Project description:Circular RNAs (circRNAs) are a unique class of single-stranded RNA molecules with a closed-loop structure that confer enhanced stability, extended protein expression, and resistance to exonucleases, making them promising candidates for RNA therapeutics. In recent years, several methods have been developed to generate circRNAs, including the traditional, scar-containing Anabaena Permuted Intron-Exon (Ana-PIE) method and newer “scarless” circularization approaches. This study introduces a novel scarless circularization method, Split-Coxsackievirus B3-Anabaena Permuted Intron-Exon (Split-CVB3 Ana-PIE, SCAP). Scarless circular RNAs generated using the SCAP system were systematically compared to their scarred counterparts produced by the Ana-PIE system in terms of circularization efficiency, protein expression, stability, and immune response. The SCAP system achieved circularization efficiencies comparable to those of the Ana-PIE system while significantly enhancing protein expression. Scarless circular RNAs exhibited similar stability to scarred circular RNAs and did not trigger significant immune responses. These findings highlight the potential of scarless circular RNAs in gene therapy and vaccine development, demonstrating that removing extraneous sequences improves translation efficiency without compromising stability or immunogenicity. This study provides a foundation for the rational design of circular RNAs, with future efforts focusing on diverse target genes, optimized delivery platforms, and in vivo validation.
Project description:Purpose: We are using the illumina sequencing to compare the false positive and true positive circular RNA findings to confine the method to detect the true circular RNAs Methods: The testis whole transcriptome profiling was generated from 4-week mouse testis using illumina Nextseq, duplicated. The sequence reads that passed quality filters were analyzed at the transcript isoform level with TopHat followed by Cufflinks. Results: our data suggest that circular RNAs identified based on junction sequences in the RNA-seq reads, especially those from Illumina Hiseq sequencing, mostly result from template-switching events during reverse transcription by MMLV-derived reverse transcriptases. It is critical to employ reverse transcriptases lacking terminal transferase activity (e.g., MonsterScript) to construct sequencing library or perform RT-PCR for identification and quantification of true circular RNAs. Conclusions: Our study represents the first detailed analysis of retinal transcriptomes, with biologic replicates, generated by RNA-seq technology. The optimized data analysis workflows reported here should provide a framework for comparative investigations of expression profiles. Our results show that NGS offers a comprehensive and more accurate quantitative and qualitative evaluation of mRNA content within a cell or tissue. We conclude that RNA-seq based transcriptome characterization would expedite genetic network analyses and permit the dissection of complex biologic functions. The wild type mouse testis RNAs were constructed NGS library by two different enzyme, then parallel sequenced in illumina Nextseq
Project description:Purpose: We are using the illumina sequencing to compare the false positive and true positive circular RNA findings to confine the method to detect the true circular RNAs Methods: The testis whole transcriptome profiling was generated from 4-week mouse testis using illumina Nextseq, duplicated. The sequence reads that passed quality filters were analyzed at the transcript isoform level with TopHat followed by Cufflinks. Results: our data suggest that circular RNAs identified based on junction sequences in the RNA-seq reads, especially those from Illumina Hiseq sequencing, mostly result from template-switching events during reverse transcription by MMLV-derived reverse transcriptases. It is critical to employ reverse transcriptases lacking terminal transferase activity (e.g., MonsterScript) to construct sequencing library or perform RT-PCR for identification and quantification of true circular RNAs. Conclusions: Our study represents the first detailed analysis of retinal transcriptomes, with biologic replicates, generated by RNA-seq technology. The optimized data analysis workflows reported here should provide a framework for comparative investigations of expression profiles. Our results show that NGS offers a comprehensive and more accurate quantitative and qualitative evaluation of mRNA content within a cell or tissue. We conclude that RNA-seq based transcriptome characterization would expedite genetic network analyses and permit the dissection of complex biologic functions.
