Improvements to the HITS-CLIP protocol eliminate widespread mispriming artifacts.
ABSTRACT: High-throughput sequencing of RNA isolated by crosslinking immunoprecipitation (HITS-CLIP) allows for high resolution, genome-wide mapping of RNA-binding proteins. We found that substantial mispriming during reverse transcription results in the overrepresentation of sequences complementary to the primer used for reverse transcription. Up to 45% of peaks in publicly available HITS-CLIP libraries are attributable to this artifact, and the majority of libraries have detectable levels of mispriming. We also found that standard techniques for validating miRNA-target interactions fail to differentiate between artifactual peaks and physiologically relevant peaks. Here, we present a modification to the HITS-CLIP protocol that effectively eliminates this artifact. Argonaute HITS-CLIP on the MCF-7 breast cancer cell line treated with 17β-estradiol for 0, 6 or 24 hours using a nested reverse transcriptions pimer and protected or unprotected reverse PCR primers for library amplification.
Project description:We used a genome-wide approach (High-throughput sequencing of RNA isolated by crosslinking immunoprecipitation, or HITS-CLIP) to define direct miRNA-mRNA interactions in three breast cancer subtypes (estrogen receptor positive, Her2 amplified and triple negative). Focusing on steroid receptor signaling, we identified two novel regulators of the ER pathway (miR-9-5p and miR-193a/b-3p), which together target multiple genes involved in ER signaling. Moreover, this approach enabled the definition of miR-9-5p as a global regulator of steroid receptor signaling in breast cancer. Finally, we show that miRNA targets and networks defined by our analysis are predictive of patient outcomes and provide global insight into miRNA regulation in breast cancer. Argonaute HITS-CLIP on three representative breast cancer cell lines (each in triplicate).
Project description:Includes HITS-CLIP and PAR-CLIP of AEG1, including negative controls Overall design: AEG-1 bound RNA profiles examinated by HITS-CLIP and PAR-CLIP, coupled with deep sequencing, in duplicate for HITS-CLIP, using Illumina HiSeq.
Project description:The exon junction complex (EJC) is a central effector of mRNAs fate, linking nuclear processing to mRNA transport, translation and surveillance. Little is known about its transcriptome-wide targets. We used high-throughput sequencing after crosslinking and immunoprecipitation (HITS-CLIP) in human cells to identify the binding sites of the DEAD-box helicase eIF4AIII, an EJC core component. CLIP reads form peaks mainly located in spliced mRNAs. Most expressed exons harbour peaks equally distributed between the canonical EJC region ∼24 nucleotides upstream of exonic junctions and other non-canonical regions. Unexpectedly, both are preferentially associated to unstructured and purine-rich sequences containing the motif GAAGA, a potential binding site of EJC-associated factors. Therefore, EJC positions vary spatially and quantitatively between exons. This transcriptome-wide mapping of human eIF4AIII reveals unanticipated aspects of the EJC and broadens its potential impact on post-transcriptional regulation. To identify direct RNA binding sites of the EJC core component eIF4AIII, two biological CLIP-seq replicates were performed in HeLa cells. Additionally, mRNA-seq of the HeLa transcriptome was performed to normalize for the mRNA expression levels.
Project description:In order to identify YBX1 binding sites on endogenous RNA, we performed HITS-CLIP on endogenous YBX1 We used a previously published method to perform HITS-CLIP on endogenous YBX1 (Licatalosi D, et al. 2008, Nature 456:464-U22)
Project description:In order to identify YBX1 binding sites on tRNA fragments, we performed small-RNA HITS-CLIP on endogenous YBX1 We used a previously published method to perform HITS-CLIP on endogenous YBX1 (Chi SW, et al. 2009, Nature 460:479)
Project description:Non-stressed and UV-stressed IMR-32 cells were subjected to HITS-CLIP to monitor nELAVL binding changes during AD progression Nonstressed and stressed IMR-32 cells were UV-irradiated and subjected to nELAVL HITS-CLIP (detailed desription in accompanying paper)