scholarly journals Functional characterization of human Polycomb-like 3 isoforms identifies them as components of distinct EZH2 protein complexes

2011 ◽  
Vol 434 (2) ◽  
pp. 333-342 ◽  
Author(s):  
Gaylor Boulay ◽  
Claire Rosnoblet ◽  
Cateline Guérardel ◽  
Pierre-Olivier Angrand ◽  
Dominique Leprince
Keyword(s):  
Cell Fate ◽  
Target Genes ◽  
Protein Complexes ◽  
Functional Characterization ◽  
Polycomb Group ◽  
Phd Finger ◽  
Reverse Transcription Pcr ◽  
Tudor Domain ◽  
Self Association ◽  
Polycomb Repressive Complex 1

PcG (Polycomb group) proteins are conserved transcriptional repressors essential to regulate cell fate and to maintain epigenetic cellular memory. They work in concert through two main families of chromatin-modifying complexes, PRC1 (Polycomb repressive complex 1) and PRC2–4. In Drosophila, PRC2 contains the H3K27 histone methyltransferase E(Z) whose trimethylation activity towards PcG target genes is stimulated by PCL (Polycomb-like). In the present study, we have examined hPCL3, one of its three human paralogues. Through alternative splicing, hPCL3 encodes a long isoform, hPCL3L, containing an N-terminal TUDOR domain and two PHDs (plant homeodomains) and a smaller isoform, hPCL3S, lacking the second PHD finger (PHD2). By quantitative reverse transcription–PCR analyses, we showed that both isoforms are widely co-expressed at high levels in medulloblastoma. By co-immunoprecipitation analyses, we demonstrated that both isoforms interact with EZH2 through their common TUDOR domain. However, the hPCL3L-specific PHD2 domain, which is better conserved than PHD1 in the PCL family, is also involved in this interaction and implicated in the self-association of hPCL3L. Finally, we have demonstrated that both hPCL3 isoforms are physically associated with EZH2, but in different complexes. Our results provide the first evidence that the two hPCL3 isoforms belong to different complexes and raise important questions about their relative functions, particularly in tumorigenesis.

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.

PIASγ controls stability and facilitates SUMO-2 conjugation to CoREST family of transcriptional co-repressors

2018 ◽  
Vol 475 (8) ◽  
pp. 1441-1454
Author(s):  
Julián Esteban Sáez ◽  
Cristian Arredondo ◽  
Carlos Rivera ◽  
María Estela Andrés
Keyword(s):  
Cell Fate ◽  
Target Genes ◽  
Protein Complexes ◽  
Control Cell ◽  
E3 Ligase ◽  
Cell Fate Determination ◽  
Fate Determination ◽  
Sumo Protease ◽  
Protein Levels ◽  
The Stability

CoREST family of transcriptional co-repressors regulates gene expression and cell fate determination during development. CoREST co-repressors recruit with different affinity the histone demethylase LSD1 (KDM1A) and the deacetylases HDAC1/2 to repress with variable strength the expression of target genes. CoREST protein levels are differentially regulated during cell fate determination and in mature tissues. However, regulatory mechanisms of CoREST co-repressors at the protein level have not been studied. Here, we report that CoREST (CoREST1, RCOR1) and its homologs CoREST2 (RCOR2) and CoREST3 (RCOR3) interact with PIASγ (protein inhibitor of activated STAT), a SUMO (small ubiquitin-like modifier)-E3-ligase. PIASγ increases the stability of CoREST proteins and facilitates their SUMOylation by SUMO-2. Interestingly, the SUMO-conjugating enzyme, Ubc9 also facilitates the SUMOylation of CoREST proteins. However, it does not change their protein levels. Specificity was shown using the null enzymatic form of PIASγ (PIASγ-C342A) and the SUMO protease SENP-1, which reversed SUMOylation and the increment of CoREST protein levels induced by PIASγ. The major SUMO acceptor lysines are different and are localized in nonconserved sequences among CoREST proteins. SUMOylation-deficient CoREST1 and CoREST3 mutants maintain a similar interaction profile with LSD1 and HDAC1/2, and consequently maintain similar repressor capacity compared with wild-type counterparts. In conclusion, CoREST co-repressors form protein complexes with PIASγ, which acts both as SUMO E3-ligase and as a protein stabilizer for CoREST proteins. This novel regulation of CoREST by PIASγ interaction and SUMOylation may serve to control cell fate determination during development.

scholarly journals PTE, a novel module to target Polycomb Repressive Complex 1 to the Cyclin D2 oncogene

2017 ◽  
Author(s):  
Sarina R. Cameron ◽  
Soumyadeep Nandi ◽  
Tatyana G. Kahn ◽  
Juan I. Barrasa ◽  
Per Stenberg ◽  
...  
Keyword(s):  
Cpg Island ◽  
Protein Complexes ◽  
Cpg Islands ◽  
Biochemical Properties ◽  
Polycomb Group ◽  
Cyclin D2 ◽  
Polycomb Response Element ◽  
Multiple Protein ◽  
Polycomb Repression ◽  
Polycomb Repressive Complex 1

