Project description:EZH2 plays an important role in stem cell renewal and maintenance by inducing gene silencing via its histone methyltransferase activity. Previously, we showed EZH2 downregulation markedly enhances neuron differentiation of human mesenchymal stem cells (hMSCs). To understand how EZH2 regulates neuron differentiation of hMSCs, we wanted to identify the target genes of EZH2. For this reasons we performed ChIP-on-chip experiments using specific EZH2 antibodies followed by a human promoter array for the whole human genome. The 3A6-hMSCs were differentiated into neuron for 5 days, and then 109 cells were harvested for the ChIP-on-chip assay. The procedure was based on the manufacturer's instructions (NimbleGen).
Project description:EZH2 plays an important role in stem cell renewal and maintenance by inducing gene silencing via its histone methyltransferase activity. Previously, we showed EZH2 downregulation markedly enhances neuron differentiation of human mesenchymal stem cells (hMSCs). To understand how EZH2 regulates neuron differentiation of hMSCs, we wanted to identify the target genes of EZH2. For this reasons we performed ChIP-on-chip experiments using specific EZH2 antibodies followed by a human promoter array for the whole human genome.
Project description:The polycomb repressor complex 2 molecule EZH2 is now known to play a role in essential cellular processes, namely, cell fate decisions, cell cycle regulation, senescence, cell differentiation, and cancer development/progression. EZH2 inhibitors have recently been developed; however, their effectiveness and underlying molecular mechanisms in many malignancies have not yet been elucidated in detail. Although the functional role of EZH2 in tumorigenesis in neuroblastoma (NB) has been investigated, mutations of EZH2 have not been reported. A Kaplan-Meier analysis on the event free- and overall survival of NB patients indicated that the highexpression of EZH2 correlated with an unfavorable prognosis. In order to elucidate the functional roles of EZH2 in NB tumorigenesis and its aggressiveness, we knocked down EZH2 in NB cell lines using lentivirus systems. The knockdown of EZH2 significantly induced NB cell differentiation, e.g. neurite extension, and the neuronal differentiation markers, NF68 and GAP43. EZH2 inhibitors also induced NB cell differentiation. We performed a comprehensive transcriptome analysis using Human Gene Expression Microarrays and found that NTRK1 (TrkA) is one of the EZH2-related suppression targets. The depletion of NTRK1 canceled EZH2 knockdown-induced NB cell differentiation. Our integrative methylome, transcriptome, and chromatin immunoprecipitation assays using NB cell lines and clinical samples clarified that the NTRK1 P1 and P2 promoter regions were regulated differently by DNA methylation and EZH2-related histone modifications. The NTRK1 transcript variants 1/2, which were regulated by EZH2-related H3K27me3 modifications at the P1 promoter region, were strongly expressed in favorable, but not unfavorable NB. The depletion and inhibition of EZH2 successfully induced NTRK1 transcripts and functional proteins. Collectively, these results indicate that EZH2 plays important roles in preventing the differentiation of NB cells and also that EZH2-related NTRK1 transcriptional regulation may be the key pathway for NB cell differentiation.
Project description:Mesendoderm (ME) differentiation of human embryonic stem cells (hESCs) is directed by various extrinsic signals together with intrinsic epigenetic modifications. However, the dynamics of epigenetic modifications and their regulation to initiate ME differentiation remain elusive. In this study, we report that H3K27me3 is decreased during ME initiation, which is essential for the subsequent differentiation by collaborative effects of Activin and Wnt signaling. Mechanistically, Activin decreases the H3K27me3 level via disruption of the SUZ12-EZH2 interaction and EZH2 degradation mediated by Smad2. Our data suggest a two-step process of ME initiation: firstly H3K27me3-marked epigenetic priming and secondly transcription activation. Our findings unravel a critical role of H3K27me3 priming and a direct interaction between extrinsic signals and epigenetic modifications during ME initiation.
Project description:Epigenetic alterations appear to modulate Myc signaling. We investigated the role of the histone demethylase JMJD2B in Myc-mediated neuroblastoma pathogenesis. We demonstrate that Myc physically interacts with and recruits this epigenetic modifier, which removes repressive H3K9 methyl marks from Myc-target genes. JMJD2B regulates neuroblastoma proliferation and, together with MYCN amplification, identifies a subgroup of poor prognosis patients. We identify a novel histone demethylase inhibitor, ciclopirox, which targets JMJD2B and, consequently, Myc signaling, thereby inhibiting neuroblastoma proliferation and inducing differentiation. In xenograft studies, genetic and pharmacologic inhibition of JMJD2B resulted in significant tumor growth restriction. Our findings provide insight into epigenetic regulation of Myc via histone methylation and proof-of-concept for pharmacologic inhibition of histone demethylases to target Myc signaling in cancer. 8 samples were treated with vehicle or ciclopirox.
