Effect of T350 phosphorylation on gene repression activity of EZH2 in BJ cells
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ABSTRACT: The Polycomb group (PcG) protein enhancer of zeste homolog 2 (EZH2) plays an essential role in histone methylation-mediated epigenetic gene silencing. We demonstrate that under physiological conditions, cyclin-dependent kinase 1 (CDK1) and 2 (CDK2) bind to and phosphorylate EZH2 at threonine 350 (T350) in an evolutionally conserved motif. T350 phosphorylation is required for EZH2 function in silencing of genes that promote differentiation and inhibit proliferation and migration. Blockage of T350 phosphorylation by generating a T350A mutation largely diminishes the global effect of EZH2 on gene silencing. Four experiments have been designed. BJ cells were transfected with si-Control, si-EZH2, si-EZH2 plus RNAi resistant lentivirus expressed EZH2, or si-EZH2 plus RNAi resistant lentivirus expressed T350A mutant for 60 hours. Each experiment was triplicated.
Project description:The Polycomb group (PcG) protein enhancer of zeste homolog 2 (EZH2) plays an essential role in histone methylation-mediated epigenetic gene silencing. We demonstrate that under physiological conditions, cyclin-dependent kinase 1 (CDK1) and 2 (CDK2) bind to and phosphorylate EZH2 at threonine 350 (T350) in an evolutionally conserved motif. T350 phosphorylation is required for EZH2 function in silencing of genes that promote differentiation and inhibit proliferation and migration. Blockage of T350 phosphorylation by generating a T350A mutation largely diminishes the global effect of EZH2 on gene silencing. Seven experiments have been designed. LNCaP cells were transfected with si-Control, si-EZH2, si-EZH2 plus RNAi resistant EZH2 plasmid, or si-EZH2 plus RNAi resistant T350A mutated EZH2 plsamid for 60 hours, or treated with DMSO, 5 uM TSA, or 10 uM Roscovitine for 24 hours. Two replicates per experiment.
Project description:The Polycomb group (PcG) protein enhancer of zeste homolog 2 (EZH2) plays an essential role in histone methylation-mediated epigenetic gene silencing. We demonstrate that under physiological conditions, cyclin-dependent kinase 1 (CDK1) and 2 (CDK2) bind to and phosphorylate EZH2 at threonine 350 (T350) in an evolutionally conserved motif. T350 phosphorylation is required for EZH2 function in silencing of genes that promote differentiation and inhibit proliferation and migration. Blockage of T350 phosphorylation by generating a T350A mutation largely diminishes the global effect of EZH2 on gene silencing.
Project description:The Polycomb group (PcG) protein enhancer of zeste homolog 2 (EZH2) plays an essential role in histone methylation-mediated epigenetic gene silencing. We demonstrate that under physiological conditions, cyclin-dependent kinase 1 (CDK1) and 2 (CDK2) bind to and phosphorylate EZH2 at threonine 350 (T350) in an evolutionally conserved motif. T350 phosphorylation is required for EZH2 function in silencing of genes that promote differentiation and inhibit proliferation and migration. Blockage of T350 phosphorylation by generating a T350A mutation largely diminishes the global effect of EZH2 on gene silencing.
Project description:Lentivirus mediated RNAi was used to silence TCEB1 expression in PC-3 prostate cancer cell line. Whole human genome microarray was used to study changes in gene expression induced by the silencing.
Project description:In order to Sp1 and EZH2-specific gene expression pattern in breast cancer, small interfering RNA for Sp1 and EZH2 was transfected in MDA-MB-231 cells. Four groups of samples are included: 1. si control (siCT_1, siCT_2, siCT_3). 2. siSp1 (siSp1_1, sisSp1_2, siSp1_3). 3. si control (siCT_A, siCT_B, siCT_C). 4. siEZH2 (siZEH2_1, siZEH2_2,siEZJ2_3). Gene expression profiles of Sp1 and EZH2 depleted cells were compared to that of siRNA controls. Experiments were performed in MDA-MB-231 cells.
Project description:Unveiling the molecular mechanisms of tissue remodelling following injury is imperative to elucidate its regenerative capacity and aberrant repair in disease. Using different omics approaches, we identified enhancer of zester homolog 2 (EZH2) as a key regulator that initiates a fibrotic cascade in injured lung epithelium. Epithelial-injury-driven enrichment of nuclear transforming growth factor-b-activated kinase 1 (TAK1) mediates EZH2 phosphorylation to facilitate the release of EZH2 from polycomb repressive complex 2 (PRC2). This process leads to the establishment of a fibrotic transcriptional complex of EZH2, RNA-polymerase II (POL2) and nuclear actin, which orchestrates aberrant epithelial lung repair programs. The liberation of EZH2 from PRC2 is accompanied by an EZH2-EZH1 switch to preserve silencing at non-target genes. Loss of epithelial TAK1, EZH2 or blocking nuclear actin influx attenuates the fibrotic cascade and restores respiratory homeostasis. Accordingly, EZH2 inhibition significantly improves outcomes in a pulmonary fibrosis mouse model. Our results reveal an important non-canonical function of EZH2, paving the way for new therapeutic interventions in fibrotic lung diseases.