AbstractPolycomb Group proteins are essential epigenetic repressors. They form multiple protein complexes of which two kinds, PRC1 and PRC2, are indispensable for repression. Although much is known about their biochemical properties, how PRC1 and PRC2 are targeted to specific genes is poorly understood. Here we establish the Cyclin D2 (CCND2) oncogene as a simple model to address this question. We provide the evidence that coordinated recruitment of PRC1 and PRC2 complexes to CCND2 involves a combination of a specialized PRC1 targeting element (PTE) and an adjacent CpG-island, which together act as a human Polycomb Response Element. Chromatin immunoprecipitation analysis of CCND2 in different transcriptional states indicates that histone modifications produced by PRC1 and PRC2 are not sufficient to recruit either of the complexes. However, catalytic activity of PRC2 helps to anchor PRC1 at the PTE. Our analyses suggest that coordinated targeting of PRC1 and PRC2 complexes by juxtaposed AT-rich PTEs and CpG-islands may be a general feature of Polycomb repression in mammals.

scholarly journals Knowing When to Silence: Roles of Polycomb-Group Proteins in SAM Maintenance, Root Development, and Developmental Phase Transition

2020 ◽  
Vol 21 (16) ◽  
pp. 5871
Author(s):  
Bowen Yan ◽  
Yanpeng Lv ◽  
Chunyu Zhao ◽  
Xiaoxue Wang
Keyword(s):  
Phase Transition ◽  
Root Development ◽  
Target Genes ◽  
Polycomb Group ◽  
Developmental Phase ◽  
Heterochromatin Protein 1 ◽  
Heterochromatin Protein ◽  
Developmental Defects ◽  
Histone 3 ◽  
Polycomb Repressive Complex 1

Polycomb repressive complex 1 (PRC1) and PRC2 are the major complexes composed of polycomb-group (PcG) proteins in plants. PRC2 catalyzes trimethylation of lysine 27 on histone 3 to silence target genes. Like Heterochromatin Protein 1/Terminal Flower 2 (LHP1/TFL2) recognizes and binds to H3K27me3 generated by PRC2 activities and enrolls PRC1 complex to further silence the chromatin through depositing monoubiquitylation of lysine 119 on H2A. Mutations in PcG genes display diverse developmental defects during shoot apical meristem (SAM) maintenance and differentiation, seed development and germination, floral transition, and so on so forth. PcG proteins play essential roles in regulating plant development through repressing gene expression. In this review, we are focusing on recent discovery about the regulatory roles of PcG proteins in SAM maintenance, root development, embryo development to seedling phase transition, and vegetative to reproductive phase transition.

scholarly journals Polycomb Factor PHF19 Controls Cell Growth and Differentiation Toward Erythroid Pathway in Chronic Myeloid Leukemia Cells

2021 ◽  
Vol 9 ◽  
Author(s):  
Marc García-Montolio ◽  
Cecilia Ballaré ◽  
Enrique Blanco ◽  
Arantxa Gutiérrez ◽  
Sergi Aranda ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Chronic Myeloid Leukemia ◽  
Cell Fate ◽  
Myeloid Leukemia ◽  
Target Genes ◽  
Leukemia Cell ◽  
Adult Stem Cell ◽  
Erythroid Differentiation ◽  
Polycomb Group ◽  
Leukemia Cells

Polycomb group (PcG) of proteins are a group of highly conserved epigenetic regulators involved in many biological functions, such as embryonic development, cell proliferation, and adult stem cell determination. PHD finger protein 19 (PHF19) is an associated factor of Polycomb repressor complex 2 (PRC2), often upregulated in human cancers. In particular, myeloid leukemia cell lines show increased levels of PHF19, yet little is known about its function. Here, we have characterized the role of PHF19 in myeloid leukemia cells. We demonstrated that PHF19 depletion decreases cell proliferation and promotes chronic myeloid leukemia (CML) differentiation. Mechanistically, we have shown how PHF19 regulates the proliferation of CML through a direct regulation of the cell cycle inhibitor p21. Furthermore, we observed that MTF2, a PHF19 homolog, partially compensates for PHF19 depletion in a subset of target genes, instructing specific erythroid differentiation. Taken together, our results show that PHF19 is a key transcriptional regulator for cell fate determination and could be a potential therapeutic target for myeloid leukemia treatment.

scholarly journals Interactions with RNA direct the Polycomb group protein SCML2 to chromatin where it represses target genes

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Roberto Bonasio ◽  
Emilio Lecona ◽  
Varun Narendra ◽  
Philipp Voigt ◽  
Fabio Parisi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Epigenetic Regulation ◽  
Target Genes ◽  
Rna Binding ◽  
Regulation Of Gene Expression ◽  
Polycomb Group ◽  
Polycomb Group Protein ◽  
Binding Region ◽  
Group Protein ◽  
Polycomb Repressive Complex 1

