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Chromatin insulator bodies are nuclear structures that form in response to osmotic stress and cell death.

ABSTRACT: Chromatin insulators assist in the formation of higher-order chromatin structures by mediating long-range contacts between distant genomic sites. It has been suggested that insulators accomplish this task by forming dense nuclear foci termed insulator bodies that result from the coalescence of multiple protein-bound insulators. However, these structures remain poorly understood, particularly the mechanisms triggering body formation and their role in nuclear function. In this paper, we show that insulator proteins undergo a dramatic and dynamic spatial reorganization into insulator bodies during osmostress and cell death in a high osmolarity glycerol-p38 mitogen-activated protein kinase-independent manner, leading to a large reduction in DNA-bound insulator proteins that rapidly repopulate chromatin as the bodies disassemble upon return to isotonicity. These bodies occupy distinct nuclear territories and contain a defined structural arrangement of insulator proteins. Our findings suggest insulator bodies are novel nuclear stress foci that can be used as a proxy to monitor the chromatin-bound state of insulator proteins and provide new insights into the effects of osmostress on nuclear and genome organization.

SUBMITTER: Schoborg T

PROVIDER: S-EPMC3718971 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Chromatin insulator bodies are nuclear structures that form in response to osmotic stress and cell death

Project description: Not available

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Transiently transfected purine biosynthetic enzymes form stress bodies.

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Stress-induced mRNP granules: Form and function of processing bodies and stress granules.

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Nuclear ULK1 promotes cell death in response to oxidative stress through PARP1.

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Ephemeral Protein Binding to DNA Shapes Stable Nuclear Bodies and Chromatin Domains.

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NURF301 contributes to gypsy chromatin insulator-mediated nuclear organization

Project description:Chromatin insulators are DNA-protein complexes that can prevent the spread of repressive chromatin and block communication between enhancers and promoters to regulate gene expression. In Drosophila, the gypsy chromatin insulator complex consists of three core proteins: CP190, Su(Hw), and Mod(mdg4)67.2. These factors concentrate at nuclear foci termed insulator bodies, and their normal localization is correlated with proper insulator function. Here, we identified NURF301/E(bx), a nucleosome remodeling factor, as a novel regulator of gypsy insulator body localization through a high-throughput RNAi imaging screen. NURF301 promotes gypsy-dependent insulator barrier activity and physically interacts with gypsy insulator proteins. Using ChIP-seq, we found that NURF301 co-localizes with insulator proteins genome-wide, and NURF301 promotes chromatin association of Su(Hw) and CP190 at gypsy insulator binding sites. These effects correlate with NURF301-dependent nucleosome repositioning. At the same time, CP190 and Su(Hw) are also required for recruitment of NURF301 to chromatin. Finally, Oligopaint FISH combined with immunofluorescence revealed that NURF301 promotes 3D contact between insulator bodies and gypsy binding site DNA, and NURF301 is required for proper nuclear positioning of gypsy binding sites. Our data provide new insights into how a nucleosome remodeling factor and insulator proteins cooperatively contribute to nuclear organization.

2022-10-14 | PXD032165 | Pride

U bodies are cytoplasmic structures that contain uridine-rich small nuclear ribonucleoproteins and associate with P bodies.

Project description:Uridine-rich small nuclear ribonucleoproteins (U snRNPs) are involved in key steps of pre-mRNA processing in the nucleus of eukaryotic cells. U snRNPs are enriched in the nucleus in discrete organelles that include speckles, Cajal bodies, and histone locus bodies. However, most U snRNPs are assembled in the cytoplasm, not in the nucleus. Despite extensive biochemical information, little is known about the spatial organization of U snRNPs in the cytoplasm. Here we show that U snRNPs in Drosophila are concentrated in discrete cytoplasmic structures, which we call U bodies, because they contain the major U snRNPs. In addition to snRNPs, U bodies contain essential snRNP assembly factors, suggesting that U bodies are sites for assembly or storage of snRNPs before their import into the nucleus. U bodies invariably associate with P bodies, which are involved in RNA surveillance and decay. Genetic disruption of P body components affects the organization of U bodies, suggesting that the two cytoplasmic bodies may cooperate in regulating aspects of snRNP metabolism. The identification of U bodies provides an opportunity to correlate specific biochemical steps of snRNP biogenesis with structural features of the cytoplasm.

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Stress induced nuclear granules form in response to accumulation of misfolded proteins in Caenorhabditis elegans.

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Transcriptional response of Mycoplasma genitalium to osmotic stress.

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