H2A.Z marks antisense promoters and has positive effects on antisense transcript levels in budding yeast
Ontology highlight
ABSTRACT: The histone variant H2A.Z, which has been reported to have both activating and repressive effects on gene expression, is known to occupy nucleosomes at the 5’ ends of protein-coding genes. We now find that H2A.Z is also significantly enriched in gene coding regions and at the 3’ ends of genes in budding yeast, where it co-localises with histone marks associated with active promoters. By comparing H2A.Z binding to global gene expression in budding yeast strains engineered so that normally unstable transcripts are abundant, we show that H2A.Z is required for normal levels of antisense transcripts as well as sense ones. High levels of H2A.Z at antisense promoters are associated with decreased antisense transcript levels when H2A.Z is deleted, indicating that H2A.Z has an activating effect on antisense transcripts. Decreases in antisense transcripts affected by H2A.Z are accompanied by increased levels of paired sense transcripts. Therefore, the effect of H2A.Z on protein coding gene expression is a reflection of its importance for normal levels of both sense and antisense transcripts.
Project description:The histone variant H2A.Z, which has been reported to have both activating and repressive effects on gene expression, is known to occupy nucleosomes at the 5’ ends of protein-coding genes. We now find that H2A.Z is also significantly enriched in gene coding regions and at the 3’ ends of genes in budding yeast, where it co-localises with histone marks associated with active promoters. By comparing H2A.Z binding to global gene expression in budding yeast strains engineered so that normally unstable transcripts are abundant, we show that H2A.Z is required for normal levels of antisense transcripts as well as sense ones. High levels of H2A.Z at antisense promoters are associated with decreased antisense transcript levels when H2A.Z is deleted, indicating that H2A.Z has an activating effect on antisense transcripts. Decreases in antisense transcripts affected by H2A.Z are accompanied by increased levels of paired sense transcripts. Therefore, the effect of H2A.Z on protein coding gene expression is a reflection of its importance for normal levels of both sense and antisense transcripts. Htz1 ChIP-seq in wild-type (WT) and rrp6Δ yeast, along with negative control ChIP-seq in htz1Δ and input control. Strand-specific transcriptomic profiles of WT, htz1Δ, rrp6Δ and htz1Δrrp6Δ. Replicates are present for all samples except the negative and input control ChIP samples.
Project description:We characterized the expression patterns of sense-antisense transcripts, based on available cDNA sequences, in colon (colorectal) cancer tissues and in normal tissues surrounding the cancer tissues. Although expression balances (ratios) of most of sense and antisense transcript pairs did not change between patients or between normal and cancer tissues, we found 68 sense-antisense transcripts whose expression balances were altered specifically in colon cancer tissues. We conducted DNA microarray analyses by using the same set of probes designed for 2621 sense-antisense pairs to detect transcripts expressed in colon cancer tissues. These probes comprise 2358 pairs for the detection of protein-coding transcripts only, 250 pairs for the detection of protein-coding transcripts paired with non-protein-coding transcripts, and 13 pairs for the detection of non-protein-coding transcripts only.
Project description:Hight throughput techniques have revealed huge complexity in antisense RNAs in many organisms. We have explored the complexity of this class of transcripts and functional links to Polycomb silencing thought analysis of non-coding RNAs of Arabidopsis FLC. FLC is repressed and epigenetically silenced by prolonged cold, enabling plants to undergo the floral transition. Single nucleotide resolution tiling array revealed long non-coding transcripts covering the entire FLC locus. The most abundant of these are capped and polyadenylated, initiate over a 100 nucleotide window just downstream of the sense polyA site, are differentially spliced and terminate either within the sense gene or its promoter. Their levels correlate with FLC sense transcripts in all mutants and conditions tested except cold treatment. The antisense transcripts were strongly but transiently cold-induced, much earlier than other vernalization markers, and this coincided with reduction in sense FLC transcription but not sense FLC mRNA levels. Addition of the FLC antisense 5'/sense 3' region to a GFP transgene was sufficient to confer cold-induced silencing of thet fusion; however this silencing was not epigenetically manteined. These processes were all independent of the function of the Polycomb proteins required for maintenance of FLC silencing. Our data suggest that FLC antisense transcripts induce transient FLC transcriptional silencing, possibly through promoter interference, with the epigenetic silencing requiring subsequent recruitment of Polycomb machinery.
Project description:Hight throughput techniques have revealed huge complexity in antisense RNAs in many organisms. We have explored the complexity of this class of transcripts and functional links to Polycomb silencing thought analysis of non-coding RNAs of Arabidopsis FLC. FLC is repressed and epigenetically silenced by prolonged cold, enabling plants to undergo the floral transition. Single nucleotide resolution tiling array revealed long non-coding transcripts covering the entire FLC locus. The most abundant of these are capped and polyadenylated, initiate over a 100 nucleotide window just downstream of the sense polyA site, are differentially spliced and terminate either within the sense gene or its promoter. Their levels correlate with FLC sense transcripts in all mutants and conditions tested except cold treatment. The antisense transcripts were strongly but transiently cold-induced, much earlier than other vernalization markers, and this coincided with reduction in sense FLC transcription but not sense FLC mRNA levels. Addition of the FLC antisense 5'/sense 3' region to a GFP transgene was sufficient to confer cold-induced silencing of thet fusion; however this silencing was not epigenetically manteined. These processes were all independent of the function of the Polycomb proteins required for maintenance of FLC silencing. Our data suggest that FLC antisense transcripts induce transient FLC transcriptional silencing, possibly through promoter interference, with the epigenetic silencing requiring subsequent recruitment of Polycomb machinery. Total seedling RNA from different genotypes and different conditions: WT, FRIGIDA, 35s::FCA (giving overexpression of FCA), FRIGIDA + 2 weeks cold, FRIGIDA + 2 weeks cold + 7 days warm.
