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1.
Nat Commun ; 11(1): 4906, 2020 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-32999292

RESUMO

The CRISPR-Cas12a RNA-guided complexes have tremendous potential for nucleic acid detection but are limited to the picomolar detection limit without an amplification step. Here, we develop a platform with engineered crRNAs and optimized conditions that enabled us to detect various clinically relevant nucleic acid targets with higher sensitivity, achieving a limit of detection in the femtomolar range without any target pre-amplification step. By extending the 3'- or 5'-ends of the crRNA with different lengths of ssDNA, ssRNA, and phosphorothioate ssDNA, we discover a self-catalytic behavior and an augmented rate of LbCas12a-mediated collateral cleavage activity as high as 3.5-fold compared to the wild-type crRNA and with significant improvement in specificity for target recognition. Particularly, the 7-mer DNA extension to crRNA is determined to be universal and spacer-independent for enhancing the sensitivity and specificity of LbCas12a-mediated nucleic acid detection. We perform a detailed characterization of our engineered ENHANCE system with various crRNA modifications, target types, reporters, and divalent cations. With isothermal amplification of SARS-CoV-2 RNA using RT-LAMP, the modified crRNAs are incorporated in a paper-based lateral flow assay that can detect the target with up to 23-fold higher sensitivity within 40-60 min.


Assuntos
Proteínas de Bactérias/metabolismo , Betacoronavirus/genética , Proteínas Associadas a CRISPR/metabolismo , Endodesoxirribonucleases/metabolismo , Técnicas de Amplificação de Ácido Nucleico/métodos , RNA Viral/isolamento & purificação , Transativadores/metabolismo , Betacoronavirus/isolamento & purificação , Sistemas CRISPR-Cas , Técnicas de Laboratório Clínico , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Infecções por Coronavirus/diagnóstico , Infecções por Coronavirus/virologia , DNA de Cadeia Simples , Pandemias , Pneumonia Viral , RNA Guia/genética , RNA Viral/genética
2.
PLoS Comput Biol ; 16(9): e1008194, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32936799

RESUMO

CRISPR screens are a powerful technology for the identification of genome sequences that affect cellular phenotypes such as gene expression, survival, and proliferation. By targeting non-coding sequences for perturbation, CRISPR screens have the potential to systematically discover novel functional sequences, however, a lack of purpose-built analysis tools limits the effectiveness of this approach. Here we describe RELICS, a Bayesian hierarchical model for the discovery of functional sequences from CRISPR screens. RELICS specifically addresses many of the challenges of non-coding CRISPR screens such as the unknown locations of functional sequences, overdispersion in the observed single guide RNA counts, and the need to combine information across multiple pools in an experiment. RELICS outperforms existing methods with higher precision, higher recall, and finer-resolution predictions on simulated datasets. We apply RELICS to published CRISPR interference and CRISPR activation screens to predict and experimentally validate novel regulatory sequences that are missed by other analysis methods. In summary, RELICS is a powerful new analysis method for CRISPR screens that enables the discovery of functional sequences with unprecedented resolution and accuracy.


Assuntos
Sistemas CRISPR-Cas/genética , Genômica/métodos , Análise de Sequência de DNA/métodos , Software , Teorema de Bayes , Humanos , Células Jurkat , RNA Guia/genética
3.
Nat Commun ; 11(1): 4903, 2020 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-32994412

RESUMO

The CRISPR-Cas9 system has increased the speed and precision of genetic editing in cells and animals. However, model generation for drug development is still expensive and time-consuming, demanding more target flexibility and faster turnaround times with high reproducibility. The generation of a tightly controlled ObLiGaRe doxycycline inducible SpCas9 (ODInCas9) transgene and its use in targeted ObLiGaRe results in functional integration into both human and mouse cells culminating in the generation of the ODInCas9 mouse. Genomic editing can be performed in cells of various tissue origins without any detectable gene editing in the absence of doxycycline. Somatic in vivo editing can model non-small cell lung cancer (NSCLC) adenocarcinomas, enabling treatment studies to validate the efficacy of candidate drugs. The ODInCas9 mouse allows robust and tunable genome editing granting flexibility, speed and uniformity at less cost, leading to high throughput and practical preclinical in vivo therapeutic testing.


