Project description:Here we demonstrate a natural antisense transcript of notch-1 that interacts with the sense transcript and regulates its availability and pace of G1 phase of cell cycle.
Project description:A core imprint of metazoan life is that perturbations of cell cycle are offset by compensatory changes in successive cellular generations. This trait enhances robustness of multicellular growth and requires transmission of signaling cues within a cell lineage. Notably, the identity and mode of activity of transgenerational signals remain largely unknown. Here we report the discovery of a natural antisense transcript encoded in exon 25 of notch-1 locus (nAS25) by which mother cells control the fate of notch-1 transcript in daughter cells to buffer against perturbations of cell cycle. The antisense transcript is transcribed at G1 phase of cell cycle from a bi-directional E2F1-dependent promoter in the mother cell where the titer of nAS25 is calibrated to the length of G1. Transmission of the antisense transcript from mother to daughter cells stabilizes notch-1 sense transcript in G0 phase of daughter cells by masking it from RNA editing and resultant nonsense-mediated degradation. In consequence, nAS25-mediated amplification of notch-1 signaling reprograms G1 phase in daughter cells to compensate for the altered dynamics of the mother cell. The function of nAS25/notch-1 in integrating G1 phase history of the mother cell into that of daughter cells is compatible with the predicted activity of a molecular oscillator, slower than cyclins, that coordinates cell cycle within cell lineage.
Project description:The Affymetrix GeneChip Wheat Genome Array currently provides the most comprehensive coverage of the wheat genome for a microarray. In addition to using this resource for transcript expression studies and hybridization-based DNA marker discovery, we endeavored to use the GeneChip to discover the expression of natural antisense transcript (NAT) pairs. By using alternative target preparation schemes, both the sense- and antisense-strand derived transcripts were labeled and hybridized to the Wheat GeneChip. To enable maximum discovery, five different tissue types were selected for assay, and the wheat cultivar ‘Chinese Spring’ was used considering that most of the GeneChip probe sequences were based on sequencing of this genome. [PLEXdb(http://www.plexdb.org) has submitted this series at GEO on behalf of the original contributor, Tristan Coram. The equivalent experiment is TA21 at PLEXdb.]
Project description:In yeast, alcohol dehydrogenase I (Adh1) is an abundant zinc binding protein that is required for the conversion of acetaldehyde to ethanol. Through transcriptome profiling of the Schizosaccharomyces pombe genome, we identified a natural antisense transcript at the adh1 locus that is induced in response to zinc-limitation. This antisense transcript (adh1AS) shows a reciprocal expression pattern to that the adh1 mRNA partner. In this study we show that increased expression of the adh1AS transcript in zinc-limited cells is necessary for the repression of adh1 gene expression and that the increased level of the adh1AS transcript in zinc-limited cells is a result of two mechanisms. At the transcriptional level, the adh1AS transcript is expressed at a high level in zinc-limited cells. In addition to this transcriptional control, adh1AS transcripts preferentially accumulate in zinc-limited cells when the adh1AS transcript is expressed from a constitutive promoter. This secondary mechanism requires the simultaneous expression of adh1. Our studies reveal how multiple mechanisms can synergistically control the ratio of sense to antisense transcripts, and highlight a novel mechanism by which adh1 gene expression can be controlled by cellular zinc availability
Project description:In yeast, alcohol dehydrogenase I (Adh1) is an abundant zinc binding protein that is required for the conversion of acetaldehyde to ethanol. Through transcriptome profiling of the Schizosaccharomyces pombe genome, we identified a natural antisense transcript at the adh1 locus that is induced in response to zinc-limitation. This antisense transcript (adh1AS) shows a reciprocal expression pattern to that the adh1 mRNA partner. In this study we show that increased expression of the adh1AS transcript in zinc-limited cells is necessary for the repression of adh1 gene expression and that the increased level of the adh1AS transcript in zinc-limited cells is a result of two mechanisms. At the transcriptional level, the adh1AS transcript is expressed at a high level in zinc-limited cells. In addition to this transcriptional control, adh1AS transcripts preferentially accumulate in zinc-limited cells when the adh1AS transcript is expressed from a constitutive promoter. This secondary mechanism requires the simultaneous expression of adh1. Our studies reveal how multiple mechanisms can synergistically control the ratio of sense to antisense transcripts, and highlight a novel mechanism by which adh1 gene expression can be controlled by cellular zinc availability Sense and antisense expression of the S. pombe transcriptome was measured under zinc-limiting and zinc-replete conditions, using 3 replicates of each condition and an anti-RNA/DNA antibody labeling technique.
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.
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