Dynamic methylation pattern of the methyltransferase1o (Dnmt1o) 5′‐flanking region during mouse oogenesis and spermatogenesis |
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Authors: | Yeoung‐Gyu Ko Jisoo Yun Hyoung Joon Park Satoshi Tanaka Kunio Shiota Jae‐Hyeon Cho |
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Affiliation: | 1. Animal Genetic Resources Station, National Institute of Animal Science, RDA, Namwon, Korea;2. Department of Molecular Science and Technology, Ajou University, Suwon, Korea;3. Institute of Life Science, College of Veterinary Medicine, Gyeongsang National University, Jinju, Korea;4. Department of Animal Resource Sciences/Veterinary Medical Sciences, The University of Tokyo, Tokyo, Japan |
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Abstract: | DNA methyltransferase1o (Dnmt1o), which is specific to oocyte and preimplantation embryo, plays a role in maintaining DNA methylation in mammalian cells. Here, we investigated the methylation status of CpGs sites in the Dnmt1o 5′‐flanking region in germ cells at different stages of oogenesis or spermatogenesis. The methylation levels of the CpG sites at the 5′‐flanking regions were hypermethylated in growing oocytes of all follicular stages, while the oocytes in meiotic metaphase II (MII) were demethylated. The methylation pattern within the CpGs sites in the 5′‐flanking region, however, was dramatically changed during spermatogenesis. We observed that there was significant non‐CpG methylation both in MII oocytes and spermatocytes. Although a low methylation level in non‐CpG sites was observed in primary and secondary oocytes, the CpA site of position 25 and CpT site of position 29 within the no‐CpG region in the 5′‐flanking region of Dnmt1o was highly methylated in MII oocytes. During spermatogenesis, the low degree of methylation at CpG sites in spermatocytes increased to a higher degree in sperm, while the high ratio of methylation in non‐CpG sites in spermatocytes decreased. Together, germ cells showed inverted methylation patterns between CpG and non‐CpG sites in the Dnmt1o 5′‐upstream region, and the methylation pattern during oogenesis did not drastically change, remaining generally hypomethylated at the MII stage. Mol. Reprod. Dev. 80: 212–222, 2013. © 2013 Wiley Periodicals, Inc. |
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Keywords: | methyltransferase1o (Dnmt1o) DNA methylation oogenesis spermatogenesis |
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