Project description:Here we present the CLASH analysis of AGO2 in HEK293 cells to address the small RNA repertoire and uncover their physiological targets. We developed an optimized bioinformatics approach of chimeric read identification to detect chimeras of high confidence. We report thousands of Ago2 target sites driven by microRNAs, but also a substantial number of Ago2 ‘drivers’ derived from fragments of other small RNAs such as tRNAs, snoRNAs, rRNAs and others. Target validation of several miRNAs delivered by 3’ Quantseq RNA-Seq.
Project description:Here we present the CLASH analysis of AGO2 in HEK293 cells to address the small RNA repertoire and uncover their physiological targets. We developed an optimized bioinformatics approach of chimeric read identification to detect chimeras of high confidence. We report thousands of Ago2 target sites driven by microRNAs, but also a substantial number of Ago2 ‘drivers’ derived from fragments of other small RNAs such as tRNAs, snoRNAs, rRNAs and others. Target validation of several miRNAs delivered by 3’ Quantseq RNA-Seq.
Project description:We report the identification of potential novel RNA targets for box C/D snoRNAs in human HEK293 cells, using the approaches of UV crosslinking and sequencing of hybrids (CLASH), and formaldehyde crosslinking and sequencing of hybrids (FLASH).
Project description:By shaping gene expression profiles, small RNAs (sRNAs) enable bacteria to efficiently adapt to changes in their environment. To better understand how Escherichia coli acclimatizes to nutrient availability, we performed UV cross-linking, ligation and sequencing of hybrids (CLASH) to uncover Hfq-associated RNA-RNA interactions at specific growth stages. We demonstrate that Hfq CLASH robustly captures bona fide RNA-RNA interactions identified hundreds of novel sRNA base-pairing interactions, including many sRNA-sRNA interactions and involving 3’UTR-derived sRNAs. We rediscovered known and identified novel sRNA seed sequences. The sRNA-mRNA interactions identified by CLASH have strong base-pairing potential and are highly enriched for complementary sequence motifs, even those supported by only a few reads. Yet, steady state levels of most mRNA targets were not significantly affected upon over-expression of the sRNA regulator. Our results reinforce the idea that the reproducibility of the interaction, not base-pairing potential, is a stronger predictor for a regulatory outcome.
Project description:As a core RISC component, Ago2 associates with miRNAs and target mRNAs. To identify these mRNAs, we ran lysate from HEK293T cells over a FLAG resin from 2 conditions: +FLAG-Ago2, +mock transfection. To identify mRNAs associated with specific miRNAs, we ran lysate from HEK293T cells over a FLAG resin from 2 conditions: +FLAG-Ago2 & miR-1, and +FLAG-Ago2 & miR-124. Set of arrays that are part of repeated experiments Compound Based Treatment: mock transfected Keywords: Biological Replicate
Project description:LINE1s are abundant retroelements comprising 17% of human genome. Naturally, genomic LINE1s are tightly repressed by epigenetic mechanism; however, if relieved, they can be detrimental to genome stability by their transposition capability. So, a supervising mechanism that quickly re-represses the leaky LINE1s is demanded. Here we show that de-repressed LINE1s generate small RNAs, L1-siRNAs, which SETDB1 and AGO2 recognize, then move into searching for a transcript with sequence complementarity, and ultimately re-install a repression mechanism at LINE1 5’-untranslated region (5’UTR) by depositing trimethyl-H3K9 (H3K9me3). Immunoprecipitation (IP) results showed that SETDB1, AGO2, and L1-siRNA bound to each other and Chromatin-IP-seq and small-RNA-seq results demonstrated that they sat at the same locus within the 5’UTR. SETDB1, AGO2, and L1-siRNA all were necessary for LINE1 repression, particularly the evolutionary young and transposition-competent families such as L1HS/L1PA1 and L1PA2. KAP1, which frequently partners with SETDB1 for silencing local chromatin, was dispensible for the repression of young L1PAs. Our findings indicate that, as a surveillance mechanism, the L1-siRNA-triggered, SETDB1-AGO2-effected repair of epigenetic errors at the 5’UTR establishes a homeostatic re-repression mechanism on inadvertently de-repressed LINE1 copies over the genome.