EIF4A3 - Modified iCLIP
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ABSTRACT:
PROVIDER: PRJEB11647 | ENA |
REPOSITORIES: ENA
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Project description:The modified iCLIP protocol is based on the previously described protocol (Huppertz et al., 2014) with modifications that enable the definition of readthrough cDNAs. HeLa cells were crosslinked with 0.15mJ/cm2 254nm UV light. Protein G Dynabeads were used for immunoprecipitations (IP). For each IP, 100 l of beads were washed in iCLIP lysis buffer (50mM Tris-HCL pH 7.4, 100mM NaCl, 1% NP-40, 0.1% SDS, 0.5% sodium deoxycholate), and incubated with the anti-eIF4A3 antibody or polyclonal mAb BB7 serum anti-PTBP1. To prepare the cell lysate, the cells were lysed with 1 mL iCLIP lysis buffer (final concentration 2mg/mL), sonicated (Bioruptor, 5x5 sec on/off), incubated with RNase I (1-2 x10-3 U/mL for eIF4A3) at 37C for 3 min, and centrifuged. After the pellet had dissolved, the mixture was diluted with H2O to 1000 L and an additional centrifugation was performed. The supernatant of the iCLIP lysis buffer (1 mL) and the MSB lysis buffer (1 ml) were combined and added to the antibody-coupled beads, which were then rotated at 4C for 2 h (final urea concentration 175 mM). The beads were then washed with high-salt washing buffer (50mM Tris-HCL pH 7.4, 1M NaCl, 1% NP-40, 0.1% SDS, 0.5% sodium deoxycholate). After the first round of washes, the library was split into 10%, which were radioactively labelled (according to the basic iCLIP protocol), and 90%, which proceed through 3 adapter addition, an additional phosphorylation (0.2 l PNK, 0.4 l cold ATP (1mM), 0.4 l 10x PNK buffer, 3 l water) and a 5 marker ligation (6 l water, 5 l 4X ligation buffer, 2 l RNA ligase, 1 l RNasin, 2 l 5 marker (100 M), 4 l PEG400). The sequence of the 5 marker is CAGUCCGACGAUC, which corresponds to the Illumina short RNA 5 Adapter (RA5), part #15013205; this sequence is not complementary to the primers used for amplification of iCLIP cDNA libraries (Huppertz et al., 2014). We then produced sequence reads of 120 nt using the Illumina HiSeq platform for eIF4A3 iCLIP. The rest of the protocol was carried out as previously described (Huppertz et al., 2014). Huppertz, I., Attig, J., D'Ambrogio, A., Easton, L.E., Sibley, C.R., Sugimoto, Y., Tajnik, M., Konig, J., and Ule, J. (2014). iCLIP: protein-RNA interactions at nucleotide resolution. Methods 65, 274-287.
2016-11-24 | E-MTAB-4000 | biostudies-arrayexpress
Project description:HeLa cells were cultured in DMEM, supplemented with 10% (v/v) FCS and penicillin/streptomycin under 5% CO2 at 37°C. For iCLIP, HeLa cells expressing eIF4A3-GFP or PTB-GFP were induced with doxycycline to adjust the level of recombinant protein to the level of the endogenous counterpart and irradiated with 150 mJ/cm2 UV light (254 nm). The iCLIP cDNA libraries for eIF4A3 and PTB were sequenced with 50 bp on an Illumina HiSeq instrument.
2015-08-11 | E-MTAB-2599 | biostudies-arrayexpress
Project description:This experiment uses iCLIP to identify the binding pattern of the spliceosomal protein PRPF8 on RNA. The data shows that PRPF8 binds strongly and specifically in the region 12 to 14nt upstream of 5' splice sites (5ss). Due to PRPF8's role in the formation of the catalytically active spliceosome, this data can be used as a readout of 5ss selection. Here, we performed iCLIP on HeLa cells treated with control or EIF4A3 siRNA, with 4 replicate samples per condition and eIF4A3 protein levels reduced ~50% in knockdown. We investigated the role of the exon junction complex (EJC) in suppressing 5ss that are reconstituted at the junction of two canonical exons (RS-5ss) - selection of these splice sites would result in recursive splicing of canonical exons. We plotted the crosslink sites of reads that span an exon-exon junction, seperating reads that span RS-5ss from those that do not. We found that reads that span an RS-5ss are enriched at the 12-14nt window associated with 5ss selection, while reads that span other exon-exon junctions are not enriched. This effect is magnified greatly by knockdown of eIF4A3. The results indicate that RS-5ss can be used by the spliceosome, but that this process is usually repressed by the EJC. This data is evidence of recursive splicing of canonical exons and the role of the EJC in repressing recursive splicing.
2018-10-14 | E-MTAB-7269 | biostudies-arrayexpress
Project description:iCLIP of eIF4A3 and PTB in HeLa cells
| PRJEB6381 | ENA
Project description:The exon junction complex is deposited at 24nt upstream of exon-exon junctions, but not at every junction. The core complex is comprosed of 4 proteins, eIF4A3, Magoh, Y14 and MLN51. Here we performed immunoprecipitation of Y14 with subsequent iCLIP of eIF4A3 in HeLa cells to identify the crosslink sites of the exon junction complex, in particular eIF4A3.
2016-11-24 | E-MTAB-3618 | biostudies-arrayexpress
Project description:We added an oligonucleotide to the 5′ end of RNA fragments —5′ marker— to differentiate between truncated and read–through cDNAs. By applying the protocol to PTBP1 and eIF4A3 iCLIP, we determined that the start sites of read–through cDNAs are enriched in adenosines, while the truncated cDNAs preferentially contained thymidines at their starts.
2018-06-15 | E-MTAB-6927 | biostudies-arrayexpress
Project description:PRPF8 iCLIP on HeLa cells in response to eIF4A3 Knockdown
| PRJEB29040 | ENA
Project description:This experiments was performed in HeLa cells according to the iCLIP protocol with the following modifications: no antiRNase was used and the concentration of RNase I was 0.5 U/ml. In iCLIP4, the dephosphorylation step was omitted from the standard protocol. The rest of the protocol was identical to the previously published iCLIP protocol )Huppertz I, Attig J, D'Ambrogio A, Easton LE, Sibley CR, Sugimoto Y, Tajnik M, Knig J, Ule J: iCLIP: protein-RNA interactions at nucleotide resolution. Methods 2014, 65:274-287).
2016-11-24 | E-MTAB-5026 | biostudies-arrayexpress
Project description:Modified iCLIP sequencing of HEK293 cells with antibody PTBP1
| PRJEB15159 | ENA