Polycomb- and REST-associated histone deacetylases are independent pathways toward a mature neuronal phenotype - PubMed (original) (raw)

Polycomb- and REST-associated histone deacetylases are independent pathways toward a mature neuronal phenotype

James C McGann et al. Elife. 2014.

Abstract

The bivalent hypothesis posits that genes encoding developmental regulators required for early lineage decisions are poised in stem/progenitor cells by the balance between a repressor histone modification (H3K27me3), mediated by the Polycomb Repressor Complex 2 (PRC2), and an activator modification (H3K4me3). In this study, we test whether this mechanism applies equally to genes that are not required until terminal differentiation. We focus on the RE1 Silencing Transcription Factor (REST) because it is expressed highly in stem cells and is an established global repressor of terminal neuronal genes. Elucidation of the REST complex, and comparison of chromatin marks and gene expression levels in control and REST-deficient stem cells, shows that REST target genes are poised by a mechanism independent of Polycomb, even at promoters which bear the H3K27me3 mark. Specifically, genes under REST control are actively repressed in stem cells by a balance of the H3K4me3 mark and a repressor complex that relies on histone deacetylase activity. Thus, chromatin distinctions between pro-neural and terminal neuronal genes are established at the embryonic stem cell stage by two parallel, but distinct, repressor pathways.

Keywords: ES cells; Polycomb; REST; chromosomes; developmental biology; genes; histone deacetylase; mouse; neuronal; poised; stem cells.

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Conflict of interest statement

The authors declare that no competing interests exist.

Figures

Figure 1.

Figure 1.. PRC2 establishes H3K27me3 in ESCs independent of REST repression.

(A) A limited number of REST-occupied sites are associated with domains of H3K27me3 enrichment in ESCs, even if defined more broadly (+/− 1 kb). (B) H3K27me3 levels are stable in_Rest_ −/− ESCs in the majority of regions targeted by PRC2. The scatter-plot shows the relative enrichment of H3K27me3 ChIP-Seq signal in wild type (WT, x-axis) and_Rest_ −/− ESCs (y-axis) at regions targeted by PRC2 in WT ESCs. (C) As in (B), but at identified REST-binding sites. (D) Chromatin immunoprecipitation analysis showing H3K27me3-enrichment changes at RE1 sites near PRC2-targeted regions in WT and Rest −/− ESCs (* indicates p < 0.05), normalized for H3 density. DOI:

http://dx.doi.org/10.7554/eLife.04235.005

Figure 1—figure Supplement 1.

Figure 1—figure Supplement 1.. REST is required for recruitment of co-factors to RE1 sites in ESCs.

ChIP assays were performed in WT and_Rest_ −/− ESCs using antibody against Sin3a, Cdyl, CoREST1, CoREST2, Hdac2, G9a, and Kdm1a to compare recruitment of endogenous co-factors at the RE1 sites near_Igsf21_, Kcnk9,Erich1, Npas4, and_Rad51_. ChIP assays done in parallel with normal rabbit IgG are included as a negative control. DOI:

http://dx.doi.org/10.7554/eLife.04235.006

Figure 1—figure Supplement 2.

Figure 1—figure Supplement 2.. Detection of REST binding to PRC2 members is biochemically possible, but a true interaction is unlikely.

(A) Immunoprecipitation was performed with streptavidin beads from biotin-tagged REST ESCs or BirA control ESCs and the demarcated proteins were assayed by Western blot. (B) Previously published ChIP-seq data sets were interrogated over H3K27me3 peaks and REST peaks normalized to the signal found at the H3K27me3 peaks. DOI:

http://dx.doi.org/10.7554/eLife.04235.007

Figure 1—figure Supplement 3.

Figure 1—figure Supplement 3.. Characteristics of REST-bound loci.

(A) Regions with multiple RE1 motifs show a strong association with REST. REST ChIP-Seq data displayed as sequence tags aligned to the mouse genome assembly (mm9) viewed in the UCSC genome browser. Green and red hash marks represent sequences matching the forward and reverse strands, respectively. Consensus RE1 sequence motifs are indicated by black hash marks. All views are shown at an equal size relative to the scale bar. (B) FIMO definition of the RE1 motif was derived from ChIP-seq peaks. (C) Relative enrichment of REST measured by ChIP-Seq was confirmed by ChIP-qPCR. ChIP assays were performed using antibody raised against a peptide corresponding to a fragment of mouse REST in WT (red bars) and_Rest_ −/− (blue bars) in ESCs at regions associated with RE1 motifs and regions lacking an RE1 site (Oct4 and MageA8). (D) REST targets associated with trimethylation of histone H3K4 or H3K27 enrichment are preferentially localized near gene promoters. Graph shows the percentage of REST-bound regions that overlap with domains of the bivalent histone modification pattern consisting of H3K4me3 and H3K27me3 enrichment (red bars), H3K4me3 enrichment alone (green bars), or without overlap to either modification (tan bars). DOI:

http://dx.doi.org/10.7554/eLife.04235.008

Figure 1—figure Supplement 4.

Figure 1—figure Supplement 4.. H3K27me3 levels from WT and Rest −/− ESCs are as similar as H3K27me3 levels from different published reports.

