CRISPR-Cas9 induces large structural variants at on-target and off-target sites in vivo that segregate across generations

To investigate the extent and distribution of unintended mutations induced by CRISPR-Cas9 in vivo, we edited the genome of fertilized zebrafish eggs and investigated DNA from >1100 larvae, juvenile and adult fish in the F0 and F1 generations. Four guide RNAs (gRNAs) were used, selected from 23 gRNAs with high on-target efficiency in vivo in previous functional experiments. CRISPR-Cas9 outcomes were analyzed by long-read sequencing of on-target sites and off-target sites detected in vitro. In founder larvae, on-target editing of the four gRNAs was 93-97% efficient, and three sites across two gRNAs were identified with in vivo off-target editing. Seven percent of the CRISPR-Cas9 editing outcomes correspond to structural variants (SVs), i.e., insertions and deletions ≥50 bp. The adult founder fish displayed a mosaic pattern of editing events in somatic and germ cells. The F1 generation contained high levels of genome editing, with all alleles of 46 examined F1 juvenile fish affected by on-target mutations, including four cases of SVs. In addition, 26% of the juvenile F1 fish (n=12) carried off-target mutations. These CRISPR-induced off-target mutations in F1 fish were successfully validated in pooled larvae from the same founder parents. In conclusion, we demonstrate that large SVs and off-target mutations can be introduced in vivo and passed through the germline to the F1 generation. The results have important consequences for the use of CRISPR-Cas9 in clinical applications, where pre-testing for off-target activity and SVs on patient material is advisable to reduce the risk of unanticipated effects with potentially large implications.

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Amplification-free long-read sequencing reveals unforeseen CRISPR-Cas9 off-target activity

Genome Biology ◽

10.1186/s13059-020-02206-w ◽

2020 ◽

Vol 21 (1) ◽

Author(s):

Ida Höijer ◽

Josefin Johansson ◽

Sanna Gudmundsson ◽

Chen-Shan Chin ◽

Ignas Bunikis ◽

...

Keyword(s):

Genomic Dna ◽

Human Fibroblasts ◽

Target Prediction ◽

Human Cell Line ◽

Cleavage Sites ◽

Guide Rna ◽

Target Sites ◽

Long Read ◽

Target Activity

Abstract Background One ongoing concern about CRISPR-Cas9 genome editing is that unspecific guide RNA (gRNA) binding may induce off-target mutations. However, accurate prediction of CRISPR-Cas9 off-target activity is challenging. Here, we present SMRT-OTS and Nano-OTS, two novel, amplification-free, long-read sequencing protocols for detection of gRNA-driven digestion of genomic DNA by Cas9 in vitro. Results The methods are assessed using the human cell line HEK293, re-sequenced at 18x coverage using highly accurate HiFi SMRT reads. SMRT-OTS and Nano-OTS are first applied to three different gRNAs targeting HEK293 genomic DNA, resulting in a set of 55 high-confidence gRNA cleavage sites identified by both methods. Twenty-five of these sites are not reported by off-target prediction software, either because they contain four or more single nucleotide mismatches or insertion/deletion mismatches, as compared with the human reference. Additional experiments reveal that 85% of Cas9 cleavage sites are also found by other in vitro-based methods and that on- and off-target sites are detectable in gene bodies where short-reads fail to uniquely align. Even though SMRT-OTS and Nano-OTS identify several sites with previously validated off-target editing activity in cells, our own CRISPR-Cas9 editing experiments in human fibroblasts do not give rise to detectable off-target mutations at the in vitro-predicted sites. However, indel and structural variation events are enriched at the on-target sites. Conclusions Amplification-free long-read sequencing reveals Cas9 cleavage sites in vitro that would have been difficult to predict using computational tools, including in dark genomic regions inaccessible by short-read sequencing.

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Amplification-free long read sequencing reveals unforeseen CRISPR-Cas9 off-target activity

10.1101/2020.02.09.940486 ◽

2020 ◽

Cited By ~ 3

Author(s):

Ida Höijer ◽

Josefin Johansson ◽

Sanna Gudmundsson ◽

Chen-Shan Chin ◽

Ignas Bunikis ◽

...

