Department of Cytophysiology, Faculty of Biology and Environmental Protection, University of Lodz, 90-236 Lodz, Poland.
Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdansk University of Technology, 80-233 Gdansk, Poland.
Cells. 2021 Dec 3;10(12):3409. doi: 10.3390/cells10123409.
Experiments on root meristem cells exposed to 150 µM cadmium chloride (CdCl) were undertaken to analyse epigenetic changes, mainly with respect to DNA replication stress. Histone modifications examined by means of immunofluorescence labeling included: (1) acetylation of histone H3 on lysine 56 (H3K56Ac), involved in transcription, S phase, and response to DNA damage during DNA biosynthesis; (2) dimethylation of histone H3 on lysine 79 (H3K79Me2), correlated with the replication initiation; (3) phosphorylation of histone H3 on threonine 45 (H3T45Ph), engaged in DNA synthesis and apoptosis. Moreover, immunostaining using specific antibodies against 5-MetC-modified DNA was used to determine the level of DNA methylation. A significant decrease in the level of H3K79Me2, noted in all phases of the CdCl-treated interphase cell nuclei, was found to correspond with: (1) an increase in the mean number of intranuclear foci of H3K56Ac histones (observed mainly in S-phase), (2) a plethora of nuclear and nucleolar labeling patterns (combined with a general decrease in H3T45Ph), and (3) a decrease in DNA methylation. All these changes correlate well with a general viewpoint that DNA modifications and post-translational histone modifications play an important role in gene expression and plant development under cadmium-induced stress conditions.
对暴露于 150µM 氯化镉（CdCl）的根分生组织细胞进行实验，以分析表观遗传变化，主要是针对 DNA 复制应激。通过免疫荧光标记检查的组蛋白修饰包括：（1）赖氨酸 56 上的组蛋白 H3 乙酰化（H3K56Ac），参与转录、S 期以及在 DNA 生物合成过程中对 DNA 损伤的反应；（2）赖氨酸 79 上的组蛋白 H3 二甲基化（H3K79Me2），与复制起始相关；（3）组蛋白 H3 上苏氨酸 45 的磷酸化（H3T45Ph），参与 DNA 合成和细胞凋亡。此外，使用针对 5-甲基胞嘧啶修饰 DNA 的特异性抗体进行免疫染色，以确定 DNA 甲基化水平。在 CdCl 处理的间期细胞核的所有相中，发现 H3K79Me2 水平显著降低，这与以下几点有关：（1）核内 H3K56Ac 组蛋白的平均核内焦点数量增加（主要在 S 期观察到），（2）核内和核仁标记模式的大量出现（与 H3T45Ph 的普遍减少相结合），（3）DNA 甲基化减少。所有这些变化都与一个普遍观点很好地相关，即 DNA 修饰和翻译后组蛋白修饰在镉诱导的应激条件下的基因表达和植物发育中发挥重要作用。
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