Polycomb repressive complex-1 (PRC1) is essential for the epigenetic regulation of gene expression. SCML2 is a mammalian homolog of Drosophila SCM, a Polycomb-group protein that associates with PRC1. In this study, we show that SCML2A, an SCML2 isoform tightly associated to chromatin, contributes to PRC1 localization and also directly enforces repression of certain Polycomb target genes. SCML2A binds to PRC1 via its SPM domain and interacts with ncRNAs through a novel RNA-binding region (RBR). Targeting of SCML2A to chromatin involves the coordinated action of the MBT domains, RNA binding, and interaction with PRC1 through the SPM domain. Deletion of the RBR reduces the occupancy of SCML2A at target genes and overexpression of a mutant SCML2A lacking the RBR causes defects in PRC1 recruitment. These observations point to a role for ncRNAs in regulating SCML2 function and suggest that SCML2 participates in the epigenetic control of transcription directly and in cooperation with PRC1.

scholarly journals Parallel PRC2/cPRC1 and vPRC1 pathways silence lineage-specific genes and maintain self-renewal in mouse embryonic stem cells

2020 ◽  
Vol 6 (14) ◽  
pp. eaax5692 ◽  
Author(s):  
J. A. Zepeda-Martinez ◽  
C. Pribitzer ◽  
J. Wang ◽  
D. Bsteh ◽  
S. Golumbeanu ◽  
...  
Keyword(s):  
Cell Fate ◽  
Target Genes ◽  
Embryonic Stem ◽  
Mouse Embryonic Stem Cell ◽  
Transcriptional Repressors ◽  
Self Renewal ◽  
Repressive Chromatin ◽  
Genetic Perturbations ◽  
Polycomb Repressive Complex 1 ◽  
Lineage Specific Genes

The transcriptional repressors Polycomb repressive complex 1 (PRC1) and PRC2 are required to maintain cell fate during embryonic development. PRC1 and PRC2 catalyze distinct histone modifications, establishing repressive chromatin at shared targets. How PRC1, which consists of canonical PRC1 (cPRC1) and variant PRC1 (vPRC1) complexes, and PRC2 cooperate to silence genes and support mouse embryonic stem cell (mESC) self-renewal is unclear. Using combinatorial genetic perturbations, we show that independent pathways of cPRC1 and vPRC1 are responsible for maintenance of H2A monoubiquitylation and silencing of shared target genes. Individual loss of PRC2-dependent cPRC1 or PRC2-independent vPRC1 disrupts only one pathway and does not impair mESC self-renewal capacity. However, loss of both pathways leads to mESC differentiation and activation of a subset of lineage-specific genes co-occupied by relatively high levels of PRC1/PRC2. Thus, parallel pathways explain the differential requirements for PRC1 and PRC2 and provide robust silencing of lineage-specific genes.

scholarly journals RING1 Interacts with Multiple Polycomb-Group Proteins and Displays Tumorigenic Activity

1999 ◽  
Vol 19 (1) ◽  
pp. 57-68 ◽  
Author(s):  
David P. E. Satijn ◽  
Arie P. Otte
Keyword(s):  
Gene Expression ◽  
Protein Interactions ◽  
Mammalian Cells ◽  
Protein Complexes ◽  
Cellular Transformation ◽  
Polycomb Group ◽  
Expression Levels ◽  
Self Association

ABSTRACT Polycomb-group (PcG) proteins form large multimeric protein complexes that are involved in maintaining the transcriptionally repressive state of genes. Previously, we reported that RING1 interacts with vertebrate Polycomb (Pc) homologs and is associated with or is part of a human PcG complex. However, very little is known about the role of RING1 as a component of the PcG complex. Here we undertake a detailed characterization of RING1 protein-protein interactions. By using directed two-hybrid and in vitro protein-protein analyses, we demonstrate that RING1, besides interacting with the human Pc homolog HPC2, can also interact with itself and with the vertebrate PcG protein BMI1. Distinct domains in the RING1 protein are involved in the self-association and in the interaction with BMI1. Further, we find that the BMI1 protein can also interact with itself. To better understand the role of RING1 in regulating gene expression, we overexpressed the protein in mammalian cells and analyzed differences in gene expression levels. This analysis shows that overexpression of RING1 strongly represses En-2, a mammalian homolog of the well-characterized Drosophila PcG target geneengrailed. Furthermore, RING1 overexpression results in enhanced expression of the proto-oncogenes c-jun and c-fos. The changes in expression levels of these proto-oncogenes are accompanied by cellular transformation, as judged by anchorage-independent growth and the induction of tumors in athymic mice. Our data demonstrate that RING1 interacts with multiple human PcG proteins, indicating an important role for RING1 in the PcG complex. Further, deregulation of RING1 expression leads to oncogenic transformation by deregulation of the expression levels of certain oncogenes.

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