Project description:Loss of function of the tumor suppressor BRCA1 (Breast Cancer 1) protein is responsible for numerous familial and sporadic breast cancers. We previously identified PABP1 as a novel BRCA1 partner and showed that BRCA1 modulates translation through its interaction with PABP1. We showed that the global translation was diminished in BRCA1-depleted cells and increased in BRCA1-overexpressing cells. Our findings raised the question whether BRCA1 affects translation of all cytoplasmic cellular mRNAs or whether it specifically targets a subset of mRNAs. In the present study, we investigated which mRNAs are regulated by BRCA1 using a microarray analysis of polysome-associated RNAs from BRCA1-depleted MCF7 cells, a human breast cancer cell line. We isolated mRNAs from the high-molecular-weight polysomes (fractions 12 to 18) and total cellular cytoplasmic mRNAs from the cytoplasmic fraction of MCF7 cells transiently expressing either siRNA directed against BRCA1 or control siRNA. Since we were interested in identifying the mRNAs that were translationally regulated by BRCA1, we determined the relative translatability of each mRNA. The relative translatability of an mRNA was determined by normalizing the change in abundance in polysomal mRNA to the change in abundance in total cytoplasmic mRNA for each mRNA.
Project description:THO2 and HPR1 proteins were co-depleted from Drosophila S2 cells and their role in mRNA export analysed by comparing total RNA and cytoplasmic RNA
Project description:Posttranscriptional regulation is emerging as a key factor in glucocorticoid (GC)-mediated gene regulation. We investigated the role of the human glucocorticoid receptor (GR) as an RNA-binding protein and its effect on mRNA turnover in human airway epithelial cells. Cell treatment with the potent GC budesonide accelerated the decay of CCL2 mRNA (t1/2=8±1 min vs. 62±17 min in DMSO-treated cells) and CCL7 mRNA (t1/2=15±4 min vs. 114±37 min), but not that of CCL5 mRNA (t1/2=231±8 min vs. 266±5 min) in the BEAS-2B cell line. This effect was inhibited by pre-incubation with an anti-GR antibody, indicating that GR itself plays a role in the turnover of these transcripts. Co-immunoprecipitation and biotin pulldown experiments showed that GR associates with CCL2 and CCL7 mRNAs, but not CCL5 mRNA. These methods confirmed CCL2 mRNA targeting by GR in human primary airway epithelial cells. Association of the GR was localized to the 5’UTR of CCL2 mRNA, and further mapped to nucleotides 44-60. The collection of transcripts associated with GR, identified by immunoprecipitation of GR-mRNA complexes followed by microarray analysis, revealed 479 transcripts that associated with GR. Computational analysis of the primary sequence and secondary structures of these transcripts yielded a GC-rich motif, which was shown to bind to GR in vitro. This motif was used to predict binding of GR to an additional 7889 transcripts. These results indicate that cytoplasmic GR interacts with a subset of mRNA through specific sequences and can regulate turnover rates, suggesting a novel posttranscriptional role for GR as an RNA-binding protein. The BEAS-2B cell line is derived from human tracheal epithelium transformed by an adenovirus 12-SV40 hybrid virus. For isolation of glucocorticoid receptor-associated transcripts, cytoplasmic lysates obtained from 1.6x107 cells/condition, 4 replicates per condition, were used to generate a collection of transcripts associated with GR by immunoprecipitation of the GR-mRNA complexes. The RNA from these IP's were extracted and labeled with the Illumina TotalPrep RNA Amplification Kit which generates biotin-labeled cRNA. This was hybridized to Illumina's Sentrix HumanRef-8,v3 Expression BeadChips. The data from 3 replicates of GR-IP and 4 replicates of Control-IP were used for global analysis of GR-mRNA interactions.
Project description:Cells were grown to ~50% confluency before RNA polymerase activity was blocked with 10 µg/mL Actinomycin D (Sigma) in DMSO. Control cells were treated with DMSO alone. Transcriptional inhibition of N2A cells was conducted for 32 h with cells harvested at time zero (0 h) and after 30 min, 2, 4, 8, 16 and 32 h. Inhibition of 3T3 cells was conducted for 24 h with harvesting at time zero (0 h) and after 30 min, 2, 4, 8 and 24 h.
