2026-05-11 東京大学
MBD8はLDL2のタンパク質安定性を高め転写抑制に働く
＜関連情報＞
- https://www.s.u-tokyo.ac.jp/ja/press/11137/
- https://academic.oup.com/nar/article/54/9/gkag361/8667323
MBD8は、シロイヌナズナにおけるH3K9me2の下流でのLDL2を介した転写抑制に必要である MBD8 is required for LDL2-mediated transcriptional repression downstream of H3K9me2 in Arabidopsis
Shusei Mori,Akihisa Osakabe,Juliarni,Yuriko Tanaka,Mami Hirayama,Soichi Inagaki,Tetsuji Kakutani
Nucleic Acids Research Published:11 May 2026
DOI:https://doi.org/10.1093/nar/gkag361
Abstract
Histone H3 lysine 9 methylation (H3K9me) is a conserved epigenetic mark for transcriptional gene repression. In Arabidopsis, H3K9 dimethylation (H3K9me2) promotes the removal of a transcription-associated mark, H3K4 monomethylation (H3K4me1), and this process within genes requires the histone demethylase LDL2. However, how LDL2 specifically functions in genes that accumulate H3K9me2 remains unknown. Here, we show that methyl-CpG-binding domain protein 8 (MBD8) binds to LDL2 and plays a role in H3K4me1 removal and transcriptional gene repression downstream of H3K9me2. MBD8 preferentially binds GC-poor DNA, regardless of its cytosine methylation status. Interestingly, LDL2 protein levels were significantly reduced in the mbd8 mutant background, suggesting that MBD8 stabilizes the LDL2 protein, facilitating H3K4me1 removal and the transcriptional repression of H3K9me2-marked genes. The domain necessary for the MBD8–LDL2 interaction is conserved among plants. Notably, MBD8 lacking the MBD domain still complemented the effect of MBD8 on H3K4me1 levels and the developmental phenotypes. We propose that MBD proteins have diverse functions beyond their methylated DNA-binding capabilities.