Keyword(s):

Binding Sites ◽

De Novo ◽

Target Prediction ◽

Human Cell Line ◽

Guide Rna ◽

Target Sites ◽

Long Read ◽

Target Binding

AbstractA much-debated concern about CRISPR-Cas9 genome editing is that unspecific guide RNA (gRNA) binding may induce off-target mutations. However, accurate prediction of CRISPR-Cas9 off-target sites and activity is challenging. Here we present SMRT-OTS and Nano-OTS, two amplification-free long-read sequencing protocols for detection of gRNA driven digestion of genomic DNA by Cas9. The methods were assessed using the human cell line HEK293, which was first re-sequenced at 18x coverage using highly accurate (HiFi) SMRT reads to get a detailed view of all on- and off-target binding regions. We then applied SMRT-OTS and Nano-OTS to investigate the specificity of three different gRNAs, resulting in a set of 55 high-confidence gRNA binding sites identified by both methods. Twenty-five (45%) of these sites were not reported by off-target prediction software, either because they contained four or more single nucleotide mismatches or insertion/deletion mismatches, as compared with the human reference. We further discovered that a heterozygous SNP can cause allele-specific gRNA binding. Finally, by performing a de novo genome assembly of the HiFi reads, we were able to re-discover 98.7% of the gRNA binding sites without any prior information about the human reference genome. This suggests that CRISPR-Cas9 off-target sites can be efficiently mapped also in organisms where the genome sequence is unknown. In conclusion, the amplification-free sequencing protocols revealed many gRNA binding sites in vitro that would be difficult to predict based on gRNA sequence alignment to a reference. Nevertheless, it is still unknown whether in vivo off-target editing would occur at these sites.

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A systematic evaluation of data processing and problem formulation of CRISPR off-target site prediction

10.1101/2021.09.30.462534 ◽

2021 ◽

Author(s):

Ofir Yaish ◽

Maor Asif ◽

Yaron Orenstein

Keyword(s):

Data Processing ◽

Gene Editing ◽

Target Site ◽

Systematic Evaluation ◽

Guide Rna ◽

Guide Rnas ◽

Target Sites ◽

Evaluation Of Data

AbstractCRISPR/Cas9 system is widely used in a broad range of gene-editing applications. While this gene-editing technique is quite accurate in the target region, there may be many unplanned off-target edited sites. Consequently, a plethora of computational methods have been developed to predict off-target cleavage sites given a guide RNA and a reference genome. However, these methods are based on small-scale datasets (only tens to hundreds of off-target sites) produced by experimental techniques to detect off-target sites with a low signal-to-noise ratio. Recently, CHANGE-seq, a new in vitro experimental technique to detect off-target sites, was used to produce a dataset of unprecedented scale and quality (more than 200,000 off-target sites over 110 guide RNAs). In addition, the same study included GUIDE-seq experiments for 58 of the guide RNAs to produce in vivo measurements of off-target sites. Here, we fill the gap in previous computational methods by utilizing these data to perform a systematic evaluation of data processing and formulation of the CRISPR off-target site prediction problem. Our evaluations show that data transformation as a pre-processing phase is critical prior to model training. Moreover, we demonstrate the improvement gained by adding potential inactive off-target sites to the training datasets. Furthermore, our results point to the importance of adding the number of mismatches between the guide RNA and the off-target site as a feature. Finally, we present predictive off-target in vivo models based on transfer learning from in vitro. Our conclusions will be instrumental to any future development of an off-target predictor based on high-throughput datasets.

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Construction of adenovirus vectors simultaneously expressing four multiplex, double-nicking guide RNAs of CRISPR/Cas9 and in vivo genome editing

Scientific Reports ◽

10.1038/s41598-021-83259-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tomoko Nakanishi ◽

Aya Maekawa ◽

Mariko Suzuki ◽

Hirotaka Tabata ◽

Kumiko Sato ◽

...

