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Efficient tobacco rattle virus-induced gene editing in tomato mediated by the CRISPR/Cas9 system.
Plant virus-based sgRNA delivery strategy has been widely applied for efficient genome editing across various plant species, leveraging its significant advantages in the rapid expression and expansion of sgRNA through virus replication and movement. However, the efficacy of the virus-induced gene editing (VIGE) tool in tomato has yet to be explored. In this paper, we established a TRV-mediated CRISPR/Cas9 genome editing system in the somatic cells of tomato, reporting the validation of VIGE and evaluating the mutagenesis efficiency in both tomato leaves and fruits using high-throughput sequencing. The results demonstrated an approximate 65% efficiency of VIGE in tomato leaves for the selected target genes, with VIGE efficiency reaching up to 50% in tomato fruits. This research not only introduces an efficient tool for reverse genetics but also reveals substantial potential of VIGE in surpassing traditional tissue culture techniques for creating heritable mutations in tomato.
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Generating Mutant Renal Cell Lines Using CRISPR Technologies.
Gene editing using the CRISPR/Cas9 system is an extremely efficient approach for generating mutations within the genomic DNA of immortalized cell lines. This procedure begins with a straightforward cloning step to generate a single plasmid encoding the Cas9 enzyme as well as a synthetic guide RNA (sgRNA) which is selected to target specific sites within the genome. This plasmid is transfected into cells either alone, in order to generate random insertion-deletion alleles ("indels") at the desired locus via the nonhomologous end-joining pathway, or in conjunction with a homology-directed repair template oligonucleotide to generate a specific point mutation. Here we describe a procedure to perform gene editing in IMCD3 and HEK293 cells and to subsequently isolate clonal cell lines carrying mutations of interest.
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Virus-Like Particles as a Nonviral CRISPR/Cas Editing Delivery Tool.
Virus-like particles (VLPs) are self-assembling viral protein complexes that mimic native virions while lacking replicative and infectious capacity. By retaining efficient cellular entry and cargo protection, they overcome key limitations of viral vectors, including insertional mutagenesis and strong immunogenicity. Their ease of production, flexible cargo capacity, and tunable tropism make them highly versatile tools. Here, we describe a protocol for generating VSV-G-pseudotyped VLPs that deliver CRISPR/Cas9 RNPs and their functional validation in surrogate cell lines.
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Decoupling the bridge helix of Cas12a results in a reduced trimming activity, increased mismatch sensitivity and impaired conformational transitions.
The widespread and versatile prokaryotic CRISPR-Cas systems (clustered regularly interspaced short palindromic repeats and associated Cas proteins) constitute powerful weapons against foreign nucleic acids. Recently, the single-effector nuclease Cas12a that belongs to the type V CRISPR-Cas system was added to the Cas enzymes repertoire employed for gene editing purposes. Cas12a is a bilobal enzyme composed of the REC and Nuc lobe connected by the wedge, REC1 domain and bridge helix (BH). We generated BH variants and integrated biochemical and single-molecule FRET (smFRET) studies to elucidate the role of the BH for the enzymatic activity and conformational flexibility of Francisella novicida Cas12a. We demonstrate that the BH impacts the trimming activity and mismatch sensitivity of Cas12a resulting in Cas12a variants with improved cleavage accuracy. smFRET measurements reveal the hitherto unknown open and closed state of apo Cas12a. BH variants preferentially adopt the open state. Transition to the closed state of the Cas12a-crRNA complex is inefficient in BH variants but the semi-closed state of the ternary complex can be adopted even if the BH is deleted in its entirety. Taken together, these insights reveal that the BH is a structural element that influences the catalytic activity and impacts conformational transitions of FnCas12a.
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Gene Editing and Human Pluripotent Stem Cells: Tools for Advancing Diabetes Disease Modeling and Beta-Cell Development.
