Randomized CRISPR-Cas Transcriptional Perturbation Screening Reveals Protective Genes against Alpha-Synuclein Toxicity
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ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae
PROVIDER: GSE87547 | GEO | 2017/10/01
SECONDARY ACCESSION(S): PRJNA345160
REPOSITORIES: GEO
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Project description:Synthetic transcriptional activators based on CRISPR/Cas technology can be enhanced by intrinsically disordered regions (IDRs). However, the potential of all IDRs in this regard remains uncertain, and the mechanisms underlying their influence are a subject of debate. Here, we examined 12 well-known IDRs by fusing them to the dCas9-VP64 activator. Our findings reveal that seven IDRs could augment activation, albeit independently of their phase separation properties. Moreover, modular domains (MDs), which facilitate multivalent interactions but are ineffective in enhancing dCas9-VP64 activity on their own, showed substantial enhancement in transcriptional activation when combined with dCas9-VP64-IDR. By varying the number of gRNA binding sites and combining dCas9-VP64 with the IDRs and MDs of different multivalent capabilities, we uncovered that optimal, rather than maximal, cis-trans cooperativity enables the most robust activation. Finally, targeting promoter-enhancer pairs with our IDR-enhanced activation system yielded synergistic effects, potentially further amplifiable by induced functional chromatin looping.
2024-06-01 | GSE248523 | GEO
Project description:Synthetic transcriptional activators based on CRISPR/Cas technology can be enhanced by intrinsically disordered regions (IDRs). However, the potential of all IDRs in this regard remains uncertain, and the mechanisms underlying their influence are a subject of debate. Here, we examined 12 well-known IDRs by fusing them to the dCas9-VP64 activator. Our findings reveal that seven IDRs could augment activation, albeit independently of their phase separation properties. Moreover, modular domains (MDs), which facilitate multivalent interactions but are ineffective in enhancing dCas9-VP64 activity on their own, showed substantial enhancement in transcriptional activation when combined with dCas9-VP64-IDR. By varying the number of gRNA binding sites and combining dCas9-VP64 with the IDRs and MDs of different multivalent capabilities, we uncovered that optimal, rather than maximal, cis-trans cooperativity enables the most robust activation. Finally, targeting promoter-enhancer pairs with our IDR-enhanced activation system yielded synergistic effects, potentially further amplifiable by induced functional chromatin looping.
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Project description:We previously performed a tiling CRISPR activation (CRISPRa) screen in Jurkat T cells to discover enhancers controlling IL2RA expression. This screen identified six regions where recruitment of dCas9-VP64 was sufficient to drive increased expression of IL2RA. We named these putative enhancers CRISPRa Responsive Elements (CaREs). To examine transcriptome-wide consequences of dCas9-VP64 recruitment to IL2RA CaREs, we performed RNA-Seq on HuT78 cells stably expressing dCas9-VP64 and gRNAs targeting the IL2RA TSS, CaRE3, or CaRE4, or stimulated with anti-CD3/CD28 antibodies.
2017-04-26 | GSE98177 | GEO
Project description:The genome-wide perturbation of transcriptional networks with CRISPR-Cas technology has primarily involved systematic and targeted gene modulation. Here, we developed PRISM (Perturbing Regulatory Interactions by Synthetic Modulators), a screening platform that uses randomized CRISPR-Cas transcription factors (crisprTFs) to globally perturb transcriptional networks. By applying PRISM to a yeast model of Parkinson's disease (PD), we identified guide RNAs (gRNAs) that modulate transcriptional networks and protect cells from alpha-synuclein (?Syn) toxicity. One gRNA identified in this screen outperformed the most protective suppressors of ?Syn toxicity reported previously, highlighting PRISM's ability to identify modulators of important phenotypes. Gene expression profiling revealed genes differentially modulated by this strong protective gRNA that rescued yeast from ?Syn toxicity when overexpressed. Human homologs of top-ranked hits protected against ?Syn-induced cell death in a human neuronal PD model. Thus, high-throughput and unbiased perturbation of transcriptional networks via randomized crisprTFs can reveal complex biological phenotypes and effective disease modulators.
