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
Similar Datasets
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: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.
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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.
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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
Project description:This SuperSeries is composed of the SubSeries listed below.
2024-06-26 | GSE262385 | GEO
Project description:Immortalised HaCaT keratinocytes were transduced with Cas9 and the CRISPR-KO v1.1 genome-wide gRNA library. The gRNA library was prepared from genomic DNA isolated 14 days post library transduction. gRNA representation will be compared to the original CRISPR-KO v1.1 library to reveal genes essential for HaCaT survival and growth.
| EGAS00001002714 | EGA
Project description:Since their discovery, microRNAs (miRNA)s have been widely studied in almost every field of biology and medicine, leading to the identification of important gene regulation circuits and cellular mechanisms. However, investigations are generally focused on the analysis of their downstream targets and biological functions in overexpression and knockdown approaches, while miRNAs endogenous levels and activity remain poorly investigated. Here, we used the cellular plasticity-regulating process of epithelial-to-mesenchymal transition (EMT) as a model to show the efficacy of a plasmid-based fluorescent sensor to separate cells with distinct EMT signatures, based on miR-200b/c activity. The system was further combined with a CRISPR-Cas9 screening platform to unbiasedly identify miR-200b/c upstream regulating genes. The sensor allows to infer miRNAs fundamental biological properties, as profiling of sorted cells indicated miR-200b/c as a molecular switch between EMT differentiation and proliferation, and suggested a role for metabolic enzymes in miR-200/EMT regulation. Analysis of miRNAs’ endogenous levels and activity could lead to a better comprehension of their biological role in physiology and disease.
2020-12-01 | GSE154429 | GEO
Project description:In human, mouse, and Drosophila, the spliceosomal complex U1 snRNP (U1) protects transcripts from premature cleavage and polyadenylation at proximal intronic polyadenylation signals (PAS). These U1-mediated effects preserve transcription integrity, and are known as telescripting. The watchtower role of U1 throughout transcription is clear. What is less clear is whether cleavage and polyadenylation factors (CPFs) are simply patrolled or if they might actively antagonize U1 recruitment. In addressing this question, we found that, in the introns of human, mouse, and Drosophila, and of 14 other eukaryotes, including multi- and single-celled species, the conserved AATAAA PAS-a major target for CPFs-is selected against. This selective pressure, approximated using DNA strand asymmetry, is detected for peripheral and internal introns alike. Surprisingly, it is more pronounced within-rather than outside-the action range of telescripting, and particularly intense in the vicinity of weak 5' splice sites. Our study uncovers a novel feature of eukaryotic genes: that the AATAAA PAS is universally counter-selected in spliceosomal introns. This pattern implies that CPFs may attempt to access introns at any time during transcription. However, natural selection operates to minimize this access. By corroborating and extending previous work, our study further indicates that CPF access to intronic PASs might perturb the recruitment of U1 to the adjacent 5' splice sites. These results open the possibility that CPFs may impact the splicing process across eukaryotes.
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