Project description:Activity-dependent neuroprotective protein (ADNP) is one of the most frequent autism spectrum disorder-associated gene products known to date. Here we show that Adnp interacts with the chromatin remodeler Chd4 and the heterochromatin protein HP1 to form a stable complex, which we refer to as ChAHP. Genetic ablation of ChAHP components or DNA binding sites in embryonic stem cells prematurely activates lineage-specific genes, revealing an important role for Adnp in restraining the differentiation capacity of pluripotent cells. Adnp targets the ChAHP complex to specific sequence motifs at euchromatic loci, representing an H3K9 methylation-independent mechanism of HP1 recruitment and gene silencing.
Project description:The family of Heterochromatin Protein 1 (HP1) consists of highly conserved proteins, which have important functions in the nucleus of eukaryotic cells. In mammals there are three HP1 paralogs: HP1(alpha), Hp1(beta), and Hp1(gamma)They are encoded by the Cbx5, Cbx1, and Cbx3 genes, respectively. Hp1 and Hp1 stably interact with Chd4 and Adnp to form the ChAHP complex. In this project, Chd4, Adnp, and the three Cbx genes were endogenously tagged with a FLAG-Avi tag in mouse embryonic stem cells. The tagged proteins were subjected to tandem-affinity purification and analysis by mass spectrometry.
Project description:Histone H3 lysine 9 (H3K9) methylation and heterochromatin protein 1 (HP1) are well conserved epigenetic silencing mark and its reader molecule, and crucial for heterochromatin formation. However, the details of the importance of H3K9 methylation and HP1 in heterochromatin formation still remain unclear. One of the reason is the redundancy problem, as there are multiple reader molecules for H3K9 methylation, including HP1, and HP1 itself functions as a hub that recruits various effector molecules. To overcome the redundancy issue, we took synthetic biology approach and introduced H3K9 methylation and HP1 into budding yeast Saccharomyces cerevisiae, which does not have this system, and examined its impact on transcription and chromatin compaction. We observed that mammalian H3K9 methyltransferase can induce genome wide H3K9 di- and tri-methylation (H3K9me2,3) in budding yeast, and that HP1 accumulates over the H3K9 methylated regions. However, H3K9 methylation occurred mainly in the gene body region of the genes and excluded around TSS where H3K9ac pre-exists. Correspondingly, expression of H3K9 methyltransferase and HP1 did not affect transcription in budding yeast, including repression. ATAC-seq analysis also showed no impact on chromatin accessibility, and Hi-C-seq analysis of chromatin 3D structure revealed no significant differences. These results suggest that even though H3K9 methylation and recruitment of HP1 play essential roles in epigenetic regulation of heterochromatin, they are not sufficient to build up heterochromatin, at least at gene body regions, and further participation of effector molecules, including downstream factors of HP1, is required.
Project description:Histone H3 lysine 9 (H3K9) methylation and heterochromatin protein 1 (HP1) are well conserved epigenetic silencing mark and its reader molecule, and crucial for heterochromatin formation. However, the details of the importance of H3K9 methylation and HP1 in heterochromatin formation still remain unclear. One of the reason is the redundancy problem, as there are multiple reader molecules for H3K9 methylation, including HP1, and HP1 itself functions as a hub that recruits various effector molecules. To overcome the redundancy issue, we took synthetic biology approach and introduced H3K9 methylation and HP1 into budding yeast Saccharomyces cerevisiae, which does not have this system, and examined its impact on transcription and chromatin compaction. We observed that mammalian H3K9 methyltransferase can induce genome wide H3K9 di- and tri-methylation (H3K9me2,3) in budding yeast, and that HP1 accumulates over the H3K9 methylated regions. However, H3K9 methylation occurred mainly in the gene body region of the genes and excluded around TSS where H3K9ac pre-exists. Correspondingly, expression of H3K9 methyltransferase and HP1 did not affect transcription in budding yeast, including repression. ATAC-seq analysis also showed no impact on chromatin accessibility, and Hi-C-seq analysis of chromatin 3D structure revealed no significant differences. These results suggest that even though H3K9 methylation and recruitment of HP1 play essential roles in epigenetic regulation of heterochromatin, they are not sufficient to build up heterochromatin, at least at gene body regions, and further participation of effector molecules, including downstream factors of HP1, is required.
Project description:Histone H3 lysine 9 (H3K9) methylation and heterochromatin protein 1 (HP1) are well conserved epigenetic silencing mark and its reader molecule, and crucial for heterochromatin formation. However, the details of the importance of H3K9 methylation and HP1 in heterochromatin formation still remain unclear. One of the reason is the redundancy problem, as there are multiple reader molecules for H3K9 methylation, including HP1, and HP1 itself functions as a hub that recruits various effector molecules. To overcome the redundancy issue, we took synthetic biology approach and introduced H3K9 methylation and HP1 into budding yeast Saccharomyces cerevisiae, which does not have this system, and examined its impact on transcription and chromatin compaction. We observed that mammalian H3K9 methyltransferase can induce genome wide H3K9 di- and tri-methylation (H3K9me2,3) in budding yeast, and that HP1 accumulates over the H3K9 methylated regions. However, H3K9 methylation occurred mainly in the gene body region of the genes and excluded around TSS where H3K9ac pre-exists. Correspondingly, expression of H3K9 methyltransferase and HP1 did not affect transcription in budding yeast, including repression. ATAC-seq analysis also showed no impact on chromatin accessibility, and Hi-C-seq analysis of chromatin 3D structure revealed no significant differences. These results suggest that even though H3K9 methylation and recruitment of HP1 play essential roles in epigenetic regulation of heterochromatin, they are not sufficient to build up heterochromatin, at least at gene body regions, and further participation of effector molecules, including downstream factors of HP1, is required.