Project description:<p>High throughput RNA Sequencing has revealed that the human genome is widely transcribed. However, the extent of natural antisense transcription, the molecular mechanisms by which natural antisense transcripts (NATs) might affect their cognate sense genes, and the role of NATs in cancer are less well understood. Here, we use strand-specific paired-end RNA sequencing (ssRNASeq) on a cohort of 376 cancer patients covering 9 tissue types to comprehensively characterize the landscape of antisense expression. Our results reveal that greater than 60% of annotated transcripts have measureable antisense expression and the expression of sense and antisense transcript pairs is in general positively correlated. Furthermore, by studying the expression of sense/antisense pairs across tissues we identify lineage-specific, ubiquitous and cancer-specific antisense loci. Our results raise the possibility that NATs participate in the regulation of well-known tumor suppressors and oncogenes. Finally, this study provides a catalogue of cancer related genes with significant antisense transcription (oncoNAT). This resource will allow researchers to investigate the molecular mechanisms of sense/antisense regulation and further advance our understanding of their role in cancer.</p>
Project description:Previous RNA profiling studies revealed co-expression of overlapping sense/antisense (s/a) transcripts in pro- and eukaryotic organisms. Functional analyses in yeast have shown that certain s/a mRNA/mRNA and mRNA/lncRNA pairs form stable double-stranded RNAs (dsRNAs) that affect transcript stability. Little is known, however, about the genome-wide prevalence of dsRNA formation and its potential functional implications during growth and development in diploid budding yeast. To address this question, we monitored dsRNAs in a Saccharomyces cerevisiae strain expressing the ribonuclease DCR1 and the RNA binding protein AGO1 from Naumovozyma castellii. We identify dsRNAs at 347 s/a loci that express partially or completely overlapping transcripts during mitosis, meiosis or both stages of the diploid life cycle. We associate dsRNAs with s/a loci previously thought to be exclusively regulated by antisense interference, and others that encode antisense RNAs, which downregulate sense mRNA-encoded protein levels. To facilitate hypothesis building we developed the Sense/Antisense double-stranded RNA (SensR) expression viewer. Users are able to retrieve different graphical displays of dsRNA and RNA expression data using genome coordinates and systematic or standard names for mRNAs and different types of stable or cryptic long non-coding RNAs (lncRNAs). Our data are a useful resource for improving yeast genome annotation and for work on RNA-based regulatory mechanisms controlling transcript and protein levels. The data are also interesting from an evolutionary perspective, since natural antisense transcripts that form stable dsRNAs have been detected in many species from bacteria to humans. The SensR viewer is freely accessible at https://sensr.genouest.org.
Project description:Increasing numbers of sense–antisense transcripts (SATs), which are transcribed from the same chromosomal location but in opposite directions, have been identified in various eukaryotic species, but the biological meanings of most SATs remain unclear. To improve understanding of natural sense–antisense transcription, we performed comparative expression profiling of SATs conserved among humans and mice. Using custom oligo-arrays loaded with probes that represented SATs with both protein-coding and non-protein–coding transcripts, we showed that 33% of the 291 conserved SATs displayed identical expression patterns in the two species. Among these SATs, expressional balance inversion of sense–antisense genes was mostly observed in testis at a tissue-specific manner. Northern analyses of the individual conserved SAT loci revealed that: (1) a smeary hybridization pattern was present in mice, but not in humans, and (2) small RNAs (about 60 to 80 nt) were detected from the exon-overlapping regions of SAT loci. In addition, further analyses showed marked alteration of sense–antisense expression balance throughout spermatogenesis in testis. These results suggest that conserved SAT loci are rich in potential regulatory roles that will help us understand this new class of transcripts underlying the mammalian genome. Keywords: Expression profile of mouse and human sense-antisense transcript
Project description:We characterized the expression patterns of sense-antisense transcripts, based on available cDNA sequences, in colon (colorectal) cancer tissues and in normal tissues surrounding the cancer tissues. Although expression balances (ratios) of most of sense and antisense transcript pairs did not change between patients or between normal and cancer tissues, we found 68 sense-antisense transcripts whose expression balances were altered specifically in colon cancer tissues.
Project description:Comparison of sense (forward probes) and antisense (reverse probes on U74 v1 gene arrays) transcripts in mouse kidney and brain. Positive calls related to antisense transcripts were compared to the cognate signals on the 430 version of mouse genome arrays to obtain genes that co expressed sense and antisense transcripts. This had to be done manually because divergent probe IDs on the two chip generations. Keywords: Qualitative comparison of expression
Project description:Comparison of sense (forward probes) and antisense (reverse probes on U74 v1 gene arrays) transcripts in mouse kidney and brain. Positive calls related to antisense transcripts were compared to the cognate signals on the 430 version of mouse genome arrays to obtain genes that co expressed sense and antisense transcripts. This had to be done manually because divergent probe IDs on the two chip generations. Experiment Overall Design: The first Affymetrix U74 mouse gene chips contains reversely oriented probe sets. These probes will hybridize to natural antisense transcripts that overlap with the sense transcript in the cognate area. Affymetrix provided a mask to identify the reverse probes. Positive calls with these reverse probes will give an estimate of the antisense transcriptome in that particular tissue. Comparison of the reversely oriented probes with correctly annotated probes will reveal the expression ratio of sense and antisense transcripts.