Assuntos
Sistemas CRISPR-Cas/genética , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Descoberta de Drogas/métodos , Edição de Genes/métodos , Neoplasias Pulmonares/tratamento farmacológico , Animais , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Proteína 9 Associada à CRISPR/genética , Carcinoma Pulmonar de Células não Pequenas/genética , Linhagem Celular Tumoral , Doxiciclina/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais/métodos , Feminino , Expressão Gênica/efeitos dos fármacos , Expressão Gênica/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Vetores Genéticos/genética , Células HEK293 , Ensaios de Triagem em Larga Escala/métodos , Humanos , Neoplasias Pulmonares/genética , Masculino , Camundongos , Camundongos Transgênicos , RNA Guia/genética , Recombinação Genética/efeitos dos fármacos , Reprodutibilidade dos Testes , Ativação Transcricional/efeitos dos fármacos , Transfecção/métodos , Transgenes/genética
4.
PLoS Genet ; 16(8): e1008953, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32776944

RESUMO

Apoptosis of cochlear hair cells is a key step towards age-related hearing loss. Although numerous genes have been implicated in the genetic causes of late-onset, progressive hearing loss, few show direct links to the proapoptotic process. By genome-wide linkage analysis and whole exome sequencing, we identified a heterozygous p.L183V variant in THOC1 as the probable cause of the late-onset, progressive, non-syndromic hearing loss in a large family with autosomal dominant inheritance. Thoc1, a member of the conserved multisubunit THO/TREX ribonucleoprotein complex, is highly expressed in mouse and zebrafish hair cells. The thoc1 knockout (thoc1 mutant) zebrafish generated by gRNA-Cas9 system lacks the C-startle response, indicative of the hearing dysfunction. Both Thoc1 mutant and knockdown zebrafish have greatly reduced hair cell numbers, while the latter can be rescued by embryonic microinjection of human wild-type THOC1 mRNA but to significantly lesser degree by the c.547C>G mutant mRNA. The Thoc1 deficiency resulted in marked apoptosis in zebrafish hair cells. Consistently, transcriptome sequencing of the mutants showed significantly increased gene expression in the p53-associated signaling pathway. Depletion of p53 or applying the p53 inhibitor Pifithrin-α significantly rescued the hair cell loss in the Thoc1 knockdown zebrafish. Our results suggested that THOC1 deficiency lead to late-onset, progressive hearing loss through p53-mediated hair cell apoptosis. This is to our knowledge the first human disease associated with THOC1 mutations and may shed light on the molecular mechanism underlying the age-related hearing loss.


Assuntos
Proteínas de Ligação a DNA/genética , Surdez/genética , Células Ciliadas Auditivas Internas/metabolismo , Proteínas de Ligação a RNA/genética , Proteína Supressora de Tumor p53/genética , Animais , Apoptose/genética , Benzotiazóis/farmacologia , Proteína 9 Associada à CRISPR/genética , Proteínas de Ligação a DNA/deficiência , Surdez/patologia , Modelos Animais de Doenças , Regulação da Expressão Gênica/efeitos dos fármacos , Técnicas de Inativação de Genes , Células Ciliadas Auditivas/metabolismo , Células Ciliadas Auditivas/patologia , Células Ciliadas Auditivas Internas/patologia , Humanos , Camundongos , Mutação , RNA Guia/genética , Transdução de Sinais/efeitos dos fármacos , Tolueno/análogos & derivados , Tolueno/farmacologia , Proteína Supressora de Tumor p53/antagonistas & inibidores , Sequenciamento Completo do Exoma , Peixe-Zebra/genética
5.
Nat Commun ; 11(1): 4072, 2020 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-32792663

RESUMO

Cpf1-linked base editors broaden the targeting scope of programmable cytidine deaminases by recognizing thymidine-rich protospacer-adjacent motifs (PAM) without inducing DNA double-strand breaks (DSBs). Here we present an unbiased in vitro method for identifying genome-wide off-target sites of Cpf1 base editors via whole genome sequencing. First, we treat human genomic DNA with dLbCpf1-BE ribonucleoprotein (RNP) complexes, which convert C-to-U at on-target and off-target sites and, then, with a mixture of E. coli uracil DNA glycosylase (UDG) and DNA glycosylase-lyase Endonuclease VIII, which removes uracil and produces single-strand breaks (SSBs) in vitro. Whole-genome sequencing of the resulting digested genome (Digenome-seq) reveals that, on average, dLbCpf1-BE induces 12 SSBs in vitro per crRNA in the human genome. Off-target sites with an editing frequency as low as 0.1% are successfully identified by this modified Digenome-seq method, demonstrating its high sensitivity. dLbCpf1-BEs and LbCpf1 nucleases often recognize different off-target sites, calling for independent analysis of each tool.


