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CRISPRMatch: An Automatic Calculation and Visualization Tool for High-throughput CRISPR Genome-editing Data Analysis.
Custom-designed nucleases, including CRISPR-Cas9 and CRISPR-Cpf1, are widely used to realize the precise genome editing. The high-coverage, low-cost and quantifiability make high-throughput sequencing (NGS) to be an effective method to assess the efficiency of custom-designed nucleases. However, contrast to standardized transcriptome protocol, the NGS data lacks a user-friendly pipeline connecting different tools that can automatically calculate mutation, evaluate editing efficiency and realize in a more comprehensive dataset that can be visualized. Here, we have developed an automatic stand-alone toolkit based on python script, namely CRISPRMatch, to process the high-throughput genome-editing data of CRISPR nuclease transformed protoplasts by integrating analysis steps like mapping reads and normalizing reads count, calculating mutation frequency (deletion and insertion), evaluating efficiency and accuracy of genome-editing, and visualizing the results (tables and figures). Both of CRISPR-Cas9 and CRISPR-Cpf1 nucleases are supported by CRISPRMatch toolkit and the integrated code has been released on GitHub (https://github.com/zhangtaolab/CRISPRMatch).
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Efficient Editing of the Nuclear APT Reporter Gene in Chlamydomonas reinhardtii via Expression of a CRISPR-Cas9 Module.
The clustered regularly interspaced short palindromic repeat/CRISPR-associated protein 9 (CRISPR/Cas9) technology is a versatile and useful tool to perform genome editing in different organisms ranging from bacteria and yeast to plants and mammalian cells. For a couple of years, it was believed that the system was inefficient and toxic in the alga Chlamydomonas reinhardtii. However, recently the system has been successfully implemented in this model organism, albeit relying mostly on the electroporation of ribonucleoproteins (RNPs) into cell wall deficient strains. This requires a constant source of RNPs and limits the application of the technology to strains that are not necessarily the most relevant from a biotechnological point of view. Here, we show that transient expression of the Streptococcus pyogenes Cas9 gene and sgRNAs, targeted to the single-copy nuclear apt9 gene, encoding an adenine phosphoribosyl transferase (APT), results in efficient disruption at the expected locus. Introduction of indels to the apt9 locus results in cell insensitivity to the otherwise toxic compound 2-fluoroadenine (2-FA). We have used agitation with glass beads and particle bombardment to introduce the plasmids carrying the coding sequences for Cas9 and the sgRNAs in a cell-walled strain of C. reinhardtii (CC-125). Using sgRNAs targeting exons 1 and 3 of apt9, we obtained disruption efficiencies of 3 and 30% on preselected 2-FA resistant colonies, respectively. Our results show that transient expression of Cas9 and a sgRNA can be used for editing of the nuclear genome inexpensively and at high efficiency. Targeting of the APT gene could potentially be used as a pre-selection marker for multiplexed editing or disruption of genes of interest.
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Perspectives of Sickle Cell Disease Stakeholders on Heritable Genome Editing.
Advances in CRISPR technology and the announcement of the first gene-edited babies have sparked a global dialogue about the future of heritable genome editing (HGE). There has been an international call for public input to inform a substantive debate about benefits and risks of HGE. This study investigates the views of the sickle cell disease (SCD) community. We utilized a mixed-methods approach to examine SCD stakeholders' views in the United States. We found SCD stakeholders hold a nuanced view of HGE. Assuming the technology is shown to be safe and effective, they are just as supportive of HGE as genetics professionals, but more supportive than the general public. However, they are also concerned about the potential implications of HGE, despite this support. As discourse surrounding HGE advances, it is crucial to engage disease communities and other key stakeholders whose lives could be altered by these interventions.
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Identification of Mycobacterium tuberculosis intracellular survival-related virulence factors via CRISPR-based eukaryotic-like secretory protein mutant library screen.
