scholarly journals Global changes of H3K27me3 domains and Polycomb group protein distribution in the absence of recruiters Spps or Pho

2018 ◽  
Vol 115 (8) ◽  
pp. E1839-E1848 ◽  
Author(s):  
J. Lesley Brown ◽  
Ming-an Sun ◽  
Judith A. Kassis
Keyword(s):  
Binding Sites ◽  
Target Genes ◽  
Polycomb Group ◽  
Global Changes ◽  
Polycomb Group Protein ◽  
Protein Distribution ◽  
Wild Type ◽  
Group Protein ◽  
Polycomb Response Elements ◽  
Active Genes

Polycomb group (PcG) proteins maintain the silenced state of key developmental genes in animals, but how these proteins are recruited to specific regions of the genome is still poorly understood. In Drosophila, PcG proteins are recruited to Polycomb response elements (PREs) that include combinations of sites for sequence specific DNA binding “PcG recruiters,” including Pho, Cg, and Spps. To understand their roles in PcG recruitment, we compared Pho-, Cg-, and Spps-binding sites against H3K27me3 and key PcG proteins by ChIP-seq in wild-type and mutant third instar larvae. H3K27me3 in canonical Polycomb domains is decreased after the reduction of any recruiter. Reduction of Spps and Pho, but not Cg, causes the redistribution of H3K27me3 to heterochromatin. Regions with dramatically depleted H3K27me3 after Spps knockout are usually accompanied by decreased Pho binding, suggesting their cooperative binding. PcG recruiters, the PRC2 component E(z), and the PRC1 components Psc and Ph cobind thousands of active genes outside of H3K27me3 domains. This study demonstrates the importance of distinct PcG recruiters for the establishment of unique Polycomb domains. Different PcG recruiters can act both cooperatively and independently at specific PcG target genes, highlighting the complexity and diversity of PcG recruitment mechanisms.

scholarly journals SUMOylation of the polycomb group protein L3MBTL2 facilitates repression of its target genes

2013 ◽  
Vol 42 (5) ◽  
pp. 3044-3058 ◽  
Author(s):  
Christina Stielow ◽  
Bastian Stielow ◽  
Florian Finkernagel ◽  
Maren Scharfe ◽  
Michael Jarek ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Target Genes ◽  
Polycomb Group ◽  
Hek293 Cells ◽  
Polycomb Group Protein ◽  
Wild Type ◽  
C Terminus ◽  
Lysine Residues ◽  
Group Protein

Abstract Lethal(3) malignant brain tumour like 2 (L3MBTL2) is an integral component of the polycomb repressive complex 1.6 (PRC1.6) and has been implicated in transcriptional repression and chromatin compaction. Here, we show that L3MBTL2 is modified by SUMO2/3 at lysine residues 675 and 700 close to the C-terminus. SUMOylation of L3MBTL2 neither affected its repressive activity in reporter gene assays nor it’s binding to histone tails in vitro. In order to analyse whether SUMOylation affects binding of L3MBTL2 to chromatin, we performed ChIP-Seq analysis with chromatin of wild-type HEK293 cells and with chromatin of HEK293 cells stably expressing either FLAG-tagged SUMOylation-competent or SUMOylation-defective L3MBTL2. Wild-type FLAG-L3MBTL2 and the SUMOylation-defective FLAG-L3MBTL2 K675/700R mutant essentially occupied the same sites as endogenous L3MBTL2 suggesting that SUMOylation of L3MBTL2 does not affect chromatin binding. However, a subset of L3MBTL2-target genes, particularly those with low L3MBTL2 occupancy including pro-inflammatory genes, was de-repressed in cells expressing the FLAG-L3MBTL2 K675/700R mutant. Finally, we provide evidence that SUMOylation of L3MBTL2 facilitates repression of these PRC1.6-target genes by balancing the local H2Aub1 levels established by the ubiquitinating enzyme RING2 and the de-ubiquitinating PR–DUB complex.

scholarly journals SIRT1 affects DNA methylation of polycomb group protein target genes, a hotspot of the epigenetic shift observed in ageing

2015 ◽  
Vol 9 (1) ◽  
Author(s):  
Luisa A Wakeling ◽  
Laura J Ions ◽  
Suzanne M Escolme ◽  
Simon J Cockell ◽  
Tianhong Su ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Target Genes ◽  
Polycomb Group ◽  
Polycomb Group Protein ◽  
Protein Target ◽  
Group Protein

scholarly journals USP7 Cooperates with SCML2 To Regulate the Activity of PRC1

2015 ◽  
Vol 35 (7) ◽  
pp. 1157-1168 ◽  
Author(s):  
Emilio Lecona ◽  
Varun Narendra ◽  
Danny Reinberg
Keyword(s):  
Chromatin Immunoprecipitation ◽  
Essential Role ◽  
Target Genes ◽  
Polycomb Group ◽  
Histone H2a ◽  
Polycomb Group Protein ◽  
Specific Component ◽  
Group Protein ◽  
The Common ◽  
Polycomb Repressive Complex 1

