A role for Widely Interspaced Zinc finger (WIZ) in retention of the G9a methyltransferase on chromatin
ABSTRACT: G9a and GLP lysine methyltransferases form a heterodimeric complex that is responsible for the bulk of cellular mono- and di-methylation on histone H3 lysine 9 (H3K9me1/me2). Widely Interspaced Zinc finger (WIZ) associates with the G9a/GLP protein complex, but its role in lysine methylation is poorly defined. Here, we show that WIZ regulates global H3K9me2 levels through a mechanism that involves retention of G9a on chromatin. We also show that WIZ-mediated chromatin loss of G9a/GLP results in altered gene expression and protein-protein interactions that are distinguishable from that of using a molecule-induced enzymatic inhibitor towards G9a/GLP – thus providing evidence that the G9a/GLP/WIZ complex has unique functions when bound to chromatin that are independent of the H3K9me2 mark DMSO, UNC0638, NS, and siWIZ treatments to HEK293T cells, assessing G9a and H3K9me2 localization, each performed in duplicate, plus one input control for each cell condition. 30 samples total.
Project description:G9a (EHMT2) and the G9a-like protein GLP (EHMT1) form a stable G9a/GLP heterodimer in embryonic stem cells and function cooperatively to establish and maintain the abundant repressive H3K9me2 modification, in addition to modifying several non-histone proteins. The G9a-dependent H3K9me2 is implicated in lineage-specific gene silencing and covers large chromosomal domains. While the mechanism of H3K9me2maintenance by G9a/GLP is known, how new patterns of this modification are established is not well understood. With this in mind, we used FLAG affinity purification of G9a under two different stringency conditions (150 and 300 mM NaCl) coupled with mass spectrometry to identify proteins stably associated with G9a/GLP, which could serve as potential recruiters of the complex to unmodified chromatin.
Project description:AIM: We performed RNA-sequencing experiments seeking genes whose expression changed due to nerve injury. In addition, we wanted to test whether inhibition of the methyl transferase G9a/GLP, that methylates H3K9me2, could reverse those expression changes due to nerve ligation. G9a/GLP methylase was pharmacologically inhibited using UNC0638. METHOD: We generated cDNA libraries from RNA purified from DRGs obtained from Sham operated (4), SNL (4), and SNL plus UNC0638 (3) rats. We sequenced the cDNA libraries generating single end 50 bp reads on the illumina HiSeq 2500 platform. Sequencing reads were aligned to the rat genome rn4 using TopHat RESULTS: We were able to map 16876 genes, from which 2035 changed their expression values at least two fold when we compared SNL to Sham operated (p≤ 0.01). There were 1205 upregulated and 832 down-regulated genes. Next, we focused on genes whose expression was either up or down-regulated 2 fold due to nerve ligation, and the values would be normalized to control level after G9a/GLP inhibito (UNC0638)r treatment. We identified 639 genes in our data set that behave this way We generated cDNA libraries from RNA purified from DRGs obtained from Sham operated (4), SNL (4), and SNL plus UNC0638 (3) rats. We sequenced the cDNA libraries generating single end 50 bp reads on the illumina HiSeq 2500 platform. Sequencing reads were aligned to the rat genome rn4 using TopHat
Project description:We profiled chromatin accessibility across the genome of HSPCs treated with either a small molecule inhibitor of G9a/GLP or DMSO. We observed that chromatin accessibility is dramatically altered at the regions of H3K9me2 nucleation. We have characterized the regions of H3K9me2 nucleation, revealing that H3K9me2 is nucleated in HSPCs at CpG islands (CGIs) and CGI-like sequences across the genome. Our analysis furthermore revealed a bias of H3K9me2 nucleation towards regions with low rates of C->T deamination, which typically lack DNA methylation. Lastly we examined the interaction of H3K9me2 and DNA methylation and determined that chromatin accessibility changes upon loss of H3K9me2 are dependent on the presence of DNA methylation. Examination of chromatin remodeling with FAIRE-seq in HSPCs treated with either a small molecule inhibitor of G9a/GLP or DMSO
Project description:Lysine methylation of histone proteins regulates chromatin dynamics and plays important roles in diverse physiological and pathological processes. However, beyond histone proteins, the proteome-wide extent of lysine methylation is largely unknown. We have developed the naturally occurring MBT domain repeats of L3MBTL1 (3xMBT) to serve as a universal affinity reagent for detecting, enriching, and identifying proteins carrying a mono- or dimethylated lysine. The domain is broadly specific for methylated lysine ("pan-specific") and can be applied to any biological system. In experiments using two different instruments (experiment 1 - Orbitrap Elite, experiment 2 - Orbitrap Velos) we have used SILAC to compare proteins captured by 3xMBT to proteins captured by the D355N mutant, which does not bind methylated lysine. Data was analyzed using MaxQuant version 220.127.116.11 using default parameters except that mono and di-methylated lysine were included as variable modifications and modification-specific false discovery rate was set to 10%. Several hundred proteins are specifically enriched by 3xMBT and we have directly detected lysine methylation on about two dozen. We have also used our approach to identify candidate in-cell substrates of G9a and the related methyltransferase GLP. Three-way SILAC was used to compare methylated proteins between cells treated with UNC0638, a specific inhibitor of G9a and GLP, and cells treated with vehicle control. We find reduced capture of the known G9a substrates WIZ and ACIN1, as well as identifying DNA ligase 1 as a potential target for G9a/GLP. Together, our results demonstrate a powerful new approach for global and quantitative analysis of methylated lysine, and they represent the first systems biology understanding of lysine methylation.