Assuntos
Citidina/metabolismo , Endonucleases/metabolismo , Sequenciamento Completo do Genoma/métodos , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Citidina/genética , DNA/genética , DNA/metabolismo , Endonucleases/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Edição de Genes , Genoma Humano/genética , Células HEK293 , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , RNA Guia/genética
6.
Plant Mol Biol ; 104(3): 297-307, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32748081

RESUMO

KEY MESSAGE: We have developed multiplex genome editing toolkits for citrus that significantly improve citrus genome editing efficacy. CRISPR/Cas systems have been engineered for genome editing in many organisms, including plants. However, the gene editing efficiency in citrus via CRISPR technology remains too low to be implemented for genetic improvement in practice. Moreover, it is very difficult to obtain homozygous or biallelic knockout mutants in citrus. Here, we have developed multiplex genome editing toolkits for citrus including PEG-mediated protoplast transformation, a GFP reporter system that allows the rapid assessment of CRISPR constructs, citrus U6 promoters with improved efficacy, and tRNA-mediated or Csy4-mediated multiplex genome editing. Using the toolkits, we successfully conducted genome modification of embryogenic protoplast cells and epicotyl tissues. We have achieved a biallelic mutation rate of 44.4% and a homozygous mutation rate of 11.1%, representing a significant improvement in citrus genome editing efficacy. In addition, our study lays the foundation for nontransgenic genome editing of citrus.


Assuntos
Citrus/genética , Edição de Genes/métodos , Genoma de Planta/genética , Homozigoto , Mutação , Sistemas CRISPR-Cas , Técnicas de Inativação de Genes , Genes de Plantas/genética , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas , Protoplastos , RNA Guia/genética , RNA de Transferência/genética
7.
Nat Commun ; 11(1): 4132, 2020 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-32807781

RESUMO

Precise genome editing using CRISPR-Cas9 is a promising therapeutic avenue for genetic diseases, although off-target editing remains a significant safety concern. Guide RNAs shorter than 16 nucleotides in length effectively recruit Cas9 to complementary sites in the genome but do not permit Cas9 nuclease activity. Here we describe CRISPR Guide RNA Assisted Reduction of Damage (CRISPR GUARD) as a method for protecting off-targets sites by co-delivery of short guide RNAs directed against off-target loci by competition with the on-target guide RNA. CRISPR GUARD reduces off-target mutagenesis while retaining on-target editing efficiencies with Cas9 and base editor. However, we discover that short guide RNAs can also support base editing if they contain cytosines within the deaminase activity window. We explore design rules and the universality of this method through in vitro studies and high-throughput screening, revealing CRISPR GUARD as a rapidly implementable strategy to improve the specificity of genome editing for most genomic loci. Finally, we create an online tool for CRISPR GUARD design.


Assuntos
Edição de Genes/métodos , RNA Guia/metabolismo , Sistemas CRISPR-Cas/genética , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/fisiologia , Humanos , Mutagênese/genética , Mutagênese/fisiologia , RNA Guia/genética
8.
Nat Protoc ; 15(9): 3030-3063, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32807909

RESUMO

Materials that sense and respond to biological signals in their environment have a broad range of potential applications in drug delivery, medical devices and diagnostics. Nucleic acids are important biological cues that encode information about organismal identity and clinically relevant phenotypes such as drug resistance. We recently developed a strategy to design nucleic acid-responsive materials using the CRISPR-associated nuclease Cas12a as a user-programmable sensor and material actuator. This approach improves on the sensitivity of current DNA-responsive materials while enabling their rapid repurposing toward new sequence targets. Here, we provide a comprehensive resource for the design, synthesis and actuation of CRISPR-responsive hydrogels. First, we provide guidelines for the synthesis of Cas12a guide RNAs (gRNAs) for in vitro applications. We then outline methods for the synthesis of both polyethylene glycol-DNA (PEG-DNA) and polyacrylamide-DNA (PA-DNA) hydrogels, as well as their controlled degradation using Cas12a for the release of cargos, including small molecules, enzymes, nanoparticles and living cells within hours. Finally, we detail the design and assembly of microfluidic paper-based devices that use Cas12a-sensitive hydrogels to convert DNA inputs into a variety of visual and electronic readouts for use in diagnostics. Following the initial validation of the gRNA and Cas12a components (1 d), the synthesis and testing of either PEG-DNA or PA-DNA hydrogels require 3-4 d of laboratory time. Optional extensions, including the release of primary human cells or the design of the paper-based diagnostic, require an additional 2-3 d each.


