Project description:We examined the effects of loss of su(Hw) on gene expression in both carefully staged 3rd instar larvae (selected at the soft white pre-pupae stage) and wing imaginal discs from these animals. su(Hw) null animals were generated by crossing su(Hw)v mutants with a deficiency (Df(3R)ED5644), homozygous individuals were recognised be the lack of the dominat Tb marker carried on the TM6B marker. Keywords: ChIP-chip
Project description:Suppressor of Hairy-wing [Su(Hw)] is a globally expressed twelve-zinc finger transcription factor in Drosophila. Su(Hw) is well-known for its role in establishing the gypsy insulator within the gypsy retrotransposon. A direct role of Su(Hw) in gene activation and repression was uncovered through the study in the Drosophila oogenesis, revealing that Su(Hw)-dependent repression of neuronal genes is essential for egg production. Motivated from the spatially restricted expression of Su(Hw) in the testis, we investigated the role of Su(Hw) in spermatogenesis. We discovered that Su(Hw) is required for sperm development and male fertility. Data presented here examined the transcriptional role of Su(Hw) in the Drosophila testis. These studies identified ~400 genes with altered expression in the absence of Su(Hw). Coupled with whole-genome Su(Hw) binding profiles, we identified 145 direct targets of Su(Hw) regulation, of which ~80% show increased transcription upon Su(Hw) loss. Upregulated Su(Hw) targets are enriched for neuronal expression, emphasizing that Su(Hw) represents a functional homolog of mammalian REST that represses neuronal gene expression in non-neuronal tissues.
Project description:Insulators delimit independent transcriptional domains within genomes by constraining enhancer and silencer action. These transcriptional effects depend upon DNA recognition by insulator binding proteins that recruit partners that protect against inappropriate long range modulation of non-target promoters. Insulator binding proteins are broadly expressed during development, with largely constitutive binding to thousands of genomic sites. Yet, tissue-specific transcriptional changes result from the loss of individual insulator binding proteins. To understand the molecular basis for such effects, we are studying the classic Drosophila insulator protein Suppressor of Hairy-wing [Su(Hw)]. Genetic studies show that loss of this broadly expressed insulator protein prevents oocyte development. To determine the basis for the block in oogenesis, we coupled transcriptional analyses in su(Hw) mutant ovaries with genome-wide definition of Su(Hw) binding in this tissue. These studies identified 71 direct targets of Su(Hw) regulation, with nearly 70% of these genes showing increased RNA accumulation when Su(Hw) is lost. Surprisingly, derepressed Su(Hw) target genes correspond to genes normally highly expressed in neural tissues, suggesting that Su(Hw) has a critical role in silencing neural genes in the ovary. Support for this postulate was obtained by genetic studies. We found that oocyte production was restored in su(Hw) mutant females that carry a deletion of one allele of the elav family RNA binding protein 9 (Rbp9) gene. These su(Hw) null oocytes can be fertilized, with evidence that embryos lacking Su(Hw) show compromised development. Our studies extend the known transcriptional activities of Su(Hw), indicating that Su(Hw) can function as an insulator, activator and repressor, the latter function being essential for oogenesis. These findings highlight that insulator proteins are versatile transcriptional regulatory proteins, suggesting that tissue specific contributions to transcription result from direct regulation of individual genes.
Project description:Suppressor of Hairy-wing [Su(Hw)] is a multi-zinc finger DNA binding factor required for gypsy insulator function and female germline development in Drosophila. The enhancer-blocking and barrier functions of the gypsy retrotransposon involve Su(Hw) binding to twelve clustered Su(Hw) binding sites (SBSs) and recruitment of the Centrosomal Protein of 190 kD (CP190) and Modifier of mdg4 67.2 kD isoform (Mod67.2) insulator proteins. In contrast, the Su(Hw) germline function involves binding to non-clustered genomic SBSs and does not require CP190 or Mod67.2. Here, we use genome-wide expression analyses in the ovary to identify the first Su(Hw) regulated target genes. Ovaries for RNA isolation were dissected from 4-6 hour old virgin females of wild type (Canton S and BL15598) and su(Hw) null sterile mutants (su(Hw)A2663/v and su(Hw)Pb/2) Drosophila melanogaster. At this stage of development, ovaries only contain egg chamber stages 1-8. Loss of Su(Hw) causes apoptosis at stage 9. Thus, the experimental design compares transcriptional changes in the ovary prior to induction nof apoptosis in su(Hw) mutants.
Project description:ChIP-chip experiments with NimbleGen whole-genome tiling arrays to compare Su(Hw), dCTCF, BEAF, and CP190 localization on DNA in Kc and Mbn2 cells revealed that BEAF is a third subclass of CP190-containing insulators. The DNA binding proteins, Su(Hw), dCTCF, and BEAF show unique distribution patterns with respect to the location and expression level of genes, suggesting diverse roles for these three subclasses of insulators in genome organization. Notably, cell line specific localization sites for all three DNA binding proteins as well as CP190 indicate multiple levels at which insulators can be regulated to affect gene expression.
