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PROVIDER: PRJNA150121 | ENA |
REPOSITORIES: ENA
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Project description:This SuperSeries is composed of the following subset Series: GSE34857: Sequence-specific targeting of dosage compensation in Drosophila favors an active chromatin context (ChIP-chip) GSE34858: Sequence-specific targeting of dosage compensation in Drosophila favors an active chromatin context (mRNA) Refer to individual Series
2012-03-19 | E-GEOD-34859 | biostudies-arrayexpress
Project description:Sequence-specific targeting of dosage compensation in Drosophila favors an active chromatin context (mRNA)
| PRJNA156275 | ENA
Project description:Sequence-specific targeting of dosage compensation in Drosophila favors an active chromatin context (ChIP-chip)
| PRJNA156273 | ENA
Project description:Dosage compensation serves as a model for understanding how chromatin-modification enzymes are targeted to initiate and maintain gene regulation. In Drosophila, the MSL complex associates with active genes specifically on the male X chromosome to acetylate histone H4 at lysine 16, and increase expression of most X-linked genes approximately two-fold. To date, no DNA sequence has been discovered to explain the specificity of MSL binding. We previously hypothesized that sequence-specific targeting occurs at initiation or “chromatin entry sites”, but binding to the majority of sites is sequence-independent. Here we characterize more than 150 potential entry sites by ChIP-chip and ChIP-seq and discover a common GA-rich MSL recognition element (MRE). The motif is only slightly enriched on the X chromosome (~2 fold), but this is doubled when considering its preferential location within or 3’ to active X-linked genes (>4 fold enrichment). When inserted on an autosome, a newly identified site can direct local MSL spreading to flanking active genes on the autosome. These results provide strong evidence for both sequence-dependent and -independent steps in MSL targeting of dosage compensation to the male X chromosome.
2008-08-22 | GSE11485 | GEO
Project description:Long non-coding RNAs are involved in dosage compensation both in mammals and in Drosophila by inducing changes in the X-chromosome chromatin structure. In Drosophila melanogaster, roX1 and roX2 are long non-coding RNAs that together with proteins form the male-specific lethal (MSL) complex, which coats the entire male X-chromosome and mediates dosage compensation by increased transcriptional output. It has been shown that in polytene chromosomes, in absence of both roX1 and roX2, the MSL-complex is decreased on the male X-chromosome and found relocated to the chromocenter, and the 4th chromosome. Here we address the role of roX RNAs in MSL-complex targeting and in the evolution of dosage compensation in Drosophila. We performed ChIP-seq experiments and show that MSL-complex recruitment to high affinity sites (HAS) on the X-chromosome is independent on roX and that the HAS sequence motif is conserved in D. simulans. Additionally, a complete and enzymatically active MSL-complex is recruited to six specific genes on the 4th chromosome. Interestingly, our sequence analysis shows that in the absence of roX RNAs, the MSL-complex has affinity to regions enriched in Hoppel transposable elements and to repeats in general. We hypothesize that roX mutants reveal an ancient targeting of the MSL-complex and propose that the role of roX RNAs is to restrict MSL-complex from binding to heterochromatin.
2014-11-07 | GSE58768 | GEO
Project description:The Drosophila MSL complex mediates dosage compensation by increasing transcription of the single X chromosome in males approximately two-fold. This is accomplished through recognition of the X chromosome and subsequent acetylation of histone H4K16 on X-linked genes. Initial binding to the X is thought to occur at a subset of sites. However, the consensus sequence motif of entry sites (“MSL recognition element” or MRE) is only slightly enriched on the X (~2 fold), and only a fraction of them is utilized by the MSL complex. Here we ask whether chromatin context could distinguish between utilized and non-utilized copies of the motif, by comparing their relative enrichment for histone modifications and chromosomal proteins mapped in the NHGRI modENCODE project. Through a comparative analysis of the chromatin features in male S2 cells, which contain MSL complex, and female Kc cells, which lack the complex, we find that the presence of active chromatin modifications, together with an elevated local GC content in surrounding sequence, has strong predictive value for functional MSL entry sites, independent of MSL binding. We tested these sites for function in Kc cells by RNAi knockdown of Sxl, resulting in induction of MSL complex. We show that ectopic MSL expression in Kc cells leads to H4K16 acetylation around these sites, and a relative increase in X chromosome transcription. Collectively, our results support a model in which a pre-existing active chromatin environment, coincident with H3K36me3, contributes to MSL entry site selection. The consequences of MSL targeting of the male X chromosome include increase in nucleosome lability, enrichment for H4K16 acetylation and JIL-1 kinase, and depletion of linker histone H1 on active X-linked genes. Our finding serves as a model to understand how chromatin and local sequence features are involved in the selection of functional protein binding sites in the genome. The key Drosophila female sex determinant protein, SXL, represses dosage compensation by inhibiting MSL2 translation. Loss of SXL results in the expression, stabilization, and targetting of the MSL complex in female cells. Therefore, depletion of SXL by RNA interference (RNAi) in female Kc cells will lead to a MSL2-dependent increase in transcription from the female X chromosomes, consistent with the induction of dosage compensation. In this experiment, we generated gene expression profiles of Kc cells of control (GFP), Sxl RNAi and Sxl-Msl2 RNAi experiments.
