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JMJ 24 binds to RDR 2 and is required for the basal level transcription of silenced loci in Arabidopsis
Author(s) -
Deng Shulin,
Xu Jun,
Liu Jun,
Kim SangHee,
Shi Suhua,
Chua NamHai
Publication year - 2015
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12924
Subject(s) - biology , dna methylation , genetics , transcription (linguistics) , rna , rna directed dna methylation , methylation , gene silencing , gene , gene expression , linguistics , philosophy
Summary Transposable elements ( TE s) and repetitive sequences are ubiquitously present in eukaryotic genomes which are in general epigenetically silenced by DNA methylation and/or histone 3 lysine 9 methylation (H3K9me). RNA ‐directed DNA methylation (Rd DM ) is the major pathway that initiates de novo DNA methylation in Arabidopsis and sets up a self‐reinforcing silencing loop between DNA methylation and H3K9me. However, a key issue is the requirement of a basal level transcript from the target loci to initiate the RNA ‐based silencing. How the heterochromatic silenced loci are transcribed remains largely unknown. Here, we show that JMJ 24, a JmjC domain‐containing protein counteracts H3K9me to promote basal level transcription of endogenous silenced loci in Arabidopsis. JMJ 24 functionally resembles the fission yeast JmjC protein Epe1. The transcript promoted by JMJ 24 is, at least in part, processed to small RNA to initiate the Rd DM . Genome‐wide transcriptome profiling indicates that transcript levels of TE s are more likely regulated by JMJ 24, compared with protein‐coding genes. Our data suggest that JMJ 24 plays a conserved role in promoting basal level transcription of endogenous silenced loci to reinforce the silencing. We also provide evidence of a physical association between JMJ 24 and RNA ‐dependent RNA polymerase 2 ( RDR 2), which represents an evolved property of the RNA silencing pathway.