Transduction of RNA-directed DNA methylation signals to repressive histone marks in Arabidopsis thaliana.
RNA-directed modification of histones is essential for the maintenance of heterochromatin in higher eukaryotes. In plants, cytosine methylation is an additional factor regulating inactive chromatin, but the mechanisms regulating the coexistence of cytosine methylation and repressive histone modification remain obscure. In this study, we analysed the mechanism of gene silencing mediated by MORPHEUS' MOLECULE1 (MOM1) of Arabidopsis thaliana. Transcript profiling revealed that the majority of up-regulated loci in mom1 carry sequences related to transposons and homologous to the 24-nt siRNAs accumulated in wild-type plants that are the hallmarks of RNA-directed DNA methylation (RdDM). Analysis of a single-copy gene, SUPPRESSOR OF drm1 drm2 cmt3 (SDC), revealed that mom1 activates SDC with concomitant reduction of di-methylated histone H3 lysine 9 (H3K9me2) at the tandem repeats in the promoter region without changes in siRNA accumulation and cytosine methylation. The reduction of H3K9me2 is not observed in regions flanking the tandem repeats. The results suggest that MOM1 transduces RdDM signals to repressive histone modification in the core region of RdDM.
Numa
Hisataka
H
Division of Genome and Biodiversity Research, National Institute of Agrobiological Sciences, Tsukuba, Japan.
Kim
Jong-Myong
JM
Matsui
Akihiro
A
Kurihara
Yukio
Y
Morosawa
Taeko
T
Ishida
Junko
J
Mochizuki
Yoshiki
Y
Kimura
Hiroshi
H
Shinozaki
Kazuo
K
Toyoda
Tetsuro
T
Seki
Motoaki
M
Yoshikawa
Manabu
M
Habu
Yoshiki
Y
D000074183:ATPases Associated with Diverse Cellular Activities; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003596:Cytosine / Q000378:metabolism; D019175:DNA Methylation; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D056426:Genetic Loci; D006657:Histones / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D029681:Arabidopsis Proteins; D006657:Histones; D009687:Nuclear Proteins; D018749:RNA, Plant; D034741:RNA, Small Interfering; D014157:Transcription Factors; D003596:Cytosine; D000074183:ATPases Associated with Diverse Cellular Activities; C409208:MOM protein, Arabidopsis