title: JMJ24 binds to RDR2 and is required for the basal level transcription of silenced loci in Arabidopsis.
abstract: Transposable elements (TEs) 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 (RdDM) 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 JMJ24, a JmjC domain-containing protein counteracts H3K9me to promote basal level transcription of endogenous silenced loci in Arabidopsis. JMJ24 functionally resembles the fission yeast JmjC protein Epe1. The transcript promoted by JMJ24 is, at least in part, processed to small RNA to initiate the RdDM. Genome-wide transcriptome profiling indicates that transcript levels of TEs are more likely regulated by JMJ24, compared with protein-coding genes. Our data suggest that JMJ24 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 JMJ24 and RNA-dependent RNA polymerase 2 (RDR2), which represents an evolved property of the RNA silencing pathway.
authors.affiliation: Laboratory of Plant Molecular Biology, Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.|State Key Laboratory of Biocontrol and Key Laboratory of Gene Engineering of the Ministry of Education, Sun Yat-sen University, Guangzhou, 510275, China.
authors.forename: Shulin
authors.initials: S
authors.lastname: Deng
authors.affiliation: Laboratory of Plant Molecular Biology, Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Xu
authors.affiliation: Laboratory of Plant Molecular Biology, Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Laboratory of Plant Molecular Biology, Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.
authors.forename: Sang-Hee
authors.initials: SH
authors.lastname: Kim
authors.affiliation: State Key Laboratory of Biocontrol and Key Laboratory of Gene Engineering of the Ministry of Education, Sun Yat-sen University, Guangzhou, 510275, China.
authors.forename: Suhua
authors.initials: S
authors.lastname: Shi
authors.affiliation: Laboratory of Plant Molecular Biology, Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.
authors.forename: Nam-Hai
authors.initials: NH
authors.lastname: Chua
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D056484:Jumonji Domain-Containing Histone Demethylases / Q000235:genetics / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D008745:Methylation; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism; D010802:Phylogeny; D030821:Plants, Genetically Modified; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000378:metabolism; D020079:Terminal Repeat Sequences; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; D009687:Nuclear Proteins; D029702:Schizosaccharomyces pombe Proteins; C475031:epe1 protein, S pombe; C000608068:JMJ24 protein, Arabidopsis; D056484:Jumonji Domain-Containing Histone Demethylases; C519655:RDR2 protein, Arabidopsis; D012324:RNA-Dependent RNA Polymerase; D008239:Lysine
keywords: Arabidopsis thaliana; DNA methylation; Jumonji; RNA-dependent RNA polymerase; histone methylation; transcriptional gene silencing; transposable elements