PURPOSE OF REVIEW: This review will focus on the multiple approaches to gene editing and address the potential use of genetically modified human pluripotent stem cell-derived beta cells (SC-β) as a tool to study human beta-cell development and model their function in diabetes. We will explore how new variations of CRISPR/Cas9 gene editing may accelerate our understanding of beta-cell developmental biology, elucidate novel mechanisms that establish and regulate beta-cell function, and assist in pioneering new therapeutic modalities for treating diabetes. RECENT FINDINGS: Improvements in CRISPR/Cas9 target specificity and homology-directed recombination continue to advance its use in engineering stem cells to model and potentially treat disease. We will review how CRISPR/Cas9 gene editing is informing our understanding of beta-cell development and expanding the therapeutic possibilities for treating diabetes and other diseases. Here we focus on the emerging use of gene editing technology, specifically CRISPR/Cas9, as a means of manipulating human gene expression to gain novel insights into the roles of key factors in beta-cell development and function. Taken together, the combined use of SC-β cells and CRISPR/Cas9 gene editing will shed new light on human beta-cell development and function and accelerate our progress towards developing new therapies for patients with diabetes.
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CRISPR-Cas9-Guided Genetic Manipulation of Patient-Derived Brain Tumor Cells.
CRISPR-Cas9 technology has revolutionized scientific research and has provided scientists with the ability to change DNA bases specifically and precisely at predetermined sites. The CRISPR-Cas9 knockout (KO) and activation (a) platforms developed by Hart et al. and Sanson et al. allow for RNA-directed genome editing to both decrease or increase gene expression, respectively [1, 2]. In this chapter the two techniques, CRISPR KO and CRISPRa, will be discussed and explained in further detail for optimized application against patient derived brain tumor cells.
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Avoiding the off-target effects of CRISPR/cas9 system is still a challenging accomplishment for genetic transformation.
The recent disclosure of a human embryo subjected to a genetic transformation using the CRISPR/cas9 system give rise to several concerns on ethical questions about its uncontrolled use in humans. Although CRISPR/cas9 has demonstrated its efficiency, this system still lacks the capability to avoid the introduction of undesirable mutations through the target genome. In this Letter, we present several undesirable impacts that CRISPR/cas9 system have in the genetic transformation of the human genome. We briefly discuss, using the very recent literature from distinct high impact journals, the main concerns related to CRISPR/cas9 to deal with off-target effects and how the research community has treated it.
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Directed Evolution of CRISPR/Cas Systems for Precise Gene Editing.
CRISPR technology is a universal tool for genome engineering that has revolutionized biotechnology. Recently identified unique CRISPR/Cas systems, as well as re-engineered Cas proteins, have rapidly expanded the functions and applications of CRISPR/Cas systems. The structures of Cas proteins are complex, containing multiple functional domains. These protein domains are evolutionarily conserved polypeptide units that generally show independent structural or functional properties. In this review, we propose using protein domains as a new way to classify protein engineering strategies for these proteins and discuss common ways to engineer key domains to modify the functions of CRISPR/Cas systems.
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CRISPR/Cas9 Gene Editing of Human Histone H2A Variant H2AX and MacroH2A.
Histone H2A variants play important roles in maintaining the integrity of the genome. For example, the histone variant H2AX is phosphorylated on Ser139 (called γH2AX) at DNA double-strand breaks (DSB) and serves as a signal for the initiation of downstream DNA damage response (DDR) factor recruitment and DNA repair activities within damaged chromatin. For decades, genetic studies in human cells involving DNA damage signaling and repair factors have relied mostly on either knockdown by RNA interference (i.e., shRNA and siRNA) or the use of mouse embryonic fibroblasts derived from knockout (KO) mice. Recent advances in gene editing using ZNF nuclease, TALEN, and CRISPR/Cas9 have allowed the generation of human KO cell lines, allowing genetic models for studying the DDR, including histone H2A variants in human cells. Here, we describe a detailed protocol for generating and verifying KO of H2AX and macroH2A histone H2A variants using CRISPR/Cas9 gene editing in human cancer cell lines. This protocol allows the use and development of genetic systems in human cells to study histone variants and their functions, including within the DDR.
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In Silico Design of gRNA for CRISPR/Cas9-Mediated Gene Knockout.
CRISPR/Cas9 stands as a revolutionary and versatile gene editing technology. At its core, the Cas9 DNA endonuclease is guided with precision by a specifically designed single-guide RNA (gRNA). This guidance system facilitates the introduction of double-stranded breaks (DSBs) within the DNA. Subsequent imprecise repairs, mainly through the non-homologous end-joining (NHEJ) pathway, yield insertions or deletions, resulting in frameshift mutations. These mutations are instrumental in achieving the successful knockout of the target gene. In this chapter, we describe all necessary steps to create and design a gRNA for a gene knockout to a target gene before to transfer it to a target plant.
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