Assuntos
Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Técnicas e Procedimentos Diagnósticos , Sistemas de Liberação de Medicamentos/métodos , Liberação Controlada de Fármacos , Materiais Inteligentes/química , Resinas Acrílicas/química , Proteínas de Bactérias/metabolismo , Sequência de Bases , Proteínas Associadas a CRISPR/metabolismo , DNA/química , DNA/genética , Endodesoxirribonucleases/metabolismo , Humanos , Células K562 , Polietilenoglicóis/química , RNA Guia/genética
9.
Nucleic Acids Res ; 48(15): 8704-8723, 2020 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-32738044

RESUMO

Trypanosoma brucei is a parasitic protozoan that undergoes a complex life cycle involving insect and mammalian hosts that present dramatically different nutritional environments. Mitochondrial metabolism and gene expression are highly regulated to accommodate these environmental changes, including regulation of mRNAs that require extensive uridine insertion/deletion (U-indel) editing for their maturation. Here, we use high throughput sequencing and a method for promoting life cycle changes in vitro to assess the mechanisms and timing of developmentally regulated edited mRNA expression. We show that edited CYb mRNA is downregulated in mammalian bloodstream forms (BSF) at the level of editing initiation and/or edited mRNA stability. In contrast, edited COIII mRNAs are depleted in BSF by inhibition of editing progression. We identify cell line-specific differences in the mechanisms abrogating COIII mRNA editing, including the possible utilization of terminator gRNAs that preclude the 3' to 5' progression of editing. By examining the developmental timing of altered mitochondrial mRNA levels, we also reveal transcript-specific developmental checkpoints in epimastigote (EMF), metacyclic (MCF), and BSF. These studies represent the first analysis of the mechanisms governing edited mRNA levels during T. brucei development and the first to interrogate U-indel editing in EMF and MCF life cycle stages.


Assuntos
Estabilidade de RNA/genética , RNA Mensageiro/genética , RNA Mitocondrial/genética , RNA de Protozoário/genética , Trypanosoma brucei brucei/genética , Mitocôndrias/genética , Proteínas de Protozoários/genética , Edição de RNA/genética , RNA Guia/genética , Trypanosoma brucei brucei/metabolismo
10.
Mol Cell ; 79(3): 416-424.e5, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32645367

RESUMO

CRISPR-Cas12c/d proteins share limited homology with Cas12a and Cas9 bacterial CRISPR RNA (crRNA)-guided nucleases used widely for genome editing and DNA detection. However, Cas12c (C2c3)- and Cas12d (CasY)-catalyzed DNA cleavage and genome editing activities have not been directly observed. We show here that a short-complementarity untranslated RNA (scoutRNA), together with crRNA, is required for Cas12d-catalyzed DNA cutting. The scoutRNA differs in secondary structure from previously described tracrRNAs used by CRISPR-Cas9 and some Cas12 enzymes, and in Cas12d-containing systems, scoutRNA includes a conserved five-nucleotide sequence that is essential for activity. In addition to supporting crRNA-directed DNA recognition, biochemical and cell-based experiments establish scoutRNA as an essential cofactor for Cas12c-catalyzed pre-crRNA maturation. These results define scoutRNA as a third type of transcript encoded by a subset of CRISPR-Cas genomic loci and explain how Cas12c/d systems avoid requirements for host factors including ribonuclease III for bacterial RNA-mediated adaptive immunity.


