The Polycomb group protein Ring1 regulates dorsoventral patterning of the mouse telencephalon

SummaryPatterning of the dorsal-ventral (D-V) axis of the mammalian telencephalon is fundamental to the formation of distinct functional regions including the neocortex and ganglionic eminences. Morphogenetic signaling by bone morphogenetic protein (BMP), Wnt, Sonic hedgehog (Shh), and fibroblast growth factor (FGF) pathways determines regional identity along this axis. It has remained unclear, however, how region-specific expression patterns of these morphogens along the D-V axis are established, especially at the level of epigenetic (chromatin) regulation. Here we show that epigenetic regulation by Ring1, an essential Polycomb group (PcG) protein, plays a key role in formation of ventral identity in the mouse telencephalon. Deletion of the Ring1b or both Ring1a and Ring1b genes in neuroepithelial cells of the mouse embryo attenuated expression of the gene for Shh, a key morphogen for induction of ventral identity, and induced misexpression of dorsal marker genes including those for BMP and Wnt ligands in the ventral telencephalon. PcG protein–mediated trimethylation of histone H3 on lysine-27 (H3K27me3) was also apparent at BMP and Wnt ligand genes in wild-type embryos. Importantly, forced activation of Wnt or BMP signaling repressed the expression of Shh in organotypic and dissociated cultures of the early-stage telencephalon. Our results thus indicate that epigenetic regulation by PcG proteins—and, in particular, that by Ring1— confers a permissive state for the induction of Shh expression through suppression of BMP and Wnt signaling pathways, which in turn allows the development of ventral identity in the telencephalon.

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The Polycomb group protein Ring1 regulates dorsoventral patterning of the mouse telencephalon

Nature Communications ◽

10.1038/s41467-020-19556-5 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Hikaru Eto ◽

Yusuke Kishi ◽

Nayuta Yakushiji-Kaminatsui ◽

Hiroki Sugishita ◽

Shun Utsunomiya ◽

...

Keyword(s):

Wnt Signaling ◽

Ectopic Expression ◽

Regional Identity ◽

Polycomb Group ◽

Polycomb Group Protein ◽

Specific Expression ◽

Ventral Telencephalon ◽

Functional Regions ◽

Wnt Ligands ◽

Group Protein

Abstract Dorsal-ventral patterning of the mammalian telencephalon is fundamental to the formation of distinct functional regions including the neocortex and ganglionic eminence. While Bone morphogenetic protein (BMP), Wnt, and Sonic hedgehog (Shh) signaling are known to determine regional identity along the dorsoventral axis, how the region-specific expression of these morphogens is established remains unclear. Here we show that the Polycomb group (PcG) protein Ring1 contributes to the ventralization of the mouse telencephalon. Deletion of Ring1b or both Ring1a and Ring1b in neuroepithelial cells induces ectopic expression of dorsal genes, including those for BMP and Wnt ligands, as well as attenuated expression of the gene for Shh, a key morphogen for ventralization, in the ventral telencephalon. We observe PcG protein–mediated trimethylation of histone 3 at lysine-27 and binding of Ring1B at BMP and Wnt ligand genes specifically in the ventral region. Furthermore, forced activation of BMP or Wnt signaling represses Shh expression. Our results thus indicate that PcG proteins suppress BMP and Wnt signaling in a region-specific manner and thereby allow proper Shh expression and development of the ventral telencephalon.

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Gene Profiling in the Adipose Fin of Salmonid Fishes Supports Its Function as a Flow Sensor

Genes ◽

10.3390/genes11010021 ◽

2019 ◽

Vol 11 (1) ◽

pp. 21

Author(s):

Raphael Koll ◽

Joan Martorell Ribera ◽

Ronald M. Brunner ◽

Alexander Rebl ◽

Tom Goldammer

Keyword(s):