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Project description:Low NTN4 expression is correlated with breast cancer proliferation and metastasis, while the molecular mechanism of NTN4 has not been fully explored. Here, the breast cancer cells SKBR3 stably expressing dCas9-VP64 and MS-P65-HSG1 were generated by transducing a lentiviral plasmid containing lenti-dCAS-VP64-Blast (Addgene plasmid # 61425) and lenti-EF1a-MS2–p65–HSF1-2A-Hygro-WPRE (Addgene plasmid # 89308), followed by selection and maintained using 10 μg/mL of blasticidin and 200 μg/mL of hygromycin. SKBR3-dCas9-VP64-MPH cells were further transduced with a doxycycline (Dox)-induced expressing sgRNA targeting NTN4 promoter. The successfully transfected cells were selected and maintained with puromycin at a concentration of 0.5 μg/mL for SKBR3-dCas9-VP64-MPH. SKBR3-dCas9-VP64-MPH-AC-sgRNA cells were treated with or without 50 ng/μL Dox (three biological repeats for both groups) to induce NTN4 overexpressing. Total RNA was extracted using TRIzol according to the manufacturer’s instructions. The quality of RNA samples was examined by Agilent BioAnalyser 2100. The samples were subjected to RNA-sequencing analysis on the BGISEQ-500 system by Beijing Genomics Institute (BGI, China). The clean-tag reads were aligned to the reference genome and reference genes using HISAT2 and Bowtie2. The matched reads were calculated and then normalized using RSEM software. Differential gene expression was analyzed using DESeq2 and was carried out further to explore the mechanism of NTN4 in breast cancer.
2022-05-27 | GSE197635 | GEO
Project description:We generated dCas9-KRAB (dK) Tg mice and gRNA targeting Slc25a44 Tg mice. Slc25a44 knockdown mice were obtained by crossing these two Tg mice. Brown adipose tissue from Slc25a44 KD mice (dK+;gRNA+) and littermate control mice (either dK+ or gRNA+) were collected and subjected to transcriptome profiling by RNA-seq.
2019-07-12 | E-MTAB-7987 | biostudies-arrayexpress
Project description:RNA-Seq after Cas9-gRNA transfection with different length gRNAs we performed PolyA Selection and RNA-Seq on cells transfected with dCas9-VPR and a gRNA of each length (20nt, 16nt, or 14nt) targeting ACTC1, MIAT, or HBG1/2
2015-07-15 | E-GEOD-70694 | biostudies-arrayexpress
Project description:Background: The CRISPR/Cas9 toolbox has recently been expanded to include approaches for modulating gene expression. To successfully build on this work, and apply it for answering biological questions, it is important to establish it in a broad range of circumstances. Genome-scale CRISPR interference (CRISPRi) has been used in human cells lines, however the rules for designing effective guide RNAs (gRNAs) in different organisms are not well known. We sought to determine rules that determine gRNA effectiveness at transcriptional repression in Saccharomyces cerevisiae. Results: We created an inducible single plasmid CRISPRi system for gene repression in yeast, and used it to analyze fitness effects of gRNAs under 18 small molecule treatments. Our approach correctly identified previously-described chemical-genetic interactions, as well as a new mechanism of suppressing fluconazole toxicity by repression of the ERG25 gene. Assessment of multiple target loci across treatments allowed us to determine generalizable features associated with gRNA efficacy. Guides that target regions with low nucleosome occupancy and high chromatin accessibility were clearly more effective. We also found the best region to target gRNAs was between the transcription start site (TSS) and 200bp upstream of the TSS. Finally, unlike nuclease-proficient Cas9 in human cells, point mutations were tolerated equally well by truncated (18 nt specificity sequence) and full length (20 nt) gRNAs, however, 18 nt gRNAs were generally less potent than full length gRNAs. Conclusions: Our results establish a powerful functional genomics screening