Assuntos
Bactérias/genética , Proteínas de Bactérias/genética , Sistemas CRISPR-Cas , Endodesoxirribonucleases/genética , Genoma Bacteriano/imunologia , RNA Bacteriano/genética , Pequeno RNA não Traduzido/genética , Bactérias/classificação , Bactérias/imunologia , Bactérias/metabolismo , Proteínas de Bactérias/metabolismo , Sequência de Bases , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Endodesoxirribonucleases/metabolismo , Escherichia coli/genética , Escherichia coli/imunologia , Escherichia coli/metabolismo , Conformação de Ácido Nucleico , Filogenia , RNA Bacteriano/química , RNA Bacteriano/metabolismo , RNA Guia/genética , RNA Guia/metabolismo , Pequeno RNA não Traduzido/química , Pequeno RNA não Traduzido/metabolismo , Alinhamento de Sequência , Homologia de Sequência do Ácido Nucleico
11.
Nat Commun ; 11(1): 3455, 2020 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-32661245

RESUMO

CRISPR-based genetic screening has revolutionized cancer drug target discovery, yet reliable, multiplex gene editing to reveal synergies between gene targets remains a major challenge. Here, we present a simple and robust CRISPR-Cas12a-based approach for combinatorial genetic screening in cancer cells. By engineering the CRISPR-AsCas12a system with key modifications to the Cas protein and its CRISPR RNA (crRNA), we can achieve high efficiency combinatorial genetic screening. We demonstrate the performance of our optimized AsCas12a (opAsCas12a) through double knockout screening against epigenetic regulators. This screen reveals synthetic sick interactions between Brd9&Jmjd6, Kat6a&Jmjd6, and Brpf1&Jmjd6 in leukemia cells.


Assuntos
Proteínas de Bactérias/genética , Proteínas Associadas a CRISPR/genética , Sistemas CRISPR-Cas , Endodesoxirribonucleases/genética , Edição de Genes , Regulação Leucêmica da Expressão Gênica , Leucemia/genética , Animais , Proliferação de Células , Epigênese Genética , Biblioteca Gênica , Engenharia Genética , Genoma Humano , Células HEK293 , Humanos , Células K562 , Camundongos , Células NIH 3T3 , Domínios Proteicos , RNA Guia/genética
12.
Gene ; 758: 144975, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32707302

RESUMO

Dip2C is highly expressed in brain and many other tissues but its biological functions are still not clear. Genes regulated by Dip2C in brain have never been studied. The clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein (Cas) systems, adaptive immune systems of bacteria and archaea, have been recently developed and broadly used in genome editing. Here, we describe targeted gene deletions of Dip2c gene in mice via CRISPR/Cas9 system and study of brain transcriptome under Dip2C regulation. The CRISPR/Cas9 system effectively generated targeted deletions of Dip2c by pronuclei injection of plasmids that express Cas9 protein and two sgRNAs. We achieved targeted large fragment deletion with efficiencies at 14.3% (1/7), 66.7% (2/3) and 20% (1/5) respectively in 3 independent experiments, averaging 26.7%. The large deletion DNA segments are 160.4 kb (Dip2CΔ160kb), spanning from end of exon 4 to mid of exon 38. A mouse with two base pair deletion was generated from a single sgRNA targeting in exon 4 (Dip2cΔ2bp) by non-homologous end joining (NHEJ). Loss of gene expression for Dip2c mRNA was confirmed by quantitative real-time PCR (qPCR). Dip2C-regulated genes and pathways in brain were investigated through RNAseq of Dip2cΔ2bp. In total, 838 genes were found differentially regulated, with 252 up and 586 down. Gene ontology (GO) analysis indicated that DEGs in brain are enriched in neurological functions including 'memory', 'neuropeptide signaling pathway', and 'response to amphetamine' while KEGG analysis shows that 'neuroactive ligand-receptor interaction pathway' is the most significantly enriched. DEGs Grid2ip, Grin2a, Grin2c, Grm4, Gabbr2, Gabra5, Gabre, Gabrq, Gabra6 and Gabrr2 are among the highly regulated genes by Dip2C. Results confirm Dip2C may play important roles in brain development and function.


