Project description:Patterns of DNA methylation are established during gametogenesis. The catalytically-inactive adaptor Dnmt3L is crucial to ensure this occurs correctly. In vitro, Dnmt3L binds to the N terminal tail of histone H3 but the function of this interaction during development is unknown. Here we show that Dnmt3L-histone H3 interaction is necessary for spermatogenesis. Mutant animals exhibit reduced fertility, defective methylation establishment at retrotransposons coupled with their reactivation and meiotic catastrophe. The spermatogonial stem cell pool is also defective, with mutant cells displaying marked changes in gene expression. Genome-wide methylation analysis reveals reductions in CG methylation as well as severe loss of non-CG methylation suggesting that non-CG methylation is specifically sensitive to the ability of Dnmt3L to bind histone H3. MethylC-Seq of wild-type and Dnmt3LA/A 1dpp prospermatagonia
Project description:Patterns of DNA methylation are established during gametogenesis. The catalytically-inactive adaptor Dnmt3L is crucial to ensure this occurs correctly. In vitro, Dnmt3L binds to the N terminal tail of histone H3 but the function of this interaction during development is unknown. Here we show that Dnmt3L-histone H3 interaction is necessary for spermatogenesis. Mutant animals exhibit reduced fertility, defective methylation establishment at retrotransposons coupled with their reactivation and meiotic catastrophe. The spermatogonial stem cell pool is also defective, with mutant cells displaying marked changes in gene expression. Genome-wide methylation analysis reveals reductions in CG methylation as well as severe loss of non-CG methylation suggesting that non-CG methylation is specifically sensitive to the ability of Dnmt3L to bind histone H3.
Project description:DNA methyltransferase 3A (DNMT3A) and DNA methyltransferase 3-Like (DNMT3L) form functional heterotetramers and ATRX-DNMT3-DNMT3L (ADD) domains, shared by both DNMT3A and DNMT3L, recognizes histone H3 tail unmethylated at lysine-4 (H3K4me0) to deposit DNA methylation properly in mammalian germ cells. However, the combinational and differential role of ADD domains of DNMT3A and DNMT3L in vivo has not been fully defined. Here we analyze both female and male germ cells derived from mouse with amino-acid substitutions in ADD domains of DNMT3A and/or DNMT3L that impair their domain function. Loss of either DNMT3A-ADD or DNMT3L-ADD domain function shows moderate reduction of global CG methylation level, but in different degree, in both germ cells. However, when both DNMT3A and DNMT3L lost their ADD domain functions, reduction of the global CG methylation level is much more severe and comparable with that of Dnmt3a/3L knockout germ cells. In contrast, such double mutant germ cells have thousands of genomic regions where non-CG methylation is aberrantly accumulated. These results highlight a critical role of the combinational function of ADD domains for the robust CG and non-CG methylation in germ cells.
Project description:DNA methyltransferase 3A (DNMT3A) and DNA methyltransferase 3-Like (DNMT3L) form functional heterotetramers and ATRX-DNMT3-DNMT3L (ADD) domains, shared by both DNMT3A and DNMT3L, recognizes histone H3 tail unmethylated at lysine-4 (H3K4me0) to deposit DNA methylation properly in mammalian germ cells. However, the combinational and differential role of ADD domains of DNMT3A and DNMT3L in vivo has not been fully defined. Here we analyze both female and male germ cells derived from mouse with amino-acid substitutions in ADD domains of DNMT3A and/or DNMT3L that impair their domain function. Loss of either DNMT3A-ADD or DNMT3L-ADD domain function shows moderate reduction of global CG methylation level, but in different degree, in both germ cells. However, when both DNMT3A and DNMT3L lost their ADD domain functions, reduction of the global CG methylation level is much more severe and comparable with that of Dnmt3a/3L knockout germ cells. In contrast, such double mutant germ cells have thousands of genomic regions where non-CG methylation is aberrantly accumulated. These results highlight a critical role of the combinational function of ADD domains for the robust CG and non-CG methylation in germ cells.
Project description:DNA methylation occurs in both CG and non-CG sequence contexts. Non-CG methylation is abundant in plants, and is mediated by CHROMOMETHYLASE (CMT) and DOMAINS REARRANGED METHYLTRANSFERASE (DRM) proteins; however its roles remain poorly understood. Here we characterize the roles of non-CG methylation in Arabidopsis thaliana. We show that a poorly characterized methyltransferase, CMT2, is a functional methyltransferase in vitro and in vivo. CMT2 specifically binds histone H3 lysine 9 (H3K9) dimethylation and methylates non-CG cytosines at sites that are also regulated by H3K9 dimethylation. By generating different combinations of non-CG methylation mutants, we reveal the contributions and redundancies between each methyltransferase in DNA methylation patterning and in regulating transposable elements (TEs) and protein-coding genes. We also demonstrate extensive dependencies of small RNA accumulation and H3K9 methylation patterning on non-CG methylation, suggesting self-reinforcing mechanisms between these epigenetic factors. The results suggest that non-CG methylation patterns are critical in shaping the histone modification and small non-coding RNA landscapes.
