Cited by 493CRISPR and Genetic EngineeringRNA regulation and diseaseCAR-T cell therapy research

A highly specific SpCas9 variant is identified by in vivo screening in yeast

Open access
Casini, Antonio, Olivieri, Michele, Petris, Gianluca, Montagna, Claudia, Reginato, Giordano, Maule, Giulia, Lorenzin, Francesca, Prandi, Davide +4 more·2018·Nature Biotechnology

Abstract

Despite the utility of CRISPR-Cas9 nucleases for genome editing, the potential for off-target activity limits their application, especially for therapeutic purposes. We developed a yeast-based assay to identify optimized Streptococcus pyogenes Cas9 (SpCas9) variants that enables simultaneous evaluation of on- and off-target activity. We screened a library of SpCas9 variants carrying random mutations in the REC3 domain and identified mutations that increased editing accuracy while maintaining editing efficiency. We combined four beneficial mutations to generate evoCas9, a variant that has fidelity exceeding both wild-type (79-fold improvement) and rationally designed Cas9 variants (fourfold average improvement), while maintaining near wild-type on-target editing efficiency (90% median residual activity). Evaluating evoCas9 on endogenous genomic loci, we demonstrated a substantially improved specificity and observed no off-target sites for four of the eight single guide RNAs (sgRNAs) tested. Finally, we showed that following long-term expression (40 d), evoCas9 strongly limited the nonspecific cleavage of a difficult-to-discriminate off-target site and fully abrogated the cleavage of two additional off-target sites.

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Crossref · 10.1038/nbt.4066

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  • The absolute on-target activity of evoCas9, SpCas9-HF1 and eSpCas9 are not dramatically reduced as compared to SpCas9.

    “Meanwhile, the absolute on-target activity of these Cas9 mutants are not dramatically reduced as compared to SpCas9 (Casini et al., 2018).”

    From Off-target effects in CRISPR/Cas9 gene editing (2023) · cites this paper as Casini et al., 2018

    The comparative on-target activity passage (labelled Abstract; no page given) reports near-wild-type targeting efficiency for evoCas9 and eSpCas9(1.1) at most tested loci. It reports lower cleavage efficiency for SpCas9-HF1—60% median residual activity versus 90% for evoCas9—so the claim that none of the three mutants has substantially reduced activity is not fully supported. (LLM, conf=0.89)

    Experimental — accuracy not yet measured
  • CRISPR-nucleases have been successfully used to induce NHEJ to knockout genes or genomic regulatory elements, including permanent repair of splicing defects in CFTR minigene models.

    “CRISPR-nucleases have been successfully used to induce NHEJ to knockout genes or genomic regulatory elements25,26. This includes permanent repair of splicing defects in CFTR minigene models27 as an alternative to the transient and inefficient use of oligonucleotides or spliceosome-mediated RNA trans-splicing (SMaRT) strategies28,29.”

    From Allele specific repair of splicing mutations in cystic fibrosis through AsCas12a genome editing (2019) · cites this paper as [26]

    The paper reports a Cas9-based EGFP disruption assay and measures editing-induced indels, supporting the general point that CRISPR nucleases can disrupt a gene. Our copy does not establish that these knockouts occurred through NHEJ or demonstrate knockout of regulatory elements. The CFTR minigene repair claim is attached to citation 27, not to this source. (LLM, conf=0.83)

    Experimental — accuracy not yet measured
  • evoCas9 exhibits fidelity exceeding SpCas9-HF1 and eSpCas9.

    “This screen identified four key beneficial point mutations in SpCas9, giving rise to evoCas9, a variant that exhibits fidelity exceeding SpCas9-HF1 and eSpCas9 (Kleinstiver et al., 2015; Casini et al., 2018).”

    From Off-target effects in CRISPR/Cas9 gene editing (2023) · cites this paper as Casini et al., 2018

  • evoCas9, SpCas9-HF1 and eSpCas9 reduced the number of off-target sites by 98.7%, 95.4% and 94.1%, respectively, relative to wildtype SpCas9.

    “They found that the number of off-target sites reduced by 98.7%, 95.4% and 94.1%, respectively.”

    From Off-target effects in CRISPR/Cas9 gene editing (2023) · cites this paper as Casini et al., 2018

  • A series of optimized mutations in SpCas9 have greatly improved the editing specificity of Cas9 variants without substantially attenuating the editing activity.

    “In addition, a series of optimized mutations in SpCas9 have greatly improved the editing specificity of Cas9 variants without substantially attenuating the editing activity.”

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Cites

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1 of the 44 references couldn’t be matched to a known paper.

Research works printed but not linked: 1

  1. [38]Brinkman EK Chen T Amendola M van Steensel B Easy quantitative assessment of genome editing by sequence trace decomposition Nucleic Acids Research 2014 42 e168 25300484 PMC4267669

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Authors
Casini, A., Olivieri, M., Petris, G., Montagna, C., Reginato, G., Maule, G., Lorenzin, F., Prandi, D., Romanel, A., Demichelis, F., Inga, A., & Cereseto, A.
Affiliations
University of Trento (IT)
Corresponding author
  • Casini, Antonio
  • Cereseto, Anna
Venue
Nature Biotechnology
Published
2018-01-29
Volume
36
Issue
3
Pages
265-271
ISSN
  • 0733-222X (ISSN-L)
  • 1087-0156
  • 1546-1696
OpenAlex
W2787206763
Cited by
493
References
44
Citations by year
2026: 33 · 2025: 48 · 2024: 65 · 2023: 43 · 2022: 82 · 2021: 62 · 2020: 70 · 2019: 63 · 2018: 26 · 2017: 1
FWCI
19.66
Type
journal article
Language
en
Open access
Locations
  • Nature Biotechnology (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
  • Institutional Research Information System (Università degli Studi di Trento) (submittedVersion, other-oa)
  • Institutional Research Information System (University of Udine) (submittedVersion)
Funders
Università degli Studi di Trento
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › CRISPR and Genetic Engineering
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › RNA regulation and disease
  • Health Sciences › Medicine › Oncology › CAR-T cell therapy research
Keywords
SpCas9, off-target effects, editing specificity, yeast-based screening, single guide RNA, genome editing, CRISPR/Cas9
MeSH terms
Gene Editing, CRISPR-Associated Protein 9, RNA, Guide, CRISPR-Cas Systems, Mutation, Streptococcus pyogenes, Substrate Specificity, RNA, Guide, Kinetoplastida, CRISPR-Cas Systems

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