USP7 is a protein deubiquitinase with an essential role in development. Here, we provide evidence that USP7 regulates the activity of Polycomb repressive complex 1 (PRC1) in coordination with SCML2. There are six versions of PRC1 defined by the association of one of the PCGF homologues (PCGF1 to PCGF6) with the common catalytic subunit RING1B. First, we show that SCML2, a Polycomb group protein that associates with PRC1.2 (containing PCGF2/MEL18) and PRC1.4 (containing PCGF4/BMI1), modulates the localization of USP7 and bridges USP7 with PRC1.4, allowing for the stabilization of BMI1. Chromatin immunoprecipitation (ChIP) experiments demonstrate that USP7 is found at SCML2 and BMI1 target genes. Second, inhibition of USP7 leads to a reduction in the level of ubiquitinated histone H2A (H2Aub), the catalytic product of PRC1 and key for its repressive activity. USP7 regulates the posttranslational status of RING1B and BMI1, a specific component of PRC1.4. Thus, not only does USP7 stabilize PRC1 components, its catalytic activity is also necessary to maintain a functional PRC1, thereby ensuring appropriate levels of repressive H2Aub.

scholarly journals The iab-7 Polycomb Response Element Maps to a Nucleosome-Free Region of Chromatin and Requires Both GAGA and Pleiohomeotic for Silencing Activity

2001 ◽  
Vol 21 (4) ◽  
pp. 1311-1318 ◽  
Author(s):  
Rakesh K. Mishra ◽  
Jozsef Mihaly ◽  
Stéphane Barges ◽  
Annick Spierer ◽  
François Karch ◽  
...  
Keyword(s):  
Binding Sites ◽  
Polycomb Group ◽  
Polycomb Group Protein ◽  
Gaga Factor ◽  
Response Element ◽  
Polycomb Response Element ◽  
Free Region ◽  
Group Protein

ABSTRACT In the work reported here we have undertaken a functional dissection of a Polycomb response element (PRE) from the iab-7 cis-regulatory domain of the Drosophila melanogasterbithorax complex (BX-C). Previous studies mapped the iab-7PRE to an 860-bp fragment located just distal to the Fab-7boundary. Located within this fragment is an ∼230-bp chromatin-specific nuclease-hypersensitive region called HS3. We have shown that HS3 is capable of functioning as a Polycomb-dependent silencer in vivo, inducing pairing-dependent silencing of amini-white reporter. The HS3 sequence contains consensus binding sites for the GAGA factor, a protein implicated in the formation of nucleosome-free regions of chromatin, and Pleiohomeotic (Pho), a Polycomb group protein that is related to the mammalian transcription factor YY1. We show that GAGA and Pho interact with these sequences in vitro and that the consensus binding sites for the two proteins are critical for the silencing activity of theiab-7 PRE in vivo.

MES-2, a maternal protein essential for viability of the germline in Caenorhabditis elegans, is homologous to a Drosophila Polycomb group protein

Development ◽  
1998 ◽  
Vol 125 (13) ◽  
pp. 2457-2467 ◽  
Author(s):  
R. Holdeman ◽  
S. Nehrt ◽  
S. Strome
Keyword(s):  
Gene Expression ◽  
Caenorhabditis Elegans ◽  
Germ Cells ◽  
Target Genes ◽  
Essential Feature ◽  
Primordial Germ Cells ◽  
Polycomb Group ◽  
Polycomb Group Protein ◽  
Maternal Contribution ◽  
Group Protein

A unique and essential feature of germ cells is their immortality. In Caenorhabditis elegans, germline immortality requires the maternal contribution from four genes, mes-2, mes-3, mes-4 and mes-6. We report here that mes-2 encodes a protein similar to the Drosophila Polycomb group protein, Enhancer of zeste, and in the accompanying paper that mes-6 encodes another Polycomb group protein. The Polycomb group is responsible for maintaining proper patterns of expression of the homeotic and other genes in Drosophila. It is thought that Polycomb group proteins form heteromeric complexes and control gene expression by altering chromatin conformation of target genes. As predicted from its similarity to a Polycomb group protein, MES-2 localizes to nuclei. MES-2 is found in germline nuclei in larval and adult worms and in all nuclei in early embryos. By the end of embryogenesis, MES-2 is detected primarily in the two primordial germ cells. The correct distribution of MES-2 requires the wild-type functions of mes-3 and mes-6. We hypothesize that mes-2 encodes a maternal regulator of gene expression in the early germline; its function is essential for normal early development and viability of germ cells.