Project description:DNA methylation occurs in both CG and non-CG sequence contexts. Non-CG methylation is abundant in plants, and is mediated by CHROMOMETHYLASE (CMT) and DOMAINS REARRANGED METHYLTRANSFERASE (DRM) proteins; however its roles remain poorly understood. Here we characterize the roles of non-CG methylation in Arabidopsis thaliana. We show that a poorly characterized methyltransferase, CMT2, is a functional methyltransferase in vitro and in vivo. CMT2 specifically binds histone H3 lysine 9 (H3K9) dimethylation and methylates non-CG cytosines at sites that are also regulated by H3K9 dimethylation. By generating different combinations of non-CG methylation mutants, we reveal the contributions and redundancies between each methyltransferase in DNA methylation patterning and in regulating transposable elements (TEs) and protein-coding genes. We also demonstrate extensive dependencies of small RNA accumulation and H3K9 methylation patterning on non-CG methylation, suggesting self-reinforcing mechanisms between these epigenetic factors. The results suggest that non-CG methylation patterns are critical in shaping the histone modification and small non-coding RNA landscapes. Eighteen mRNA-seq samples, five smRNA-seq samples, five bisulfite-seq samples, twenty ChIP-seq samples. Bisulfite-seq data for cmt2-7 single mutants, cmt3 single mutants, drm1/2 double mutants, drm1/2 cmt3 triple mutants are deposited in GSE39901. Processed wiggle format files for all datasets can be downloaded at http://genomes.mcdb.ucla.edu/AthBSseq/
Project description:Gene expression in eukaryotes is tightly linked to the methylation state of specific lysine residues within the N-terminal region of the core histone proteins. While the mechanisms connecting histone lysine methylation to effector protein recruitment and control of gene activity are increasingly well understood, it remains unknown whether non-histone chromatin proteins are targets for similar modification-recognition systems. Here we show that histone H3 and the H3 methyltransferase G9a share a conserved methylation motif that is both necessary and sufficient to mediate in vivo interaction with the potent epigenetic regulator Heterochromatin Protein 1 (HP1). As with H3, G9a-HP1 interaction is dependent on lysine methylation and can be reversed by adjacent phosphorylation. NMR analysis demonstrates that the HP1 chromodomain recognizes methyl-G9a through a binding mode similar to that used in recognition of methyl-H3, and that adjacent phosphorylation directly antagonizes G9a-HP1 interaction. In addition to uncovering the chromodomain as a generalized methyl-lysine binding module, these data identify histone-like modification cassettes (or âhistone mimicsâ) as an entirely new class of non-histone methylation targets, and directly demonstrate the relevance of the principles underlying the histone code to the regulation of non-histone proteins. Experiment Overall Design: Two independent Affymetrix gene expression microarray analyses were performed on samples from G9a-deleted MEFs reconstituted with empty vector (delta), wild type FLAG-G9a (WT), FLAG-G9a K165A (K165A) or FLAG-G9a H1093K catalytic mutant (H1093K).
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:Gene expression in eukaryotes is tightly linked to the methylation state of specific lysine residues within the N-terminal region of the core histone proteins. While the mechanisms connecting histone lysine methylation to effector protein recruitment and control of gene activity are increasingly well understood, it remains unknown whether non-histone chromatin proteins are targets for similar modification-recognition systems. Here we show that histone H3 and the H3 methyltransferase G9a share a conserved methylation motif that is both necessary and sufficient to mediate in vivo interaction with the potent epigenetic regulator Heterochromatin Protein 1 (HP1). As with H3, G9a-HP1 interaction is dependent on lysine methylation and can be reversed by adjacent phosphorylation. NMR analysis demonstrates that the HP1 chromodomain recognizes methyl-G9a through a binding mode similar to that used in recognition of methyl-H3, and that adjacent phosphorylation directly antagonizes G9a-HP1 interaction. In addition to uncovering the chromodomain as a generalized methyl-lysine binding module, these data identify histone-like modification cassettes (or “histone mimics”) as an entirely new class of non-histone methylation targets, and directly demonstrate the relevance of the principles underlying the histone code to the regulation of non-histone proteins. Keywords: methylation analysis
Project description:Functional genomic states are maintained by reinforcing chromatin interactions that exclude the components of other states. Plant heterochromatin features methylation of histone H3 at lysine 9 (H3K9me) and extensive DNA methylation. However, DNA methylation is also catalyzed by a mostly euchromatic small RNA-directed pathway (RdDM) thought to seek H3K9me. How RdDM is excluded from H3K9me-rich heterochromatin is unclear. Here we show that without histone H1, RdDM enters heterochromatin, preferentially at nucleosome linker DNA. Surprisingly, this does not require SHH1, the RdDM component that binds H3K9me. Furthermore, H3K9me is dispensable for RdDM, as is CG DNA methylation. Instead, we find that non-CG methylation is specifically required for small RNA biogenesis, and without H1 small RNA production quantitatively expands to non-CG methylated loci. Our results demonstrate that H1 enforces the separation of euchromatic and heterochromatic DNA methylation pathways by excluding the small RNA-generating branch of RdDM from non-CG methylated heterochromatin.