Rainbow Trout ◽

Expression Patterns ◽

Head Kidney ◽

Nerve Fibers ◽

Flow Sensor ◽

Sensory Function ◽

Gene Profiling ◽

Marker Genes ◽

Specific Expression ◽

Adipose Fin

In stock enhancement and sea-ranching procedures, the adipose fin of hundreds of millions of salmonids is removed for marking purposes annually. However, recent studies proved the significance of the adipose fin as a flow sensor and attraction feature. In the present study, we profiled the specific expression of 20 neuron- and glial cell-marker genes in the adipose fin and seven other tissues (including dorsal and pectoral fin, brain, skin, muscle, head kidney, and liver) of the salmonid species rainbow trout Oncorhynchus mykiss and maraena whitefish Coregonus maraena. Moreover, we measured the transcript abundance of genes coding for 15 mechanoreceptive channel proteins from a variety of mechanoreceptors known in vertebrates. The overall expression patterns indicate the presence of the entire repertoire of neurons, glial cells and receptor proteins on the RNA level. This quantification suggests that the adipose fin contains considerable amounts of small nerve fibers with unmyelinated or slightly myelinated axons and most likely mechanoreceptive potential. The findings are consistent for both rainbow trout and maraena whitefish and support a previous hypothesis about the innervation and potential flow sensory function of the adipose fin. Moreover, our data suggest that the resection of the adipose fin has a stronger impact on the welfare of salmonid fish than previously assumed.

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Six4, a Putative myogeninGene Regulator, Is Not Essential for Mouse Embryonal Development

Molecular and Cellular Biology ◽

10.1128/mcb.21.10.3343-3350.2001 ◽

2001 ◽

Vol 21 (10) ◽

pp. 3343-3350 ◽

Cited By ~ 78

Author(s):

Hidenori Ozaki ◽

Yoko Watanabe ◽

Katsumasa Takahashi ◽

Ken Kitamura ◽

Akira Tanaka ◽

...

Keyword(s):

Molecular Markers ◽

Dorsal Root ◽

Skeletal Muscles ◽

Early Stage ◽

Expression Patterns ◽

Homologous Region ◽

Specific Expression ◽

Sine Oculis ◽

Branchial Arches ◽

Deficient Mice

ABSTRACT Six4 is a member of the Six family genes, homologues of Drosophila melanogaster sine oculis. The gene is thought to be involved in neurogenesis, myogenesis, and development of other organs, based on its specific expression in certain neuronal cells of the developing embryo and in adult skeletal muscles. To elucidate the biological roles of Six4, we generatedSix4-deficient mice by replacing the Sixhomologous region and homeobox by the β-galactosidase gene. 5-Bromo-4-chloro-3-indolyl-β-d-galactopyranoside staining of the heterozygous mutant embryos revealed expression ofSix4 in cranial and dorsal root ganglia, somites, otic and nasal placodes, branchial arches, Rathke's pouch, apical ectodermal ridges of limb buds, and mesonephros. The expression pattern was similar to that of Six1 except at the early stage of embryonic day 8.5. Six4-deficient mice were born according to the Mendelian rule with normal gross appearance and were fertile. No hearing defects were detected. Six4-deficient embryos showed no morphological abnormalities, and the expression patterns of several molecular markers, e.g., myogenin andNeuroD3 (neurogenin1), were normal. Our results indicate that Six4 is not essential for mouse embryogenesis and suggest that other members of the Six family seem to compensate for the loss of Six4.

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The Polycomb Group Protein Suz12 Is Required for Embryonic Stem Cell Differentiation

Molecular and Cellular Biology ◽

10.1128/mcb.01432-06 ◽

2007 ◽

Vol 27 (10) ◽

pp. 3769-3779 ◽

Cited By ~ 461

Author(s):

Diego Pasini ◽

Adrian P. Bracken ◽

Jacob B. Hansen ◽

Manuela Capillo ◽

Kristian Helin

Keyword(s):

Cell Differentiation ◽

Transcriptional Activation ◽

Es Cells ◽

Embryonic Stem ◽

Stem Cell Differentiation ◽

Polycomb Group ◽

Embryonic Stem Cell Differentiation ◽

Es Cell ◽

Polycomb Group Protein ◽

Specific Expression

ABSTRACT Polycomb group (PcG) proteins form multiprotein complexes, called Polycomb repressive complexes (PRCs). PRC2 contains the PcG proteins EZH2, SUZ12, and EED and represses transcription through methylation of lysine (K) 27 of histone H3 (H3). Suz12 is essential for PRC2 activity and its inactivation results in early lethality of mouse embryos. Here, we demonstrate that Suz12 −/− mouse embryonic stem (ES) cells can be established and expanded in tissue culture. The Suz12 −/− ES cells are characterized by global loss of H3K27 trimethylation (H3K27me3) and higher expression levels of differentiation-specific genes. Moreover, Suz12 −/− ES cells are impaired in proper differentiation, resulting in a lack of repression of ES cell markers as well as activation of differentiation-specific genes. Finally, we demonstrate that the PcGs are actively recruited to several genes during ES cell differentiation, which despite an increase in H3K27me3 levels is not always sufficient to prevent transcriptional activation. In summary, we demonstrate that Suz12 is required for the establishment of specific expression programs required for ES cell differentiation. Furthermore, we provide evidence that PcGs have different mechanisms to regulate transcription during cellular differentiation.

