Project description:BRAHMA (BRM) is a conserved SWI/SNF-type chromatin remodeling ATPase implicated in many key nuclear events. Histone H3 Lysine 27 (H3K27) demethylases specifically remove the repressive histone mark, trimethylation of H3K27 (H3K27me3). Both proteins are thought to play active roles in regulating gene activities at the chromatin level, but their genome-wide coordination remains to be determined. In Arabidopsis thaliana, RELATIVE OF EARLY FLOWERING 6 (REF6, also known as JMJ12) is the first identified plant H3K27 demethylase. Here, genome-wide analyses revealed that REF6 targets to thousands of genes across the Arabidopsis genome and co-localizes with BRM at more than 1,000 genes, many of which are genes involved in response to various stimuli, especially plant hormones. Loss of REF6 activity results in decreased BRM occupancy at hundreds of BRM-REF6 co-targets, indicating that REF6 is required for the recruitment of BRM to chromatin. Further, REF6 targets to genomic loci that contains the CTCTGTTT motif in vivo Examination of BRM occupancy in 14-day-old wt and ref6-1 seedlings. Examination of REF6 occupancy in 14-day-old wt and brm-1 seedlings. Examination of global RNA expression in 14-day-old wt, brm-1, ref6-1 and brm-1 ref6-1 seedlings. Examination of H3K27me3 profiles in 14-day-old wt, brm-1, ref6-1, and brm-1 ref6-1 seedlings.
Project description:RELATIVE OF EARLY FLOWERING 6 (REF6/JMJ12), a Jumonji C (JmjC)-domain-containing histone demethylase, directly recognizes the CTCTGYTY motif by its zinc-finger domains to demethylate H3K27me3 at specific loci in Arabidopsis genome. Here we show that the recognition of CTCTGYTY motif by REF6 is prevented by DNA methylation. REF6 prefers to bind DNA hypo-methylated regions in vivo. DNA cytosine-methylation decreases REF6 binding affinity in vitro, and the crystal structure of ZnF-clusters showed that REF6 prefers unmethylated DNA sequences. Furthermore, REF6 displayed ectopic binding on multiple new target loci in drm1 drm2 cmt2 cmt3 (ddcc) quadruple mutants, where non-CG methylation was largely diminished. Collectively, this study reveals a novel targeting crosstalk between an H3K27me3 demethylase and DNA methylation.
Project description:We report genome-wide binding targets of REF6, a H3K27me3 demethylase and also high-throughput profiling of histone modifications of H3K27me3 in Arabidopsis flowers. Using chromatin-immunoprecipitation followed by high-throughput sequencing, we mapped thousands of binding targets of REF6 in flowers and in addition, we used a second fixative, DSG to capture more indirect targets of REF6. In order to investigate the function of indirect binding of REF6 represented H3K27me3 demethylase, the binding targets of DNA binding domain deleted REF6 were identified in the triple mutant background in which REF6 and its two homologs were mutated. Meanwhile, the H3K27me3 marked regions in both wild type and triple mutant flowers were defined. By analyzing the differentially enriched H3K27me3 region and REF6 binding profile, we found that REF6 functions to determine the boundary of H3K27me3 regions. Comparison of binding profiles of REF6 in flowers and in seedlings (ref) revealed a tissue-specific binding manner. More importantly, we found that the indirect binding of REF6 is mediated by trans factors and this indirect binding is crucial for REF6 function, especially in reproductive organs in Arabidopsis. Our results provide novel molecular insights into REF6 functions.
Project description:BRAHMA (BRM) is a conserved SWI/SNF-type chromatin remodeling ATPase implicated in many key nuclear events. Histone H3 Lysine 27 (H3K27) demethylases specifically remove the repressive histone mark, trimethylation of H3K27 (H3K27me3). Both proteins are thought to play active roles in regulating gene activities at the chromatin level, but their genome-wide coordination remains to be determined. In Arabidopsis thaliana, RELATIVE OF EARLY FLOWERING 6 (REF6, also known as JMJ12) is the first identified plant H3K27 demethylase. Here, genome-wide analyses revealed that REF6 targets to thousands of genes across the Arabidopsis genome and co-localizes with BRM at more than 1,000 genes, many of which are genes involved in response to various stimuli, especially plant hormones. Loss of REF6 activity results in decreased BRM occupancy at hundreds of BRM-REF6 co-targets, indicating that REF6 is required for the recruitment of BRM to chromatin. Further, REF6 targets to genomic loci that contains the CTCTGTTT motif in vivo
Project description:Dynamic trimethylation of histone H3 at Lys27 (H3K27me3) affects gene expression and controls plant development and environmental responses. In Arabidopsis thaliana, RELATIVE OF EARLY FLOWERING 6/JUMONJI DOMAIN-CONTAINING PROTEIN 12 (REF6/JMJ12) demethylates H3K27me3 by recognizing a specific DNA motif; however, little is known about how REF6 activates target gene expression after recognition, especially in environmental responses. In response to warm ambient temperature, plants undergo thermomorphogenesis, which involves accelerated growth, early flowering, and changes in morphology. Here we show that REF6 regulates thermomorphogenesis and cooperates with the transcription factor PHYTOCHROME INTERACTING FACTOR 4 (PIF4) to synergistically activate thermo-responsive genes under warm ambient temperature. The ref6 loss-of-function mutants exhibited attenuated hypocotyl elongation at warm temperature, partially due to down-regulation of GIBBERELLIN 20-OXIDASE2 (GA20ox2) and BASIC HELIX-LOOP-HELIX 87 (bHLH87). REF6 enzymatic activity is necessary for warm ambient temperature responses. Together, our results provide direct evidence of an epigenetic modifier and a transcription factor working together to respond to the environment.
Project description:This SuperSeries is composed of the following subset Series: GSE25444: Differential gene expression in ref6-1 GSE25446: Genome-wide comparison of H3K27me3 difference between ref6-1 and wild type Col Refer to individual Series
Project description:BRAHMA (BRM) is a conserved SWI/SNF-type chromatin remodeling ATPase implicated in many key nuclear events. Histone H3 Lysine 27 (H3K27) demethylases specifically remove the repressive histone mark, trimethylation of H3K27 (H3K27me3). Both proteins are thought to play active roles in regulating gene activities at the chromatin level, but their genome-wide coordination remains to be determined. In Arabidopsis thaliana, RELATIVE OF EARLY FLOWERING 6 (REF6, also known as JMJ12) is the first identified plant H3K27 demethylase. Here, genome-wide analyses revealed that REF6 targets to thousands of genes across the Arabidopsis genome and co-localizes with BRM at more than 1,000 genes, many of which are genes involved in response to various stimuli, especially plant hormones. Loss of REF6 activity results in decreased BRM occupancy at hundreds of BRM-REF6 co-targets, indicating that REF6 is required for the recruitment of BRM to chromatin. Further, REF6 targets to genomic loci that contains the CTCTGTTT motif in vivo