Assuntos
Encéfalo/metabolismo , Regulação da Expressão Gênica/genética , Proteínas de Neoplasias/genética , Transcriptoma/genética , Animais , Encéfalo/citologia , Encéfalo/crescimento & desenvolvimento , Sistemas CRISPR-Cas , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Feminino , Deleção de Genes , Edição de Genes/métodos , Técnicas de Inativação de Genes , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Camundongos Knockout , RNA Guia/genética
13.
Proc Natl Acad Sci U S A ; 117(31): 18424-18430, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32690674

RESUMO

Most classic genetic approaches utilize binary modifications that preclude the identification of key knockdowns for essential genes or other targets that only require moderate modulation. As a complementary approach to these classic genetic methods, we describe a plasmid-based library methodology that affords bidirectional, graded modulation of gene expression enabled by tiling the promoter regions of all 969 genes that comprise the ito977 model of Saccharomyces cerevisiae's metabolic network. When coupled with a CRISPR-dCas9-based modulation and next-generation sequencing, this method affords a library-based, bidirection titration of gene expression across all major metabolic genes. We utilized this approach in two case studies: growth enrichment on alternative sugars, glycerol and galactose, and chemical overproduction of betaxanthins, leading to the identification of unique gene targets. In particular, we identify essential genes and other targets that were missed by classic genetic approaches.


Assuntos
RNA Fúngico/genética , RNA Guia/genética , Saccharomyces cerevisiae/genética , Sistemas CRISPR-Cas , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Regulação Fúngica da Expressão Gênica , Biblioteca Gênica , Plasmídeos/genética , Plasmídeos/metabolismo , Regiões Promotoras Genéticas , RNA Fúngico/metabolismo , RNA Guia/metabolismo , Saccharomyces cerevisiae/metabolismo
14.
Nat Commun ; 11(1): 3596, 2020 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-32681048

RESUMO

CRISPR effectors, which comprise a CRISPR-Cas protein and a guide (g)RNA derived from the bacterial immune system, are widely used for target-specific genome editing. When the gRNA recognizes genomic loci with sequences that are similar to the target, deleterious mutations can occur. Off-target mutations with a frequency below 0.5% remain mostly undetected by current genome-wide off-target detection techniques. Here we report a method to effectively detect extremely small amounts of mutated DNA based on predicted off-target-specific amplification. In this study, we used various genome editors to induce intracellular genome mutations, and the CRISPR amplification method detected off-target mutations at a significantly higher rate (1.6~984 fold increase) than an existing targeted amplicon sequencing method. In the near future, CRISPR amplification in combination with genome-wide off-target detection methods will allow detection of genome editor-induced off-target mutations with high sensitivity and in a non-biased manner.


Assuntos
Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , DNA/genética , Sistemas CRISPR-Cas , Edição de Genes , Humanos , Mutação , RNA Guia/genética
15.
Nucleic Acids Res ; 48(15): 8601-8616, 2020 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-32687187

RESUMO

The CRISPR-Cas9 system is widely used for target-specific genome engineering. CRISPR-Cas12a (Cpf1) is one of the CRISPR effectors that controls target genes by recognizing thymine-rich protospacer adjacent motif (PAM) sequences. Cas12a has a higher sensitivity to mismatches in the guide RNA than does Cas9; therefore, off-target sequence recognition and cleavage are lower. However, it tolerates mismatches in regions distant from the PAM sequence (TTTN or TTN) in the protospacer, and off-target cleavage issues may become more problematic when Cas12a activity is improved for therapeutic purposes. Therefore, we investigated off-target cleavage by Cas12a and modified the Cas12a (cr)RNA to address the off-target cleavage issue. We developed a CRISPR-Cas12a that can induce mutations in target DNA sequences in a highly specific and effective manner by partially substituting the (cr)RNA with DNA to change the energy potential of base pairing to the target DNA. A model to explain how chimeric (cr)RNA guided CRISPR-Cas12a and SpCas9 nickase effectively work in the intracellular genome is suggested. Chimeric guide-based CRISPR- Cas12a genome editing with reduced off-target cleavage, and the resultant, increased safety has potential for therapeutic applications in incurable diseases caused by genetic mutations.