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Identification and characterization of interactions between the vertebrate polycomb-group protein BMI1 and human homologs of polyhomeotic.

Molecular and Cellular Biology ◽

10.1128/mcb.17.4.2326 ◽

1997 ◽

Vol 17 (4) ◽

pp. 2326-2335 ◽

Cited By ~ 107

Author(s):

M J Gunster ◽

D P Satijn ◽

K M Hamer ◽

J L den Blaauwen ◽

D de Bruijn ◽

...

Keyword(s):

Protein Interactions ◽

Expression Patterns ◽

Polycomb Group ◽

Polycomb Group Protein ◽

Protein Protein Interactions ◽

Human Proteins ◽

Group Protein ◽

The Individual ◽

Domain I ◽

Homology Domains

In Drosophila melanogaster, the Polycomb-group (PcG) genes have been identified as repressors of gene expression. They are part of a cellular memory system that is responsible for the stable transmission of gene activity to progeny cells. PcG proteins form a large multimeric, chromatin-associated protein complex, but the identity of its components is largely unknown. Here, we identify two human proteins, HPH1 and HPH2, that are associated with the vertebrate PcG protein BMI1. HPH1 and HPH2 coimmunoprecipitate and cofractionate with each other and with BMI1. They also colocalize with BMI1 in interphase nuclei of U-2 OS human osteosarcoma and SW480 human colorectal adenocarcinoma cells. HPH1 and HPH2 have little sequence homology with each other, except in two highly conserved domains, designated homology domains I and II. They share these homology domains I and II with the Drosophila PcG protein Polyhomeotic (Ph), and we, therefore, have named the novel proteins HPH1 and HPH2. HPH1, HPH2, and BMI1 show distinct, although overlapping expression patterns in different tissues and cell lines. Two-hybrid analysis shows that homology domain II of HPH1 interacts with both homology domains I and II of HPH2. In contrast, homology domain I of HPH1 interacts only with homology domain II of HPH2, but not with homology domain I of HPH2. Furthermore, BMI1 does not interact with the individual homology domains. Instead, both intact homology domains I and II need to be present for interactions with BMI1. These data demonstrate the involvement of homology domains I and II in protein-protein interactions and indicate that HPH1 and HPH2 are able to heterodimerize.

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Characterization of Interactions between the Mammalian Polycomb-Group Proteins Enx1/EZH2 and EED Suggests the Existence of Different Mammalian Polycomb-Group Protein Complexes

Molecular and Cellular Biology ◽

10.1128/mcb.18.6.3586 ◽

1998 ◽

Vol 18 (6) ◽

pp. 3586-3595 ◽

Cited By ~ 159

Author(s):

Richard G. A. B. Sewalt ◽

Johan van der Vlag ◽

Marco J. Gunster ◽

Karien M. Hamer ◽

Jan L. den Blaauwen ◽

...

Keyword(s):

Gene Expression ◽

Protein Complexes ◽

Expression Patterns ◽

Polycomb Group ◽

Polycomb Group Protein ◽

Sex Combs ◽

Group Protein ◽

Nuclear Domains ◽

Z Protein

ABSTRACT In Drosophila melanogaster, thePolycomb-group (PcG) andtrithorax-group (trxG) genes have been identified as repressors and activators, respectively, of gene expression. Both groups of genes are required for the stable transmission of gene expression patterns to progeny cells throughout development. Several lines of evidence suggest a functional interaction between the PcG and trxG proteins. For example, genetic evidence indicates that the enhancer of zeste [E(z)] gene can be considered both a PcG and a trxGgene. To better understand the molecular interactions in which the E(z) protein is involved, we performed a two-hybrid screen with Enx1/EZH2, a mammalian homolog of E(z), as the target. We report the identification of the human EED protein, which interacts with Enx1/EZH2. EED is the human homolog ofeed, a murine PcG gene which has extensive homology with the Drosophila PcG gene extra sex combs(esc). Enx1/EZH2 and EED coimmunoprecipitate, indicating that they also interact in vivo. However, Enx1/EZH2 and EED do not coimmunoprecipitate with other human PcG proteins, such as HPC2 and BMI1. Furthermore, unlike HPC2 and BMI1, which colocalize in nuclear domains of U-2 OS osteosarcoma cells, Enx1/EZH2 and EED do not colocalize with HPC2 or BMI1. Our findings indicate that Enx1/EZH2 and EED are members of a class of PcG proteins that is distinct from previously described human PcG proteins.

