Jakubek Patrycja, Rajić Jovana, Kuczyńska Monika, Suliborska Klaudia, Heldt Mateusz, Dziedziul Karol, Vidaković Melita, Namieśnik Jacek, Bartoszek Agnieszka
Faculty of Chemistry, Gdańsk University of Technology, 80-233 Gdańsk, Poland.
Laboratory of Mitochondrial Biology and Metabolism, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 02-093 Warsaw, Poland.
Antioxidants (Basel). 2023 Mar 20;12(3):754. doi: 10.3390/antiox12030754.
The role of catechins in the epigenetic regulation of gene expression has been widely studied; however, if and how this phenomenon relates to the redox properties of these polyphenols remains unknown. Our earlier study demonstrated that exposure of the human colon adenocarcinoma HT29 cell line to these antioxidants affects the expression of redox-related genes. In particular, treatment with (-)-epigallocatechin (EGC) downregulated transcription of gene encoding sulfiredoxin-1 (SRXN1), the peroxidase involved in the protection of cells against hydrogen peroxide-induced oxidative stress. The aim of this study was to investigate whether the observed downregulation was accompanied by changes in the DNA methylation level of its promoter and, if so, whether it was correlated with the redox properties of catechins. The impact on DNA methylation profile in HT29 cells treated with different concentrations of five catechins, varying in chemical structures and standard reduction potentials as well as susceptibility to oxidation, was monitored by a methylation-sensitive high-resolution melting technique employing the promoter region as a model target. We demonstrated that catechins, indeed, are able to modulate DNA methylation of the SRXN1 gene in a redox-related manner. The nonlinear method in the statistical analysis made it possible to fish out two parameters (charge transfer in oxidation process and time of electron transfer ), whose strong interactions correlated with observed modulation of DNA methylation by catechins. Based on these findings, we present a proof-of-concept that DNA methylation, which limits expression and thus restricts the multidirectional antioxidant action of SRXN1, may represent a mechanism protecting cells against reductive stress caused by particularly fast-reacting reductants such as EGC and (-)-epicatechin gallate (ECG) in our study.
儿茶素在基因表达表观遗传调控中的作用已得到广泛研究；然而，这种现象是否以及如何与这些多酚的氧化还原特性相关仍不清楚。我们早期的研究表明，将人结肠腺癌HT29细胞系暴露于这些抗氧化剂会影响氧化还原相关基因的表达。特别是，用（-）-表没食子儿茶素（EGC）处理会下调编码硫氧还蛋白-1（SRXN1）的基因转录，硫氧还蛋白-1是一种过氧化物酶，参与保护细胞免受过氧化氢诱导的氧化应激。本研究的目的是调查观察到的下调是否伴随着其启动子DNA甲基化水平的变化，如果是，是否与儿茶素的氧化还原特性相关。通过采用启动子区域作为模型靶点的甲基化敏感高分辨率熔解技术，监测了用不同浓度的五种儿茶素处理HT29细胞对DNA甲基化谱的影响，这五种儿茶素在化学结构、标准还原电位以及氧化敏感性方面各不相同。我们证明，儿茶素确实能够以氧化还原相关的方式调节SRXN1基因的DNA甲基化。统计分析中的非线性方法使得能够找出两个参数（氧化过程中的电荷转移和电子转移时间），它们之间的强相互作用与观察到的儿茶素对DNA甲基化的调节相关。基于这些发现，我们提出了一个概念验证，即DNA甲基化限制了SRXN基因的表达，从而限制了其多向抗氧化作用，这可能代表了一种保护细胞免受我们研究中特别快速反应的还原剂如EGC和（-）-表儿茶素没食子酸酯（ECG）引起的还原应激的机制。
