The essential process of dosage compensation equalizes X-chromosome gene expression between C. elegans XO males and XX hermaphrodites through a dosage compensation complex (DCC) that resembles condensin. The DCC binds to both X chromosomes of hermaphrodites to repress transcription by half. Here we show that post-translational modification by the SUMO conjugation pathway is essential for sex-specific assembly of the DCC onto X. Depletion of the SUMO peptide in vivo severely disrupts binding of particular DCC subunits and causes changes in X-linked gene expression similar to those caused by disrupting genes encoding DCC subunits. Three DCC subunits are themselves SUMOylated, and depletion of SUMO preferentially reduces their binding to X, suggesting that SUMOylation of DCC subunits is essential for robust association with X. DCC SUMOylation is triggered by the signal that initiates DCC assembly onto X. The initial step of assembly--binding of X-targeting factors to recruitment sites on X (rex sites)--is independent of SUMOylation, but robust binding of the complete complex requires SUMOylation. SUMOylated DCC subunits are enriched at rex sites, and SUMOylation enhances interactions between X-targeting factors and condensin subunits that facilitate DCC binding beyond the low level achieved without SUMOylation. DCC subunits also participate in condensin complexes essential for chromosome segregation, but their SUMOylation occurs only in the context of the DCC. Our results reinforce a newly emerging theme in which multiple proteins of a complex are SUMOylated in response to a specific stimulus, leading to accelerated complex formation and enhanced function.
SUMOylation is essential for sex-specific assembly and function of the Caenorhabditis elegans dosage compensation complex on X chromosomes.
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An MLL/COMPASS subunit functions in the C. elegans dosage compensation complex to target X chromosomes for transcriptional regulation of gene expression.
Sex, Disease
View SamplesHere we exploit the essential process of Xchromosome dosage compensation to elucidate basic mechanisms that control the assembly, genomewide binding, and function of gene regulatory complexes that act over large chromosomal territories. We demonstrate that a subunit of C. elegans MLL/COMPASS, a gene-activation complex, acts within the dosage compensation complex (DCC), a condensin complex, to target the DCC to both X chromosomes of hermaphrodites and thereby reduce chromosome-wide gene expression. The DCC binds to two categories of sites on X: rex sites that recruit the DCC in an autonomous, sequence- dependent manner, and dox sites that reside primarily in promoters of expressed genes and bind the DCC robustly only when attached to X. We find that DCC mutants that abolish rex-site binding do not eliminate dox-site binding, but instead reduce it to the level observed at autosomal binding sites in wild-type animals. Changes in DCC binding to these non-rex sites occur throughout development and correlate with transcriptional activity of adjacent genes. Moreover, autosomal DCC binding is enhanced by rex-site binding in cis in X-autosome fusion chromosomes. Thus, dox and autosomal sites exhibit similar binding properties. Our data support a model for DCC binding in which low-level DCC binding at dox and autosomal sites is dictated by intrinsic properties correlated with high transcriptional activity. Sex-specific DCC recruitment to rex sites then greatly elevates DCC binding to dox sites in cis, which lack intrinsically high DCC affinity on their own. We also show here that the C. elegans DCC achieves dosage compensation through its effects on transcription.
An MLL/COMPASS subunit functions in the C. elegans dosage compensation complex to target X chromosomes for transcriptional regulation of gene expression.
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A condensin-like dosage compensation complex acts at a distance to control expression throughout the genome.
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View SamplesIn many species, a dosage compensation complex (DCC) is targeted to X chromosomes of one sex to equalize levels of X gene products between males (1X) and females (2X). Here we identify cis-acting regulatory elements that target the C. elegans X chromosome for repression by the DCC. The DCC binds to discrete, dispersed sites on X of two types. rex sites recruit the DCC in an autonomous, DNA sequence-dependent manner using a 12 bp consensus motif that is enriched on X. This motif is critical for DCC binding, is clustered in rex sites, and confers much of X-chromosome specificity. Motif variants enriched on X by 3.8-fold or more are highly predictive (95%) for rex sites. In contrast, dox sites lack the X-enriched variants and cannot bind the DCC when detached from X. dox sites are more prevalent than rex sites and, unlike rex sites, reside preferentially in promoters of some expressed genes. These findings fulfill predictions for a targeting model in which the DCC binds to recruitment sites on X and disperses to discrete sites lacking autonomous recruitment ability. To relate DCC binding to function, we identified dosage-compensated and non-compensated genes on X. Unexpectedly, many genes of both types have bound DCC, but many do not, suggesting the DCC acts over long distances to repress X gene expression. Remarkably, the DCC binds to autosomes, but at far fewer sites and rarely at consensus motifs. DCC disruption causes opposite effects on expression of X and autosomal genes. The DCC thus acts at a distance to impact expression throughout the genome.
A condensin-like dosage compensation complex acts at a distance to control expression throughout the genome.