2012-03-19 | E-GEOD-34858 | biostudies-arrayexpress
Project description:Dosage compensation in D. melanogaster males is achieved via targeting of the MSL complex to X chromosomal genes. This is proposed to involve initial sequence-specific recognition of the X at ~150-300 chromatin entry sites, and subsequent spreading to nearby active genes. Here we test a model in which the spreading step requires transcription and is sequence-independent. We ask whether, in the native context of the X chromosome, MSL complex will target genes of autosomal origin. We find that MSL complex does bind such genes, but only if transcriptionally active. Targeting is accompanied by acetylation of the histone H4K16 residue and two-fold transcriptional up-regulation. We conclude that the presence of a long-sought specific DNA sequence within X-linked genes is not obligatory for MSL complex binding. Instead, physical linkage and transcription play the pivotal roles in the identification of MSL targets irrespective of their origin and DNA sequence. Keywords: Epigenetics
2009-08-20 | GSE17729 | GEO
Project description:Dosage compensation in D. melanogaster males is achieved via targeting of the MSL complex to X chromosomal genes. This is proposed to involve initial sequence-specific recognition of the X at ~150-300 chromatin entry sites, and subsequent spreading to nearby active genes. Here we test a model in which the spreading step requires transcription and is sequence-independent. We ask whether, in the native context of the X chromosome, MSL complex will target genes of autosomal origin. We find that MSL complex does bind such genes, but only if transcriptionally active. Targeting is accompanied by acetylation of the histone H4K16 residue and two-fold transcriptional up-regulation. We conclude that the presence of a long-sought specific DNA sequence within X-linked genes is not obligatory for MSL complex binding. Instead, physical linkage and transcription play the pivotal roles in the identification of MSL targets irrespective of their origin and DNA sequence. Keywords: Epigenetics ChIP-seq measurements of MSL complex binding and input control. Chromatin was prepared from third instar male larvae of a genotype y w TrojanElephant; MSL3-TAP; msl3. TrojanElephant is a mini-white- and yellow-marked transposition of genomic region spanning 65 kb from cg13773 to snRNP70K. MSL3-TAP is a mini-white-marked TAP-tagged genomic msl3 transgene. IgG beads were used for pull-down.
2009-08-20 | E-GEOD-17729 | biostudies-arrayexpress
Project description:The Drosophila MSL complex mediates dosage compensation by increasing transcription of the single X chromosome in males approximately two-fold. This is accomplished through recognition of the X chromosome and subsequent acetylation of histone H4K16 on X-linked genes. Initial binding to the X is thought to occur at a subset of sites. However, the consensus sequence motif of entry sites (M-bM-^@M-^\MSL recognition elementM-bM-^@M-^] or MRE) is only slightly enriched on the X (~2 fold), and only a fraction of them is utilized by the MSL complex. Here we ask whether chromatin context could distinguish between utilized and non-utilized copies of the motif, by comparing their relative enrichment for histone modifications and chromosomal proteins mapped in the NHGRI modENCODE project. Through a comparative analysis of the chromatin features in male S2 cells, which contain MSL complex, and female Kc cells, which lack the complex, we find that the presence of active chromatin modifications, together with an elevated local GC content in surrounding sequence, has strong predictive value for functional MSL entry sites, independent of MSL binding. We tested these sites for function in Kc cells by RNAi knockdown of Sxl, resulting in induction of MSL complex. We show that ectopic MSL expression in Kc cells leads to H4K16 acetylation around these sites, and a relative increase in X chromosome transcription. Collectively, our results support a model in which a pre-existing active chromatin environment, coincident with H3K36me3, contributes to MSL entry site selection. The consequences of MSL targeting of the male X chromosome include increase in nucleosome lability, enrichment for H4K16 acetylation and JIL-1 kinase, and depletion of linker histone H1 on active X-linked genes. Our finding serves as a model to understand how chromatin and local sequence features are involved in the selection of functional protein binding sites in the genome. The key Drosophila female sex determinant protein, SXL, represses dosage compensation by inhibiting MSL2 translation. Loss of SXL results in the expression, stabilization, and targetting of the MSL complex in female cells. Therefore, depletion of SXL by RNA interference (RNAi) in female Kc cells will lead to a MSL2-dependent increase in transcription from the female X chromosomes, consistent with the induction of dosage compensation. In this experiment, we generated ChIP-chip profiles of H4K16 acetylation (H4K16ac) in Kc cells of control (GFP) and Sxl RNAi. For ChIP, we used Upstate (now Millipore) anti-H4K16ac antibody, catalog # 07-329, lot #JBC1355376.
2012-03-19 | E-GEOD-34857 | biostudies-arrayexpress
Project description:Hi-C and 4C-seq anlaysis of Drosophila S2 cells Drosophila dosage compensation is an important model system for defining how active chromatin domains are formed. The Male-specific lethal dosage compensation complex (MSLc) increases transcript levels of genes along the length of the single male X-chromosome to equalize with that on the two female X-chromosomes. The strongest binding sites for MSLc cluster together in three-dimensional space independent of MSLc because clustering occurs in both sexes. CLAMP, a non-sex specific, ubiquitous zinc finger protein, binds synergistically with MSLc to enrich the occupancy of both factors on the male X-chromosome. Here, we demonstrate that CLAMP promotes the observed clustering of MSLc bindings sites. Genome-wide, CLAMP promotes interactions between active chromatin regions and represses interactions between inactive chromatin regions. Moreover, the X-enriched CLAMP protein promotes longer-range interactions on the active X-chromosome than autosomes. Overall, we define how long-range interactions, mediated by a locally-enriched ubiquitous transcription factor, generate a three-dimensional active chromatin domain.
2019-12-01 | GSE130545 | GEO