Project description:The oocytes of most animals arrest at diplotene or diakinesis, but resume meiosis (meiotic maturation) in response to hormones. In C. elegans, maturation of the –1 oocyte requires the presence of sperm, Gas-adenylate cyclase-PKA signaling in the gonadal sheath cells, and germline function of two Tis11-like CCCH zinc-finger proteins, OMA-1 and OMA-2 (OMA proteins). Prior studies indicate that the OMA proteins redundantly repress the translation of specific mRNAs in oocytes (zif-1, mom-2, nos-2, glp-1) and early embryos (mei-1). We purified OMA-1-containing ribonucleoprotein particles (RNPs) and identified mRNAs that associate with OMA-1 in oocytes using microarrays. We examined the relative abundances of mRNAs in OMA-1 RNPs using high-throughput RNA sequencing. Previously identified targets of OMA-dependent translational repression in oocytes were found to be both enriched (>2-fold relative to input RNA) and abundant in purified OMA-1 RNPs. Furthermore, we verified that some of the newly identified mRNAs that share these characteristics are translationally repressed by OMA-1/2 in oocytes through sequences in their 3’UTRs. Although meiotic maturation is stimulated by sperm, we found that the mRNAs copurifying with OMA-1 are not significantly different in the presence and absence of sperm, suggesting that sperm-dependent signaling does not modify the suite of mRNAs stably associated with OMA-1. Further, several tested OMA-1-associated mRNAs were shown to be translationally repressed in both the presence and absence of sperm. C. elegans mRNAs that co-purify with OMA-1 were identified by deep-sequencing using the Illumina HiSeq 2000
Project description:The oocytes of most animals arrest at diplotene or diakinesis, but resume meiosis (meiotic maturation) in response to hormones. In C. elegans, maturation of the –1 oocyte requires the presence of sperm, Gas-adenylate cyclase-PKA signaling in the gonadal sheath cells, and germline function of two Tis11-like CCCH zinc-finger proteins, OMA-1 and OMA-2 (OMA proteins). Prior studies indicate that the OMA proteins redundantly repress the translation of specific mRNAs in oocytes (zif-1, mom-2, nos-2, glp-1) and early embryos (mei-1). We purified OMA-1-containing ribonucleoprotein particles (RNPs) and identified mRNAs that associate with OMA-1 in oocytes using microarrays. We examined the relative abundances of mRNAs in OMA-1 RNPs using high-throughput RNA sequencing. Previously identified targets of OMA-dependent translational repression in oocytes were found to be both enriched (>2-fold relative to input RNA) and abundant in purified OMA-1 RNPs. Furthermore, we verified that some of the newly identified mRNAs that share these characteristics are translationally repressed by OMA-1/2 in oocytes through sequences in their 3’UTRs. Although meiotic maturation is stimulated by sperm, we found that the mRNAs copurifying with OMA-1 are not significantly different in the presence and absence of sperm, suggesting that sperm-dependent signaling does not modify the suite of mRNAs stably associated with OMA-1. Further, several tested OMA-1-associated mRNAs were shown to be translationally repressed in both the presence and absence of sperm. RNA co-purifiying with OMA-1 (IP RNA) was isolated and compared to total lysate RNA (input RNA). Immunopurifications were performed, in triplicate, from lysates made from two different sterile strains. Sterile fog-1 adults lack sperm. Sterile spe-9 adults contain fertilization-incompetent sperm that promote meiotic maturation.
Project description:Using staged embryos, we find many more genes with poised RNA polymerase than had been observed previously in C. elegans embryos, suggesting that early embryos accumulate poised PolII, and that poising is dynamic. Embryos were staged at the 8E and Bean stages of development prior to ChIP-seq
Project description:This submission data was generated in Angela Stathopoulos's lab. Project goal was to map Su(H) associated regions on Drosophila melanogaster genome. In Drosophila embryos, a nuclear gradient of Dorsal (Dl) directs differential gene expression along the dorsoventral (DV) axis, translating it into distinct domains separated by sharp boundaries between future mesodermal, neural and ectodermal territories. However, the mechanisms used to differentially position gene expression boundaries along this axis are not fully understood. Here, we show that the transcription factor Suppressor of Hairless [Su(H)] influences the positioning of dorsal boundaries for many genes expressed along the DV axis. Synthetic reporter constructs provide molecular evidence that Su(H) binding sites support repression and act to counterbalance activation through Dl and the ubiquitous activator Zelda. Overall, our study highlights a role for broadly expressed repressors, like Su(H), and organization of transcription factor binding sites within cis-regulatory modules as important elements controlling spatial domains of gene expression, to facilitate flexible positioning of boundaries across the entire DV axis. 1 g of 2-4 hour yw embryos were used. Two replicate ChIP-seq samples were analyzed using goat (Santa cruz goat polyclonal #sc-15813), and rabbit (Santa cruz rabbit polyclonal #sc-25761) antibodies.
