Project description:Fly strains were obtained from the Bloomington Stock Center. The chromosomes containing the gene deletion mod(mdg4)L3101 {y[1] w[1118]; P{w[+mC]=lacW}mod(mdg4)[L3101]/TM3, Ser[1]}, HP1 {In(1)w[m4h]; Su(var)205[5]/In(2L)Cy,In(2R)Cy, Cy[1]}, mod(mdg4)G16853 {w[1118]; P{w[+mC]=EP}mod(mdg4)[G16853]/TM6C, Sb[1]}, and Jil-1Scim {y[1]; P{y[+mDint2] w[BR.E.BR]=SUPor-P}JIL-1[Scim] ry[506]} were introgressed into the genetic background y[1]; bw[1]; e[4]; ci[1] ey[R] to generate the strains Mod(mdg4)/+, Su(var)205/+ and JIL-1/+. All females used in the introgression were collected within 7 hours after eclosion. For gene expression analyses, flies were grown in incubators at 25°C, 65% of relative humidity, and constant light. Newly emerged male adults flies harboring the mutations and the Y chromosomes Yohio and Ycongo(Mod(mdg4)/+;Yohio and Mod(mdg4)/+;Ycongo, Su(var)205/+;Yohio and Su(var)205/+;Ycongo, and JIL-1/+;Yohio and JIL-1/+;Ycongo) were collected and aged for 2 days at the same rearing condition before they were flash-frozen in liquid nitrogen. Four replicas of each sample were collected and stored at -80°C. Total RNA was extracted from whole flies using TRIzol (Life Technologies). The synthesis of cDNA and its labeling with fluorescent dyes (Cy3 and Cy5) as well as hybridization reactions were carried out using 3DNA protocols and reagents (Genisphere). The genetic interaction of the Y chromosome and the mutation was studied by the following contrasts: 1) male flies Mod(mdg4)/+;Yohio versus male flies Mod(mdg4)/+;Ycongo; 2) male flies Su(var)205/+;Yohio versus male flies Su(var)205/+;Ycongo; 3) male flies JIL-1/+;Yohio versus male flies JIL-1/+;Ycongo). As reference we used the same genetic background without the mutations [+/+;Ycongo (background 2) and +/+;Yohio (background 2)]. Slides were scanned using Axon 400B scanner (Axon Instruments) and GenePix Pro 6.0 software. Foreground fluorescence of dye intensities was normalized by the Loess method in Bioconductor / Limma.
Project description:Fly strains were obtained from the Bloomington Stock Center. The chromosomes containing the gene deletion mod(mdg4)L3101 {y[1] w[1118]; P{w[+mC]=lacW}mod(mdg4)[L3101]/TM3, Ser[1]}, HP1 {In(1)w[m4h]; Su(var)205[5]/In(2L)Cy,In(2R)Cy, Cy[1]}, mod(mdg4)G16853 {w[1118]; P{w[+mC]=EP}mod(mdg4)[G16853]/TM6C, Sb[1]}, and Jil-1Scim {y[1]; P{y[+mDint2] w[BR.E.BR]=SUPor-P}JIL-1[Scim] ry[506]} were introgressed into the genetic background y[1]; bw[1]; e[4]; ci[1] ey[R] to generate the strains Mod(mdg4)/+, Su(var)205/+ and JIL-1/+. All females used in the introgression were collected within 7 hours after eclosion. For gene expression analyses, flies were grown in incubators at 25°C, 65% of relative humidity, and constant light. Newly emerged male adults flies harboring the mutations and the Y chromosomes Yohio and Ycongo(Mod(mdg4)/+;Yohio and Mod(mdg4)/+;Ycongo, Su(var)205/+;Yohio and Su(var)205/+;Ycongo, and JIL-1/+;Yohio and JIL-1/+;Ycongo) were collected and aged for 2 days at the same rearing condition before they were flash-frozen in liquid nitrogen. Four replicas of each sample were collected and stored at -80°C. Total RNA was extracted from whole flies using TRIzol (Life Technologies). The synthesis of cDNA and its labeling with fluorescent dyes (Cy3 and Cy5) as well as hybridization reactions were carried out using 3DNA protocols and reagents (Genisphere). The genetic interaction of the Y chromosome and the mutation was studied by the following contrasts: 1) male flies Mod(mdg4)/+;Yohio versus male flies Mod(mdg4)/+;Ycongo; 2) male flies Su(var)205/+;Yohio versus male flies Su(var)205/+;Ycongo; 3) male flies JIL-1/+;Yohio versus male flies JIL-1/+;Ycongo). As reference we used the same genetic background without the mutations [+/+;Ycongo (background 2) and +/+;Yohio (background 2)]. Slides were scanned using Axon 400B scanner (Axon Instruments) and GenePix Pro 6.0 software. Foreground fluorescence of dye intensities was normalized by the Loess method in Bioconductor / Limma. Dye "swaps," loop design.