Keyword(s):

Target Gene ◽

Animal Experiments ◽

Adenovirus Vector ◽

Mouse Embryonic Fibroblast ◽

Newborn Mouse ◽

Guide Rnas ◽

One Step ◽

Target Effect

AbstractSimultaneous expression of multiplex guide RNAs (gRNAs) is valuable for knockout of multiple genes and also for effective disruption of a gene by introducing multiple deletions. We developed a method of Tetraplex-guide Tandem for construction of cosmids containing four and eight multiplex gRNA-expressing units in one step utilizing lambda in vitro packaging. Using this method, we produced an adenovirus vector (AdV) containing four multiplex-gRNA units for two double-nicking sets. Unexpectedly, the AdV could stably be amplified to the scale sufficient for animal experiments with no detectable lack of the multiplex units. When the AdV containing gRNAs targeting the H2-Aa gene and an AdV expressing Cas9 nickase were mixed and doubly infected to mouse embryonic fibroblast cells, deletions were observed in more than 80% of the target gene even using double-nicking strategy. Indels were also detected in about 20% of the target gene at two sites in newborn mouse liver cells by intravenous injection. Interestingly, when one double-nicking site was disrupted, the other was simultaneously disrupted, implying that two genes in the same cell may simultaneously be disrupted in the AdV system. The AdVs expressing four multiplex gRNAs could offer simultaneous knockout of four genes or two genes by double-nicking cleavages with low off-target effect.

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CTCF Interacts with and Recruits the Largest Subunit of RNA Polymerase II to CTCF Target Sites Genome-Wide

Molecular and Cellular Biology ◽

10.1128/mcb.01993-06 ◽

2007 ◽

Vol 27 (5) ◽

pp. 1631-1648 ◽

Cited By ~ 104

Author(s):

Igor Chernukhin ◽

Shaharum Shamsuddin ◽

Sung Yun Kang ◽

Rosita Bergström ◽

Yoo-Wook Kwon ◽

...

Keyword(s):

Rna Polymerase ◽

Rna Polymerase Ii ◽

Gene Activation ◽

Ctcf Binding ◽

Pol Ii ◽

Genome Wide ◽

Target Sites ◽

On Chip

ABSTRACT CTCF is a transcription factor with highly versatile functions ranging from gene activation and repression to the regulation of insulator function and imprinting. Although many of these functions rely on CTCF-DNA interactions, it is an emerging realization that CTCF-dependent molecular processes involve CTCF interactions with other proteins. In this study, we report the association of a subpopulation of CTCF with the RNA polymerase II (Pol II) protein complex. We identified the largest subunit of Pol II (LS Pol II) as a protein significantly colocalizing with CTCF in the nucleus and specifically interacting with CTCF in vivo and in vitro. The role of CTCF as a link between DNA and LS Pol II has been reinforced by the observation that the association of LS Pol II with CTCF target sites in vivo depends on intact CTCF binding sequences. “Serial” chromatin immunoprecipitation (ChIP) analysis revealed that both CTCF and LS Pol II were present at the β-globin insulator in proliferating HD3 cells but not in differentiated globin synthesizing HD3 cells. Further, a single wild-type CTCF target site (N-Myc-CTCF), but not the mutant site deficient for CTCF binding, was sufficient to activate the transcription from the promoterless reporter gene in stably transfected cells. Finally, a ChIP-on-ChIP hybridization assay using microarrays of a library of CTCF target sites revealed that many intergenic CTCF target sequences interacted with both CTCF and LS Pol II. We discuss the possible implications of our observations with respect to plausible mechanisms of transcriptional regulation via a CTCF-mediated direct link of LS Pol II to the DNA.

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Trio deep-sequencing does not reveal unexpected off-target and on-target mutations in Cas9-edited rhesus monkeys

Nature Communications ◽

10.1038/s41467-019-13481-y ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 8

Author(s):

Xin Luo ◽

Yaoxi He ◽

Chao Zhang ◽

Xiechao He ◽

Lanzhen Yan ◽

...