Project description:RNAi targeting a conserved C. elegans cyclophilin, sig-7, causes defective development and embryonic arrest consistent with a global defect in transcription. The goal of this study was to compare the location of RNA Pol II in sig-7(RNAi) embryos to the localization in L4440/RNAi control embryos to examine the global effect of loss of sig-7 on RNA Pol II regulation and its distribution within gene bodies anti-AMA-1 ChIP in 2 replicates each of sig-7(RNAi) and RNAi control early stage embryos
Project description:ChIP-Seq peak calling of CP190 in wild-type and Ibf2 mutant Drosophila melanogaster third instar larvae Two wild-type and two Ibf2 mutant Drosophila melanogaster third instar larvae were sequenced.
Project description:The present study extends the analysis initiated in a previous report in the popular HD transgenic mouse strain N171-82Q (82Q) (Valor et al., 2013), to other diverse mHtt-expressing animal and cellular models. We show that bulk histone hypoacetylation is not a general rule. Moreover, examination of other histone post-traslational modifications led to a detailed study of the trimethylation of lysine 4 of histone H3 (H3K4me3), which is tightly associated with active genes (Lopez-Atalaya et al., 2013), by combining both single-gene and genome-wide approaches. Comparison of the 82Q and another animal model, the R6/1 strain, revealed that changes in the levels of bulk H3K4me3 may be correlated with the degree of methylation impairment for specific genes. Yet, these changes are restricted to few genomic positions. In any case, and reminiscent of the situation with histone acetylation (Valor et al., 2013; McFarland et al., 2012), deficits in histone H3 methylation do not follow a straight relationship with transcriptional dysregulation. Genome-wide profiling by high throughput sequencing of H3K4me3 in the adult hippocampus of N171-82Q (HD) and their wild-type littermates mice (WT). Chromatin immunoprecipitation (ChIP) was carried out using pooled whole hippocampal tissue from 3 mice. DNA libraries (HD, WT, input) were constructed and single-end sequenced (1x50bp) in HiSeq 2500 platform (Illumina).
Project description:We report the presence of extensive, transcriptionally controlled oscillations in the C. elegans, developmental transcriptome. Furthermore, using ribosome profiling, we show that these oscillating transcripts are actively translated. Examination of two timecourses that were collected over C. elegans development and analyzed by RNA-seq of "RiboMinus" libraries
Project description:Transcriptional dysregulation is an important early feature of polyglutamine diseases. One of its proposed causes is defective neuronal histone acetylation, but important aspects of this hypothesis, such as the precise genomic topography of acetylation deficits and the relationship between transcriptional and acetylation alterations at the whole-genome level, remain unknown. The new techniques for the mapping of histone posttranslational modifications at genomic scale enable such global analyses and are challenging important assumptions concerning the role of specific histone modifications in gene expression. We examined here the genome-wide correlation of histone acetylation and gene expression defects in a mouse model of early-onset Huntington’s disease. Our analyses identified hundreds of loci that were hypoacetylated for H3K9,14 and H4K12 in the chromatin of these mice. Surprisingly, few genes with altered transcript levels in mutant mice showed significant changes in these acetylation marks and vice versa. Our screen, however, identified a subset of genes in which H3K9,14 deacetylation and transcriptional dysregulation concur. Genes in this group were consistently affected in different brain areas, mouse models and tissue from patients, which suggests a role in the etiology of this pathology. Overall, the combination of histone acetylation and gene expression screenings demonstrates that histone deacetylation and transcriptional dysregulation are two early, largely independent, manifestations of polyglutamine disease and suggests that additional epigenetic marks or mechanisms are required for explaining the full range of transcriptional alterations associated with this disorder. Examination of 2 different histone modifications in the hippocampus of wild-type and HD mice (PrP-htt-N171-82Q (Schilling et al., 1999)). Samples were obtained from 10 week old mice.