UNLABELLED: Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb), remains a serious infectious disease posing significant global health challenges. A critical evolutionary feature of M.tb is its genome encoding a set of eukaryotic-like secretory proteins, which facilitate intracellular survival by manipulating host immune responses. However, the specific eukaryotic-like secretory proteins that facilitate M.tb intracellular survival and their regulatory mechanisms on host immunity remain uncharacterized. In this study, a mutant library comprising 137 potential eukaryotic-like secretory proteins was constructed using clustered regularly interspaced short palindromic repeats (CRISPR)-non-homologous end joining genome editing technology. Subsequently, macrophages were infected with the mutant library, and CRISPR sequencing enabled preliminary identification of virulence factors associated with bacterial intracellular persistence. To validate the screen, two genes (Rv0066c and Rv3139) exhibiting the most pronounced reduction in intracellular survival rates when mutated were selected for the construction of large-fragment knockout strains (ΔRv0066c and ΔRv3139). Subsequent macrophage infection assays reconfirmed the impaired intracellular survival of these two mutants. RNA-seq analysis was conducted to characterize host gene expression profiles during ΔRv0066c-infected macrophage interactions. RNA-seq analysis of macrophages infected with wild-type and ΔRv0066c strains identified 138 differentially expressed genes, with 75 upregulated and 63 downregulated in ΔRv0066c. Gene ontology clustering of these differentially expressed genes highlighted molecular functions related to chemokine binding, chemokine-mediated signaling pathways, Ras protein signal transduction, and calcineurin-mediated signaling. Collectively, this work established a potential eukaryotic-like secretory protein mutant library and identified two novel M.tb effectors governing intracellular survival, providing potential new targets for anti-TB drug development. IMPORTANCE: Eukaryotic-like secretory proteins that subvert host immunity to enable intracellular persistence are a key evolutionary adaptation of Mycobacterium tuberculosis (M.tb). In this study, we established a mutant library targeting 137 potential eukaryotic-like secretory proteins through clustered regularly interspaced short palindromic repeats (CRISPR)-non-homologous end joining genome editing technology. The library was subjected to macrophage infection assays, and CRISPR sequencing enabled identification of M.tb persistence-associated virulence determinants. Validation screens highlighted two genes (Rv0066c and Rv3139) that displayed the most significant intracellular survival defects to generate large-fragment knockout strains (ΔRv0066c and ΔRv3139). Macrophage infection experiments reconfirmed the compromised intracellular viability of both mutants. RNA-seq profiling of ΔRv0066c-infected macrophages identified 138 differentially expressed genes, with functional enrichment in chemokine signaling, Ras protein signal transduction, and calcineurin-mediated signaling. To conclude, this study identified two novel M.tb effectors contributing to intracellular survival as potential new targets for anti-TB drug development.
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Development of a fast and easy method for Escherichia coli genome editing with CRISPR/Cas9.
BACKGROUND: Microbial genome editing is a powerful tool to modify chromosome in way of deletion, insertion or replacement, which is one of the most important techniques in metabolic engineering research. The emergence of CRISPR/Cas9 technique inspires various genomic editing methods. RESULTS: In this research, the goal of development of a fast and easy method for Escherichia coli genome editing with high efficiency is pursued. For this purpose, we designed modular plasmid assembly strategy, compared effects of different length of homologous arms for recombination, and tested different sets of recombinases. The final technique we developed only requires one plasmid construction and one transformation of practice to edit a genomic locus with 3 days and minimal lab work. In addition, the single temperature sensitive plasmid is easy to eliminate for another round of editing. Especially, process of the modularized editing plasmid construction only takes 4 h. CONCLUSION: In this study, we developed a fast and easy genome editing procedure based on CRISPR/Cas9 system that only required the work of one plasmid construction and one transformation, which allowed modification of a chromosome locus within 3 days and could be performed continuously for multiple loci.
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CRISPR-Cpf1 assisted genome editing of Corynebacterium glutamicum.
Corynebacterium glutamicum is an important industrial metabolite producer that is difficult to genetically engineer. Although the Streptococcus pyogenes (Sp) CRISPR-Cas9 system has been adapted for genome editing of multiple bacteria, it cannot be introduced into C. glutamicum. Here we report a Francisella novicida (Fn) CRISPR-Cpf1-based genome-editing method for C. glutamicum. CRISPR-Cpf1, combined with single-stranded DNA (ssDNA) recombineering, precisely introduces small changes into the bacterial genome at efficiencies of 86-100%. Large gene deletions and insertions are also obtained using an all-in-one plasmid consisting of FnCpf1, CRISPR RNA, and homologous arms. The two CRISPR-Cpf1-assisted systems enable N iterative rounds of genome editing in 3N+4 or 3N+2 days. A proof-of-concept, codon saturation mutagenesis at G149 of γ-glutamyl kinase relieves L-proline inhibition using Cpf1-assisted ssDNA recombineering. Thus, CRISPR-Cpf1-based genome editing provides a highly efficient tool for genetic engineering of Corynebacterium and other bacteria that cannot utilize the Sp CRISPR-Cas9 system.
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CRISPR/Cas12a-mediated CHO genome engineering can be effectively integrated at multiple stages of the cell line generation process for bioproduction.
