A drosophila protein that imparts directionality on a chromatin insulator is an enhancer of position-effect variegation

Gerasimova, T. I.; Gdula, David A.; Gerasimov, Denis V.; Симонова, О. Б.; Corcés, Victor G.

doi:10.1016/0092-8674(95)90031-4

Cited by 283 publications

(315 citation statements)

References 36 publications

Supporting

Mentioning

300

Contrasting

Unclassified

Order By: Relevance

“…For transgenic lines, we produced a new vector, YAL, derived from YES (Patton et al, 1992). YAL contains the Antennapedia promoter driving LacZ as reporter, yellow as transformation marker, and flanked by suppressor of Hairywing -binding site boundary sequences (Gerasimova et al, 1995). IRE and upstream regulatory element (URE) fragments were cloned into SalI-XbaI-XhoI targets sites of YAL polylinker, keeping the native orientation relative to the basal promoter.…”

Section: Plasmid Vector Transgenic Lines and Site-directed Mutagenesismentioning

confidence: 99%

Transcription ofDrosophilaTroponin I Gene Is Regulated by Two Conserved, Functionally Identical, Synergistic Elements

Marín

Toledo-Rodriguez

Ferrús

2004

MBoC

View full text Add to dashboard Cite

The Drosophila wings-up A gene encodes Troponin I. Two regions, located upstream of the transcription initiation site (upstream regulatory element) and in the first intron (intron regulatory element), regulate gene expression in specific developmental and muscle type domains. Based on LacZ reporter expression in transgenic lines, upstream regulatory element and intron regulatory element yield identical expression patterns. Both elements are required for full expression levels in vivo as indicated by quantitative reverse transcription-polymerase chain reaction assays. Three myocyte enhancer factor-2 binding sites have been functionally characterized in each regulatory element. Using exon specific probes, we show that transvection is based on transcriptional changes in the homologous chromosome and that Zeste and Suppressor of Zeste 3 gene products act as repressors for wings-up A. Critical regions for transvection and for Zeste effects are defined near the transcription initiation site. After in silico analysis in insects (Anopheles and Drosophila pseudoobscura) and vertebrates (Ratus and Coturnix), the regulatory organization of Drosophila seems to be conserved. Troponin I (TnI) is expressed before muscle progenitors begin to fuse, and sarcomere morphogenesis is affected by TnI depletion as Z discs fail to form, revealing a novel developmental role for the protein or its transcripts. Also, abnormal stoichiometry among TnI isoforms, rather than their absolute levels, seems to cause the functional muscle defects. INTRODUCTIONContractile protein systems are widely represented in most cell types as a force generator device (Davison et al., 2000). In muscles, troponin I (TnI) is a key element in the protein complex that regulates sliding of thin over thick filaments (Farah and Reinach, 1995;Geeves and Lehrer, 1998;Squire and Morris, 1998;Maytum et al., 2003). Several TnI protein isoforms are generated, either from transcription of independent genes (e.g., vertebrates) or from differential splicing of a single gene primary transcript (e.g., Drosophila). Amino acid substitutions in constitutive or alternatively spliced exons in TnI can lead to pathological conditions such as familial hypertrophic cardiomyopathy (Carrier et al., 1993;Coonar and McKenna, 1997) and distal arthrogryposis (Sung et al., 2003), due to abnormal interactions with other sarcomere components. Also, TnI is a relevant indicator of heart failure (Lewinter and Vanburen, 2002) and a potent angiogenesis inhibitor through its interaction with polycystin-2 (Li et al., 2003). The potential applications that this knowledge could provide, however, are handicapped by the scant information on the regulatory mechanisms of TnI gene expression. This issue is particularly relevant in the context of future gene therapy strategies and justifies this in vivo study of the regulatory mechanism of the Drosophila homologue. In addition, this study takes advantage of the fact that TnI in Drosophila is encoded by a single gene, wings up A (wupA), and that isoform replacem...

show abstract

Section: Plasmid Vector Transgenic Lines and Site-directed Mutagenesismentioning

confidence: 99%

Transcription ofDrosophilaTroponin I Gene Is Regulated by Two Conserved, Functionally Identical, Synergistic Elements

Marín

Toledo-Rodriguez

Ferrús

2004

MBoC

View full text Add to dashboard Cite

show abstract

“…In flies the most studied insulator element is gypsy, which when placed between two enhancers in a series of enhancers found in the yellow locus, blocks the action of all enhancers distal to the insertion but has no effect on those more proximal to the promoter (3). It has been shown that the insulator action of gypsy is mediated by a DNA-binding protein, Suppressor of Hairy wing [Su(Hw)], and a cofactor, Mod(mdg4) (4). Gypsy elements appear to localize to the nuclear envelope, where they cluster and organize the neighboring chromatin into loop domains (5).…”

mentioning

confidence: 99%

The 5′-HS4 chicken β-globin insulator is a CTCF-dependent nuclear matrix-associated element

Yusufzai

Felsenfeld

2004

Proc. Natl. Acad. Sci. U.S.A.

