Project description:METTL14 (methyltransferase-like 14) is an RNA binding protein that partners with METTL3 to mediate N6-methyladenosine (m6A) methylation of mRNA. Recent studies identified a function for METTL3 in heterochromatin and transcription, but the role of METTL14 in these contexts remains unclear. Here we show that METTL14 binds and regulates mouse embryonic stem cell bivalent domains, which are marked with tri-methylation at lysine 27 of histone H3 (H3K27me3) and tri-methylation at lysine 4 of histone H3 (H3K4me3). Knockout of Mettl14 results in decreased H3K27me3 but increased H3K4me3 levels at bivalent regions, resulting in the resolution of the bivalency and in increased transcription. We demonstrate that bivalent domain regulation by METTL14 is independent of METTL3 or m6A modification. Instead, METTL14 enhances H3K27me3 and reduces H3K4me3 by interacting with and probably recruiting the histone 3 lysine 27 (H3K27) methyltransferase complex PRC2 and the histone 3 lysine 4 (H3K4) demethylases KDM5B to chromatin. Our findings identify a METTL3-independent function of METTL14, important for maintaining the bivalent domains in mESCs, thus revealing a new mechanism of bivalent domain regulation in mammals.
Project description:METTL14 (methyltransferase-like 14) is an RNA binding protein that partners with METTL3 to mediate N6-methyladenosine (m6A) methylation of mRNA. Recent studies identified a function for METTL3 in heterochromatin and transcription, but the role of METTL14 in these contexts remains unclear. Here we show that METTL14 binds and regulates mouse embryonic stem cell bivalent domains, which are marked with tri-methylation at lysine 27 of histone H3 (H3K27me3) and tri-methylation at lysine 4 of histone H3 (H3K4me3). Knockout of Mettl14 results in decreased H3K27me3 but increased H3K4me3 levels at bivalent regions, resulting in the resolution of the bivalency and in increased transcription. We demonstrate that bivalent domain regulation by METTL14 is independent of METTL3 or m6A modification. Instead, METTL14 enhances H3K27me3 and reduces H3K4me3 by interacting with and probably recruiting the histone 3 lysine 27 (H3K27) methyltransferase complex PRC2 and the histone 3 lysine 4 (H3K4) demethylases KDM5B to chromatin. Our findings identify a METTL3-independent function of METTL14, important for maintaining the bivalent domains in mESCs, thus revealing a new mechanism of bivalent domain regulation in mammals.
Project description:Post-translational modifications of histones play important roles in modulating chromatin structure and regulating gene expression. We have previously shown that over two thirds of Arabidopsis genes contain histone H3 methylation at lysine-4 (H3K4me), and that tri-methylation of H3K4 (H3K4me3) is preferentially located at actively transcribed genes. In addition, several Arabidopsis mutants with locus-specific loss of H3K4me have been found to display various developmental abnormalities. These findings suggest that H3K4me3 may play important roles in maintaining the normal expression of a large number of genes. However, the major enzyme(s) responsible for H3K4me3 has yet to be identified in plants, making it difficult to address questions regarding the mechanisms and functions of H3K4me3. Here we describe the characterization of SET DOMAIN GROUP 2 (SDG2), a large Arabidopsis protein containing a histone lysine methyltransferase domain. We found that SDG2 homologues are highly conserved in plants, and that the Arabidopsis SDG2 gene is broadly expressed during development. In addition, the loss of SDG2 leads to severe and pleiotropic phenotypes as well as the mis-regulation of a large number of genes. Consistent with our finding that SDG2 is a robust and specific H3K4 methyltransferase in vitro, the loss of SDG2 leads to a drastic decrease in H3K4me3 in vivo. Taken together, these results suggest that SDG2 is the major enzyme responsible for H3K4me3 in Arabidopsis, and that SDG2-dependent H3K4m3 is critical for regulating gene expression and plant development.
Project description:In eukaryotic cells, environmental and developmental signals alter chromatin structure and modulate gene expression. Heterochromatin constitutes the transcriptionally inactive state of the genome and in plants and mammals is generally characterized by DNA methylation and histone modifications such as histone H3 lysine 9 (H3K9) methylation. In Arabidopsis thaliana DNA methylation and H3K9 methylation are usually colocated and set up a mutually self reinforcing and stable state. Here, in contrast, we found that SUVR5, a plant Su(var)3-9 homolog with a SET histone methyltransferase domain, mediates H3K9me2 deposition and regulates gene expression in a DNA-methylation-independent manner. SUVR5 binds DNA through its zinc fingers and represses the expression of a subset of stimulus response genes. This represents a novel mechanism for plants to regulate their chromatin and transcriptional state, which may allow for the adaptability and modulation necessary to rapidly respond to extracellular cues. one experiment and one control.
Project description:Polycomb-group proteins form multimeric protein complexes involved in transcriptional silencing. The Polycomb Repressive complex 2 (PRC2) contains the Suppressor of Zeste-12 protein (Suz12) and the histone methyltransferase Enhancer of Zeste protein-2 (Ezh2). This complex, catalyzing the di- and tri-methylation of histone H3 lysine 27, is essential for embryonic development and stem cell renewal. However, the role of Polycomb-group protein complexes in the control of the intestinal epithelial cell (IEC) phenotype is not known. We investigated the impact of Suz 12 depletion on gene expression in IEC-6 cells.
