Cui Xiaojuan, Xu Liumeiyang, Tian Nan, Peng Jianjun
College of Life Sciences and Health, Hunan University of Science and Technology, Xiangtan 411201, China.
Int J Mol Sci. 2025 Apr 1;26(7):3280. doi: 10.3390/ijms26073280.
DNA methylation is a common epigenetic modification of DNA levels in the genome of eukaryotic cells, and an aberrant elevation of DNA methylation in gene promoter regions can inhibit gene expression. DNA methyltransferases (DNMTs) are involved in genomic DNA methylation, divided into maintenance DNA methyltransferases and de novo methylases, which are expressed to different degrees in the testis and ovaries. 5-aza-2'-deoxycytidine (5-aza-dC) is a cytidine analog with a strong methylation inhibition. In this experiment, medaka fish fries were treated with 5-aza-dC at 0 μg/L, 50 μg/L, and 100 μg/L. It was found that 100 g/L concentration of 5-aza-dC inhibited both body length and body weight of the adult fish, while 50 g/L concentration had no significant difference. In addition, paraffin section observation and gonad index statistics showed that after 100 g/L concentration of 5-aza-dC treatment, the gonad index of female fish increased significantly, but the gonad index of male fish had no significant difference. And the development of sperms and ovaries was normal without significant difference. Finally, we found that 5-aza-dC not only significantly decreased the transcription levels of and , but also significantly increased the expression levels of female-related genes such as , and , and significantly decreased the expression levels of male-related genes such as , and . The DNA methylation patterns of and genes were altered. This work provides more references for understanding the mechanism of DNA methylation affecting sex determination in fish.
DNA甲基化是真核细胞基因组中DNA水平常见的表观遗传修饰，基因启动子区域DNA甲基化异常升高会抑制基因表达。DNA甲基转移酶（DNMTs）参与基因组DNA甲基化，分为维持性DNA甲基转移酶和从头甲基化酶，它们在睾丸和卵巢中的表达程度不同。5-氮杂-2'-脱氧胞苷（5-aza-dC）是一种具有强烈甲基化抑制作用的胞苷类似物。在本实验中，用0μg/L、50μg/L和100μg/L的5-aza-dC处理青鳉鱼苗。发现100μg/L浓度的5-aza-dC抑制成年鱼的体长和体重，而50μg/L浓度则无显著差异。此外，石蜡切片观察和性腺指数统计表明，100μg/L浓度的5-aza-dC处理后，雌鱼的性腺指数显著增加，但雄鱼的性腺指数无显著差异。精子和卵巢的发育正常，无显著差异。最后，我们发现5-aza-dC不仅显著降低了 和 的转录水平，还显著增加了 、 和 等雌性相关基因的表达水平，并显著降低了 、 和 等雄性相关基因的表达水平。 和 基因的DNA甲基化模式发生了改变。这项工作为理解DNA甲基化影响鱼类性别决定的机制提供了更多参考。