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View SamplesThe classification of neurons into distinct types is an ongoing effort aimed at revealing and understanding the diversity of the components of the nervous system. Recently available methods allow us to determine the gene expression pattern of individual neurons in the mammalian cerebral cortex to generate powerful categorization schemes. For a thorough understanding of neuronal diversity such genetic categorization schemes need to be combined with traditional classification parameters like position, axonal projection or response properties to sensory stimulation. Here we describe a method to link the gene expression of individual neurons with their position, axonal projection or sensory response properties. Neurons are labeled in vivo based on their anatomical or functional properties and, using patch clamp pipettes, their RNA individually harvested in vitro for RNAseq. With this method we can determine the genetic expression pattern of functionally and anatomically identified individual neurons. Overall design: single cortical neurons were patch clamped and the RNA harvested; single neuron mRNA profiles were generated by deep sequencing
Correlating Anatomy and Function with Gene Expression in Individual Neurons by Combining <i>in Vivo</i> Labeling, Patch Clamp, and Single Cell RNA-seq.
Cell line, Subject
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Relationship between gene body DNA methylation and intragenic H3K9me3 and H3K36me3 chromatin marks.
Specimen part, Cell line
View SamplesMouse trophoblast stem cells were treated for 48 hours with two different stealth ds-siRNA against Elts2 and expression compared to samples treated with Invitrogen's mediumGC control and to no treatment samples.
Elf5 and Ets2 maintain the mouse extraembryonic ectoderm in a dosage dependent synergistic manner.
Specimen part
View SamplesThis is one of expressional parts of the study. These data were correlated to epigenetic marks and CG density of genes in analyzed cells. The whole study has a following summary: To elucidate possible roles of DNA methylation and chromatin marks in transcription, we performed epigenetic profiling of chromosome 19 in human bronchial epithelial cells (HBEC) and in the colorectal cancer cell line HCT116 as well as its counterpart with double knockout of DNMT1 and DNMT3B (HCT116-DKO). We found that H3K9me3 forms intragenic chromatin blocks along genes with low CpG density in the gene body. Analysis of H3K36me3 profiles indicated that this mark associates either with active genes with low CpG density and H3K9me3 in the gene body or with active genes with high CpG density and DNA hypermethylation in the gene body. In HCT116 cells with double knockout of DNMT1 and DNMT3B, transcription of genes with low CpG density in the gene body was highly elevated and associated with promoter DNA demethylation and rearrangement of H3K9me3 and H3K36me3 occupation. Our finding suggests that similar to DNA methylation, H3K9me3 may play a role in intragenic gene regulation. Further, we observed that a combination of low CpG density in gene bodies together with H3K9me3 and H3K36me3 marking is a specific epigenetic feature of zinc finger (ZNF) genes, which comprise 90% of all genes carrying both histone marks on chromosome 19. For high CpG density genes, transcription and H3K36me3 occupancy were not changed in condition of partial or intensive loss of DNA methylation in gene bodies in the HCT116-DKO cell line. siRNA experiments with SETD2 knockdown in both HBEC and HCT116-DKO cell lines failed to reduce DNA methylation in gene bodies under conditions of H3K36me3 depletion. Our study suggests that the H3K36me3 and DNA methylation marks in gene bodies are established independently from each other and points to similar functional roles of intragenic DNA methylation and intragenic H3K9me3 for CpG-rich and CpG-poor genes, respectively.
Relationship between gene body DNA methylation and intragenic H3K9me3 and H3K36me3 chromatin marks.
Specimen part, Cell line
View SamplesCell fate specification is accompanied by global changes in gene expression from patterns of maintaining stem/progenitor cells to patterns for supporting differentiation. To ensure a proper transition, it is conceivable that genes important for differentiation are kept silent in stem/progenitor cells yet can be readily activated. RNA polymerase II (Pol II) pausing and bivalent chromatin marks are two paradigms that are suited for establishing such a poised state of gene expression, however, their contributions to gene regulation in development are not well understood. Here, using neural progenitor cells (NPCs) and their daughter neurons co-purified from the embryonic mouse cerebral cortex, we characterized Pol II pausing and H3K4me3/H3K27me3 marks in this in vivo setting of neurogenesis. We show that genes paused in NPCs or neurons are well correlated with their respective cell type-specific functions, but pausing and pause release did not predict gene activation. Bivalent chromatin marks, on the other hand, poised the marked genes in NPCs for activation in neurons. Interestingly, our data also revealed a positive correlation between H3K27me3 and paused Pol II. This study thus reveals cell-type specific Pol II pausing and gene activation-associated bivalency during mammalian neuronal differentiation. Overall design: Transcriptome analyses in neural progenitor cells (NPCs) and their daughter neurons, and their relationship with RNA polymerase II pausing and histone bivalent mark
Dynamics of RNA Polymerase II Pausing and Bivalent Histone H3 Methylation during Neuronal Differentiation in Brain Development.
Specimen part, Subject
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