Project description:UV cross-linking and immunoprecipitation (CLIP) and individual-nucleotide resolution CLIP (iCLIP) are the most frequently used methods to study protein-RNA interactions in the intact cells and tissues, but their relative advantages or inherent biases have not been evaluated. To benchmark CLIP and iCLIP method, we performed iCLIP with Nova protein, which is the most extensively studied protein by CLIP. Further, we assessed UV-C-induced cross-linking preferences, by exploiting the UV-independent formation of covalent RNA cross-links of the mutant RNA methylase NSUN2.
Project description:Stau2 iCLIP of mouse brain was performed to identify RNA binding sites of Stau2 protein in mouse brain cells. The experiment was performed in triplicate, and each of the replicates was split into two separate halves at the cDNA stage, which together led to 6 separate datasets. The iCLIP protocol includes the following steps; Embryonic day 18 whole mouse brain was dissociated and irradiated with UV-C light, and the cells were then lysed using a buffer containing detergents. The RNAs were partially digested, and Stau2 and the cross-linked RNA fragments were immunoprecipitated using anti-Stau2 antibody. A DNA adaptor was then ligated to the RNA fragments and the cross-linked RNAs were further purified by SDS-PAGE and nitrocellulose membrane transfer. The RNAs were extracted from the membrane by proteinase K treatment, and converted into a high-throughput DNA sequencing compatible library by reverse transcription and PCR. For further details, see the methods of the associated manuscript. Note that the sequence reads start with (3 nucleotides of unique molecular identifiers) + (4 nucleotides of experimental barcode) + (2 nucleotides of unique molecular identifiers) followed by the sequence of the cross-linked RNA fragments.
Project description:This experiment identifies hnRNP A1 binding sites transcriptome-wide in Hela cells. HeLa cells with inducible expression of T7-tagged hnRNP A1 were grown to approximately 90% confluence and then subject to iCLIP analysis (following the protocol from Huppertz et al. 2014 (iCLIP: protein-RNA interactions at nucleotide resolution)). The iCLIP library was sequenced using Illumina's HighSeq 1500
Project description:The studies of spliceosomal interactions are challenging due to their dynamic nature. Here we developed spliceosome iCLIP, which immunoprecipitates SmB along with snRNPs and auxiliary RNA binding proteins (RBPs) to simultaneously map the spliceosomal binding to human snRNAs and pre-mRNAs. This identified 9 distinct regions on pre-mRNAs, which overlap with position-dependent binding patterns of 15 RBPs. Using spliceosome iCLIP, we additionally identified >50,000 branchpoints (BPs) that have canonical features, unlike those identified by RNA-seq. The iCLIP BPs generally overlap with the computationally predicted BPs, and alternative BPs are associated with extended regions of structurally accessible RNA. We find that the position and strength of BPs defines the binding patterns of SF3 and U2AF complexes, whereas the RNA structure around BPs affects the sensitivity of exons to perturbation of these complexes. Our findings introduce spliceosome iCLIP as a new method for transcriptomic studies of BPs and splicing mechanisms.
Project description:iCLIP experiments tomap the RNA binding sites of the RNA-binding protein Unkempt across the transcriptome in SH-SY5Y cells, HeLa cells with ectopic Unk expression and mouse E15 embryonic brain samples. Expression of Unk is normally largely restricted to the nervous system. We therefore mapped the binding sites in human SH-SY5Y and mouse E15 brain to detect its physiological binding sites (in SH-SY5Y, we also performed the RNAseq experiment upon Unk knockdown). HeLa cells on the other hand normally don't express Unk, but convert to neuron-like shape when the protein is ectopically expressed. So, here we hoped to identify those binding events (and hence target transcripts) that are critical for this morphological transformation.
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).