Project description:The methyltransferase G9a was found to play a role in the disease progression of a murine model of AML. Mouse HSPCs were transformed with HoxA9/Meis1 and treated with G9a/GLP inhibitor UNC0638. We used microarrays to detail the global program of gene expression that depends on the methyltransferase activity of G9a in murine AML cells.
Project description:Histone H3 lysine 9 (H3K9) is a target for posttranslational histone methylation associated with gene repression. Most of H3K9me2 modification in mammalian cells is mediated by histone methyltransferase G9a that is essential for mouse embryo development and plays an oncogenic role in acute myeloid leukemia (AML), a highly malignant blood cancer. In this study, ChIP-sequencing was used to conduct a detailed whole-genomic characterization of the localization and expression of H3K9me2 and to identify epigenetic changes associated with normal myeloid differentiation and AML. Genome-wide computational analysis using hidden Markov model was employed to map multiple associations of chromatin modification topographies with transcription in leukemia and define chromosomal domains undergoing epigenetic changes in AML Overall design: ChIP-Seq with antibodies against H3K9me2 was used with normal human granulocytes (2 samples), CD34+ hematopoietic progenitors (2 samples), K562 cells (2 intact samples and 2 samples treated with G9a inhibitor UNC0638), and primary myeloblasts from 8 different acute myeloid leukemia samples. Each H3K9me2 ChIP-seq was repeated twice. In addition, control experiments for antibody specificity were conducted with ChIP input DNA (16 samples), and ChIP-seq with antibodies against histone H3K9me3 (4 samples), histone H3K4me2 (1 sample), and nonmodified histone H3 C-tail (2 samples).
Project description:Transcriptional profiling of HEK293T cells following treatment with a small molecule inhibitor of catalytic activity of the G9a lysine methyltransferase (UNC0638, 1 micromolar, 48 hours), or siRNA against WIZ or G9a (72 hours treatment). Overall design: Two condition experiment, UNC0638 vs DMSO, G9a siRNA vs control siRNA, or WIZ siRNA vs control siRNA. Biological replicates: UNC0638 vs DMSO 5 biological replicates with 2 dye swap experiments; G9a siRNA vs control siRNA, 2 biological replicates; WIZ siRNA vs control siRNA, 2 biological replicates with 2 dye swap experiments.
Project description:G9a/GLP and Polycomb Repressive Complex 2 (PRC2) are two major epigenetic silencing machineries, which in particular methylate histone H3 on lysines 9 and 27 (H3K9 and H3K27), respectively. Although evidence of a crosstalk between H3K9 and H3K27 methylations has started to emerge, their actual interplay remains elusive. Here, we show that PRC2 and G9a/GLP interact physically and functionally. Moreover, combining different genome-wide approaches, we demonstrate that Ezh2 and G9a/GLP share an important number of common genomic targets, encoding developmental and neuronal regulators. Furthermore, we show that G9a enzymatic activity modulates PRC2 genomic recruitment to a subset of its target genes. Taken together, our findings demonstrate an unanticipated interplay between two main histone lysine methylation mechanisms, which cooperate to maintain silencing of a subset of developmental genes. Microarray has been perform in triplicate on total extract RNA from mES cell (TT2 : Wildtype and KOs G9a-/-, GLP-/-, G9a-/- and GLP-/-)
Project description:We use ChIP-Seq and RNA-Seq technology to profile the H3K9me2 modification and transcription under different conditions of GLP activity. GLP and G9a are major H3K9 dimethylases, and are essential for mouse early embryonic development. Here we report that GLP and G9a possess intrinsic histone methylation propagating activities. The histone methyltransferase activities of GLP and G9a are stimulated by neighboring nucleosomes pre-methylated at H3K9. These stimulation events function in cis and are dependent on H3K9 methylation binding activities of ankyrin repeats domains in GLP and G9a. In mouse embryonic stem cells (ESCs) harboring a mutant GLP lacking H3K9 methylation propagating activity, pluripotent genes display a delayed kinetics in establishing H3K9 methylation and gene silencing during differentiation. Disruption of the H3K9 methylation propagating activity of GLP in mice causes growth retardation of the embryos, ossification defects of calvaria and early postnatal lethality. We propose that GLP¡¯s ability to rapidly propagate H3K9 methylation is required for efficient gene silencing during programmed cell fate transition. H3K9me2 and H3K9me1 are ChIPped and sequenced in WT mESC and GLP-mutant mESCs, and RNA-Seq was done for those cells as well.
Project description:G9a/GLP and Polycomb Repressive Complex 2 (PRC2) are two major epigenetic silencing machineries, which in particular methylate histone H3 on lysines 9 and 27 (H3K9 and H3K27), respectively. Although evidence of a crosstalk between H3K9 and H3K27 methylations has started to emerge, their actual interplay remains elusive. Here, we show that PRC2 and G9a/GLP interact physically and functionally. Moreover, combining different genome-wide approaches, we demonstrate that Ezh2 and G9a/GLP share an important number of common genomic targets, encoding developmental and neuronal regulators. Furthermore, we show that G9a enzymatic activity modulates PRC2 genomic recruitment to a subset of its target genes. Taken together, our findings demonstrate an unanticipated interplay between two main histone lysine methylation mechanisms, which cooperate to maintain silencing of a subset of developmental genes. ChIP-seq has been performed for G9a and Ezh2 in wild type TT2 mES cells or in mES cells lacking both G9a and GLP (G9a-/-GLP-/-). As a control, input DNA was saved before immunoprecipitation. Note that the two inputs (Input_TT2_0 and Input_TT2_1) have been combined and used as control for Ezh2 and G9a ChIP-seq.