Project description:We constructed a DBR1 knockout cell line (C22) using CRISPR in HEK293T cells. Through mapping of lariat reads, lariat levels in the DBR1 - samples are shown to increase dramatically (~20x) relative to wild type cells. Over 60% of this increase in lariat levels is abrogated upon rescue of DBR1 - cells with a DBR1 expression vector
Project description:We used CRISPR in HEK293T cells to create two DBR1 knockout cell lines (C19 and C22). After high-throughput sequencing of total RNA extracted from these cells, we performed lariat read mapping using the method described in "Large-scale mapping of branchpoints in human pre-mRNA transcripts in vivo" (Taggart et al, 2012). We found lariats in the two DBR1- cell lines to be ~20-fold enriched relative to the levels observed in the HEK293T control samples.
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:Probes flanking all predicted Candida albicans ORFs are used to detect intron sequences that accumulate in a debranchase (DBR1) mutant. We synthesized cDNA from RNA from both wild-type and dbr1-delta mutant strains grown under standard (YEPD) or various mixed conditions, labeled the two populations differentially, and hybridized them together on our microarray.
Project description:Protein-RNA interaction networks are essential to understand gene regulation control. Identifying the binding sites of RNA-binding proteins (RBPs) by CLIP (UV-crosslinking and immunoprecipitation) represents one of the most powerful methods to map in vivo protein-RNA interactions. However, the traditional CLIP protocol is technically challenging, which requires radioactive labeling and suffers from material loss during PAGE-membrane transfer procedures. Here we introduce a super-efficient CLIP method (GoldCLIP) that omits all gel purification steps. This nonisotopic method allowed us to perform highly reproducible CLIP experiments with classical RBP such as PTB in human cell lines. In principle, our method guarantees sequencing library constructions, providing the protein of interest can be successfully crosslinked to RNAs in living cells. GoldCLIP is readily applicable to diverse factors to uncover their endogenous targets.
Project description:We used DNA microarrays to define the physiological roles of the Tap efflux pump in M. bovis BCG during the exponential and the stationary phase of in vitro growth. For this purpose we constructed a M. bovis BCG strain in which the tap gene was inactivated by the insertion of a hygromycin resistance cassette (Ω-hyg). When the gene expression patterns of the tap mutant were compared to the wild-type strain, almost no differences were observed during exponential growth; only seven genes slightly increased their expression. In contrast, more that 100 genes showed a variation in their level of expression during stationary growth. More than ten representative genes were chosen from the microarray experiments and their expression was measured by quantitative RT-PCR using sigA as invariant internal control. In support to the gene expression profiling data, the mRNA levels of all selected genes was significantly different in the tap mutant strain relative to control. A functional category analysis (http://tuberculist.epfl.ch/index.html) of the genes differentially expressed revealed a high proportion belonging to the Virulence, Detoxification, Adaptation (VDA), Intermediary Metabolism and Respiration (IMR), Conserved Hypotheticals (CH), and Cell Wall and Cell Processing (CWCP) categories suggesting a major adaptation to a stress generated by inactivation of the tap efflux pump gene.