146

128

View full text Add to dashboard Cite

The protein CTCF plays an essential role in the action of a widely distributed class of vertebrate enhancer-blocking insulators, of which the first example was found in a DNA sequence element, HS4, at the 5 end of the chicken ␤-globin locus. HS4 contains a binding site for CTCF that is necessary and sufficient for insulator action. Purification of CTCF has revealed that it interacts with proteins involved in subnuclear architecture, notably nucleophosmin, a 38-kDa nucleolar phosphoprotein that is concentrated in nuclear matrix preparations. In this report we show that both CTCF and the HS4 insulator element are incorporated in the matrix; HS4 incorporation depends on the presence of an intact CTCF-binding site. However the DNA sequence in the neighborhood of HS4 is not like that of canonical matrix attachment regions, and its incorporation into the matrix fraction is not sensitive to ribonuclease, suggesting that the insulator is a distinct matrix-associated element.I nsulators are DNA sequence elements that can act either to block the extension of a condensed chromatin domain into a transcriptionally active region (barrier activity), or to prevent the interaction of a distal enhancer with a promoter when placed between the two (1, 2). Elements with the latter property, called enhancer blocking insulators, have been found in Drosophila and in vertebrates. In flies the most studied insulator element is gypsy, which when placed between two enhancers in a series of enhancers found in the yellow locus, blocks the action of all enhancers distal to the insertion but has no effect on those more proximal to the promoter (3). It has been shown that the insulator action of gypsy is mediated by a DNA-binding protein, Suppressor of Hairy wing [Su(Hw)], and a cofactor, Mod(mdg4) (4). Gypsy elements appear to localize to the nuclear envelope, where they cluster and organize the neighboring chromatin into loop domains (5). It is thought that the loop domain structure gives rise to the insulating activity either by preventing regulatory elements on different loops from interacting or by interfering with a ''tracking'' signal that would ordinarily proceed from enhancer to promoter (6-8). Loop domains can be established by attachment to other fixed sites in the nucleus. For example, a barrier function that prevents heterochromatinization of an active gene can be generated by tethering DNA elements to nuclear pore proteins (9). Loop domains can also arise simply from interactions that cause the insulator-bound proteins to stick to each other.A different enhancer blocking insulator activity has been described in vertebrates. First found at the 5Ј end of the chicken ␤-globin locus, it is part of a compound element (HS4) at that site that has both barrier and enhancer-blocking action (10). These two activities are separable; the enhancer-blocking insulation arises from a single DNA site that binds the protein CTCF (11). Insulator elements that bind CTCF have also been found at many other loci including the human and mouse ␤-globin cl...

show abstract

“…The best studied TE insulator comes from the Drosophila gypsy element (7)(8)(9)(10). Gypsy is a long terminal repeat retrotransposon that contains an insulator sequence in its 5′ untranslated region.…”

mentioning

confidence: 99%

MIR retrotransposon sequences provide insulators to the human genome

Wang

Vicente-García

Seruggia

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

104

View full text Add to dashboard Cite

Insulators are regulatory elements that help to organize eukaryotic chromatin via enhancer-blocking and chromatin barrier activity. Although there are several examples of transposable element (TE)-derived insulators, the contribution of TEs to human insulators has not been systematically explored. Mammalian-wide interspersed repeats (MIRs) are a conserved family of TEs that have substantial regulatory capacity and share sequence characteristics with tRNA-related insulators. We sought to evaluate whether MIRs can serve as insulators in the human genome. We applied a bioinformatic screen using genome sequence and functional genomic data from CD4 + T cells to identify a set of 1,178 predicted MIR insulators genome-wide. These predicted MIR insulators were computationally tested to serve as chromatin barriers and regulators of gene expression in CD4 + T cells. The activity of predicted MIR insulators was experimentally validated using in vitro and in vivo enhancer-blocking assays. MIR insulators are enriched around genes of the T-cell receptor pathway and reside at T-cell-specific boundaries of repressive and active chromatin. A total of 58% of the MIR insulators predicted here show evidence of T-cell-specific chromatin barrier and gene regulatory activity. MIR insulators appear to be CCCTC-binding factor (CTCF) independent and show a distinct local chromatin environment with marked peaks for RNA Pol III and a number of histone modifications, suggesting that MIR insulators recruit transcriptional complexes and chromatin modifying enzymes in situ to help establish chromatin and regulatory domains in the human genome. The provisioning of insulators by MIRs across the human genome suggests a specific mechanism by which TE sequences can be used to modulate gene regulatory networks.

show abstract

A drosophila protein that imparts directionality on a chromatin insulator is an enhancer of position-effect variegation

Cited by 283 publications

References 36 publications

Transcription ofDrosophilaTroponin I Gene Is Regulated by Two Conserved, Functionally Identical, Synergistic Elements

Transcription ofDrosophilaTroponin I Gene Is Regulated by Two Conserved, Functionally Identical, Synergistic Elements

The 5′-HS4 chicken β-globin insulator is a CTCF-dependent nuclear matrix-associated element

MIR retrotransposon sequences provide insulators to the human genome

Contact Info

Product

Resources

About