Project description:Chromatin immunoprecipitation and sequencing for 3 histone marks (H3K27ac, H3K27me3 and H3K4me1) was performed on livers of male and female mice with a combined loss of Ezh1 and Ezh2. The DKO mouse model used in these analyses is a global deletion of Ezh1 and hepatocyte-specific deletion of Ezh2, and is described in Bae WK et al, FASEB J. 2015 May;29(5):1653-62. doi: 10.1096/fj.14-261537. PMID: 25477280.
Project description:Polycomb group (PcG) proteins initiate the formation of repressed chromatin domains and regulate developmental gene expression. A mammalian PcG protein, Enhancer of Zeste homolog 2 (Ezh2), triggers transcriptional repression by catalyzing the addition of methyl groups onto lysine-27 of histone H3 (H3K27me2/3)1. This action facilitates the binding of other PcG proteins to histone H3 and compaction of chromatin. Interestingly, there exists a paralog of Ezh2, termed Ezh1, whose primary function remains unclear. Here, we provide evidence for genome-wide association of Ezh1 with active epigenetic marks, RNA polymerase II (PolII) and mRNA production. Ezh1 depletion reduced global PolII occupancy within gene bodies and resulted in delayed transcriptional activation during differentiation of skeletal muscle cells. Conversely, ectopic expression of wild-type Ezh1 led to premature gene activation and rescued PolII-elongation defects in Ezh1-depleted cells. Collectively, these findings reveal an unanticipated role of a PcG protein in promoting mRNA transcription. Examination of 3 different histone modifications, 3 modified forms of RNA polymerase II, Ezh1, Ezh2 and mRNA levels in a skeletal muscle cells at various developmental stages.
Project description:Polycomb group proteins (PcG) are well known by their function in the regulation of developmental processes. PcG mediated regulation of genetic programs required for proper development are triggered by EZH2 H3K27 methyltransferase activity. EZH1 can partially substitute EZH2 activity. However, unlike EZH2, EZH1 is presence in differentiated and adult tissues suggesting additional biological functions. Here we show that EZH2 is predominantly expressed in neural stem cells being essential for neural stem cells self renewal and homeostasis. There, it controls the transcriptional state of cell cycle regulators, such as CIP1. But it is also necessary to regulate genes involved in surveillance and neuroepithelial polarity. In contrast, EZH1 expression is more abundant in differentiated cells within the spinal cord and its downregulation unables neural stem cells to differentiate. All together our data reveal a complementary but non-redundant role of EZH2 and EZH1 in neurogenesis.
Project description:Establishment and differentiation of mammary alveoli during pregnancy are controlled by prolactin through the transcription factor STAT5. As pregnancy progresses mammary signature genes are activated in a defined temporal order, which coincides with the recruitment of STAT5 to respective regulatory sequences. This study addressed the question whether the methyltransferase and transcriptional co-activator EZH2 controls the differentiation clock of mammary epithelium. Ablation of Ezh2 from mammary stem cells resulted in precocious differentiation of alveolar epithelium and accelerated activation of mammary signature genes. This coincided with enhanced occupancy by EZH1, Pol II and STAT5 to mammary-specific loci. Notably, loss of EZH2 did not result in overt changes in genome-wide and gene-specific H3K27me3 patterns, suggesting that enhanced EZH1 recruitment can compensate for the loss of EZH2. However, differentiated mammary epithelia failed to form in the combined absence of EZH1 and EZH2. Transplantation experiments failed to demonstrate a role for EZH2 in the biology of mammary stem and progenitor cells. In summary, while EZH1 and EZH2 serve redundant functions in the establishment of H3K27me3 and formation of mammary alveoli, the presence of EZH2 is required to obtain controlled temporal differentiation of mammary epithelium. ChIP-seq EZH1, EZH2, PolIII; WT and E2KO mammary cells
