Identifying human pre-mRNA cleavage and polyadenylation factors by genome-wide CRISPR screens in a dual fluorescence readthrough reporter
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE243457 | GEO | 2024/04/11
REPOSITORIES: GEO
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Project description:The majority of messenger RNA precursor (pre-mRNA) undergoes 3' end cleavage and polyadenylation (CPA), termed as to 3’ end processing. This processing is specified by a polyadenylation site (PAS) and adjacent RNA sequences and regulated by a large variety of core and auxiliary CPA factors. To date, most of the CPA factors have been discovered through biochemical and proteomic studies. However, genome-wide genetic identification of CPA factors has been hampered by the lack of a reliable high-throughput method. Here, we developed a dual fluorescence readthrough reporter system with a PAS inserted between two fluorescent reporters, GFP and mCherry. This system enables the measurement of 3’ end processing in living cells via flow cytometry analysis. Using this system in combination with a human CRISPR library, we conducted a genome-wide screen for CPA factors. The screens identified most of the well-known CPA factors, including most components of the core CPA machineries (i.e. CPSF, CSTF, CFI, and CFII complexes), the CPA scaffold protein SYMPK, PPP1R10 in PNUTS-PP1 complex, as well as CBLL1 (a subunit of m6A RNA methyltransferase complex). Importantly, the screens also uncovered CCNK/CDK12 as a functional core CPA machinery. Furthermore, the screens identified RPRD1B, an RNA polymerase II (RNAP II) binding protein, as a CPA factor. Further characterization showed that RPRD1B binds RNA and regulates the release of RNAP II at the 3’ end of genes. Thus, this dual fluorescence reporter coupled with CRISPR screen provides a reliable tool for identifying bona fide CAP factors, offering a platform for investigating 3’ end processing in various contexts.
2024-04-11 | GSE243456 | GEO
Project description:The majority of messenger RNA precursor (pre-mRNA) undergoes 3' end cleavage and polyadenylation (CPA), termed as to 3’ end processing. This processing is specified by a polyadenylation site (PAS) and adjacent RNA sequences and regulated by a large variety of core and auxiliary CPA factors. To date, most of the CPA factors have been discovered through biochemical and proteomic studies. However, genome-wide genetic identification of CPA factors has been hampered by the lack of a reliable high-throughput method. Here, we developed a dual fluorescence readthrough reporter system with a PAS inserted between two fluorescent reporters, GFP and mCherry. This system enables the measurement of 3’ end processing in living cells via flow cytometry analysis. Using this system in combination with a human CRISPR library, we conducted a genome-wide screen for CPA factors. The screens identified most of the well-known CPA factors, including most components of the core CPA machineries (i.e. CPSF, CSTF, CFI, and CFII complexes), the CPA scaffold protein SYMPK, PPP1R10 in PNUTS-PP1 complex, as well as CBLL1 (a subunit of m6A RNA methyltransferase complex). Importantly, the screens also uncovered CCNK/CDK12 as a functional core CPA machinery. Furthermore, the screens identified RPRD1B, an RNA polymerase II (RNAP II) binding protein, as a CPA factor. Further characterization showed that RPRD1B binds RNA and regulates the release of RNAP II at the 3’ end of genes. Thus, this dual fluorescence reporter coupled with CRISPR screen provides a reliable tool for identifying bona fide CAP factors, offering a platform for investigating 3’ end processing in various contexts.
2024-04-11 | GSE242480 | GEO
Project description:Identifying human pre-mRNA cleavage and polyadenylation factors by genome-wide CRISPR screens in a dual fluorescence readthrough reporter
| PRJNA1018528 | ENA
Project description:Identifying human pre-mRNA cleavage and polyadenylation factors by genome-wide CRISPR screens in a dual fluorescence readthrough reporter (1)
| PRJNA1013561 | ENA
Project description:Identifying human pre-mRNA cleavage and polyadenylation factors by genome-wide CRISPR screens in a dual fluorescence readthrough reporter (2)
| PRJNA1018532 | ENA
Project description:BackgroundChemogenetic profiling enables the identification of gene mutations that enhance or suppress the activity of chemical compounds. This knowledge provides insights into drug mechanism of action, genetic vulnerabilities, and resistance mechanisms, all of which may help stratify patient populations and improve drug efficacy. CRISPR-based screening enables sensitive detection of drug-gene interactions directly in human cells, but until recently has primarily been used to screen only for resistance mechanisms.ResultsWe present drugZ, an algorithm for identifying both synergistic and suppressor chemogenetic interactions from CRISPR screens. DrugZ identifies synthetic lethal interactions between PARP inhibitors and both known and novel members of the DNA damage repair pathway, confirms KEAP1 loss as a resistance factor for ERK inhibitors in oncogenic KRAS backgrounds, and defines the genetic context for temozolomide activity.ConclusionsDrugZ is an open-source Python software for the analysis of genome-scale drug modifier screens. The software accurately identifies genetic perturbations that enhance or suppress drug activity. Interestingly, analysis of new and previously published data reveals tumor suppressor genes are drug-agnostic resistance genes in drug modifier screens. The software is available at github.com/hart-lab/drugz .