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:The asynchronous timing of replication of different chromosome domains is essential for eukaryotic genome stability, but the mechanisms establishing replication timing programs remain incompletely understood. Drosophila SNF2-related factor SUUR imparts under-replication (UR) of late-replicating intercalary heterochromatin (IH) domains in polytene chromosomes. SUUR negatively regulates DNA replication fork progression across IH; however, its mechanism of action remains obscure. Here we developed a novel method termed MS-Enabled Rapid protein Complex Identification (MERCI) to isolate a stable stoichiometric native complex SUMM4 that comprises SUUR and a chromatin boundary protein Mod(Mdg4)-67.2. In vitro, Mod(Mdg4) stimulates the ATPase activity of SUUR, although neither SUUR nor SUMM4 can remodel nucleosomes. Mod(Mdg4)-67.2 and SUUR distribution patterns in vivo partially overlap, and Mod(Mdg4) is required for a normal spatiotemporal distribution of SUUR in chromosomes. SUUR and Mod(Mdg4)-67.2 mediate insulator activities of the gypsy mobile element that disrupt enhancer-promoter interactions and establish euchromatin-heterochromatin barriers in the genome. Furthermore, mutations of SuUR or mod(mdg4) reverse the locus-specific UR. These findings reveal that DNA replication can be delayed by a chromatin barrier and thus, uncover a critical role for architectural proteins in replication timing control. They also provide a biochemical link between ATP-dependent motor factors and the activity of insulators in regulation of gene expression and chromatin partitioning.
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]. RNA samples from wildtype (OR) and HP1a mutant third instar larvae were examined, using duplicate biological samples and Illumina NGS.
Project description:Here we map the localization of Mod(mdg4), including Mod(mdg4)2.2 specific and Mod(mdg4) common to all isoforms, to chromatin insulators, as well as the lethal-3 malignant brain tumor protein in Drosophila Kc cells.
Project description:Transcriptomic analysis and identification of differentially expressed genes in control vs KD Drosophila melanogaster ovaries. We compared gene expression profiles in Drosophila melanogaster ovaries in which the Snr1 or the mod(mdg4) gene have been selectively knocked down by tissues specific shRNA expression.
Project description:Here we map the localization of Mod(mdg4), including Mod(mdg4)2.2 specific and Mod(mdg4) common to all isoforms, to chromatin insulators, as well as the lethal-3 malignant brain tumor protein in Drosophila Kc cells. examination of genomic occupancy for Mod(mdg4)2.2, Mod(mdg4)BTB (all isoforms), and L(3)mbt, control samples used for Drosophila Kc were previously described (Wood, Van Bortle et al., 2011 GSE30740)
Project description:In contrast to canonical cis-splicing, trans-splicing combines exons from two distinct transcripts, yielding chimeric mRNAs. One striking example is the ubiquitously expressed modifier of mdg4 (mod(mdg4)) locus in Drosophila, where all mRNAs spanning over 30 isoforms are generated exclusively by trans-splicing. This process combines common constitutive exons with one of many alternative 3′ variable exons transcribed from independent promoters. Here, we demonstrate that trans-splicing is determined by an approximately 600-bp region located in the proximal part of the last common intron. Deletion analysis in a model system and directly within the endogenous mod(mdg4) locus revealed that this intronic region contains multiple redundant motifs for RNA-binding proteins (RBPs), which collectively determine the level of trans-splicing. By affinity purification of the in vitro transcribed proximal part of the intronic RNA, we identified specific binding of a large group of spliceosome-associated RBPs, some of which were found to have binding motifs in the intronic region of mod(mdg4) RNA, which is critical for trans-splicing.
Project description:Telomeres in Drosophila are composed of sequential non-LTR retrotransposons: Het-A, TART, TAHRE. Although their expression is highly dynamic, molecular mechanism governing these retrotransposons is poorly understood. Here, we show that specific splice variants of Mod(mdg4) act as repressors of Het-A by blocking subtelomeric enhancers in ovarian somatic cells. We found that a variant, Mod(mdg4)-N, can repress Het-A expression most efficiently among variants. Mod(mdg4)-N mutant flies show elevated Het-A expression and female sterility. Further investigation revealed that Mod(mdg4)-N-binding subtelomeric sequences exhibit enhancer-blocking activity, and recruitment of RNA polymerase II (Pol II) on subtelomeres by Mod(mdg4)-N is essential for this enhancer-blocking. Moreover, Mod(mdg4)-N functions to form chromatin boundaries of higher-order chromatin conformation but this mechanism is independent with its Pol II recruitment activity observed at telomeres/subtelomeres. This study provides an unexpected link between enhancer-blocking and telomere regulation, and two different molecular mechanisms exhibited by an insulator protein to orchestrate precise gene expression.