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Generation of mouse models carrying B cell restricted single or multiplexed loss-of-function mutations through CRISPR-Cas9 gene editing.
Here, we present a protocol to generate B cell restricted mouse models of loss-of-function genetic drivers typical of lymphoproliferative disorders, using stem cell engineering of murine strains carrying B cell restricted Cas9 expression. We describe steps for preparing lentivirus expressing sgRNA-mCherry, isolating hematopoietic stem and progenitor cells, and in vitro transduction. We then detail the transplantation of engineered cells into recipient mice and verification of gene edits. These mouse models represent versatile platforms to model complex disease traits typical of lymphoproliferative disorders. For complete details on the use and execution of this protocol, please refer to ten Hacken et al.,1 ten Hacken et al.,2 and ten Hacken et al.3.
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SpRY Cas9 Can Utilize a Variety of Protospacer Adjacent Motif Site Sequences To Edit the Candida albicans Genome.
Candida albicans is a human fungal pathogen capable of causing life-threatening infections. The ability to edit the C. albicans genome using CRISPR/Cas9 is an important tool investigators can leverage in their search for novel therapeutic targets. However, wild-type Cas9 requires an NGG protospacer adjacent motif (PAM), leaving many AT-rich regions of DNA inaccessible. A recently described near-PAMless CRISPR system that utilizes the SpRY Cas9 variant can target non-NGG PAM sequences. Using this system as a model, we developed C. albicans CRISPR/SpRY. We tested our system by mutating C. albicansADE2 and show that CRISPR/SpRY can utilize non-NGG PAM sequences in C. albicans Our CRISPR/SpRY system will allow researchers to efficiently modify C. albicans DNA that lacks NGG PAM sequences.IMPORTANCE Genetic modification of the human fungal pathogen Candida albicans allows us to better understand how fungi differ from humans at the molecular level and play essential roles in the development of therapeutics. CRISPR/Cas9-mediated genome editing systems can be used to introduce site-specific mutations to C. albicans However, wild-type Cas9 is limited by the requirement of an NGG PAM site. CRISPR/SpRY targets a variety of different PAM sequences. We modified the C. albicans CRISPR/Cas9 system using the CRISPR/SpRY as a guide. We tested CRISPR/SpRY on C. albicansADE2 and show that our SpRY system can facilitate genome editing independent of an NGG PAM sequence, thus allowing the investigator to target AT-rich sequences. Our system will potentially enable mutation of the 125 C. albicans genes which have been previously untargetable with CRISPR/Cas9. Additionally, our system will allow for precise targeting of many genomic locations that lack NGG PAM sites.
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A helicase-fused Cas9 improves large-size fragment knockin.
Homologous recombination (HR)-mediated large-size fragment knockin (ls-KI) remains inefficient in mammalian cells, even with the assistance of CRISPR-Cas9. We hypothesized that adding DNA helicase activity to CRISPR-Cas9 could enhance ls-KI efficiency. To test this, we fused MCM5, a subunit of the eukaryotic MCM2-7 helicase complex, to the N terminus of spCas9. The resulting fusion protein, termed MCCas, markedly increased knockin rates across multiple loci in different human cell lines, significantly outperforming spCas9. Remarkably, MCCas enabled efficient ls-KI with donor templates of up to 10 kb in size. MCCas-mediated ls-KI, in comparison to those mediated by spCas9, is also associated with reduced frequencies of on-target and off-target insertion and deletion (indel) events. Mechanistic investigations revealed that MCCas-mediated ls-KI relies on the canonical HR pathway, as inhibition of key processes such as end resection and strand invasion abolished the enhancement. To further validate its application, we employed MCCas to knock in the human ACE2 (hACE2) coding sequence to the rabbit genome. Consistent with our findings in human cells, MCCas led to a more than 2-fold increase in ls-KI rates in rabbit embryos compared to spCas9. Collectively, our results establish MCCas as a promising gene-editing tool with enhanced ls-KI capacity.