| S-EPMC6706933 | biostudies-literature
Project description:Translation is most often terminated when a ribosome encounters the first in-frame stop codon (UAA, UAG or UGA) in an mRNA. However, many viruses (and some cellular mRNAs) contain "stop" codons that cause a proportion of ribosomes to terminate and others to incorporate an amino acid and continue to synthesize a "readthrough", or C-terminally extended, protein. This dynamic redefinition of codon meaning is dependent on specific sequence context.We describe two versatile dual reporter systems which facilitate investigation of stop codon readthrough in vivo in intact plants, and identification of the amino acid incorporated at the decoded stop codon. The first is based on the reporter enzymes NAN and GUS for which sensitive fluorogenic and histochemical substrates are available; the second on GST and GFP.We show that the NAN-GUS system can be used for direct in planta measurements of readthrough efficiency following transient expression of reporter constructs in leaves, and moreover, that the system is sufficiently sensitive to permit measurement of readthrough in stably transformed plants. We further show that the GST-GFP system can be used to affinity purify readthrough products for mass spectrometric analysis and provide the first definitive evidence that tyrosine alone is specified in vivo by a 'leaky' UAG codon, and tyrosine and tryptophan, respectively, at decoded UAA, and UGA codons in the Tobacco mosaic virus (TMV) readthrough context.
| S-EPMC2754532 | biostudies-literature
Project description:Circular RNAs with covalently linked ends are generated from many eukaryotic protein-coding genes when the pre-mRNA splicing machinery backsplices. These mature transcripts are resistant to digestion by exonucleases and typically have much longer half-lives than their associated linear mRNAs. Circular RNAs thus have great promise as sensitive biomarkers, including for detection of transcriptional activity. Here, we show that circular RNAs can serve as markers of readthrough transcription events in Drosophila and human cells, thereby revealing mechanistic insights into RNA polymerase II transcription termination as well as pre-mRNA 3' end processing. We describe methods that take advantage of plasmids that generate a circular RNA when an upstream polyadenylation signal fails to be used and/or RNA polymerase II fails to terminate. As a proof-of-principle, we show that RNAi-mediated depletion of well-established transcription termination factors, including the RNA endonuclease Cpsf73, results in increased circular RNA output from these plasmids in Drosophila and human cells. This method is generalizable as a circular RNA can be easily encoded downstream of any genomic region of interest. Circular RNA biomarkers, therefore, have great promise for identifying novel cellular factors and conditions that impact transcription termination processes.
| S-EPMC8522170 | biostudies-literature
Project description:CRISPR-Cas9 is a powerful tool for genome engineering, but its efficiency largely depends on guide RNA (gRNA). There are multiple methods available to evaluate the efficiency of gRNAs, including the T7E1 assay, surveyor nuclease assay, deep sequencing, and surrogate reporter systems. In the present study, we developed a cleavage-based surrogate that we have named the LacI-reporter to evaluate gRNA cleavage efficiency. The LacI repressor, under the control of the EF-1α promoter, represses luciferase or EGFP reporter expression by binding to the lac operator. Upon CRISPR-Cas9 cleavage at a target site located between the EF-1α promoter and the lacI gene, repressor expression is disrupted, thereby triggering luciferase or EGFP expression. Using this system, we can quantitate gRNA cleavage efficiency by assessing luciferase activity or EGFP expression. We found a strong positive correlation between the cleavage efficiency of gRNAs measured using this reporter and mutation frequency, measured using surveyor and deep sequencing. The genome-editing efficiency of gRNAs was validated in human liver organoids. Our LacI-reporter system provides a useful tool to select efficient gRNAs for genome editing.
| S-EPMC8421217 | biostudies-literature
Project description:In eukaryotes, U1 small nuclear ribonucleoprotein (snRNP) forms spliceosomes in equal stoichiometry with U2, U4, U5 and U6 snRNPs; however, its abundance in human far exceeds that of the other snRNPs. Here we used antisense morpholino oligonucleotide to U1 snRNA to achieve functional U1 snRNP knockdown in HeLa cells, and identified accumulated unspliced pre-mRNAs by genomic tiling microarrays. In addition to inhibiting splicing, U1 snRNP knockdown caused premature cleavage and polyadenylation in numerous pre-mRNAs at cryptic polyadenylation signals, frequently in introns near (<5?kilobases) the start of the transcript. This did not occur when splicing was inhibited with U2 snRNA antisense morpholino oligonucleotide or the U2-snRNP-inactivating drug spliceostatin A unless U1 antisense morpholino oligonucleotide was also included. We further show that U1 snRNA-pre-mRNA base pairing was required to suppress premature cleavage and polyadenylation from nearby cryptic polyadenylation signals located in introns. These findings reveal a critical splicing-independent function for U1 snRNP in protecting the transcriptome, which we propose explains its overabundance.
| S-EPMC2996489 | biostudies-literature