Filters
Technology
Platform
SRP033515
Homo sapiens
3 Downloadable Samples
IlluminaHiSeq2000
Description
Background: Eukaryotic cells express a complex layer of noncoding RNAs. An intriguing family of regulatory RNAs includes transcripts from the opposite strand of protein coding genes, so called natural antisense transcripts (NATs). Here, we test the hypothesis that antisense transcription triggers RNA interference and gives rise to endogenous short RNAs (endo-siRNAs). Methods/Results: We used cloned human embryonic kidney cells (HEK293) followed by short RNAseq to investigate the small genic RNA transcriptome. 378 genes gave rise to short RNA reads that mapped to exons of RefSeq genes. The length profile of short RNAs showed a broad peak of 20-24 nucleotides, indicative of endo-siRNAs. Collapsed reads mapped predominantly to the first and the last exon of genes (74%). RNAs reads were intersected with sequences occupied by RNAPolII or bound to Argonaute (AGO1 by crosslinking, ligation, and sequencing of hybrids, CLASH). In the first exon, 94% of the reads correlated with PolII occupancy with an average density of 130 (relative units); this decreased to 65%/20 in middle exons and 54%/12 in the last exon. CLASH reads mapping to multi-exon genes showed little distribution bias with an average of about 5 CLASH reads overlapping with 60% of the endo-siRNA reads. However, endo-siRNAs (21-25 nt) intersecting with CLASH reads were enriched at the 5''end and decreased towards the 3''end. We then investigated the 378 genes with particular focus on features indicative for short RNA production; however, found that endo-siRNA numbers did not correlate with gene structures that favor convergent transcription. In contrast, our gene set was found notably over-represented in the NATsDB sense/antisense group as compared to non-overlapping and non-bidirectional groups. Moreover, read counts showed no correlation with the steady-state levels of the related mRNAs and the pattern of endo-siRNAs proved reproducible after an induced mutagenic insult. Conclusions: Our results suggest that antisense transcripts contribute to low levels of endo-siRNAs in fully differentiated human cells. A characteristic endo-siRNA footprint is being produced at sites of RNAPolII transcription which is also related to AGO1. This endo-siRNA signature represents an intriguing finding and its reproducibility suggests that the production of endo-siRNAs is a regulated process with potential homoeostatic impact. Overall design: Size selected RNASeq of 3 human embryonic kidney cell (HEK293) samples. 1 control and 2 samples exposed to 100 µg/ml ethyl methanesulfonate for 24 hrs.
Publication Title
Contribution of natural antisense transcription to an endogenous siRNA signature in human cells.
Sample Metadata Fields
No sample metadata fields
View Samples- Pseudomonas aeruginosa
- 8 Downloadable Samples
Affymetrix Pseudomonas aeruginosa Array (paeg1a)
Description
Pseudomonas aeruginosa (P. aeruginosa) lung infection is a significant cause of mortality in patients with cystic fibrosis (CF). Existing experimental data in our lab showed significantly different levels of virulence of "early" and "late" P. aeruginosa infection isolates in a C. elegans slow killing model. We wished to examine the expression profile of these isolates in order to explore genes that may be responsible for the observed differences. The expression profiles of two pairs of isolates (four isolates in total) were compared to each other using the Affymetrix P. aeruginosa PAO1 genome array, to gain insight into properties mediating virulence in these isolates. Data analysis was carried out using BIOCONDUCTOR software.
Publication Title
Modulation of gene expression by Pseudomonas aeruginosa during chronic infection in the adult cystic fibrosis lung.
Sample Metadata Fields
No sample metadata fields
View Samples