Assuntos
Proteínas de Bactérias/genética , Proteínas Associadas a CRISPR/genética , Sistemas CRISPR-Cas/genética , DNA/genética , Endodesoxirribonucleases/genética , RNA Guia/genética , Pareamento Incorreto de Bases/genética , Clivagem do DNA , Edição de Genes , Humanos , Modelos Moleculares , Mutação/genética , Conformação de Ácido Nucleico , RNA/genética , RNA Circular/genética
16.
Nature ; 583(7817): 631-637, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32641830

RESUMO

Bacterial toxins represent a vast reservoir of biochemical diversity that can be repurposed for biomedical applications. Such proteins include a group of predicted interbacterial toxins of the deaminase superfamily, members of which have found application in gene-editing techniques1,2. Because previously described cytidine deaminases operate on single-stranded nucleic acids3, their use in base editing requires the unwinding of double-stranded DNA (dsDNA)-for example by a CRISPR-Cas9 system. Base editing within mitochondrial DNA (mtDNA), however, has thus far been hindered by challenges associated with the delivery of guide RNA into the mitochondria4. As a consequence, manipulation of mtDNA to date has been limited to the targeted destruction of the mitochondrial genome by designer nucleases9,10.Here we describe an interbacterial toxin, which we name DddA, that catalyses the deamination of cytidines within dsDNA. We engineered split-DddA halves that are non-toxic and inactive until brought together on target DNA by adjacently bound programmable DNA-binding proteins. Fusions of the split-DddA halves, transcription activator-like effector array proteins, and a uracil glycosylase inhibitor resulted in RNA-free DddA-derived cytosine base editors (DdCBEs) that catalyse C•G-to-T•A conversions in human mtDNA with high target specificity and product purity. We used DdCBEs to model a disease-associated mtDNA mutation in human cells, resulting in changes in respiration rates and oxidative phosphorylation. CRISPR-free DdCBEs enable the precise manipulation of mtDNA, rather than the elimination of mtDNA copies that results from its cleavage by targeted nucleases, with broad implications for the study and potential treatment of mitochondrial disorders.


Assuntos
Toxinas Bacterianas/metabolismo , Citidina Desaminase/metabolismo , DNA Mitocondrial/genética , Edição de Genes/métodos , Genes Mitocondriais/genética , Mitocôndrias/genética , Toxinas Bacterianas/química , Toxinas Bacterianas/genética , Sequência de Bases , Burkholderia cenocepacia/enzimologia , Burkholderia cenocepacia/genética , Respiração Celular/genética , Citidina/metabolismo , Citidina Desaminase/química , Citidina Desaminase/genética , Genoma Mitocondrial/genética , Células HEK293 , Humanos , Doenças Mitocondriais/genética , Doenças Mitocondriais/terapia , Mutação , Fosforilação Oxidativa , Engenharia de Proteínas , RNA Guia/genética , Especificidade por Substrato , Sistemas de Secreção Tipo VI/metabolismo
17.
Nat Commun ; 11(1): 2730, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32483187

RESUMO

Bacteria have evolved sophisticated adaptive immune systems, called CRISPR-Cas, that provide sequence-specific protection against phage infection. In turn, phages have evolved a broad spectrum of anti-CRISPRs that suppress these immune systems. Here we report structures of anti-CRISPR protein IF9 (AcrIF9) in complex with the type I-F CRISPR RNA-guided surveillance complex (Csy). In addition to sterically blocking the hybridization of complementary dsDNA to the CRISPR RNA, our results show that AcrIF9 binding also promotes non-sequence-specific engagement with dsDNA, potentially sequestering the complex from target DNA. These findings highlight the versatility of anti-CRISPR mechanisms utilized by phages to suppress CRISPR-mediated immune systems.


Assuntos
Bactérias/metabolismo , Bacteriófagos/metabolismo , Sistemas CRISPR-Cas , DNA/metabolismo , RNA Guia/metabolismo , Proteínas Virais/metabolismo , Sequência de Aminoácidos , Bactérias/genética , Bactérias/virologia , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Bacteriófagos/genética , Microscopia Crioeletrônica , DNA/química , DNA/genética , Modelos Moleculares , Complexos Multiproteicos/química , Complexos Multiproteicos/metabolismo , Complexos Multiproteicos/ultraestrutura , Conformação de Ácido Nucleico , Ligação Proteica , Conformação Proteica , Proteus penneri/genética , Proteus penneri/metabolismo , Proteus penneri/virologia , RNA Guia/química , RNA Guia/genética , Homologia de Sequência de Aminoácidos , Proteínas Virais/química , Proteínas Virais/genética
18.
Arch Virol ; 165(8): 1827-1835, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32507978

