537 / 2019-03-11 23:32:27

AT-hook proteins increase histone modification H3K9me2 independently of DNA methylation

hsitone H3K9me2 silencing

Epigenetic Regulation > Epigenetic Regulation

Matrix attachment regions (MARs) are important for chromatin organization and gene expression. MARs are stretches of AT-rich sequences that guide binding of DNA to the nuclear matrix by recruiting MAR-binding proteins. Proteins with AT-hook motifs bind to MARs and affect the epigenetic state of target regions in animals and plants. Some AT-hook proteins are known to regulate gene expression in plants, but their functional mechanism is largely unknown. We have identified an AT-hook protein AHL10 and the SET domain-containing SU(VAR)3–9 homolog SUVH9 as interacting partners of ADMETOS (ADM). Significantly increased expression of ADM and AHL10 in Arabidopsis triploid seeds results in H3K9m2 hypermethylation in MARs. H3K9m2 hypermethylation in MARs was abolished in mutants of adm and ADM-interaction partners. Further analysis revealed that AHL10-mediated H3K9m2 hypermethylation in MARs is independent of DNA methylation. Moreover, we find that another AT-hook protein, AHL22, is capable of increasing H3K9me2 in sporophytic tissues, independent of DNA methylation. We will present our recent results in this process. Our data suggests a novel mechanism of DNA methylation-independent H3K9me2 deposition that acts on MARs.