Kim Hana, Bakshi Arundhati, Kim Joomyeong
Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America.
PLoS One. 2015 Apr 27;10(4):e0126966. doi: 10.1371/journal.pone.0126966. eCollection 2015.
Variable DNA methylation in promoter regions has been implicated in altering transcriptional regulation. The current study analyzed the evolutionary origin and DNA methylation pattern of one of the promoters of Aebp2. According to the results, the first promoter of Aebp2 has been derived from retrotransposons independently in the primate and rodent lineages. DNA methylation analyses revealed that this promoter is unmethylated in sperm, methylated in mature oocytes, and partially methylated at embryonic day 10.5 (78.3%) and 14.5 (58.3%). This promoter also shows variable levels of DNA methylation among adult organs, ranging from the highest in spleen (80%) to the lowest in tail (50%). The results from the F1 hybrid of interspecific crossing further indicated that both alleles are equally methylated without any allele bias, also supported by its biallelic expression. Therefore, the partial methylation observed among somatic tissues is an outcome of the genome-wide resetting of DNA methylation during the implantation stage, but not of the inherited allelic methylation pattern preset during gametogenesis. Taken together, mammalian Aebp2 has adopted retrotransposons as its promoter, which displays partial DNA methylation pattern of allelic- or non-allelic origin during the different stages of development.
启动子区域的可变DNA甲基化与转录调控的改变有关。本研究分析了Aebp2一个启动子的进化起源和DNA甲基化模式。结果显示，Aebp2的第一个启动子在灵长类和啮齿类谱系中独立起源于逆转座子。DNA甲基化分析表明，该启动子在精子中未甲基化，在成熟卵母细胞中甲基化，在胚胎第10.5天（78.3%）和14.5天（58.3%）时部分甲基化。该启动子在成年器官中的DNA甲基化水平也存在差异，从脾脏中最高（约80%）到尾巴中最低（约50%）。种间杂交F1代的结果进一步表明，两个等位基因的甲基化程度相同，没有任何等位基因偏差，双等位基因表达也支持这一点。因此，在体细胞组织中观察到的部分甲基化是植入期DNA甲基化全基因组重设的结果，而不是配子发生过程中预设的遗传等位基因甲基化模式的结果。综上所述，哺乳动物Aebp2采用逆转座子作为其启动子，在发育的不同阶段表现出等位基因或非等位基因起源的部分DNA甲基化模式。