Keyword(s):

Rhesus Monkeys ◽

De Novo ◽

Preclinical Model ◽

Structural Variants ◽

Sequencing Data ◽

De Novo Mutations ◽

Target Region ◽

Long Read ◽

Target Effect

AbstractCRISPR-Cas9 is a widely-used genome editing tool, but its off-target effect and on-target complex mutations remain a concern, especially in view of future clinical applications. Non-human primates (NHPs) share close genetic and physiological similarities with humans, making them an ideal preclinical model for developing Cas9-based therapies. However, to our knowledge no comprehensive in vivo off-target and on-target assessment has been conducted in NHPs. Here, we perform whole genome trio sequencing of Cas9-treated rhesus monkeys. We only find a small number of de novo mutations that can be explained by expected spontaneous mutations, and no unexpected off-target mutations (OTMs) were detected. Furthermore, the long-read sequencing data does not detect large structural variants in the target region.

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The pancreatic islet factor STF-1 binds cooperatively with Pbx to a regulatory element in the somatostatin promoter: importance of the FPWMK motif and of the homeodomain.

Molecular and Cellular Biology ◽

10.1128/mcb.15.12.7091 ◽

1995 ◽

Vol 15 (12) ◽

pp. 7091-7097 ◽

Cited By ~ 101

Author(s):

B Peers ◽

S Sharma ◽

T Johnson ◽

M Kamps ◽

M Montminy

Keyword(s):

Target Genes ◽

Gene Selection ◽

Regulatory Element ◽

Regulatory Elements ◽

Cooperative Binding ◽

Homeodomain Protein ◽

Homeodomain Proteins ◽

Target Sites

A number of homeodomain proteins have been shown to regulate cellular development by stimulating the transcription of specific target genes. In contrast to their distinct activities in vivo, however, most homeodomain proteins bind indiscriminately to potential target sites in vitro, suggesting the involvement of cofactors which specify target site selection. One such cofactor, termed extradenticle, has been shown to influence segmental morphogenesis in Drosophila melanogaster by binding cooperatively with certain homeodomain proteins to target regulatory elements. Here we demonstrate that STF-1, an orphan homeodomain protein required for pancreatic development in mammals, binds cooperatively to DNA with Pbx, the mammalian homolog of extradenticle. Cooperative binding with Pbx requires a pentapeptide motif (FPWMK) which is well conserved among a large subset of homeodomain proteins. The FPMWK motif is not sufficient to confer Pbx cooperativity on other homeodomain proteins, however; the N-terminal arm of the STF-1 homeodomain is also essential. As cooperative binding with Pbx occurs on only a subset of potential STF-1 target sites, our results suggest that Pbx may specify target gene selection in the developing pancreas by forming heterodimeric complexes with STF-1.

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Multiple Mechanisms Are Used for Growth Rate and Stringent Control of leuV Transcriptional Initiation inEscherichia coli

Journal of Bacteriology ◽

10.1128/jb.181.18.5771-5782.1999 ◽

1999 ◽

Vol 181 (18) ◽

pp. 5771-5782 ◽

Cited By ~ 17

Author(s):

Dmitry K. Pokholok ◽

Maria Redlak ◽

Charles L. Turnbough ◽

Sara Dylla ◽

Walter M. Holmes

Keyword(s):

Growth Rate ◽

Binding Site ◽

Transcription Initiation ◽

Core Promoter ◽

Cellular Level ◽

Structural Variants ◽

Stringent Control ◽

The Stability

ABSTRACT Expression of the Escherichia coli leuV operon, which contains three tRNA1 Leu genes, is regulated by several mechanisms including growth-rate-dependent control (GRDC) and stringent control (SC). Structural variants of the leuV promoter which differentially affect these regulatory responses have been identified, suggesting that promoter targets for GRDC and SC may be different and that GRDC of the leuV promoter occurs in the absence of guanosine 3′,5′-bisdiphosphate. To determine the mechanisms of the leuV promoter regulation, we have examined the stability of promoter open complexes and the effects of nucleotide triphosphate (NTP) concentration on the efficiency of theleuV promoter and its structural variants in vitro and in vivo. The leuV promoter open complexes were an order of magnitude more stable to heparin challenge than those ofrrnBp 1. The major initiating nucleotide GTP as well as other NTPs increased the stability of the leuVpromoter open complexes. When the cellular level of purine triphosphates was increased at slower growth rates by pyrimidine limitation, a 10% reduction in leuV promoter activity was seen. It therefore appears that transcription initiation from theleuV promoter is less sensitive to changes in intracellular NTP concentration than that from rrnBp 1. Comparative analysis of regulation of the leuV promoter with and without upstream activating sequences (UAS) demonstrated that the binding site for factor of inversion stimulation (FIS) located in UAS is essential for maximal GRDC. Moreover, the presence of UAS overcame the effects of leuV promoter mutations, which abolished GRDC of the leuV core promoter. However, although the presence of putative FIS binding site was essential for optimal GRDC, both mutant and wild-type leuV promoters containing UAS showed improved GRDC in a fis mutant background, suggesting that FIS protein is an important but not unique participant in the regulation of the leuV promoter.