Project description:MicroRNA (miRNA) sponges containing miRNA complementary binding sites constitute a potentially useful strategy for miRNA-inhibition therapeutics in cancer patients. Recently, naturally occurring circular RNAs (circRNAs) have been revealed to function as efficient microRNA sponges. We hypothesized that synthetic circRNA sponges targeting oncomiRs could be constructed and used to achieve potentially therapeutic microRNA loss of function. In this study, linear RNA molecules containing five miR-21 binding sites were transcribed in vitro. After dephosphorylation by calf intestinal phosphatase and phosphorylation by T4 polynucleotide kinase, circRNA sponges were circularized using 5’-3’ end ligation by T4 RNA ligase 1. Synthetic circular sponge stability was assayed in the presence of RNase R or fetal bovine serum. Luciferase reporter and cell proliferation assays were performed to assess competitive inhibition of miR-21 activity by circRNA sponges in NCI-N87 gastric cancer cells. Tandem Mass Tag (TMT) labeling proteomics analysis and Western blotting were performed to delineate effects of circRNA sponges on miR-21 downstream targeted proteins. Our experiments revealed that artificial circRNA sponges can be synthesized using enzymatic ligation. These synthetic circRNA sponges are more resistant than their linear RNA counterparts to nuclease degradation in vitro. They effectively suppress the activity of miR-21 on its downstream protein targets, including the important cancer protein DAXX. Finally, they also inhibit gastric cancer cell proliferation. Our results suggest that synthetic circRNA sponges represent a rapid, effective, convenient strategy to achieve loss of miRNA function in vitro, with potential future therapeutic application in vivo.
Project description:A large number of computational methods have been recently developed for analyzing differential gene expression (DE) in RNA-seq data. We report on a comprehensive evaluation of the commonly used DE methods using the SEQC benchmark data set and data from ENCODE project. We evaluated a number of key features including: normalization, accuracy of DE detection and DE analysis when one condition has no detectable expression. We found significant differences among the methods. Furthermore, computational methods designed for DE detection from expression array data perform comparably to methods customized for RNA-seq. Most importantly, our results demonstrate that increasing the number of replicate samples significantly improves detection power over increased sequencing depth. The Sequencing Quality Control Consortium generated two datasets from two reference RNA samples in order to evaluate transcriptome profiling by next-generation sequencing technology. Each sample contains one of the reference RNA source and a set of synthetic RNAs from the External RNA Control Consortium (ERCC) at known concentrations. Group A contains 5 replicates of the Strategene Universal Human Reference RNA (UHRR), which is composed of total RNA from 10 human cell lines, with 2% by volume of ERCC mix 1. Group B includes 5 replicate samples of the Ambion Human Brain Reference RNA (HBRR) with 2% by volume of ERCC mix 2. The ERCC spike-in control is a mixture of 92 synthetic polyadenylated oligonucleotides of 250-2000 nucleotides long that are meant to resemble human transcripts.
Project description:Natural and synthetic circular RNAs effectively impair miRNA function. MiR-21-5p is a potent oncomiR presenting ~33% of all miRNAs across cancers, ~41% in lung adenocarcinoma (LUAD), and ~68% in LUAD-derived cells. We validate and identify five main tumor suppressors targeted by miR-21-5p by deletion of the MIR21 locus in LUAD cells. Synthetic, liposome-delivered circular miR-21-5p decoys enhance expression of these tumor suppressors and severely impair tumor cell vitality at low doses. Decoy efficacy is not increased by bulging of miR-21-5p targeting sites, but associated with substantial cellular decoy stability, indicated by a half-life of ~20h. The intraperitoneal application of nanoparticle-delivered miR-21-5p decoys significantly impairs tumor growth in mouse LUAD tumor models. Decoys are well tolerated and were enriched in lung tissue. However, despite low decoy abundance, tumor suppressor expression was only increased in subcutaneous tumors. These findings suggest nanoparticle-delivered circular miRNA decoys as potent therapeutics in cancer treatment.