Most biopharmaceuticals produced today are generated using Chinese hamster ovary (CHO) cells, therefore significant attention is focused on methods to improve CHO cell productivity and product quality. The discovery of gene-editing tools, such as CRISPR/Cas9, offers new opportunities to improve CHO cell bioproduction through cell line engineering. Recently an additional CRISPR-associated protein, Cas12a (Cpf1), was shown to be effective for gene editing in eukaryotic cells, including CHO. In this study, we demonstrate the successful application of CRISPR/Cas12a for the generation of clonally derived CHO knockout (KO) cell lines with improved product quality attributes. While we found Cas12a efficiency to be highly dependent on the targeting RNA used, we were able to generate CHO KO cell lines using small screens of only 96-320 clonally derived cell lines. Additionally, we present a novel bulk culture analysis approach that can be used to quickly assess CRISPR RNA efficiency and determine ideal screen sizes for generating genetic KO cell lines. Most critically, we find that Cas12a can be directly integrated into the cell line generation process through cotransfection with no negative impact on titer or screen size. Overall, our results show CRISPR/Cas12a to be an efficient and effective CHO genome editing tool.
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CRISPR/Cas9 gene editing of a SOX9 reporter human iPSC line to produce two TRPV4 patient heterozygous missense mutant iPSC lines, MCRIi001-A-3 (TRPV4 p.F273L) and MCRIi001-A-4 (TRPV4 p.P799L).
To produce in vitro models of human chondrodysplasias caused by dominant missense mutations in TRPV4, we used CRISPR/Cas9 gene editing to introduce two heterozygous patient mutations (p.F273L and p.P799L) into an established control human iPSC line. This control line expressed a fluorescent reporter (tdTomato) at the SOX9 locus to allow real-time monitoring of cartilage differentiation by SOX9 expression. Both TRPV4 mutant iPSC lines had normal karyotypes, expressed pluripotency markers, and could differentiate into cells representative of the three embryonic germ layers. These iPSC lines, with the parental isogenic control, will be used to study TRPV4 chondrodysplasia mechanisms and explore therapeutic approaches.
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Advances in Genetic Editing of the Human Embryo.
BACKGROUND: Genetic engineering has allowed a major development of research in this field, with specialists attempting to edit the human genome, after the successful editing of the genomes of plants and animals. However, human gene editing technologies are at the center of ethical debates around the world. AREAS OF UNCERTAINTY: Ethical concerns about genetic editing of the human embryo raise several issues that can be viewed through the prism of optimism and reluctance leading to a number of recommendations regarding the acceptance of what may soon become a reality. DATA SOURCES: A literature search was conducted through PubMed, MEDLINE, Plus, Scopus, and Web of Science (2015-2022) using combinations of keywords, including: human genome or gene editing plus ethics. ETHICS AND THERAPEUTIC ADVANCES: Gene therapy is seen by researchers as a way to solve congenital diseases, multifactorial diseases in general or specific diseases such as cystic fibrosis, muscular dystrophy, or can increase resistance to HIV infection. Genome editing technologies, germline gene editing, clustered regularly interspaced short palindromic repeats gene editing technology, technologies such as zinc finger nucleases are not only advanced gene therapies that require solving technical problems, but also techniques that require complex and complete analysis of ethical problems. Genetic engineering raises many ethical concerns such as: safety concerns especially the risk of off-target effects; autonomy of the individual-with the limitation of the future generations to consent for an intervention over their genome; social justice-keeping in mind the costs of the procedures and their availability to the general population. Discussions can go further from questions such as "How can we do this?" to questions such as "Should we do this?" or "Is society ready to accept this technology and is it able to manage it rationally?" CONCLUSIONS: The ethics of biomedical research should be based on global dialogue, on the involvement of experts and the public, to achieve a broad social consensus. The fundamental review of the ethics of genetics is a desire and an opportunity of the current period.
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A CRISPR-Cas9, Cre-lox, and Flp-FRT Cascade Strategy for the Precise and Efficient Integration of Exogenous DNA into Cellular Genomes.
We describe a protocol for the precise integration of exogenous DNA into user-defined genomic loci in cultured cells. This strategy first introduces a promoter and a lox site to a specific location via a Cas9-induced double-strand break. Second, a gene of interest (GOI) is inserted into the lox site via Cre-lox recombination. Upon correct insertion, a cis-linked antibiotic resistance gene will be expressed from a promoter introduced into the genome in the first step assuring selection for correct integrants. Last, the selection cassette is excised via a Flp-FRT recombination event, leaving a precisely targeted GOI. This method is broadly applicable to any exogenous DNA to be integrated, choice of integration site, and choice of cell type. The most remarkable aspect of this versatile approach, termed "CasPi" (cascaded precise integration), is that it allows for precise genome targeting with large, frequently complex, and repetitive DNA sequences that do not integrate efficiently or at all with current genome targeting methods.
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