Project description:Heterochromatin protein 1 (HP1) is commonly seen as a key factor of repressive heterochromatin, even though a few genes are known to require HP1-chromatin for their expression. In order to obtain insight into the targeting of HP1 and its interplay with other chromatin components, we have mapped HP1 binding sites on chromosome 2 and 4 in Drosophila Kc cells using high-density oligonucleotide arrays and the DamID technique. The resulting high-resolution maps show that HP1 forms large domains in pericentric regions, but is targeted to single genes on chromosome arms. Intriguingly, HP1 shows a striking preference for exon-dense genes on chromosome arms. Furthermore, HP1 binds along entire transcription units, except for 5’ regions. Comparison with expression data shows that most of these genes are actively transcribed. HP1 target genes are also marked by the histone variant H3.3 and dimethylated histone 3 lysine 4 (H3K4me2), which are both typical of active chromatin. Interestingly, H3.3 deposition, which is usually observed along entire transcription units, is limited to the 5’ ends of HP1-bound genes. Thus, H3.3 and HP1 are mutually exclusive marks on active chromatin. Additionally, we observed that HP1-chromatin and Polycomb-chromatin are non-overlapping, but often closely juxtaposed, suggesting an interplay between both types of chromatin. These results demonstrate that HP1-chromatin is transcriptionally active and has extensive links with several other chromatin components. Keywords: DamID
Project description:Nucleus is a highly structured organelle and contains many functional compartments. While the structural basis for this complex spatial organization of compartments is unknown, a major component of this organization is likely to be the non-chromatin scaffolding called nuclear matrix (NuMat). Experimental evidence over the past decades indicates that most of the nuclear functions are at least transiently associated with the NuMat although the components of NuMat itself are poorly known. Here, we report NuMat proteome analysis from Drosophila melanogaster embryos and discuss its links with nuclear architecture and functions. In the NuMat proteome, we find structural proteins, chaperones related, DNA/RNA binding, chromatin remodeling and transcription factors. This complexity of NuMat proteome is an indicator of its structural and functional significance. Comparison of the 2D profile of NuMat proteome from different developmental stages of Drosophila embryos shows that less than half of the NuMat proteome is constant and rest of the proteins are stage specific dynamic components. This NuMat dynamics suggests a possible functional link between NuMat and the embryonic development. Finally, we also show that a subset of NuMat proteins remain associated with the mitotic chromosomes implicating their role in mitosis and possibly the epigenetic cellular memory. NuMat proteome analysis provides tools and opens up ways to understand nuclear organization and function.
Project description:Two chromosome-targeting and gene regulatory systems are present in Drosophila melanogaster. The male X-chromosome is targeted by the male-specific lethal complex believed to mediate the two-fold up-regulation of the X-linked genes. The highly heterochromatic 4th chromosome is specifically targeted by the Painting of Fourth (POF) protein which together with heterochromatin protein 1 (HP1) modulate the expression level of genes on the 4th chromosome. Here we report high-resolution mapping of POF and HP1 on the 4th chromosome using chromatin immunoprecipitation followed by tiling microarrays (ChIP-chip) in S2 cells and salivary glands. The enrichments are compared to transcript profiles of the two cell types used. POF specifically binds to genes with a strong preference for exons. The POF binding profile correlates to the binding profile of HP1 which in addition displays a typical M-bM-^@M-^\peakM-bM-^@M-^] in the promoter regions of bound genes. POF and HP1 binds to active genes and the binding correlates with levels of transcription and changes in binding levels are paralleled by a comparable change in transcription. Our results provide a high resolution description of the chromosome 4 specific gene regulatory system provided by the combinatorial effects of POF and HP1. Keywords: ChIP-chip Chromatin IP of POF, HP1 and H3K9ac in S2 cells. Three biological replicates, one replicate per array.
Project description:Two chromosome-targeting and gene regulatory systems are present in Drosophila melanogaster. The male X-chromosome is targeted by the male-specific lethal complex believed to mediate the two-fold up-regulation of the X-linked genes. The highly heterochromatic 4th chromosome is specifically targeted by the Painting of Fourth (POF) protein which together with heterochromatin protein 1 (HP1) modulate the expression level of genes on the 4th chromosome. Here we report high-resolution mapping of POF and HP1 on the 4th chromosome using chromatin immunoprecipitation followed by tiling microarrays (ChIP-chip) in S2 cells and salivary glands. The enrichments are compared to transcript profiles of the two cell types used. POF specifically binds to genes with a strong preference for exons. The POF binding profile correlates to the binding profile of HP1 which in addition displays a typical M-bM-^@M-^\peakM-bM-^@M-^] in the promoter regions of bound genes. POF and HP1 binds to active genes and the binding correlates with levels of transcription and changes in binding levels are paralleled by a comparable change in transcription. Our results provide a high resolution description of the chromosome 4 specific gene regulatory system provided by the combinatorial effects of POF and HP1. This SuperSeries is composed of the following subset Series: GSE8296: Chromatin IP of POF, HP1 and H3K9ac in S2 cells and salivary glands. GSE8297: Transcript profiling in S2 cells and salivary glands. Keywords: SuperSeries Refer to individual Series