NicOPURE: Nickless RNA Circularization and One-Step Purification with Engineered Group II Introns and Cyclizing UTRs
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PROVIDER: PRJNA1032115 | ENA |
REPOSITORIES: ENA
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Project description:Circular RNAs (circRNAs) have gained significant attention in recent years due to their diverse biological functions and potential as novel therapeutic modality. Two general mechanisms for generating circRNAs involves the utilization of group 1 and group 2 introns, which are self-splicing ribozymes found in many organisms. Although group 1 intron has been demonstrated to be highly effective in circularization, the reaction requires high temperature plus cofactors such as GTP. Consequently, undesired byproducts such as nicked RNA were generated, which requires complex purification steps before downstream applications. In this study, we have strategically designed structural elements and incorporated sequence features to enhance the efficacy of RNA circularization by group 2 introns. This innovative approach occurred at a reduced temperature and resulted in notably fewer nicks compared to group 1 introns. Furthermore, to streamline the purification process of circular RNA, we incorporated two halves of streptavidin aptamer tags into the enzymatic sites of the group 2 intron. This strategic architecture guarantees the creation of a fully operational streptavidin aptamer tag solely at the circular RNA junction site during in vitro circularization. This unique attribute facilitates a one-step purification process. The resulting "NicOPURE" system emerges as both straightforward and efficient in generating therapeutic circular mRNAs.
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Project description:Removal of introns by pre-mRNA splicing is a critical and in some cases rate-limiting step in mammalian gene expression. Deep sequencing of mouse embryonic stem cell RNA revealed many specific internal introns that are significantly more abundant than the other introns within poly(A) selected transcripts; we classify these as “detained” introns (DIs). We identified thousands of DIs flanking both constitutive and alternatively spliced exons in human and mouse cell lines. Drug inhibition of Clk SR-protein kinase activity triggered rapid splicing changes in a specific set of DIs, about half of which showed increased splicing and half increased intron detention, altering the transcript pool of over 300 genes. These data suggest a widespread mechanism by which a nuclear detained pool of mostly processed pre-mRNAs can be rapidly mobilized in response to stress or homeostatic autoregulation. v6.5 mouse embryonic stem cells were untreated, treated with the Clk kinase inhibitor KH-CB19, or treated with DMSO as a negative control. Untreated cells were harvested and a single replicate was sequenced using a custom, ligation-based, stranded library preparation protocol. Treated cells were harvested at time 0 and at 2 hours post-treatment, and poly(A)-selected RNA-seq libraries were made from biological duplicates for each treatment/time, barcoded, and sequenced by strand-specific, paired-end sequencing using the Illumina TruSeq kit.
2015-01-15 | E-GEOD-57231 | biostudies-arrayexpress
Project description:Removal of introns by pre-mRNA splicing is a critical and in some cases rate-limiting step in mammalian gene expression. Deep sequencing of mouse embryonic stem cell RNA revealed many specific internal introns that are significantly more abundant than the other introns within poly(A) selected transcripts; we classify these as “detained” introns (DIs). We identified thousands of DIs flanking both constitutive and alternatively spliced exons in human and mouse cell lines. Drug inhibition of Clk SR-protein kinase activity triggered rapid splicing changes in a specific set of DIs, about half of which showed increased splicing and half increased intron detention, altering the transcript pool of over 300 genes. These data suggest a widespread mechanism by which a nuclear detained pool of mostly processed pre-mRNAs can be rapidly mobilized in response to stress or homeostatic autoregulation.
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Project description:Efforts to identify ccRNA by sequencing by gibson circularization after template-switching 5' RACE using a cRNA-end specific primer and subsequent sequencing by Illumina miSeq. Sequencing of wild-type A/WSN/1933 and a variant bearing the mutation T677A in the PB1 subunit.
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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.
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Project description:Despite the high conservation of minor introns across eukaryotic supergroups, specific lineages have completely lost minor intron splicing, which has raised questions about their evolution and purpose. Addressing these questions requires identification of the introns that are affected by minor spliceosome inhibition. To this end, we applied principles of Linnaean taxonomy combined with position-weight matrices to produce five intron classes: minor, minor-like, hybrid, major-like and major. We classified introns across the genomes of 263 species of six eukaryotic supergroups, which can be viewed at the Minor Intron Database (MIDB). Transcriptomic analysis revealed that ~40% of the minor introns are responsive to minor spliceosome inhibition, while an additional 5% of the minor-like and hybrid introns are also affected. We propose that minor-like introns represent an intermediate in the conversion of minor to major introns and uncover the importance of a guanine at the -1 position of the 5’ splice site in facilitating this shift in spliceosome dependence. Finally, we find that minor introns are aberrantly spliced in fish and plants upon cold stress, thereby providing a potential explanation for their high degree of conservation in these lineages.
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