Project description:A forward genetics screen led to the identification of the putative chromatin regulator EDM2 as a cellular anti-silencing factor and regulator of genome DNA methylation patterns. EDM2 contains a composite PHD finger domain that recognizes both active H3K4 and repressive H3K9 methylation marks at the intronic repeat elements in genes such as the histone H3K9 demethylase gene IBM1, and is necessary for maintaining the expression of these genes by promoting mRNA distal polyadenylation. Because of its role in maintaining IBM1 expression, EDM2 is required for preventing CHG methylation in the bodies of thousands of genes.Our results thus increase the understanding of anti-silencing, genome methylation patterns, and regulation of alternative RNA processing by intronic heterochromatin. Col-0 and edm2-4 total genomic DNAs are extracted from leaves and then subjected to bisulfite convertion and sequencing in accordance with standard protocol.
Project description:A forward genetics screen led to the identification of the putative chromatin regulator EDM2 as a cellular anti-silencing factor and regulator of genome DNA methylation patterns. EDM2 contains a composite PHD finger domain that recognizes both active H3K4 and repressive H3K9 methylation marks at the intronic repeat elements in genes such as the histone H3K9 demethylase gene IBM1, and is necessary for maintaining the expression of these genes by promoting mRNA distal polyadenylation. Because of its role in maintaining IBM1 expression, EDM2 is required for preventing CHG methylation in the bodies of thousands of genes.Our results thus increase the understanding of anti-silencing, genome methylation patterns, and regulation of alternative RNA processing by intronic heterochromatin. Col-0 and edm2-4 total RNA are extracted from leaves and then polyA mRNAs are isolated for mRNA-seq.
Project description:A forward genetics screen led to the identification of the putative chromatin regulator EDM2 as a cellular anti-silencing factor and regulator of genome DNA methylation patterns. EDM2 contains a composite PHD finger domain that recognizes both active H3K4 and repressive H3K9 methylation marks at the intronic repeat elements in genes such as the histone H3K9 demethylase gene IBM1, and is necessary for maintaining the expression of these genes by promoting mRNA distal polyadenylation. Because of its role in maintaining IBM1 expression, EDM2 is required for preventing CHG methylation in the bodies of thousands of genes.Our results thus increase the understanding of anti-silencing, genome methylation patterns, and regulation of alternative RNA processing by intronic heterochromatin.
Project description:A forward genetics screen led to the identification of the putative chromatin regulator EDM2 as a cellular anti-silencing factor and regulator of genome DNA methylation patterns. EDM2 contains a composite PHD finger domain that recognizes both active H3K4 and repressive H3K9 methylation marks at the intronic repeat elements in genes such as the histone H3K9 demethylase gene IBM1, and is necessary for maintaining the expression of these genes by promoting mRNA distal polyadenylation. Because of its role in maintaining IBM1 expression, EDM2 is required for preventing CHG methylation in the bodies of thousands of genes.Our results thus increase the understanding of anti-silencing, genome methylation patterns, and regulation of alternative RNA processing by intronic heterochromatin.
Project description:In diverse eukaryotes, constitutively silent sequences, such as transposons and repeats, are marked by methylation at histone H3 lysine 9 (H3K9me). Despites the conservation and importance in the genome integrity, mechanisms to exclude H3K9m from active genes remained largely unexplored. Here we show in Arabidopsis that the exclusion depends on a histone demethylase gene, IBM1 (increase in BONSAI methylation); loss-of-function ibm1 mutation caused ectopic H3K9me in thousands of genes, which accompanies genic DNA methylation at non-CG sites. The ibm1-induced genic H3K9me depended on both histone methylase KYP/SUVH4 and DNA methylase CMT3, suggesting interdependence of two epigenetic marks – H3K9me and non-CG methylation. Notably, IBM1 enhanced loss of H3K9m in transcriptionally de-repressed sequences. Furthermore, disruption of transcription in genes induced ectopic non-CG methylation, mimicking the loss of IBM1 function. We propose that active chromatin is stabilized by the autocatalytic loop of transcription and H3K9 demethylation. This process counteracts accumulation of silent epigenetic marks, H3K9me and non-CG methylation, which is also autocatalytic.