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Pax6 defines the di-mesencephalic boundary by repressing En1 and Pax2

Development ◽

10.1242/dev.127.11.2357 ◽

2000 ◽

Vol 127 (11) ◽

pp. 2357-2365 ◽

Cited By ~ 4

Author(s):

E. Matsunaga ◽

I. Araki ◽

H. Nakamura

Keyword(s):

Neural Development ◽

Early Stage ◽

Expression Patterns ◽

Marker Gene ◽

Active Form ◽

Dominant Negative ◽

Marker Genes ◽

Posterior Commissure ◽

Dominant Negative Form ◽

Negative Form

Transcriptional factors and signaling molecules are responsible for regionalization of the central nervous system. In the early stage of neural development, Pax6 is expressed in the prosencephalon, while En1 and Pax2 are expressed in the mesencephalon. Here, we misexpressed Pax6 in the mesencephalon to elucidate the mechanism of the di-mesencephalic boundary formation. Histological analysis, expression patterns of diencephalic marker genes, and fiber trajectory of the posterior commissure indicated that Pax6 misexpression caused a caudal shift of the di-mesencephalic boundary. Pax6 repressed En1, Pax2 and other tectum (mesencephalon)-related genes such as En2, Pax5, Pax7, but induced Tcf4, a diencephalon marker gene. To know how Pax6 represses En1 and Pax2, we ectopically expressed a dominant-active or negative form of Pax6. The dominant-active form of Pax6 showed a similar but more severe phenotype than Pax6, while the dominant-negative form showed an opposite phenotype, suggesting that Pax6 acts as a transcriptional activator. Thus Pax6 may repress tectum-related genes by activating an intervening repressor. The results of misexpression experiments, together with normal expression patterns of Pax6, En1 and Pax2, suggest that repressive interaction between Pax6 and En1/Pax2 defines the di-mesencephalic boundary.

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A Polycomb and GAGA Dependent Silencer Adjoins the Fab-7 Boundary in the Drosophila Bithorax Complex

Genetics ◽

10.1093/genetics/146.4.1365 ◽

1997 ◽

Vol 146 (4) ◽

pp. 1365-1380 ◽

Cited By ~ 7

Author(s):

Kirsten Hagstrom ◽

Martin Muller ◽

Paul Schedl

Keyword(s):

Domain Boundary ◽

Expression Patterns ◽

Regulatory Region ◽

Polycomb Group ◽

Homeotic Genes ◽

Bithorax Complex ◽

Gaga Factor ◽

Independent Manner ◽

Specific Expression ◽

Restricted Pattern

The homeotic genes of the Drosophila bithorax complex are controlled by a large cis-regulatory region that ensures their segmentally restricted pattern of expression. A deletion that removes the Frontabdominal-7 cis-regulatory region (Fab-71) dominantly transforms parasegment 11 into parasegment 12. Previous studies suggested that removal of a domain boundary element on the proximal side of Fab-71 is responsible for this gain-of-function phenotype. In this article we demonstrate that the Fab-71 deletion also removes a silencer element, the iab-7 PRE, which maps to a different DNA segment and plays a different role in regulating parasegment-specific expression patterns of the Abd-B gene. The iab-7 PRE mediates pairing-sensitive silencing of mini-white, and can maintain the segmentally restricted expression pattern of a BXD, Ubx/lacZ reporter transgene. Both silencing activities depend upon Polycomb Group proteins. Pairing-sensitive silencing is relieved by removing the transvection protein Zeste, but is enhanced in a novel pairing-independent manner by the zeste1 allele. The iab-7 PRE silencer is contained within a 0.8-kb fragment that spans a nuclease hypersensitive site, and silencing appears to depend on the chromatin remodeling protein, the GAGA factor.

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

eLife ◽

10.7554/elife.02637 ◽

2014 ◽

Vol 3 ◽

Cited By ~ 32

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.

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