scholarly journals The Drosophila gypsy Insulator Supports Transvection in the Presence of the vestigial Enhancer

PLoS ONE ◽  
2013 ◽  
Vol 8 (11) ◽  
pp. e81331 ◽  
Author(s):  
Todd Schoborg ◽  
Srilalitha Kuruganti ◽  
Ryan Rickels ◽  
Mariano Labrador
Keyword(s):  
Genetics ◽  
2002 ◽  
Vol 160 (4) ◽  
pp. 1481-1487 ◽  
Author(s):  
Fabien Mongelard ◽  
Mariano Labrador ◽  
Ellen M Baxter ◽  
Tatiana I Gerasimova ◽  
Victor G Corces

AbstractTwo mutant alleles of the same gene, each located in one of the two homologous chromosomes, may in some instances restore the wild-type function of the gene. This is the case with certain combinations of mutant alleles in the mod(mdg4) gene. This gene encodes several different proteins, including Mod(mdg4)2.2, a component of the gypsy insulator. This protein is encoded by two separate transcription units that can be combined in a trans-splicing reaction to form the mature Mod(mdg4)2.2-encoding RNA. Molecular characterization of complementing alleles shows that they affect the two different transcription units. Flies homozygous for each allele are missing the Mod(mdg4)2.2 protein, whereas wild-type trans-heterozygotes are able to synthesize almost normal levels of the Mod(mdg4)2.2 product. This protein is functional as judged by its ability to form a functional insulator complex. The results suggest that the interallelic complementation in the mod(mdg4) gene is a consequence of trans-splicing between two different mutant transcripts. A conclusion from this observation is that the trans-splicing reaction that takes place between transcripts produced on two different mutant chromosomes ensures wild-type levels of functional protein.


Genetics ◽  
1999 ◽  
Vol 152 (3) ◽  
pp. 1045-1055
Author(s):  
Izanne D Zorin ◽  
Tatiana I Gerasimova ◽  
Victor G Corces

Abstract Mutations in the lawc gene result in a pleiotropic phenotype that includes homeotic transformation of the arista into leg. lawc mutations enhance the phenotype of trx-G mutations and suppress the phenotype of Pc mutations. Mutations in lawc affect homeotic gene transcription, causing ectopic expression of Antennapedia in the eye-antenna imaginal disc. These results suggest that lawc is a new member of the trithorax family. The lawc gene behaves as an enhancer of position-effect variegation and interacts genetically with mod(mdg4), which is a component of the gypsy insulator. In addition, mutations in the lawc gene cause alterations in the punctated distribution of mod(mdg4) protein within the nucleus. These results suggest that the lawc protein is involved in regulating the higher-order organization of chromatin.


2009 ◽  
Vol 38 (1) ◽  
pp. 39-47 ◽  
Author(s):  
Margarita Silicheva ◽  
Anton Golovnin ◽  
Ekaterina Pomerantseva ◽  
Aleksander Parshikov ◽  
Pavel Georgiev ◽  
...  

2014 ◽  
Vol 42 (14) ◽  
pp. 9158-9170 ◽  
Author(s):  
Ryan K. Dale ◽  
Leah H. Matzat ◽  
Elissa P. Lei

Abstract Here we introduce metaseq, a software library written in Python, which enables loading multiple genomic data formats into standard Python data structures and allows flexible, customized manipulation and visualization of data from high-throughput sequencing studies. We demonstrate its practical use by analyzing multiple datasets related to chromatin insulators, which are DNA–protein complexes proposed to organize the genome into distinct transcriptional domains. Recent studies in Drosophila and mammals have implicated RNA in the regulation of chromatin insulator activities. Moreover, the Drosophila RNA-binding protein Shep has been shown to antagonize gypsy insulator activity in a tissue-specific manner, but the precise role of RNA in this process remains unclear. Better understanding of chromatin insulator regulation requires integration of multiple datasets, including those from chromatin-binding, RNA-binding, and gene expression experiments. We use metaseq to integrate RIP- and ChIP-seq data for Shep and the core gypsy insulator protein Su(Hw) in two different cell types, along with publicly available ChIP-chip and RNA-seq data. Based on the metaseq-enabled analysis presented here, we propose a model where Shep associates with chromatin cotranscriptionally, then is recruited to insulator complexes in trans where it plays a negative role in insulator activity.


Genetics ◽  
2002 ◽  
Vol 160 (4) ◽  
pp. 1549-1560 ◽  
Author(s):  
Larisa Melnikova ◽  
Maria Gause ◽  
Pavel Georgiev

Abstract The best-characterized insulator in Drosophila melanogaster is the Su(Hw)-binding region contained within the gypsy retrotransposon. In the y2 mutant, Su(Hw) protein partially inhibits yellow transcription by blocking the function of transcriptional enhancers located distally from the yellow promoter with respect to gypsy. Previously we have shown that yellow enhancers can overcome inhibition by a downstream insulator in the yrh1 allele, when a second gypsy element is located upstream of the enhancers. To understand how two insulators neutralize each other, we isolated various deletions that terminate in the regulatory region of the yrh1 allele. To generate these alleles we used DNA elongation by gene conversion of the truncated chromosomes at the end of the yellow regulatory region. We found that gypsy insulator can function at the end of the truncated chromosome. Addition of the gypsy insulator upstream of the yellow enhancers overcomes the enhancer-blocking activity of the gypsy insulator inserted between the yellow enhancers and promoter. These results suggest that the gypsy insulators do not form separate transcriptional domains that delimit the interactions between enhancers and promoters.


Genetics ◽  
2001 ◽  
Vol 159 (4) ◽  
pp. 1649-1658
Author(s):  
Siquan Chen ◽  
Victor G Corces

Abstract Chromatin insulators are thought to regulate gene expression by establishing higher-order domains of chromatin organization, although the specific mechanisms by which these sequences affect enhancer-promoter interactions are not well understood. Here we show that the gypsy insulator of Drosophila can affect chromatin structure. The insulator itself contains several DNase I hypersensitive sites whose occurrence is dependent on the binding of the Suppressor of Hairy-wing [Su(Hw)] protein. The presence of the insulator in the 5′ region of the yellow gene increases the accessibility of the DNA to nucleases in the promoter-proximal, but not the promoter-distal, region. This increase in accessibility is not due to alterations in the primary chromatin fiber, because the number and position of the nucleosomes appears to be the same in the presence or absence of the insulator. Binding of the Su(Hw) protein to insulator DNA is not sufficient to induce changes in chromatin accessibility, and two domains of this protein, presumed to be involved in interactions with other insulator components, are essential for this effect. The presence of Modifier of mdg4 [Mod(mdg4)] protein, a second component of the gypsy insulator, is required to induce these alterations in chromatin accessibility. The results suggest that the gypsy insulator affects chromatin structure and offer insights into the mechanisms by which insulators affect enhancer-promoter interactions.


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