methylation in these cardiomyocytes, we subjected them to transcriptome and methylome analyses in the presence of TCDD. Unlike control cardiomyocytes maintained in vehicle, the TCDD-treated cardiomyocytes showed extensive gene expression changes, with a significant correlation between differential RNA expression and DNA methylation in 111 genes, many of which are key elements of pathways that regulate cardiovascular development and function. Our findings provide an important clue toward the elucidation of the complex interactions between genetic and epigenetic mechanisms after developmental TCDD exposure that may contribute to CHD.
先天性心脏病（CHD）是全球领先的出生缺陷，其病因很大程度上未知，可能是心脏发育过程中遗传和环境因素之间复杂相互作用的结果，此时心脏适应多种生理和病理生理条件。其中关键的是心肌细胞发育和出生后成熟的调节，由 DNA 甲基化的动态变化控制。我们实验室的先前工作表明，暴露于环境毒物四氯二苯并对二恶英（TCDD）会破坏负责心脏发育和功能的几个分子网络。为了测试 TCDD 在心脏中引起的破坏是否来自于心肌细胞中 DNA 甲基化和基因表达模式的变化，我们建立了一种稳定的表达 puromycin 抗性选择标记的小鼠胚胎干细胞系，该标记受心肌细胞特异性 Nkx2-5 启动子的控制。在 puromycin 的存在下分化这些细胞会诱导一系列心肌细胞特异性标记物的表达。为了评估 TCDD 处理对这些心肌细胞中基因表达和 DNA 甲基化的影响，我们在存在 TCDD 的情况下对它们进行了转录组和甲基组分析。与在载体中维持的对照心肌细胞不同，TCDD 处理的心肌细胞表现出广泛的基因表达变化，在 111 个基因中，差异 RNA 表达与 DNA 甲基化之间存在显著相关性，其中许多基因是调节心血管发育和功能的途径的关键要素。我们的发现为阐明发育性 TCDD 暴露后遗传和表观遗传机制之间的复杂相互作用提供了重要线索，这些相互作用可能导致 CHD。