Project description:In diverse eukaryotes, constitutively silent sequences, such as transposons and repeats, are marked by methylation at histone H3 lysine 9 (H3K9me). Despites the conservation and importance in the genome integrity, mechanisms to exclude H3K9m from active genes remained largely unexplored. Here we show in Arabidopsis that the exclusion depends on a histone demethylase gene, IBM1 (increase in BONSAI methylation); loss-of-function ibm1 mutation caused ectopic H3K9me in thousands of genes, which accompanies genic DNA methylation at non-CG sites. The ibm1-induced genic H3K9me depended on both histone methylase KYP/SUVH4 and DNA methylase CMT3, suggesting interdependence of two epigenetic marks – H3K9me and non-CG methylation. Notably, IBM1 enhanced loss of H3K9m in transcriptionally de-repressed sequences. Furthermore, disruption of transcription in genes induced ectopic non-CG methylation, mimicking the loss of IBM1 function. We propose that active chromatin is stabilized by the autocatalytic loop of transcription and H3K9 demethylation. This process counteracts accumulation of silent epigenetic marks, H3K9me and non-CG methylation, which is also autocatalytic. Leaves of 4-week-old plants were fixed as described previously (Saze et al, 2008). Chromatin immunoprecipitation (ChIP) was performed as described previously (Kimura et al, 2008), using antibody against H3K9me2 (CMA307, Kimura et al, 2008, PMID: 18227620). Non-immunoprecipitated DNA (input DNA) and ChIP samples were amplified, labeled, and hybridized to microarray according to the manufacturer’s instruction (Protocols for Chromatin Immunoprecipitation and Amplification, NimbleGen). Input DNA and ChIP DNA were differentially labeled with Cy3 and Cy5, respectively, and competitively hybridized to a microarray chip. We used NimbleGen 2.1M HD2 array covering entire genome of A. thaliana.
Project description:Alternative polyadenylation (APA) has recently been recognized as a universal mechanism for gene regulation, but it remains unclear how APA is controlled. Here we report that the Arabidopsis thaliana Protein Arginine Methyltransferase 10 (AtPRMT10) regulates global APA with its protein partner HLP1, a conserved hnRNP A/B protein. HLP1 binds preferentially to A-rich and U-rich cis-elements around polyadenylation sites, thereby linking AtPRMT10 to the control of APA through protein-protein interactions. AtPRMT10 mutations cause significant proximal-to-distal poly(A) site shifts largely overlapping with those in hlp1-1 mutants. Proximal polyadenylation is maintained by AtPRMT10-directed methylation and is mediated in part by methylation of HLP1 at specific arginine residues. Our findings demonstrate that arginine methylation of an RNA-binding protein adds a novel layer of regulation to widespread alternative polyadenylation.
Project description:Heterochromatin constitutes a fundamental aspect of genomes that is crucial for maintaining genome stability. In flowering plants, maintenance of heterochromatin relies on a positive feedback loop involving the histone 3 lysine nine methyltransferase (H3K9), KRYPTONITE (KYP), and the DNA methyltransferase, CHROMOMETHYLASE3 (CMT3). An H3K9 demethylase, INCREASED IN BONSAI METHYLATION 1 (IBM1), has evolved to modulate the activity of KYP-CMT3 within transcribed genes. The absence of IBM1 activity results in aberrant methylation of gene bodies, which is deleterious. This study demonstrates extensive genetic and gene expression variations in KYP, CMT3, and IBM1 within and between flowering plant species. IBM1 activity in Arabidopsis thaliana is uniquely regulated by the abundance of H3K9me2 in a repetitive sequence within an intron preceding the histone demethylase domain. This mechanism enables IBM1 to monitor global levels of H3K9me2. We discovered that the methylated intron is prevalent across flowering plants, however, its underlying sequence exhibits dynamic evolution. Its absence in species lacking gene body DNA methylation suggests its primary role in sensing H3K9me2 and preventing its integration into these constitutively expressed genes. Furthermore, our investigation uncovered Arabidopsis thaliana accessions resembling weak ibm1 mutants, several Brassicaceae species with reduced IBM1 expression, and a potential IBM1 deletion. Evolution towards reduced IBM1 activity in some flowering plants could explain the frequent natural occurrence of diminished or lost CMT3 activity, as cmt3 mutants in A. thaliana mitigate the deleterious effects of IBM1.