Project description:Epigenetic alterations appear to modulate Myc signaling. We investigated the role of the histone demethylase JMJD2B in Myc-mediated neuroblastoma pathogenesis. We demonstrate that Myc physically interacts with and recruits this epigenetic modifier, which removes repressive H3K9 methyl marks from Myc-target genes. JMJD2B regulates neuroblastoma proliferation and, together with MYCN amplification, identifies a subgroup of poor prognosis patients. We identify a novel histone demethylase inhibitor, ciclopirox, which targets JMJD2B and, consequently, Myc signaling, thereby inhibiting neuroblastoma proliferation and inducing differentiation. In xenograft studies, genetic and pharmacologic inhibition of JMJD2B resulted in significant tumor growth restriction. Our findings provide insight into epigenetic regulation of Myc via histone methylation and proof-of-concept for pharmacologic inhibition of histone demethylases to target Myc signaling in cancer. 8 samples were transfected with two different siRNAs for control, JMJD2B, MYCN and JARID1A.
Project description:Epigenetic modification by polycomb repressive complex (PRC) molecules appears to have a role in tumorigenesis and aggressiveness of neuroblastoma (NB). Embryonic Ectoderm Development (EED) is a member of PRC2 complex and binds the H3K27me3 mark deposited by EZH2, via propagation on adjacent nucleosomes. Here we studied the molecular roles of EED in MYCN-amplified neuroblastoma cells by using EED-knocked down shRNAs, EED-knocked out sgRNAs, and EED small molecule inhibitor EED226. EED suppression profoundly inhibited the NB cell proliferation and flat-and soft agar colony formation. Transcriptome analysis by microarray of the EED-KD NB cells indicated the de-repression of the cell cycle regulated and differentiation-related genes; GSEA analysis results suggested that cell cycle repressed gene sets were strongly upregulated. Further, epigenetic treatment by the combination of EED inhibitor EED226 and HDAC inhibitor valproic acid effectively suppressed NB cell proliferation and colony formation. The combinatory epigenetic treatment up-regulated the cell cycle regulation- and differentiation-related genes.
Project description:Purpose: Identify new targets in MYCN-amplified Neuroblastoma Methods: ChIP-Seq experiments were performed on Kelly and LAN-1 neuroblastoma cells by using the following antibodies: anti-EZH2 (Cell Signaling 5246S); anti-H3K27me3 (Millipore 07-449); anti-H3K4me3 (Abcam ab8580). We evaluated the global EZH2 PRC2-dependence by identifiying direct genome-wide target genes for EZH2, H3K27me3 and H3K4me3. Results: We found that EZH2 serves a PRC2-dependent function in neuroblastoma, repressing neuronal differentiation. Moreover, EZH2-regulated genes were strongly repressed in MYCN-amplified and high-risk primary tumors. Conclusion: Our study supports testing EZH2 inhibitors in patients with MYCN-amplified neuroblastoma.
Project description:The epigenetic mechanisms that enable specialized astrocytes to retain neurogenic competence throughout adult life are still poorly understood. Here we show that astrocytes that serve as neural stem cells (NSCs) in the adult mouse subventricular zone (SVZ) express the histone methyltransferase EZH2. This Polycomb repressive factor is required for neurogenesis independent of its role in SVZ NSC proliferation, as Ink4a/Arf-deficiency in Ezh2-deleted SVZ NSCs rescues cell proliferation, but neurogenesis remains defective. Olig2 is a direct target of EZH2, and repression of this bHLH transcription factor is critical for neuronal differentiation. Furthermore, Ezh2 prevents the inappropriate activation of genes that specify non-SVZ neuronal subtypes. In the human brain, SVZ cells including local astroglia also express EZH2, correlating with postnatal neurogenesis. Thus, EZH2 is an epigenetic regulator that distinguishes neurogenic SVZ astrocytes, orchestrating distinct and separable aspects of adult stem cell biology, which has important implications for regenerative medicine and oncogenesis. Examination of histone modifications (H3K27me3 and H3K4me3) in subventricular zone neural stem cells