Project description:mRNA expression levels were determined by NGS for wildtype larvae as well as for larvae lacking HP1a [Su(var)205^04/Su(var)205^05 transheterozygotes].
Project description:Suppressor of Hairy-wing [Su(Hw)] is a multi-zinc finger DNA binding factor required for gypsy insulator function and female germline development in Drosophila. The enhancer-blocking and barrier functions of the gypsy retrotransposon involve Su(Hw) binding to twelve clustered Su(Hw) binding sites (SBSs) and recruitment of the Centrosomal Protein of 190 kD (CP190) and Modifier of mdg4 67.2 kD isoform (Mod67.2) insulator proteins. In contrast, the Su(Hw) germline function involves binding to non-clustered genomic SBSs and does not require CP190 or Mod67.2. Here, we use genome-wide expression analyses in the ovary to identify the first Su(Hw) regulated target genes.
Project description:Insulators delimit independent transcriptional domains within genomes by constraining enhancer and silencer action. These transcriptional effects depend upon DNA recognition by insulator binding proteins that recruit partners that protect against inappropriate long range modulation of non-target promoters. Insulator binding proteins are broadly expressed during development, with largely constitutive binding to thousands of genomic sites. Yet, tissue-specific transcriptional changes result from the loss of individual insulator binding proteins. To understand the molecular basis for such effects, we are studying the classic Drosophila insulator protein Suppressor of Hairy-wing [Su(Hw)]. Genetic studies show that loss of this broadly expressed insulator protein prevents oocyte development. To determine the basis for the block in oogenesis, we coupled transcriptional analyses in su(Hw) mutant ovaries with genome-wide definition of Su(Hw) binding in this tissue. These studies identified 71 direct targets of Su(Hw) regulation, with nearly 70% of these genes showing increased RNA accumulation when Su(Hw) is lost. Surprisingly, derepressed Su(Hw) target genes correspond to genes normally highly expressed in neural tissues, suggesting that Su(Hw) has a critical role in silencing neural genes in the ovary. Support for this postulate was obtained by genetic studies. We found that oocyte production was restored in su(Hw) mutant females that carry a deletion of one allele of the elav family RNA binding protein 9 (Rbp9) gene. These su(Hw) null oocytes can be fertilized, with evidence that embryos lacking Su(Hw) show compromised development. Our studies extend the known transcriptional activities of Su(Hw), indicating that Su(Hw) can function as an insulator, activator and repressor, the latter function being essential for oogenesis. These findings highlight that insulator proteins are versatile transcriptional regulatory proteins, suggesting that tissue specific contributions to transcription result from direct regulation of individual genes. Ovaries for RNA isolation were dissected from 4-6 hour old virgin females of wild type, su(Hw)f/v (fertile), su(Hw)2/v (sterile) and su(Hw)Pb/2 (sterile) Drosophila melanogaster. At this stage of development, ovaries only contain egg chamber stages 1-8. Loss of Su(Hw) causes apoptosis at stage 9. Thus, the experimental design compares transcriptionl changes in the ovary prior to induction nof apoptosis in su(Hw) mutants.
Project description:There is considerable evidence that insulator elements are likely to play a key role in the organisation of the regulatory architecture of the genome. In Drosophila, one of the best studied insulator elements is the gypsy insulator in the gypsy retrotransposon whose function is dependent on the Su(Hw) Zn-finger DNA binding protein. Although there are several hundred Su(Hw) sites in the genome which are proposed to act as endogenous insulator elements, analysis of the role of the Su(Hw) protein has focussed on the gypsy insulator and few endogenous sites have yet been identified. We have used chromatin immunopurification coupled to genomic microarray analysis to identify Su(Hw) binding sites within a representative region of the Drosophila genome; the 3MB Adh region on chromosome 2L. We have located about 60 Su(Hw) binding sites across this region and this has enabled us to construct a robust new Su(Hw) binding site consensus based on these in vivo sites. In contrast to the gypsy insulator which contains 12 Su(Hw) binding sites within 340bp, the endogenous sites are not present in clusters. We identify two key features of these endogenous Su(Hw) sites. Firstly, in contrast to most analyses of DNA binding protein specificity, we find that strong matches to the binding consensus are good predictors of binding site occupancy. Secondly, examination of Su(Hw) binding site occupancy in 0-20hr embryos, 3rd larval instar brains or 3rd larval imaginal discs reveals a constant pattern of Su(Hw) binding indicating that most , if not all Su(Hw) sites are constitutively occupied. These two features support a constant genomic architectural role for the Su(Hw) protein. Keywords: ChIP-chip
Project description:The Suppressor of Hairy-wing [Su(Hw)] protein is a twelve zinc-finger DNA binding transcriptional regulator. Here, we map the genome wide association of Su(Hw) protein expressed from the novel su(Hw)M393 allele, which encodes a protein with a C350S substitution that inactivates ZF4. These analyses demonstrate that ZF4 is required for association with a subset of Su(Hw) binding sites and suggests that these sites may be primarily associated with insulator function.