Project description:Circular RNAs (circRNAs) are a large class of animal RNAs. To investigate possible circRNA functions, it is important to understand circRNA biogenesis. Besides human Alu repeats, sequence features that promote exon circularization are largely unknown. We experimentally identified new circRNAs in C. elegans. Reverse complementary sequences between introns bracketing circRNAs were significantly enriched compared to linear controls. By scoring the presence of reverse complementary sequences in human introns we predicted and experimentally validated novel circRNAs. We show that introns bracketing circRNAs are highly enriched in RNA editing or hyper-editing events. Knockdown of the double-strand RNA editing ADAR1 enzyme significantly and specifically up-regulated circRNA expression. Together, our data support a model of animal circRNA biogenesis in which competing RNA:RNA interactions of introns form larger structures which promote circularization of embedded exons, while ADAR1 antagonizes circRNA expression by melting stems within these interactions. Thus, we assign a new function to ADAR1. Examination of 12 samples in different stages of C.elegans development.
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:Circular RNAs are a large class of non-coding RNAs present in all eukaryotic taxa. Despite the identification of thousands of circular transcripts, the biological significance of most of them remains largely unexplored, partly due to the lack of effective methods for generating loss-of-function animal models. In this study, we focused on circTulp4, a highly abundant circRNA that is enriched in the brain and synaptic compartments. By creating a circTulp4-deficient mouse model, in which we mutated the splice acceptor site responsible for generating circTulp4 without affecting the corresponding linear mRNA or protein levels, we were able to conduct a comprehensive phenotypic analysis. Our results demonstrate that circTulp4 is critical in regulating neuronal and brain physiology, modulating the strength of excitatory neurotransmission and sensitivity to aversive stimuli. This study provides compelling evidence that circRNAs can regulate biologically relevant functions in neurons, with modulatory effects at multiple levels of the phenotype, establishing a proof-of-principle for the regulatory role of circRNAs in neural processes.
Project description:With advancing age, senescent cells accumulate in tissues and critically influence aging-associated diseases. We report the first catalog of a novel class of regulatory RNAs, circular RNAs, differentially expressed in senescent (non-dividing) compared with dividing human fibroblasts. Among them, we focused on the circular RNA CircPVT1, as it promoted proliferation by binding and neutralizing let-7, a microRNA capable of triggering senescence. Interestingly, by suppressing let-7, CircPVT1 selectively elevated the expression of several proliferative proteins which were otherwise repressed by let-7. In summary, we have uncovered a novel mechanism whereby circular RNAs control gene expression programs in senescent cells.
Project description:Circular RNAs (circRNAs) are a large class of animal RNAs. To investigate possible circRNA functions, it is important to understand circRNA biogenesis. Besides human Alu repeats, sequence features that promote exon circularization are largely unknown. We experimentally identified new circRNAs in C. elegans. Reverse complementary sequences between introns bracketing circRNAs were significantly enriched compared to linear controls. By scoring the presence of reverse complementary sequences in human introns we predicted and experimentally validated novel circRNAs. We show that introns bracketing circRNAs are highly enriched in RNA editing or hyper-editing events. Knockdown of the double-strand RNA editing ADAR1 enzyme significantly and specifically up-regulated circRNA expression. Together, our data support a model of animal circRNA biogenesis in which competing RNA:RNA interactions of introns form larger structures which promote circularization of embedded exons, while ADAR1 antagonizes circRNA expression by melting stems within these interactions. Thus, we assign a new function to ADAR1.
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. PARCLIP was performed as in Hafner et. al Cell 2010 with HEK293 cell lines stably expressing HIS/FLAG/HA-tagged AGO1 or AGO2. We used 4-thiouridine (4SU) to enhance the crosslink and generated cDNA libraries.
Project description:Circular RNAs are a class of non-coding RNAs mostly generated by back-splicing RNA transcripts of protein-coding gene loci. In difference to canoncial splicing, back-splicing ligates downstream splice donor site with an upstream splice acceptor generating a covalently closed circular RNA. CircRNAs have been reported to influence cellular functions by acting as miRNA sponges, regulation of host gene transcription or by protein interactions. The circRNA cZNF292 has been previously reported to be regulated under hypoxia and to influence endothelial cell angiogenesis and functions. The present data set aims to identfy protein interactions partners of cZNF292 in endothelial cells to further characterize the mechanism of action of cZNF292. Dataset comprises 8 replicates of proteins identified after biotin-based 2'O-Me RNA antisense affinity purification of the circRNA cZNF292 from HUVEC (human umbilical vein endothelial cell) lysates compared to a control probe dataset. Purification was performed without cross-linking under low salt and mild detergent conditions.