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Generation of a new DiCre expressing parasite strain for functional characterization of Plasmodium falciparum genes in blood stages.
Conditional regulation is a highly beneficial system for studying the function of essential genes in Plasmodium falciparum and dimerizable Cre recombinase (DiCre) is a recently adapted conditional regulation system suitable for this purpose. In the DiCre system, two inactive fragments of Cre are reconstituted to form a functionally active enzyme in the presence of rapamycin. Different loci have been targeted to generate parasite lines that express the DiCre enzyme. Here, we have used marker-free CRISPR-Cas9 gene editing to integrate the DiCre cassette in a redundant cg6 locus. We have shown the utility of the newly generated ∆cg6DC4 parasites in mediating robust, rapid, and highly specific excision of exogenously encoded gfp sequence. The ∆cg6DC4 parasites are also capable of conditional excision of an endogenous parasite gene, PF3D7_1246000. Conditional deletion of PF3D7_1246000 did not cause any inhibition in the asexual proliferation of the parasites. Furthermore, the health and morphology of the mutant parasites were comparable to that of the control parasites in Giemsa smears. The availability of another stable DiCre parasite strain competent for conditional excision of target genes will expedite functional characterization and validation of novel drug and vaccine targets against malaria.
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Heterologous Single-Strand DNA-Annealing and Binding Protein Enhance CRISPR-Based Genome Editing Efficiency in Komagataella phaffii.
The industrial yeast Komagataella phaffii is a highly effective platform for heterologous protein production, owing to its high protein expression and secretion capacity. Heterologous genes and proteins are involved in multiple processes, including transcription, translation, protein folding, modification, transportation, and degradation; however, engineering these proteins and genes is challenging due to inefficient genome editing techniques. We employed Pseudomonas aeruginosa phage single-stranded DNA-annealing protein (SSAP) PapRecT and P. aeruginosa single-stranded DNA-binding protein (SSB) PaSSB to introduce SSAP-SSB-based homology recombination, which facilitated K. phaffii CRISPR-based genome engineering. Specifically, a host-independent method was developed by expressing sgRNA with PapRecT-PaSSB in a single plasmid, with which only a 50 bp short homologous arm (HA) reached a 100% positive rate for CRISPR-based gene insertion, reaching 18 colony-forming units (CFU) per μg of donor DNA. Single deletion using 1000 bp HA attained 100%, reaching 68 CFUs per μg of donor DNA. Using this efficient CRISPR-based genome editing tool, we integrated three genes (INO4, GAL4-like, and PAB1) at three different loci for overexpression to realize the collaborative regulation of human-lactalbumin (α-LA) production. Specifically, we strengthened phospholipid biosynthesis to facilitate endoplasmic reticulum membrane formation and enhanced recombinant protein transcription and translation by overexpressing transcription and translation factors. The final production of α-LA in the 3 L fermentation reached 113.4 mg L-1, two times higher than that of the strain without multiple site gene editing, which is the highest reported titer in K. phaffii. The CRISPR-based genome editing method developed in this study is suitable for the synergistic multiple-site engineering of protein and biochemical biosynthesis pathways to improve the biomanufacturing efficiency.
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Breeding by Design for Functional Rice with Genome Editing Technologies.
The conventional approaches to crop breeding, which rely predominantly on time-consuming and labor-intensive methods such as traditional hybridization and mutation breeding, face challenges in efficiently introducing targeted traits and generating diverse plant populations. Conversely, the emergence of genome editing technologies has ushered in a paradigm shift, enabling the precise and expedited manipulation of plant genomes to intentionally introduce desired characteristics. One of the most widespread editing tools is the CRISPR/Cas system, which has been used by researchers to study important biology-related problems. However, the precise and effective workflow of genome editing has not been well-defined in crop breeding. In this study, we demonstrated the entire process of breeding rice varieties enriched with high levels of resistant starch (RS), a functional trait that plays a crucial role in preventing diseases such as diabetes and obesity. The workflow encompassed several key steps, such as the selection of functional SBEIIb gene, designing the single-guide RNA (sgRNA), selecting an appropriate genome editing vector, determining the vector delivery method, conducting plant tissue culture, genotyping mutation and phenotypic analysis. Additionally, the time frame necessary for each stage of the process has been clearly demonstrated. This protocol not only streamlines the breeding process but also enhances the accuracy and efficiency of trait introduction, thereby accelerating the development of functional rice varieties.