Project description:Effective silencing by RNA-interference (RNAi) depends on mechanisms that amplify and propagate the silencing signal. In some organisms, small-interfering (si) RNAs are amplified from target mRNAs by RNA-dependent RNA polymerase (RdRP). Both RdRP recruitment and mRNA silencing require Argonaute proteins, which are generally thought to degrade RNAi targets by directly cleaving them. However in C. elegans, the enzymatic activity of the primary Argonaute, RDE-1, is not required for silencing activity. We show that RDE-1 can instead recruit an endoribonuclease, RDE-8, to target RNA. RDE-8 can cleave RNA in vitro and is needed for the production of 3′ uridylated fragments of target mRNA in vivo. We also find that RDE-8 promotes RdRP activity, thereby ensuring amplification of siRNAs. Together, our findings suggest a model in which RDE-8 cleaves target mRNAs to mediate silencing, while generating 3’ uridylated mRNA fragments to serve as templates for the RdRP-directed amplification of the silencing signal.
Project description:Knockdown of EZH2 in colorectal cancer cells by lentivirus-mediated shRNA, and use total RNA for sequencing analysis after determining the efficiency of EZH2 knockdown in order to analyze the gene expression affected by EZH2.
Project description:K-RAS activating mutations occur frequently in non-small cell lung cancer (NSCLC), leading to aberrant activation of Ras-MAPK signaling pathway that contributes to the malignant phenotype. However, the development of Ras-targeted therapeutics remains challenging. Here, we show that MED23, a component of the multisubunit Mediator complex that is known to integrate signaling and gene activities, is selectively important for Ras-active lung cancer. By screening a large panel of human lung cancer cell lines with or without a Ras mutation, we found that Med23 RNAi specifically inhibits the proliferation and tumorigenicity of lung cancer cells with hyperactive Ras activity. Med23-deficiency in fibroblasts selectively inhibited the oncogenic transformation induced by Ras but not by c-Myc. Transcription factor ELK1, which is phosphorylated by MAPK for relaying the Ras signaling to MED23, was also required for the Ras-driven oncogenesis. Transcriptiome analysis revealed that MED23 and ELK1 co-regulate a common set of target genes enriched in regulating cell cycle and proliferation to support the Ras-dependency. Furthermore, correlated with the strength of Ras signaling as indicated by the ELK1 phosphorylation level, MED23 was up-regulated by Ras-transformation, and was found to be overexpressed in both Ras-mutated lung cancer cell lines and primary tumor samples. Remarkably, lower Med23 expression predicts better survival in Ras-active lung cancer patients and xenograft mice. Collectively, our findings demonstrate a critical role for MED23 in enabling the 'Ras-addiction' of lung carcinogenesis, thus providing a vulnerable target for the treatment of Ras-active lung cancer. To gain a genome-wide understanding of how MED23 and ELK1 control gene expression in Ras-active lung cancer cells, we performed gene profiling experiments to analyze the transcriptomes from control, si-Med23, or si-Elk1 A549 cells. The si-Ctrl, si-Med23 and si-Elk1 A549 cells were cultured in the normal condition. Then the cells were harvested for RNA extraction and hybridization on Affymetrix microarrays. The analysis contain 9 samples. si-Ctrl cells have three replicates (si-Ctrl#1, si-Ctrl#2 and si-Ctrl#3), and the si-Med23 or si-Elk1 group contains three different cell lines that harbor three different RNAi oligos against Med23 or Elk1 (si-Med23A, B, C and si-Elk1A, B, C).
Project description:Context: Compared with European Americans, African Americans (AAs) are more insulin resistant, have a higher insulin secretion response to glucose, and develop type 2 diabetes more often. Molecular processes and/or genetic variations contributing to altered glucose homeostasis in high-risk AAs remain uncharacterized. Objective: Adipose and muscle transcript expression profiling and genotyping were performed in 260 AAs to identify genetic regulatory mechanisms associated with insulin sensitivity (SI). We hypothesized that: 1) transcription profiles would reveal tissue-specific modulation of physiologic pathways with SI, and 2) a subset of SI-associated transcripts would be controlled by DNA sequence variants as expression quantitative traits, and these variants in turn would be associated with SI. Design and Settings: The cross-sectional research study was performed in a clinical research unit. Participants: Unrelated nondiabetic AAs were recruited for the study. Main Outcome Measures: SI was measured by frequently sampled iv glucose tolerance test. Results: The expression levels of 2212 transcripts in adipose and 145 transcripts in muscle were associated with SI. Genes involved in eIF2, eIF4-p70S6K, and mTOR signaling were modulated with SI in both tissues. Genes involved in leukocyte extravasation signaling showed adipose-specific regulation, and genes involved in oxidative phosphorylation had discordant regulation between tissues. Intersecting cis-expression quantitative trait loci results with data from transcript-SI association analysis identified cis-regulatory single nucleotide polymorphisms for 363 and 42 SI-associated transcripts in adipose and muscle, respectively. Cis-eSNPs for three SI-associated adipose transcripts, NINJ1, AGA, and CLEC10A were associated with SI. Abrogation of NINJ1 induction in THP1 macrophages modulated expression of genes in chemokine signaling, cell adhesion, and angiogenesis pathways. Conclusion: This study identified multiple pathways associated with SI; particularly discordant tissue-specific regulation of the oxidative phosphorylation pathway, and adipose-specific regulation of transcripts in the leukocyte extravasation signaling pathway that seem to be important in insulin resistance. Identification of single nucleotide polymorphisms associated with SI and with modulation of expression of SI-associated transcripts, including NINJ1, reveals novel genetic regulatory mechanisms of insulin resistance in AAs.