method, provide rules for designing effective gRNAs for gene repression, and show that 18 nt and 20 nt gRNAs exhibit similar tolerance to mismatches in the target sequence. These findings will enable effective library design and genome-wide screening in many genetic backgrounds. An expression construct was created for inducible CRISPRi in yeast. Key features include ORFs expressing dCas9-Mxi1 and the tetracycline repressor (TetR), as well as a tetracycline inducible gRNA locus containing the RPR1 promoter with a TetO site, a NotI site for cloning new gRNA specificity sequences, and the constant part of the gRNA. When yeast containing this plasmid are grown in the absence of anhydrotetracycline (ATc) TetR binds the gRNA promoter and prevents PolIII from binding and transcribing the gRNA. This in turn prevents dCas9-Mxi1 from binding the target site. In the presence of ATc, TetR dissociates and gRNA is expressed, allowing dCas9-Mxi1 to bind its target locus, and repress gene expression. gRNA libraries were cloned into this construct and transformed into yeast to create pools. Experiments were conducted in which yeast pools were grown in inducing (+ATc) and non-inducing conditions (-ATc) in the presence of different drugs. After multiple generations of growth in these conditions, yeast plasmids were minipreped and the gRNA locus was PCRed and sequenced via MiSeq. Counts of each gRNA were compared in different conditions.
2016-01-18 | E-GEOD-71490 | biostudies-arrayexpress
Project description:Integration of the HIV-1 provirus in the host genome ensures a persistent supply of latently infected cells. This latent reservoir is recalcitrant to antiretroviral therapy (ART) making lifelong treatment the only option for patients. The â??shock and killâ?? strategy aims to eradicate latent HIV by reactivating proviral gene expression followed by ART treatment. Gene specific transcriptional activation can be achieved using the RNA-guided CRISPR-Cas9 system comprising small guide RNAs (sgRNAs) with a nuclease deficient Cas9 mutant (dCas9) fused to the VP64 transactivation domain (dCas9-VP64).  We engineered this system to target 23 sites within the LTR promoter of HIV-1 and identified a â??hotspotâ?? for activation. We studied the functionality of activating sgRNAs to transcriptionally modulate the latent proviral genome across multiple different in vitro latency cell models including several J-Lat, ACH2 J1.1 and the CEM T cell model comprising a single clonal population of integrated mCherry-IRES-Tat from a full-length HIV LTR (LChIT). While we observed variable responses of latent cell models to well-characterized chemical stimuli, we detected consistent efficient activation of latent virus mediated by activator sgRNAs. In addition, transcriptome analysis of chemically treated cells revealed massive non-specific gene dysregulation whereas by comparison, dCas9-VP64/sgRNAs induced specific activation of the integrated provirus. In conclusion, we show the potential for CRISPR-mediated gene activation systems to provide enhanced efficiency and specificity in a targeted latency reactivation strategy. This represents a promising approach to a â??functional cureâ?? of HIV/AIDS. Three experimental conditions (sgRNA control, TNF treated and sgRNA against the LTR of HIV-1) were analyzed in triplicate using two sequencing lanes
2016-08-20 | E-GEOD-72259 | biostudies-arrayexpress
Project description:We demonstrate that dCas9-SunTag-DNMT3A dramatically increased CpG methylation at the HOXA5 locus in human embryonic kidney 293T cells (HEK293T). Furthermore, using a single sgRNA, dCas9-SunTag-DNMT3A was able to methylate a 4.5 kb genomic region and repress HOXA5 gene expression. Reduced representation bisulfite sequencing (RRBS) and RNA-seq showed that dCas9-SunTag-DNMT3A methylated regions of interest with minimal impact on the global DNA methylome and transcriptome.
2017-08-22 | GSE97814 | GEO