The DNA-binding polycomb group protein pleiohomeotic mediates silencing of a Drosophila homeotic gene

Development ◽  
1999 ◽  
Vol 126 (17) ◽  
pp. 3905-3913 ◽  
Author(s):  
C. Fritsch ◽  
J.L. Brown ◽  
J.A. Kassis ◽  
J. Muller
Keyword(s):  
Dna Binding ◽  
Binding Sites ◽  
Point Mutations ◽  
Polycomb Group ◽  
Homeotic Gene ◽  
Homeotic Genes ◽  
Polycomb Group Protein ◽  
Cis Acting ◽  
Group Protein

Polycomb group (PcG) proteins repress homeotic genes in cells where these genes must remain inactive during development. This repression requires cis-acting silencers, also called PcG response elements. Currently, these silencers are ill-defined sequences and it is not known how PcG proteins associate with DNA. Here, we show that the Drosophila PcG protein Pleiohomeotic binds to specific sites in a silencer of the homeotic gene Ultrabithorax. In an Ultrabithorax reporter gene, point mutations in these Pleiohomeotic binding sites abolish PcG repression in vivo. Hence, DNA-bound Pleiohomeotic protein may function in the recruitment of other non-DNA-binding PcG proteins to homeotic gene silencers.

scholarly journals Mel-18, a Polycomb Group Protein, Regulates Cell Proliferation and Senescence via Transcriptional Repression of Bmi-1 and c-Myc Oncoproteins

2007 ◽  
Vol 18 (2) ◽  
pp. 536-546 ◽  
Author(s):  
Wei-Jian Guo ◽  
Sonal Datta ◽  
Vimla Band ◽  
Goberdhan P. Dimri
Keyword(s):  
Cell Proliferation ◽  
Transcriptional Repression ◽  
Target Genes ◽  
Human Fibroblasts ◽  
Ring Finger ◽  
Polycomb Group ◽  
Polycomb Group Protein ◽  
Down Regulation ◽  
Group Protein ◽  
Bona Fide

Polycomb group (PcG) protein Bmi-1 is an important regulator of cell proliferation. It regulates cellular senescence and proliferation of cells via the transcriptional repression of INK4a/ARF locus and other target genes. Here, we report that Mel-18, a PcG ring finger protein (PCGF) transcriptionally down-regulates Bmi-1. Furthermore, the expression of Bmi-1 and Mel-18 inversely correlates in proliferating and senescent human fibroblasts. Bmi-1 down-regulation by Mel-18 results in accelerated senescence and shortening of the replicative life span in normal human cells. Importantly, using promoter-reporter, chromatin immunoprecipitation, and quantitative real-time primary transcript RT-PCR assays, and an RNA interference approach, we demonstrate that Bmi-1 is a bona fide target of c-Myc oncoprotein. Finally, our data suggest that Mel-18 regulates Bmi-1 expression during senescence via down-regulation of c-Myc. These studies link c-Myc and polycomb function in cell proliferation and senescence.

scholarly journals Retinoic Acid Receptor Isotype Specificity in F9 Teratocarcinoma Stem Cells Results from the Differential Recruitment of Coregulators to Retinoic Acid Response Elements

2007 ◽  
Vol 282 (46) ◽  
pp. 33421-33434 ◽  
Author(s):  
Robert F. Gillespie ◽  
Lorraine J. Gudas
Keyword(s):  
Stem Cells ◽  
Retinoic Acid ◽  
Target Genes ◽  
Retinoic Acid Receptor ◽  
Polycomb Group ◽  
Polycomb Group Protein ◽  
Response Elements ◽  
Acid Receptor ◽  
Group Protein ◽  
F9 Teratocarcinoma

The retinoic acid receptor (RAR) α, β2, and γ isotypes each regulate specific subsets of target genes in F9 teratocarcinoma stem cells. We used chromatin immunoprecipitation assays to monitor the association of RARγ, retinoic X receptor (RXR) α, and coregulators with the RARβ2, Hoxa1, and Cyp26A1 retinoic acid response elements (RAREs) in F9 wild type and RARα, -β2, and -γ null cells. Additionally we quantitatively monitored expression of the corresponding mRNAs. We demonstrated that the association of RARγ and/or RXRα with a RARE was not sufficient for retinoic acid (RA)-mediated transcription of the corresponding target gene. However, the ability of RARγ and/or RXRα to recruit pCIP (AIB1/ACTR/RAC-3/TRAM-1/SRC-3) and p300 to a RARE did correlate with RA-associated transcription of target mRNAs. Therefore, the specific functions of the RAR isotypes do not manifest at the level of their DNA binding but rather from a differential ability to recruit specific components of the transcriptional machinery. We also demonstrated that RA-mediated displacement of the polycomb group protein SUZ12 from a RARE was inhibited in the absence of RARγ. Thus, transcriptional components of the RAR signaling pathway are specifically required for displacement of SUZ12 from RAREs during RA-mediated differentiation of F9 cells.

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