Project description:Bulk ATAC_seq on GFP expressing FACS-isolated cells from E16.5 and P0 Six2TGC and compound Ezh1 and Ezh2 mutant kidneys( Six2TGC_Ezh2-/- , Ezh1+/-; Six2TGC_Ezh2-/-; and Ezh1-/- ; scRNA-seq analysis of NPCs (Six2/GFP+ cells) from E16.5 as well as P2 kidneys. Genotypes analyzed: Six2TGC (E16.5&P2), Six2TGCEzh2-/- (E16.5), Ezh1+/-;Six2TGCEzh2-/- (E16.5), and Ezh2-/-;Six2TGCEzh2-/- (E16.5) Six2/GFP+ nephron progenitor cells (NPCs) give rise to all epithelial cell types of the nephron, the filtering unit of the kidney. NPCs have a limited lifespan and are consumed near the time of birth. Pre-term birth or prenatal stress further shorten the lifespan of NPCs and result in nephron deficit and chronic kidney disease. Accordingly, there is a pressing need to better understand the factors that regulate NPC lifespan in order to develop novel regenerative strategies. Epigenetic factors are implicated in maintenance of organ-restricted progenitors such as NPCs, but the chromatin-based mechanisms are not well understood. In this study, we examined the role of the H3K27 methyltransferases, Enhancer of zeste (Ezh1 and Ezh2), in NPC maintenance using a combination of gene targeting, chromatin profiling, and single-cell RNA analysis. We find that Ezh2 expression correlates with NPC growth potential, and that Ezh2 is the dominant H3K27 methyltransferase in NPCs and epithelial descendants. Surprisingly, NPCs lacking H3K27me3 maintain their progenitor state albeit cycle slowly leading to formation of fewer nephrons. Unlike Ezh2 loss-of-function, dual inactivation of Ezh1 and Ezh2 triggers overexpression of the transcriptional repressor Hey1 and downregulation of Six2 and result in unscheduled activation of Wnt4-driven differentiation, early termination of nephrogenesis and severe renal dysgenesis. Double-mutant NPCs also overexpress the Six family member, Six1. However, in this context, Six1 is unable to access the closed Six2 enhancer and fails to maintain NPC stemness. At the chromatin level, Ezh1 and Ezh2 act by restricting accessibility of AP1 factors to their genomic binding motifs and their absence provokes a regulatory landscape akin of differentiated and non-lineage cells. We conclude that Ezh2 is required for NPC renewal potential, while maintenance of NPC lifespan and tempering the differentiation program require cooperation of both Ezh1 and Ezh2.
Project description:Although epigenetic mechanisms, such as specific histone modifications, control common and cell-specific genetic programs, a role for histone modifying enzymes in liver metabolism and disease has not been investigated. This report demonstrates that the combined loss of the histone methyltransferases EZH1 and EZH2 in mouse hepatocytes led to the disruption of H3K27me3 homeostasis by age three months, simple fatty liver by age six months and fatal fibrosis by age 15 months. Global and gene-specific reduction of H3K27me3 marks paralleled a concomitant increase of H3K4me3 marks at genes associated with chronic liver disease. Advanced disease was accompanied by widespread infiltration of immune cells, an increase of activated hepatic stellate cells and collagen deposition. Expression of genes from the cytochrome P450 family that control drug metabolism was already deregulated by age two months and mice were fatally hypersensitive to carbon tetrachloride (CCl4). These genetic experiments, for the first time, illustrate that the simple loss of EZH1/EZH2, which results in the disruption of epigenetic modifications, is sufficient for the progression of fatal liver disease. RNA-seq and ChIP-seq were performed in liver tissues.
Project description:PolyA-selected RNA isolated from livers of adult male and female mice with a combined loss of EZH1 and EZH2 in hepatocytes was analyzed by RNA-seq. The DKO mouse model used in these analyses is a global deletion of Ezh1 and hepatocyte-specific deletion of Ezh2, and is described in Bae WK, Kang K, Yu JH, Yoo KH, Factor VM, Kaji K, Matter M, Thorgeirsson S, Hennighausen L. FASEB J. 2015 May;29(5):1653-62. doi: 10.1096/fj.14-261537. PMID: 25477280
Project description:Transcriptional profiling of whole kidneys from Six2CreEGFP mice without (WT) or with (KO) homozygously floxed Ezh2 alleles at the age of embryonic day 17.5. This experiment aimed to uncover the genome-wide alternation in gene expression resulting from the removal of Ezh2 gene in the nephron progenitor population (Six2 positive) in combination with the removal of Ezh1 gene from germline, and successive changes to the series of events in kidney development.