Project description:eCLIP was performed for ENO1 in HeLa cells, following the protocol described by Van Nostrand et al. (2016). Libraries for six immunoprecipitation and size-matched input controls were produced. In addition, libraries were produced for two no-crosslinking controls. The libraries were sequenced using paired-end sequencing (PE125) on an Illumina HiSeq2000 platform.
Project description:Human pluripotent stem cells (hPSCs) require precise control of post-transcriptional RNA networks to maintain proliferation and survival. Using a recently developed enhanced UV crosslinking and immunoprecipitation (eCLIP) approach, we identify RNA targets of the IMP/IGF2BP family of RNA-binding proteins in hPSCs. At the broad region- and binding site-level IMP1 and IMP2 show reproducible binding to a large and overlapping set of 3'UTR-enriched targets. RNA Bind-N-Seq applied to recombinant full-length IMP1 and IMP2 reveals CA-rich motifs that are enriched in eCLIP-defined binding sites. We observe that IMP1 loss in hPSCs recapitulates IMP1 phenotypes, including a reduction in cell adhesion and an increase in cell death. For cell adhesion, in hPSCs we find IMP1 maintains levels of integrin mRNA, specifically regulating RNA stability of ITGB5. Additionally, we show IMP1 can be linked to hPSC survival via direct target BCL2. Thus, transcriptome-wide binding profiles identify hPSC targets modulating well-characterized IMP1 roles. eCLIP-seq was performed in biological replicate for IGF2BP1/IMP1 and IGF2BP2/IMP2, as well as one replicate each for IGF2BP3/IMP3, RBFOX2, and an IgG control. Each sample has a size-matched input control for analysis
Project description:Growing demand in RNA-targeted therapies and promise of miRNA-based drugs creates a need for tools that can accurately identify and quantify miRNA:target interactions at scale. The experimental capture of miRNA:mRNA interactions by ligation into chimeric RNA fragments provides a direct read out of miRNA targets by enabling profiling of miRNA targets with high-throughput sequencing. However, integration of chimeric CLIP-seq into wide practical use has been limited because the inefficiency of the miRNA:mRNA ligation step (resulting in a low rate of chimeric reads in final libraries) combined with the technical complexity of the method makes it challenging to apply to miRNAs of interest at scale. Here we describe chimeric eCLIP, in which we integrate a chimeric ligation step into AGO2 eCLIP to enable chimeric read recovery, and show that removal of the cumbersome polyacrylamide gel and nitrocellulose membrane transfer step common to CLIP techniques can be omitted for chimeric AGO2 eCLIP to create a simplified high throughput version of the assay that maintains high signal-to-noise. With the increased yield of recovered miRNA:mRNA interactions in no-gel chimeric eCLIP, we show that simple enrichment steps using either PCR or on-bead probe capture can be added to chimeric eCLIP in order to target and enrich libraries for chimeric reads specific to one or more miRNAs of interest in both cell lines and tissue samples, resulting in 30- to 175-fold increases in recovery of chimeric reads for miRNAs of interest. We further show that the same probe-capture approach can be used to recover miRNA interactions for a targeted gene of interest, revealing both distinct miRNA targeting as well as co-targeted by several miRNAs from the same seed family. RNA-seq analysis of gene expression following miRNA overexpression confirmed miRNA-mediated repression of chimeric eCLIP identified targets, and indicated that chimeric eCLIP can provide additional sensitivity to detect regulated targets among genes that either contain or lack computationally predicted miRNA target sites. Thus, we believe that chimeric eCLIP will be a useful tool for quantitative profiling of miRNA targets in varied sample types at scale, and revealing a deeper picture for regulatory networks for miRNAs of biological interest.