Project description:To accelerate previous RNA structure probing approaches, which focus on analyzing one RNA sequence at a time, we have developed FragSeq, a high-throughput RNA structure probing method that uses high-throughput RNA sequencing to identify single-stranded RNA (ssRNA) regions from fragments generated by nuclease P1, which is specific for single-stranded nucleic acids. In the accompanying study, we show that we can accurately and simultaneously map ssRNA regions in multiple non-coding RNAs with known structure in experiments probing the entire mouse nuclear transcriptome. We carried out probing in two cell types to assess reproducibility. We also identified and experimentally validated structured regions in ncRNAs never previously probed. We examined mouse nuclear RNA from two cell types: undifferentiated embryonic stem cells (UNDIFF) and cells differentiated into neural precursors (D5NP). For each cell type, nuclear RNA was purified and deproteinized, denatured, and refolded in vitro, from which we prepared three barcoded samples: "nuclease" (RNA partially digested with P1 ssRNA-specific nuclease, yielding 5'-PO4/3'-OH end chemistry at each cleavage site), "control" (control for "nuclease" sample to idenfity endogenous 5'-PO4/3'-OH), and "PNK" (same as "control" but followed by a polynucleotide kinase treatment to convert 5'-OH/3'-cyclic-phosphate ends to clonable 5'-PO4/3'-OH ends). Resulting RNA fragments were cloned using the SOLiD Small RNA Expression Kit (SREK) protocol, which ligates linkers only to 5'-PO4/3'-OH containing RNA, enriching for clones of products resulting from P1 cleavage in "nuclease" sample and selecting against random degradation. Two cell types, three treatments each, thus resulted in six barcoded samples total (barcodes 01, 02, 04, 05, 07, 08). Four other barcoded samples were prepared for separate experiments not used in our study (barcodes 03, 06, 09, 10), so their preparation is not described here. The total run of ten barcodes was done on the ABI SOLiD3 platform and a custom algorithm (FragSeq v0.0.1) was used to compute "cutting scores" (as described in our paper) that show ssRNA regions in hundreds of ncRNAs.
Project description:MicroRNA (miRNA) play a major role in the post-transcriptional regulation of gene expression. In mammals most miRNA derive from the introns of protein coding genes where they exist as hairpin structures in the primary gene transcript, synthesized by RNA polymerase II (Pol II). These are cleaved co-transcriptionally by the Microprocessor complex, comprising DGCR8 and the RNase III endonuclease Drosha, to release the precursor (pre-)miRNA hairpin, so generating both miRNA and spliced messenger RNA1-4. However, a substantial minority of miRNA originate from Pol II-synthesized long non coding (lnc) RNA where transcript processing is largely uncharacterized5. Here, we show that most lnc-pri-miRNA do not use the canonical cleavage and polyadenylation (CPA) transcription termination pathway6, but instead use Microprocessor cleavage both to release pre-miRNA and terminate transcription. We present a detailed characterization of one such lnc-pri-miRNA that generates the highly expressed liver-specific miR-1227. Genome-wide analysis then reveals that Microprocessor-mediated transcription termination is commonly used by lnc-pri-miRNA but not by protein coding miRNA genes. This identifies a fundamental difference between lncRNA and pre-mRNA processing. Remarkably, inactivation of the Microprocessor can lead to extensive transcriptional readthrough of lnc-pri-miRNA, resulting in inhibition of downstream genes by transcriptional interference. Consequently we define a novel RNase III-mediated, polyadenylation-independent mechanism of Pol II transcription termination in mammalian cells. Chromatin associated RNA-seq from sicntrl,siDrosha,siDGCR8 treated Hela cells. Same for sicntrl and siDGCR8 from Huh7 cells. Nuclear polyA + and polyA- RNA-seq from sicntrl and siDGCR8 in HeLa cells. Chromatin associated RNA-seq from siDicer treated Hela cells.
Project description:Whilst the biological function of many lncRNAs remains unknown, recent evidence has suggested that lncRNAs may be important regulators of cellular growth, differentiation and may play a significant role in cancer. Epidermal growth factor (EGF) an activator of the ERK1/2 signalling cascade is an important spatio-temporal regulator of transcription and, ultimately, of cellular growth and movement. In order to identify lncRNAs regulated by EGF signalling, we sequenced nuclear RNA in the presence or absence of EGF stimulation.
Project description:We performed mRNA 3'end sequencing experiments on three biological replicates of HeLa cells depleted of MATR3, PTBP1/2, controls, or combined depletion of MATR3/PTBP1/2. Cells were fractionated into cytoplasmic and nuclear RNAn and only the nuclear RNA was used. Library preparation was done with the QuantSeq library kit (Lexogen) according to manufacturer’s recommendations. Replicates 1 and 2 were prepared with the QuantSeq forward library kit, replicates 3 and 4 with the QuantSeq reverse library kit. All libraries were sequenced on Illumina HiSeq2 machines in a single-end manner with a read length of 100 nt.
Project description:To study the effect of Larp1 on the abundance and subcellular localization of 5'TOP containing mRNAs, Larp1 was depleted from mouse primary cortical neurons using shRNAs. RNA from subcellular compartments (neurite and soma cytoplasm) was isolated and sequenced in parallel with scrambled control shRNA expressing samples.
Project description:To study the correlation between mRNA stability and subcellular mRNA localisation we globally interferred with mRNA degradation in primary cortical neurons by overexpressing a catalytic mutant of deadenylase CAF1 that functions as a dominant negative form. Neurons were separated into subcellular compartments (neurite, soma-cytoplasm and nucleus) and sequenced in parallel with respective compartments from GFP- expressing control neuons.