Project description:Circular RNAs (circRNAs) in animals are an enigmatic class of RNAs with unknown function. To systematically explore circRNAs, we sequenced and computationally analyzed human, mouse and nematode RNA. We detected thousands of well-expressed, stable circRNAs, with oftentimes tissue/developmental stage specific expression. Sequence analysis suggested important regulatory functions for circRNAs. Indeed, we discovered that human circRNA CDR1as is densely bound by miRNA effector complexes and harbors 63 conserved binding sites for the ancient miRNA miR-7. Further analyses indicated that CDR1as functions to bind miR-7 in neuronal tissues. Human CDR1as expression in zebra fish impaired midbrain development similar to knocking down miR-7, suggesting that CDR1as is a miRNA antagonist with a miRNA binding capacity ten times higher than any other known transcript. Together, our data provide evidence that circRNAs form a large class of post-transcriptional regulators. Numerous circRNAs form by head-to-tail splicing of exons, indicating previously unrecognized regulatory potential of coding sequences. 1 Sample
Project description:We discovered the bacteria Streptomyces venezuelae can display a new form of growth termed exploration, and we used NGS to compare transcriptome profiles of cells demonstrating exploration versus static cells (not demonstrating exploration)
Project description:To explore the possible neddylation sites, GFP-IRF7 and His-NEDD8 were co-overexpressed in HEK293 cell line and GFP was immunoprecipitated, followed by SDS-PAGE and silver staining. The band detected was subjected to LC–MS/MS.
Project description:Chromosome 3p monosomy is associated with a poor clinical outcome of patients with uveal melanoma. Since a copy of the tumor suppressor miR-16 gene is lost for these patients, we postulated that a 3p loss may reduce the miR-16 amount and activity, promoting RNA derepression and tumor burden (loss of brake effect) as observed in chronic lymphocytic leukemia. Unexpectedly, we found that miR-16 expression level is not decreased despite the 3p monosomy. In contrast, our results suggested that miR-16 activity is impaired in uveal melanoma. Here, we investigated the molecular mechanism explaining the sequestration of miR-16 by RNAs. By defining the miR-16 interactome, two genes sets have been highlighted, suggesting two divergent miR-16 functions. In addition to the canonical miR-16 targets such as CCND3 and CDC25A, we identified another set of miR-16-interacting RNAs called thereafter miR-16 sponges. miR-16 binds to these RNAs sponge without inducing their decay. Mechanistically, the miR-16/RNA non-canonical base-pairing promoted stability of mRNAs involved in cancer cell proliferation. The biological relevance has been challenged in uveal melanoma. We showed that patients with poor overall survival expressed higher levels of miR-16 sponges and canonical miR-16 targets. These results strongly suggested that miR-16 is no longer able to repress its targets and, in contrast, promotes RNA stability and protein expression of oncogenes. miR-16 activity assessment using our Sponge-signature discriminates the patient’s overall survival as efficiently as the current method based on copy number variations and driver mutations detection. To conclude, miRNA loss of function due to miRNA sequestration seems to promote cancer burden by two combined events – 'loss of brake and an acceleration'. Our results highlight the oncogenic role of the non-canonical base-pairing between miRNAs/mRNAs in uveal melanoma.
Project description:To uncover exon junction complex (EJC) deposition sites on cellular mRNAs, RNA footprints of EJC immuo-purified from HEK293 cells were deep sequenced. The analysis of these data revealed that major “canonical” EJC occupancy site in vivo lies 24 nucleotides upstream of exon junctions (-24 position) and that the majority of exon junctions carry an EJC. Unexpectedly, we find that many sites further upstream of -24 position are also enriched in these EJC footprints. These "non-canonical" sites are binding sites of EJC-interacting proteins with a subset being occupied by SR proteins. Thus, an EJC-SR protein nexus exists within spliced mRNPs and is revealed here. Deep sequencing based profiling of EJC RNA footprints obtained by tandem RNA immunoprecipitation (RIPiT) of RNase I digested RNA:protein complexes.