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

Abstract

Insulator bodies are novel nuclear stress foci that can be used as a proxy to monitor the chromatin-bound state of insulator proteins.

Enhancer Control of Transcriptional Bursting

“…The alternating inhibition and coordinate bursting observed for transgenes containing the gypsy insulator (Figure 7B) is consistent with the occurrence of dynamic transitions in loop domains. Such transitions might also be due to unstable assembly of insulator protein complexes, which consist of multiple subunits including Su(Hw), Mod(mdg4)2.2 and CP190 (Ghosh et al, 2001; Pai et al, 2004; Schoborg et al, 2013). Just as live-imaging methods provide a far more dynamic view of gene activity in the Drosophila embryo as compared with fixed tissues (e.g., Bothma et al, 2014), these methods are likely to provide a more vibrant glimpse into the nature of enhancer-promoter communication.…”

The insulator protein Suppressor of Hairy wing is required for proper ring canal development during oogenesis in Drosophila

“…In order to further characterize the role of Su(Hw) in oogenesis, we used the su(Hw) e04061 mutant, created by an insertion of a piggyBac transposon at the 5’ end of the second exon, as well as the su(Hw) v mutant, which carries a deletion of the su(Hw) promoter (HARRISON et al 1992). Both homozygous su(Hw) e04061 and trans-heterozygous su(Hw) v/e04061 mutant flies show a loss of insulator activity and fertility (Supplementary Figure 1 ) (BAXLEY et al 2011; SCHOBORG et al 2013). The oogenesis phenotype of both mutant genotypes is practically indistinguishable, and to avoid genetic interference from second site mutations, we used trans-heterozygous su(Hw) v/e04061 mutant flies for phenotypic characterization.…”

“…Fly stocks used in this study included su(Hw) mutant lines: w 1118 ;PBac(RB)su(Hw) e04061 /TM6B, and y 2 w ct 6 ; su(Hw) v /TM6B (HARRISON et al 1992). Expression of Su(Hw)::eGFP [y w; P{su(Hw)::eGFP,w + }] (SCHOBORG et al 2013) was driven by various Gal4 drivers including w*; P{en 2.4 -Gal4} e22C ; w*;P{GAL4-nos.NGT40}; w*; P{nos-Gal4::VP16} (VAN DOREN et al 1998), w*; P{matalpha4-GAL-VP16}V37, and y w; P{Tj-Gal4}. For ectopic expression of Src64B we used w * ; P{UAS-Src64B.C}2.…”

“…Chromatin insulators have been discovered in a variety of organisms ranging from yeast to humans (SCHOBORG et al 2013). One of the best-characterized insulators is the Drosophila gypsy insulator, which requires the function of three major proteins: Su(Hw), which directly binds insulator DNA, Modifier of mdg4 protein [Mod(mdg4)67.2], and Centrosomal protein 190 (CP190), which bind Su(Hw), allowing chromatin insulator function (GERASIMOVA et al 1995; GHOSH et al 2001; PAI et al 2004).…”

The RNA-binding protein Rumpelstiltskin antagonizes gypsy chromatin insulator function in a tissue-specific manner

“…These concentrations of proteins might serve as focal points of insulator complex interactions, creating discrete, higher-order transcriptional domains (Byrd and Corces, 2003;Gerasimova et al, 2000;Gerasimova and Corces, 1998). However, it has also been suggested that insulator bodies represent storage sites of insulator proteins (Golovnin et al, 2008) or form as a result of certain stress conditions (Schoborg et al, 2013). Although the presence of insulator bodies is not sufficient for insulator activity (Gerasimova et al, 2007;Golovnin et al, 2008), all mutations that are known to alter the integrity of insulator bodies also affect insulator function (Capelson and Corces, 2005;Capelson and Corces, 2006;Gerasimova and Corces, 1998;Ghosh et al, 2001;Golovnin et al, 2012;Lei and Corces, 2006;Matzat et al, 2013;Matzat et al, 2012;Pai et al, 2004).…”