第43回日本分子生物学会年会

オンライン開催

2020年12月04日

3P-0034

ポスター発表

ヒトおよびアカゲザルの比較解析によるCpGアイランドプロモータの多様化 Diversification of CpG-island promoters revealed by comparative analysis between human and rhesus monkey genomes

青砥 早希1, 伏見 麻由2, 由良 敬2, 岡村 浩司3 1成育医療セ・メディカルゲノム, 2お茶大・理・生物, 3成育医療セ・システム医学

Whereas CpG dinucleotides are fairly reduced compared to other dinucleotides in mammal genomes, they tend to congregate and form CpG islands, which localize around the 5' regions of genes. In many cases, they function as promoters. Such CpG-island promoters are generally unmethylated and are often found in housekeeping genes. However, their nucleotide sequences and existence per se are not conserved between humans and mice, which may be due to evolutionary gain and loss of the regulatory regions. To analyze promoter divergence in this study, we focused on the rhesus monkey genomes in the perspective of moderate conserved sequences to the human ones. Using transcription start site data, we first validated our methods that identify orthologous promoters and found a limitation of identifying the start site only by the 5' end of curated gene models, such as NCBI RefSeq. We found that, in addition to deamination mutations, insertions and deletions of bases, repeats, and long fragments contributed to the mutations of CpG dinucleotides. We also observed that the G + C contents tended to change in CpG-poor environments, while CpG content was altered in G + C-rich environments. While loss of CpG islands can be caused by gradual decreases in CpG sites, gain of these islands appear to require two distinct nucleotide altering steps. Taken together, our findings provide novel insights into the process of acquisition and diversification of CpG-island promoters in vertebrates.