Project description:Histone H3 lysine 9 (H3K9) methylation and heterochromatin protein 1 (HP1) are well conserved epigenetic silencing mark and its reader molecule, and crucial for heterochromatin formation. However, the details of the importance of H3K9 methylation and HP1 in heterochromatin formation still remain unclear. One of the reason is the redundancy problem, as there are multiple reader molecules for H3K9 methylation, including HP1, and HP1 itself functions as a hub that recruits various effector molecules. To overcome the redundancy issue, we took synthetic biology approach and introduced H3K9 methylation and HP1 into budding yeast Saccharomyces cerevisiae, which does not have this system, and examined its impact on transcription and chromatin compaction. We observed that mammalian H3K9 methyltransferase can induce genome wide H3K9 di- and tri-methylation (H3K9me2,3) in budding yeast, and that HP1 accumulates over the H3K9 methylated regions. However, H3K9 methylation occurred mainly in the gene body region of the genes and excluded around TSS where H3K9ac pre-exists. Correspondingly, expression of H3K9 methyltransferase and HP1 did not affect transcription in budding yeast, including repression. ATAC-seq analysis also showed no impact on chromatin accessibility, and Hi-C-seq analysis of chromatin 3D structure revealed no significant differences. These results suggest that even though H3K9 methylation and recruitment of HP1 play essential roles in epigenetic regulation of heterochromatin, they are not sufficient to build up heterochromatin, at least at gene body regions, and further participation of effector molecules, including downstream factors of HP1, is required.
Project description:Both RNAi-dependent and -independent mechanisms have been implicated in the establishment of heterochromatin domains, which may be stabilized by feedback loops involving chromatin proteins and modifications of histones and DNA. Neurospora crassa sports features of heterochromatin found in higher eukaryotes, namely cytosine methylation (5mC), methylation of histone H3 lysine9 (H3K9me) and HETEROCHROMATIN PROTEIN-1 (HP1), and provides a model to investigate heterochromatin establishment and maintenance. We mapped the distribution of HP1, 5mC, H3K9me3 and H3K4me2 at 100bp-resolution and explored their interplay. HP1, H3K9me3 and DNA methylation were extensively colocalized and defined 44 heterochromatic domains on linkage group VII, all relics of repeat-induced point mutation (RIP). Interestingly, the centromere was found in a striking ~350kb heterochromatic domain with no detectable H3K4me2. 5mC was not found in genes, in contrast to the situation in plants and animals. H3K9me3 is required for HP1 localization and DNA methylation. Here, we show that localization of H3K9me3 is independent of 5mC or HP1 at virtually all heterochromatin regions. In addition, we observed complete restoration of DNA methylation patterns after depletion and reintroduction of the H3K9 methylation machinery, indicating that the signals for de novo heterochromatin formation lie upstream of H3K9 methylation. These data show that A:T rich RIPâd DNA efficently directs methylation of H3K9, which in turn, directs methylation of associated cytosines. Immunoprecipitation experiments using antibodies to 5mC, H3K9me3, epitope-tagged HP1, and H3K4me2 were performed. The immunoprecipitate fraction was labeled with Cy5 and the total input was labeled with Cy3. Samples were hybridized to a N. crassa LGVII tiling path microarray.
Project description:Both RNAi-dependent and -independent mechanisms have been implicated in the establishment of heterochromatin domains, which may be stabilized by feedback loops involving chromatin proteins and modifications of histones and DNA. Neurospora crassa sports features of heterochromatin found in higher eukaryotes, namely cytosine methylation (5mC), methylation of histone H3 lysine9 (H3K9me) and HETEROCHROMATIN PROTEIN-1 (HP1), and provides a model to investigate heterochromatin establishment and maintenance. We mapped the distribution of HP1, 5mC, H3K9me3 and H3K4me2 at 100bp-resolution and explored their interplay. HP1, H3K9me3 and DNA methylation were extensively colocalized and defined 44 heterochromatic domains on linkage group VII, all relics of repeat-induced point mutation (RIP). Interestingly, the centromere was found in a striking ~350kb heterochromatic domain with no detectable H3K4me2. 5mC was not found in genes, in contrast to the situation in plants and animals. H3K9me3 is required for HP1 localization and DNA methylation. Here, we show that localization of H3K9me3 is independent of 5mC or HP1 at virtually all heterochromatin regions. In addition, we observed complete restoration of DNA methylation patterns after depletion and reintroduction of the H3K9 methylation machinery, indicating that the signals for de novo heterochromatin formation lie upstream of H3K9 methylation. These data show that A:T rich RIP’d DNA efficently directs methylation of H3K9, which in turn, directs methylation of associated cytosines.
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).