(A) Normalized enrichment values for H3K27me3 at defined H3K27me3 peaks were derived from several previously published data sets and plotted against one another. Numbers indicate Pearson coefficient. DOI:

http://dx.doi.org/10.7554/eLife.04235.009

Figure 1—figure Supplement 5.

Figure 1—figure Supplement 5.. Ezh2-enrichment at REST-bound loci.

(A) Ezh2 occupancy was increased at RE1 sites within H3K27me3 domains that gained H3K27me3 in the absence of REST. ChIP assays were performed with anti-Ezh2 to compare enrichment at RE1 sites between WT (light orange) and_Rest_ −/− (dark orange) ESCs. DOI:

http://dx.doi.org/10.7554/eLife.04235.010

Figure 2.

Figure 2.. Chromatin modification changes due to loss of REST.

(A) REST-dependent establishment of 2Me-H3K9, measured by ChIP, is impaired at RE1 sites in_Rest_ −/− ESCs irrespective of changes in H3K27me3 levels. Oct4 and MageA8 are genes expressed in ESCs that lack RE1 sites. (B) Increased histone acetylation is detected at most RE1-associated promoters in the absence of REST, irrespective of changes in H3K27me3 levels. Oct4 and Gapdh_promoter regions are expressed in ESCs and lack RE1 sites. (C) H3K4me3 enrichment is increased at most RE1-associated promoters in_Rest −/− ESCs, independent of H3K27me3 levels (* indicates p < 0.05). DOI:

http://dx.doi.org/10.7554/eLife.04235.012

Figure 3.

Figure 3.. REST-dependent changes in expression of REST targets are correlated significantly with REST-dependent changes in H3K4me3, not H3K27me3.

(A) RNA-seq log2(Fold Change) results for_Rest_ −/− ESCs are not correlated with changes in H3K27me3 levels at REST sites or (B) REST target transcriptional start sites (TSS). (C) All REST target genes are de-repressed in_Rest_ −/− ESCs regardless of H3K27me3 or H3K4me3 status. (D) In contrast, REST targets show no transcriptional changes in_Eed_ −/− ESCs, which have highly reduced levels of H3K27me3, and genes with this mark show significant increases in expression (p < 0.005). (E) Changes in H3K4me3 enrichment in Rest −/− ESCs strongly correlate with REST target gene expression changes (p < 0.01). (F) Expression levels of H3K4me3-marked REST target genes are significantly reduced relative to H3K4me3-marked genes and de-repressed in Rest −/− ESCs (*p < 0.05, **p < 0.001). DOI:

http://dx.doi.org/10.7554/eLife.04235.013

Figure 4.

Figure 4.. REST antagonizes H3K4me3 in ESCs through histone deacetylase activity.

(A) Only treatment with the histone deacetylase inhibitor trichostatin-A (TSA) results in the increased H3K4me3 enrichment seen in_Rest_ −/− ESCs. The active_Oct4_ and GAPDH promoter regions that lack RE1 sites were included as control regions enriched for H3K4me3. (B) Changes in H3K4me3 enrichment at RE1 sites due to the loss of REST are significantly correlated with those due to TSA treatment (p < 0.01). (C) Microarray analysis reveals that HDAC inhibition by trichostatin-A (TSA) preferentially de-represses REST targets, unlike the loss of G9a or Kdm1a. (D) Changes in expression of select REST target genes due to REST loss significantly correlate with changes in expression due to HDAC inhibition with TSA (p < 0.001). DOI:

http://dx.doi.org/10.7554/eLife.04235.014

Figure 4—figure Supplement 1.

Figure 4—figure Supplement 1.. H3K9ac levels increase after TSA treatment.

(A)H3K9ac enrichment is increased after treatment with histone deacetylase inhibitor trichostatin-A (TSA) but not when other co-factors are eliminated from the REST complex. DOI:

http://dx.doi.org/10.7554/eLife.04235.015

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References

    1. Abmayr SM, Yao T, Parmely T, Workman JL. Preparation of nuclear and cytoplasmic extracts from mammalian cells. Current Protocols in Molecular Biology. 2006 doi: 10.1002/0471142727.mb1201s75. Chapter 12: Unit 12 1. - DOI - PubMed
    1. Andres ME, Burger C, Peral-Rubio MJ, Battaglioli E, Anderson ME, Grimes J, Dallman J, Ballas N, Mandel G. CoREST: a functional corepressor required for regulation of neural-specific gene expression. Proceedings of the National Academy of Sciences of USA. 1999;96:9873–9878. doi: 10.1073/pnas.96.17.9873. - DOI - PMC - PubMed
    1. Arnold P, Schöler A, Pachkov M, Balwierz PJ, Jørgensen H, Stadler MB, van Nimwegen E, Schübeler D. Modeling of epigenome dynamics identifies transcription factors that mediate Polycomb targeting. Genome Research. 2013;23:60–73. doi: 10.1101/gr.142661.112. - DOI - PMC - PubMed
    1. Bai L, Morozov AV. Gene regulation by nucleosome positioning. Trends in Genetics. 2010;26:476–483. doi: 10.1016/j.tig.2010.08.003. - DOI - PubMed
    1. Ballas N, Grunseich C, Lu DD, Speh JC, Mandel G. REST and its corepressors mediate plasticity of neuronal gene chromatin throughout neurogenesis. Cell. 2005;121:645–657. doi: 10.1016/j.cell.2005.03.013. - DOI - PubMed

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