Project description:The identification of RNAs that are recognized by RNA-binding proteins (RNA-BPs) using techniques such as Crosslinking and Immunoprecipitation (CLIP) has revolutionized the genome-wide discovery of RNA-BP RNA targets. Among the different versions of CLIP that have been developed, the use of photoactivable nucleoside analogs has resulted in high efficiency photoactivable ribonucleoside-enhanced CLIP (PAR-CLIP) in vivo. Nonetheless, PAR-CLIP has not yet been applied in prokaryotes. To determine if PAR-CLIP can be used in prokaryotes, we determined suitable conditions for the incorporation of 4-thiouridine (4SU), a photoactivable nucleoside, into E. coli RNA and for the isolation of RNA crosslinked to RNA-BPs of interest. Applying this technique to Hfq, a well-characterized regulator of small RNA (sRNA)-messenger RNA (mRNA) interactions, we showed that PAR-CLIP identified most of the known sRNA targets of Hfq, as well as functionally relevant sites of Hfq-mRNA interactions at nucleotide resolution. Based on our findings, PAR-CLIP represents an improved method to identify both the RNAs and the specific regulatory sites that are recognized by RNA-BPs in prokaryotes.
Project description:AGO-PAR-CLIP was employed to identify microRNA binding sites in BCBL-1, a Kaposi's sarcoma-associated herpesvirus (KSHV) infected B-cell line and DG75, a KSHV negative B-cell line as a control. By using our novel computational method (PARma) and differential analysis of PAR-CLIP data, highly accurate target sites of KSHV microRNAs can be defined. Examination of microRNA target sites in two different cell lines using replicate PAR-CLIP experiments
Project description:AGO-PAR-CLIP was employed to identify microRNA binding sites in BCBL-1, a Kaposi's sarcoma-associated herpesvirus (KSHV) infected B-cell line and DG75, a KSHV negative B-cell line as a control. By using our novel computational method (PARma) and differential analysis of PAR-CLIP data, highly accurate target sites of KSHV microRNAs can be defined.
Project description:This SuperSeries is composed of the following subset Series: GSE21574: Transcriptome-wide identification of RNA-binding protein and microRNA target sites by PAR-CLIP: QKI data GSE21575: Transcriptome-wide identification of RNA-binding protein and microRNA target sites by PAR-CLIP: IGF2BP data GSE21577: Transcriptome-wide identification of RNA-binding protein and microRNA target sites by PAR-CLIP: miRNA inhibition data GSE21918: Transcriptome-wide identification of RNA-binding protein and microRNA target sites by PAR-CLIP: sequencing data Refer to individual Series
Project description:Animal mRNAs are regulated by hundreds of RNA binding proteins (RBPs). The identification of RBP targets is crucial for understanding their function. A recent method, PAR-CLIP, uses photoreactive nucleosides to crosslink RBPs to target RNAs in cells prior to immunoprecipitation. Here, we establish iPAR-CLIP (in vivo PAR-CLIP) to determine, at nucleotide resolution, transcriptome-wide target sites of GLD-1, a conserved, germline-specific translational repressor in C. elegans. We identified 439 reproducible targets and demonstrate an excellent dynamic range of target detection by iPAR-CLIP. Upon GLD-1 knock-down, protein but not mRNA expression of the 439 targets was specifically and highly significantly upregulated, demonstrating functionality. Finally, we discovered strongly conserved GLD-1 binding sites nearby the start codon of target genes. We propose that GLD-1 interacts with the translation machinery nearby the start codon, a so far unknown mode of gene regulation in eukaryotes.
Project description:We developed a method for measuring non-specific background in PAR-CLIP data demonstrating that covalently crosslinked background binding is common, reproducible and apparently universal. Furthermore, we show that quantitative determination of background is essential for identifying targets of weakly binding RNA-binding proteins and can substantially improve motif analysis. To define background binding events in PAR-CLIP data we performed the standard PAR-CLIP protocol (Hafner et al., Cell 2010.) on lysates expressing a commonly used non-RBP control, FLAG-GFP. After FLAG-tag immunopurification of UV 365nm irradiated lysates prepared from cells supplemented with 4-thiouridine (4SU), RNA was partially digested with RNase T1, radiolabeled and separated by SDS-PAGE. Reads were sequenced by Illumina HiSeq. PAR-CLIP was also performed for HuR. Included as well is a total from lysates treated like PAR-CLIP, but without immunoprecipitation (see sample description for more detail).
Project description:cDNA microarray analysis to identify genes regulated by the RNA chaperone, Hfq. Four experiments were performed: 1/ Hfq+ vs Hfq- strains. 269 significantly differentially regulated genes were identified by SAM (Statistical Analysis of Microarrays), of which 120 changed more than 1.5 fold (48 increased and 72 decreased in hfq-). Amongst other genes, these experiments identified significant regulation of the sigma E and sigma 32 regulons. However, only genes induced by sigma E were similarly induced in hfq-; 8 operons repressed by sigma E were not repressed in hfq-. 2/ wt vs delta rseA. RseA is the antisigma factor for sigmaE. This comparison results in elevated steady-state levels of sigma E, and confirmed induction and repression of target regulon members. 3/ hfq+ vs hfq+ rpoE overexpression. RpoE encoding sigma E was overexpressed in an hfq+ background, confirming normal regulation of the sigma E regulon. 4/ hfq+ vs hfq- rpoE overexpression. Sigma E was overexpressed in an hfq- background. This demonstrated that 8 operons normally repressed by sigma E require hfq for this repression. The simple conclusion is that sigma E regulates small RNAs that, together with Hfq, bind target mRNAs and results in their rapid degradation. This study is detailed in Guisbert et al 2007 (J Bacteriol, 189:1963-73) Keywords: Genetic modification