Cruciform DNA is a causing factor of genome instability and chromosomal translocation, however, most studies about cruciform DNA in mammalian cells were based on palindromic sequences containing plasmids and reports about endogenous cruciform DNA are rare. In this study we observed the dynamics of endogenous cruciform DNA in mouse growing oocytes using immunofluorescence labeling method. We found cruciform DNA foci exist in transcription active growing oocytes but not in transcription inactive fully grown oocytes and colocalized with Parp1 but not with DNA damage marker γH2A.X. By analyzing the Genotype-Tissue Expression data, we found cruciform DNA-mediated chromosomal translocation in human spermatocytes is associated with the specific DNA transcription in testis. When inhibiting the transcription with α-amanitin in mouse oocytes, we found oocyte cruciform DNA foci decreased significantly. In summary, we observed the endogenous cruciform DNA in growing oocytes and our results showed that the cruciform DNA formation is transcription-dependent.

十字形DNA是基因组不稳定和染色体易位的原因，但是，关于哺乳动物细胞中十字形DNA的大多数研究都是基于包含质粒的回文序列，关于内源十字形DNA的报道很少。在这项研究中，我们观察了使用免疫荧光标记法在小鼠卵母细胞中内源十字形DNA的动力学。我们发现十字形的DNA焦点存在于转录活跃的卵母细胞中，但不存在于转录不活跃的完全卵母细胞中，与Parp1共定位，但与DNA损伤标记γH2A.X不共存。通过分析基因型组织表达数据，我们发现人类精母细胞中十字形DNA介导的染色体易位与睾丸中的特定DNA转录有关。当用α-amanitin抑制小鼠卵母细胞的转录时，我们发现卵母细胞十字形DNA灶明显减少。总之，我们观察到了正在生长的卵母细胞中的内源十字形DNA，我们的结果表明十字形DNA的形成是转录依赖性的。