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Natural Compounds from Djiboutian Medicinal Plants as Inhibitors of COVID-19 by in Silico Investigations

10.26434/chemrxiv.12325844 ◽

2020 ◽

Author(s):

abdirahman elmi ◽

S. al jawad sayem ◽

Mohamed Ahmed ◽

fatouma mohamed

Keyword(s):

Medicinal Plants ◽

Natural Compounds ◽

Binding Energies ◽

Receptor Binding Domain ◽

Global Pandemic ◽

Main Protease ◽

Target Sites ◽

Better Than

The new coronavirus type SARS-Cov 2 (severe acute respiratory syndrome), which appeared in autumn 2019 in China, became a global pandemic in a few months. In this work, we looked for the potential anti SARS-Cov 2 of the compounds isolated from three Djiboutian medicinal plants namely Acacia seyal, Cymbopogon commutatus, and Indigofera caerulea. For this we carried out a docking with nine biomolecules, β-Sitosterol , Quercetin, Catechin, Lupeol, Rutin, Kaempferol, Gallic acid, Piperitone and Limonene on three target sites which are SARS-CoV-2 main protease (Mp), SARS-CoV-2 receptor binding domain (RBD) and human furin protease. These targets are chosen because of their role in the process of penetration of the virus into human cells and its multiplication. The phenolic compounds have a very good afinity on these three target sites with binding energies of up to -9.098 kcal/mol for rutin on SARS-CoV-2 Mp, much better than the two reference drugs hydroxychloroquine (-5.816 kcal / mol) and remdesivir (-7.194 kcal/mol). These natural compounds do not present toxicities and can be used pending In vitro and In vivo evaluations.

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Nucleosomes impede Cas9 access to DNA in vivo and in vitro

eLife ◽

10.7554/elife.12677 ◽

2016 ◽

Vol 5 ◽

Cited By ~ 196

Author(s):

Max A Horlbeck ◽

Lea B Witkowsky ◽

Benjamin Guglielmi ◽

Joseph M Replogle ◽

Luke A Gilbert ◽

...

Keyword(s):

Large Scale ◽

Nucleosome Occupancy ◽

Critical Role ◽

Genetic Screens ◽

Guide Rnas ◽

Highly Active ◽

Bacterial Enzyme ◽

Eukaryotic Chromatin

The prokaryotic CRISPR (clustered regularly interspaced palindromic repeats)-associated protein, Cas9, has been widely adopted as a tool for editing, imaging, and regulating eukaryotic genomes. However, our understanding of how to select single-guide RNAs (sgRNAs) that mediate efficient Cas9 activity is incomplete, as we lack insight into how chromatin impacts Cas9 targeting. To address this gap, we analyzed large-scale genetic screens performed in human cell lines using either nuclease-active or nuclease-dead Cas9 (dCas9). We observed that highly active sgRNAs for Cas9 and dCas9 were found almost exclusively in regions of low nucleosome occupancy. In vitro experiments demonstrated that nucleosomes in fact directly impede Cas9 binding and cleavage, while chromatin remodeling can restore Cas9 access. Our results reveal a critical role of eukaryotic chromatin in dictating the targeting specificity of this transplanted bacterial enzyme, and provide rules for selecting Cas9 target sites distinct from and complementary to those based on sequence properties.

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