Project description:In eukaryotic cells, environmental and developmental signals alter chromatin structure and modulate gene expression. Heterochromatin constitutes the transcriptionally inactive state of the genome and in plants and mammals is generally characterized by DNA methylation and histone modifications such as histone H3 lysine 9 (H3K9) methylation. In Arabidopsis thaliana DNA methylation and H3K9 methylation are usually colocated and set up a mutually self reinforcing and stable state. Here, in contrast, we found that SUVR5, a plant Su(var)3-9 homolog with a SET histone methyltransferase domain, mediates H3K9me2 deposition and regulates gene expression in a DNA-methylation-independent manner. SUVR5 binds DNA through its zinc fingers and represses the expression of a subset of stimulus response genes. This represents a novel mechanism for plants to regulate their chromatin and transcriptional state, which may allow for the adaptability and modulation necessary to rapidly respond to extracellular cues. Investigation of gene expression profiles of suvr5-1, ldl1 ldl2 and suvr5 ldl1 ldl2 mutants.
Project description:In eukaryotic cells, environmental and developmental signals alter chromatin structure and modulate gene expression. Heterochromatin constitutes the transcriptionally inactive state of the genome and in plants and mammals is generally characterized by DNA methylation and histone modifications such as histone H3 lysine 9 (H3K9) methylation. In Arabidopsis thaliana DNA methylation and H3K9 methylation are usually colocated and set up a mutually self reinforcing and stable state. Here, in contrast, we found that SUVR5, a plant Su(var)3-9 homolog with a SET histone methyltransferase domain, mediates H3K9me2 deposition and regulates gene expression in a DNA-methylation-independent manner. SUVR5 binds DNA through its zinc fingers and represses the expression of a subset of stimulus response genes. This represents a novel mechanism for plants to regulate their chromatin and transcriptional state, which may allow for the adaptability and modulation necessary to rapidly respond to extracellular cues. Investigation of H3K9me2 levels in WT Col0 and suvr5-1 mature leaves 4 ChIP-chip experiments.
Project description:The Drosophila Trithorax group (TrxG) protein ASH1 remains associated with mitotic chromatin through mechanisms that are poorly understood. ASH1 dimethylates histone H3 at lysine 36 via its SET domain. Here we identify domains of the TrxG protein ASH1 that are required for mitotic chromatin attachment in living Drosophila. Quantitative live imaging demonstrates that ASH1 requires AT hooks and the BAH domain but not the SET domain for full chromatin binding in metaphase, and that none of these domains are essential for interphase binding. Genetic experiments show that disruptions of the AT hooks and the BAH domain together, but not deletion of the SET domain alone, are lethal. Transcriptional profiling demonstrates that intact ASH1 AT hooks and the BAH domain are required to maintain expression levels of a specific set of genes, including several involved in cell identity and survival. This study identifies in vivo roles for specific ASH1 domains in mitotic binding, gene regulation and survival that are distinct from its functions as a histone methyltransferase.
Project description:Enhancers play a key role in regulating cell type-specific gene expression and are marked by histone modifications such as methylation and acetylation. Mono-methylation of lysine 4 on histone H3 (H3K4me1) initially primes enhancers, preceding enhancer activation via acetylation of lysine 27 on histone H3 (H3K27ac). MLL4 is a major enhancer H3K4 mono-methyltransferase with partial functional redundancy with MLL3. However, how H3K4me1 affects enhancer regulation in cell differentiation has remained unclear. By screening several lysine-to-methionine mutants of H3.3, we first found that depletion of H3K4 methylation by H3.3K4M mutation severely impairs adipogenesis in culture. Using tissue-specific expression of H3.3K4M in mice, we further demonstrate that H3.3K4M inhibits adipose tissue and muscle development in vivo. Mechanistically, H3.3K4M destabilizes MLL3/4 proteins but not other members of the mammalian Set1-like H3K4 methyltransferase family and prevents MLL3/4-mediated enhancer activation in adipogenesis. Using tissue-specific deletion of the enzymatic SET domain of MLL3/4 in mice, we also show that deletion of the SET domain prevents adipose tissue and muscle development in vivo and inhibits adipogenesis by destabilizing MLL3/4 in vitro. Notably, H3.3K4M expression mimics MLL3/4 SET domain deletion in preventing adipogenesis. Interestingly, H3.3K4M does not affect adipose tissue maintenance and function, suggesting that MLL3/4-mediated H3K4 methylation is dispensable for the maintenance and function of differentiated adipocytes. Together, our findings suggest that H3.3K4M targets MLL3/4 to prevent enhancer activation in adipogenesis.
Project description:In eukaryotic cells, environmental and developmental signals alter chromatin structure and modulate gene expression. Heterochromatin constitutes the transcriptionally inactive state of the genome and in plants and mammals is generally characterized by DNA methylation and histone modifications such as histone H3 lysine 9 (H3K9) methylation. In Arabidopsis thaliana DNA methylation and H3K9 methylation are usually colocated and set up a mutually self reinforcing and stable state. Here, in contrast, we found that SUVR5, a plant Su(var)3-9 homolog with a SET histone methyltransferase domain, mediates H3K9me2 deposition and regulates gene expression in a DNA-methylation-independent manner. SUVR5 binds DNA through its zinc fingers and represses the expression of a subset of stimulus response genes. This represents a novel mechanism for plants to regulate their chromatin and transcriptional state, which may allow for the adaptability and modulation necessary to rapidly respond to extracellular cues. Keywords: Expression profiling by high throughput sequencing Investigation of gene expression profiles of suvr5-1, ldl1 ldl2 and suvr5 ldl1 ldl2 mutants. For more information on this study contact Dr. Elena Caro at ecarobernat-at-gmail.com