GSM2055435: RBFOX2 293T Rep2 Input; Homo sapiens; OTHER
Cells were lysed in iCLIP lysis buffer, followed by limited digestion with RNase I (Ambion), immunoprecipitation of RBP-RNA complexes with a specific antibody of interest (Protein G sheep anti-rabbit Dynabeads), and stringent washes. After dephosphorylation with FastAP (Thermo Fisher) and T4 PNK (NEB), a barcoded RNA adapter is ligated to the 3’ end (T4 RNA Ligase, NEB) (at this step, multiple replicates of the same RBP, or potentially RBPs of similar size and bound RNA amount, can be uniquely barcoded and pooled after ligation to simplify downstream steps - see Supplementary Fig. 2A). Ligations are performed on-bead (to allow washing away unincorporated adapter) in high concentration of PEG8000, which improves ligation efficiency to > 90%. Samples are then run on standard protein gels and transferred to nitrocellulose membranes, and a region 75 kDa (~150 nt of RNA) above the protein size is isolated and proteinase K (NEB) treated to isolate RNA. RNA is reverse transcribed with AffinityScript (Agilent), and treated with ExoSAP-IT (Affymetrix) to remove excess oligonucleotides. A second DNA adapter (containing a random-mer of 5 (N5) or 10 (N10) random bases at the 5’ end) is then ligated to the cDNA fragment 3’ end (T4 RNA Ligase, NEB), performed with high concentration of PEG8000 (to improve ligation efficiency) and DMSO (to decrease inhibition of ligation due to secondary structure). After cleanup (Dynabeads MyOne Silane, ThermoFisher), an aliquot of each sample is first subjected to qPCR (to identify the proper number of PCR cycles), and then the remainder is PCR amplified (Q5, NEB) and size selected via agarose gel electrophoresis.
GEO Accession
GSM2055435