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Technologies and Computational Analysis Strategies for CRISPR Applications.
The CRISPR-Cas system offers a programmable platform for eukaryotic genome and epigenome editing. The ability to perform targeted genetic and epigenetic perturbations enables researchers to perform a variety of tasks, ranging from investigating questions in basic biology to potentially developing novel therapeutics for the treatment of disease. While CRISPR systems have been engineered to target DNA and RNA with increased precision, efficiency, and flexibility, assays to identify off-target editing are becoming more comprehensive and sensitive. Furthermore, techniques to perform high-throughput genome and epigenome editing can be paired with a variety of readouts and are uncovering important cellular functions and mechanisms. These technological advances drive and are driven by accompanying computational approaches. Here, we briefly present available CRISPR technologies and review key computational advances and considerations for various CRISPR applications. In particular, we focus on the analysis of on- and off-target editing and CRISPR pooled screen data.
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Consolidating Ulva functional genomics: gene editing and new selection systems.
The green seaweed Ulva compressa is a promising model for functional biology. In addition to historical research on growth and development, -omics data and molecular tools for stable transformation are available. However, more efficient tools are needed to study gene function. Here, we expand the molecular toolkit for Ulva. We screened the survival of Ulva and its mutualistic bacteria on 14 selective agents and established that Blasticidin deaminases (BSD or bsr) can be used as selectable markers to generate stable transgenic lines. We show that Cas9 and Cas12a RNPs are suitable for targeted mutagenesis and can generate genomic deletions of up to 20 kb using the marker gene ADENINE PHOSPHORIBOSYLTRANSFERASE (APT). We demonstrate that the targeted insertion of a selectable marker via homology-directed repair or co-editing with APT is possible for nonmarker genes. We evaluated 31 vector configurations and found that the bicistronic fusion of Cas9 to a resistance marker or the incorporation of introns in Cas9 led to the most mutants. We used this to generate mutants in three nonmarker genes using a co-editing strategy. This expanded molecular toolkit now enables us to reliably make gain- and loss-of-function mutants; additional optimizations will be necessary to allow for vector-based multiplex genome editing in Ulva.
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Protocol for generating endogenous degron tags in essential transcription factors in human iPSCs via CRISPR-Cas9.
Precise genome engineering in human pluripotent stem cells remains inefficient, limiting endogenous fluorescent tagging needed to study phase-separated membraneless nuclear compartments. Here, we present a protocol for generating precise knockin alleles of essential genes in human induced pluripotent stem cells (iPSCs) via CRISPR-Cas9 editing. We describe steps for combining transient p53 inhibition, optimized transfection conditions, and fluorescence-activated cell sorting. This protocol enables recovery of viable edited clones that would otherwise be lost due to editing-induced stress or essential gene perturbation. For complete details on the use and execution of this protocol, please refer to Li et al.1.
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Clinical perspective: Advancing hemophilia treatment through gene therapy approaches.
Hemophilia, a congenital bleeding disorder, can cause arthropathy, impaired mobility, pain, and life-threatening hemorrhage events, significantly impacting quality of life for patients and caregivers. Current therapies, although effective, necessitate costly lifelong treatment, often in specialized settings. However, as a monogenic disorder caused by loss-of-function genetic variants, hemophilia is amenable to gene therapy. In this article, three primary gene therapy approaches at the forefront of clinical development are reviewed. Adeno-associated virus-based gene therapy, having secured approval in the EU, UK, and US after promising phase 3 trial results, demonstrates clear superiority over standard-of-care treatment. Lentivirus-based approaches capable of transducing dividing and nondividing cells may improve the durability of treatment and have low susceptibility to pre-existing neutralizing antibodies to viral vectors. Finally, gene editing techniques such as zinc finger nucleases and CRISPR aim to correct genetic defects directly, holding promise as novel, effective, and highly durable therapeutic strategies in adults and children with hemophilia. This review provides a comprehensive summary of the current status of these gene therapy approaches, highlighting advantages, limitations, and potential future developments.
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CRISPR/Cas9 and p53: An Odd Couple Requiring Relationship Management.
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Prime editing GEMMs to model cancer mutations.
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TO EDIT OR NOT: THE NGAGO STORY.
New genome-editing approaches always receive widespread attention. But in the case of a novel Argonaute-based technique published last spring, attention has been particularly intense.
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