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Analysis of Drosophila salivary glands and Kc cells with depleted levels of linker histone H1

ABSTRACT: This SuperSeries is composed of the SubSeries listed below.

ORGANISM(S): Drosophila melanogaster

PROVIDER: GSE44148 | GEO | 2013/04/22

SECONDARY ACCESSION(S): PRJNA189571

REPOSITORIES: GEO

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Analysis of Drosophila salivary glands and Kc cells with depleted levels of linker histone H1

Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series

2013-04-22 | E-GEOD-44148 | biostudies-arrayexpress

Analysis of Drosophila salivary glands and Kc cells with depleted levels of linker histone H1 [Affymetrix Expression]

2013-04-22 | GSE44398 | GEO

Analysis of Drosophila salivary glands and Kc cells with depleted levels of linker histone H1 [Affymetrix Expression]

Project description:Indicated cells were subjected to RNAi against linker histone H1, Nautilus (control), or GFP (control). RNA was isolated and subjected to Affymetrix GeneChIP Drosophila Genome 2.0 arrays RNA was compared from cells treated with RNAi against control (Nautilus in the case of salivary glands or GFP in the case of Kc cells) and linker histone H1. Kc cells were treated once with RNAi and RNA was collected 6 days later.

2013-04-22 | E-GEOD-44398 | biostudies-arrayexpress

Analysis of Drosophila salivary glands and Kc cells with depleted levels of linker histone H1 (Illumina smRNA-Seq]

Project description:Salivary glands or larval ovaries were isolated from transgenic flies expressing RNAi targeting Nautilus (control) or linker histone H1 using a Tub-Gal4 driver.

2013-04-22 | GSE44399 | GEO

Analysis of Drosophila salivary glands and Kc cells with depleted levels of linker histone H1 (Illumina smRNA-Seq]

Project description:Salivary glands or larval ovaries were isolated from transgenic flies expressing RNAi targeting Nautilus (control) or linker histone H1 using a Tub-Gal4 driver. ~200 larvae were used to isolate salivary glands or ovaries, independently. Total RNA was isolated using Trizol reagent following manufacturer's guidelines. Then 5 M-BM-5g of total RNA was separated on a polyacrylamide gel, and 18-29 nt small RNAs were isolated for cloning.

2013-04-22 | E-GEOD-44399 | biostudies-arrayexpress

Fine mapping of posttranslational modifications of the linker histone H1 from Drosophila melanogaster.

Project description:The linker histone H1 binds to the DNA in between adjacent nucleosomes and contributes to chromatin organization and transcriptional control. It is known that H1 carries diverse posttranslational modifications (PTMs), including phosphorylation, lysine methylation and ADP-ribosylation. Their biological functions, however, remain largely unclear. This is in part due to the fact that most of the studies have been performed in organisms that have several H1 variants, which complicates the analyses. We have chosen Drosophila melanogaster, a model organism, which has a single H1 variant, to approach the study of the role of H1 PTMs during embryonic development. Mass spectrometry mapping of the entire sequence of the protein showed phosphorylation only in the ten N-terminal amino acids, mostly at S10. For the first time, changes in the PTMs of a linker H1 during the development of a multicellular organism are reported. The abundance of H1 monophosphorylated at S10 decreases as the embryos age, which suggests that this PTM is related to cell cycle progression and/or cell differentiation. Additionally, we have found a polymorphism in the protein sequence that can be mistaken with lysine methylation if the analysis is not rigorous.

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BEN domain protein Elba2 can functionally substitute for linker histone H1 in Drosophila in vivo.

Project description:Metazoan linker histones are essential for development and play crucial roles in organization of chromatin, modification of epigenetic states and regulation of genetic activity. Vertebrates express multiple linker histone H1 isoforms, which may function redundantly. In contrast, H1 isoforms are not present in Dipterans, including D. melanogaster, except for an embryo-specific, distantly related dBigH1. Here we show that Drosophila BEN domain protein Elba2, which is expressed in early embryos and was hypothesized to have insulator-specific functions, can compensate for the loss of H1 in vivo. Although the Elba2 gene is not essential, its mutation causes a disruption of normal internucleosomal spacing of chromatin and reduced nuclear compaction in syncytial embryos. Elba2 protein is distributed ubiquitously in polytene chromosomes and strongly colocalizes with H1. In H1-depleted animals, ectopic expression of Elba2 rescues the increased lethality and ameliorates abnormalities of chromosome architecture and heterochromatin functions. We also demonstrate that ectopic expression of BigH1 similarly complements the deficiency of H1 protein. Thus, in organisms that do not express redundant H1 isoforms, the structural and biological functions performed by canonical linker histones in later development, may be shared in early embryos by weakly homologous proteins, such as BigH1, or even unrelated, non-homologous proteins, such as Elba2.

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Loss of linker histone H1 in cellular senescence.

Project description:Cellular senescence is a tumor-suppressing mechanism that is accompanied by characteristic chromatin condensation called senescence-associated heterochromatic foci (SAHFs). We found that individual SAHFs originate from individual chromosomes. SAHFs do not show alterations of posttranslational modifications of core histones that mark condensed chromatin in mitotic chromosomes, apoptotic chromatin, or transcriptionally inactive heterochromatin. Remarkably, SAHF-positive senescent cells lose linker histone H1 and exhibit increased levels of chromatin-bound high mobility group A2 (HMGA2). The expression of N-terminally enhanced green fluorescent protein (EGFP)-tagged histone H1 induces premature senescence phenotypes, including increased levels of phosphorylated p53, p21, and hypophosphorylated Rb, and a decrease in the chromatin-bound endogenous histone H1 level but not in p16 level accumulation or SAHF formation. However, the simultaneous ectopic expression of hemagglutinin-tagged HMGA2 and N-terminally EGFP-tagged histone H1 leads to significant SAHF formation (P < 0.001). It is known that histone H1 and HMG proteins compete for a common binding site, the linker DNA. These results suggest that SAHFs are a novel type of chromatin condensation involving alterations in linker DNA-binding proteins.

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Regulatory functions and chromatin loading dynamics of linker histone H1 during endoreplication in <i>Drosophila</i>.

Project description:Eukaryotic DNA replicates asynchronously, with discrete genomic loci replicating during different stages of S phase. Drosophila larval tissues undergo endoreplication without cell division, and the latest replicating regions occasionally fail to complete endoreplication, resulting in underreplicated domains of polytene chromosomes. Here we show that linker histone H1 is required for the underreplication (UR) phenomenon in Drosophila salivary glands. H1 directly interacts with the Suppressor of UR (SUUR) protein and is required for SUUR binding to chromatin in vivo. These observations implicate H1 as a critical factor in the formation of underreplicated regions and an upstream effector of SUUR. We also demonstrate that the localization of H1 in chromatin changes profoundly during the endocycle. At the onset of endocycle S (endo-S) phase, H1 is heavily and specifically loaded into late replicating genomic regions and is then redistributed during the course of endoreplication. Our data suggest that cell cycle-dependent chromosome occupancy of H1 is governed by several independent processes. In addition to the ubiquitous replication-related disassembly and reassembly of chromatin, H1 is deposited into chromatin through a novel pathway that is replication-independent, rapid, and locus-specific. This cell cycle-directed dynamic localization of H1 in chromatin may play an important role in the regulation of DNA replication timing.

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