RESUMO

Human cytomegalovirus (HCMV) infection causes high morbidity and mortality among immunocompromised patients and can remain in a latent state in host cells. Expression of the immediate-early (IE) genes sustains HCMV replication and reactivation. As a novel genome-editing tool, the clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) system has been extensively utilized to modify and edit genomic DNA. In the present study, the CRISPR/Cas9 system was used to target the IE region of the HCMV genome via specific single-guide RNAs (sgRNAs). Infection with CRISPR/Cas9/sgRNA lentiviral constructs significantly reduced viral gene expression and virion production in HFF primary fibroblasts and inhibited viral DNA production and reactivation in the THP-1 monocytic cell line. Thus, the CRISPR/Cas9/sgRNA system can accurately and efficiently target HCMV replication and reactivation and represents a novel therapeutic strategy against latent HCMV infection.


Assuntos
Sistemas CRISPR-Cas/genética , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Citomegalovirus/genética , Endonucleases/genética , Genes Virais/genética , Replicação Viral/genética , Linhagem Celular , Infecções por Citomegalovirus/virologia , DNA Viral/genética , Fibroblastos/virologia , Edição de Genes/métodos , Expressão Gênica/genética , Células HEK293 , Humanos , RNA Guia/genética , Células THP-1
19.
BMC Bioinformatics ; 21(1): 223, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32487025

RESUMO

BACKGROUND: The latest works on CRISPR genome editing tools mainly employs deep learning techniques. However, deep learning models lack explainability and they are harder to reproduce. We were motivated to build an accurate genome editing tool using sequence-based features and traditional machine learning that can compete with deep learning models. RESULTS: In this paper, we present CRISPRpred(SEQ), a method for sgRNA on-target activity prediction that leverages only traditional machine learning techniques and hand-crafted features extracted from sgRNA sequences. We compare the results of CRISPRpred(SEQ) with that of DeepCRISPR, the current state-of-the-art, which uses a deep learning pipeline. Despite using only traditional machine learning methods, we have been able to beat DeepCRISPR for the three out of four cell lines in the benchmark dataset convincingly (2.174%, 6.905% and 8.119% improvement for the three cell lines). CONCLUSION: CRISPRpred(SEQ) has been able to convincingly beat DeepCRISPR in 3 out of 4 cell lines. We believe that by exploring further, one can design better features only using the sgRNA sequences and can come up with a better method leveraging only traditional machine learning algorithms that can fully beat the deep learning models.


Assuntos
Sistemas CRISPR-Cas/genética , Edição de Genes/métodos , Aprendizado de Máquina , RNA Guia/genética , Algoritmos , Área Sob a Curva , Sequência de Bases , Bases de Dados Genéticas , Aprendizado Profundo , Células HEK293 , Humanos , Curva ROC , Reprodutibilidade dos Testes
20.
Nat Commun ; 11(1): 2697, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32483117

RESUMO

CRISPR-Cas9 nucleases are powerful genome engineering tools, but unwanted cleavage at off-target and previously edited sites remains a major concern. Numerous strategies to reduce unwanted cleavage have been devised, but all are imperfect. Here, we report that off-target sites can be shielded from the active Cas9•single guide RNA (sgRNA) complex through the co-administration of dead-RNAs (dRNAs), truncated guide RNAs that direct Cas9 binding but not cleavage. dRNAs can effectively suppress a wide-range of off-targets with minimal optimization while preserving on-target editing, and they can be multiplexed to suppress several off-targets simultaneously. dRNAs can be combined with high-specificity Cas9 variants, which often do not eliminate all unwanted editing. Moreover, dRNAs can prevent cleavage of homology-directed repair (HDR)-corrected sites, facilitating scarless editing by eliminating the need for blocking mutations. Thus, we enable precise genome editing by establishing a flexible approach for suppressing unwanted editing of both off-targets and HDR-corrected sites.


Assuntos
Sistemas CRISPR-Cas , Edição de Genes/métodos , Mutação , RNA Guia/genética , Animais , Sequência de Bases , Sítios de Ligação/genética , Biocatálise , Linhagem Celular Tumoral , Células Cultivadas , Reparo do DNA , Células HEK293 , Humanos , Camundongos , Modelos Genéticos , RNA Guia/metabolismo
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