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Protoplast-Based Functional Genomics and Genome Editing: Progress, Challenges and Applications.
Protoplast-based systems provide a powerful and versatile platform for exploring how plants sense and respond to their environment. By enabling the direct delivery of proteins, DNA, and RNA into plant cells after cell wall removal, this approach facilitates precise molecular dissection of signaling, stress adaptation, and gene regulation across both model species and economically important crops. In this review, we analyzed 1050 published articles and categorizing them by delivery methods, research focus, plant species, and tissue types. We further highlight recent advances, including the application of single-cell transcriptomics, which provides unprecedented resolution for dissecting cellular responses and offers deeper insights into the mechanisms underlying stress resilience. Importantly, protoplast regeneration is gaining renewed attention not only as a model system for studying cellular reprogramming but also as a practical platform for crop improvement. Applications of protoplast regeneration include protoplast fusion, which integrates nuclear and organellar DNA/genomes from divergent parents to accelerate breeding and enhance tolerance to both biotic and abiotic stresses. Another important application is CRISPR/Cas ribonucleoprotein (RNP)-based editing targeting stress-resilience-related genes. In asexually propagated or highly heterozygous perennial crops with limited sexual reproduction, protoplast-based RNP delivery offers a viable and regulation-compliant strategy. This approach may help address public concerns over transgenic technologies while enabling the rapid development of stress-tolerant cultivars.
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Epigenome editing based treatment: Progresses and challenges.
Epigenome editing is emerging as a transformative approach in clinical treatment, enabling precise modifications to gene expression without altering the underlying DNA sequence. The ongoing transition of epigenome editing techniques from foundational research to clinical applications highlights several key strategies. These include targeted DNA methylation/demethylation, histone modification, and transcriptional regulation. These approaches offer the potential for durable and reversible gene expression modulation, paving the way for precisely tailored therapies for genetic and complex diseases. Here, we review pioneering research, technological advancements, granted patents, and clinical trials that have been reported during the past decade. By synthesizing current research and development efforts, this review aims to provide insights into the promising landscape of epigenome editing and its potential to promote therapeutic interventions.
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Gene editing without ex vivo culture evades genotoxicity in human hematopoietic stem cells.
Gene editing the BCL11A erythroid enhancer is a validated approach to fetal hemoglobin (HbF) induction for β-hemoglobinopathy therapy, though heterogeneity in edit allele distribution and HbF response may impact its safety and efficacy. Here, we compare combined CRISPR-Cas9 editing of the BCL11A +58 and +55 enhancers with leading gene modification approaches under clinical investigation. Dual targeting of the BCL11A +58 and +55 enhancers with 3xNLS-SpCas9 and two single guide RNAs (sgRNAs) resulted in superior HbF induction, including in sickle cell disease (SCD) patient xenografts, attributable to simultaneous disruption of core half E-box/GATA motifs at both enhancers. Unintended on-target outcomes of double-strand break (DSB) repair in hematopoietic stem and progenitor cells (HSPCs), such as long deletions and centromere-distal chromosome fragment loss, are a byproduct of cellular proliferation stimulated by ex vivo culture. Editing quiescent HSPCs bypasses long deletion and micronuclei formation and preserves efficient on-target editing and engraftment function.
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Callus-specific CRISPR/Cas9 system to increase heritable gene mutations in maize.
A callus-specific CRISPR/Cas9 (CSC) system with Cas9 gene driven by the promoters of ZmCTA1 and ZmPLTP reduces somatic mutations and improves the production of heritable mutations in maize. The CRISPR/Cas9 system, due to its editing accuracy, provides an excellent tool for crop genetic breeding. Nevertheless, the traditional design utilizing CRISPR/Cas9 with ubiquitous expression leads to an abundance of somatic mutations, thereby complicating the detection of heritable mutations. We constructed a callus-specific CRISPR/Cas9 (CSC) system using callus-specific promoters of maize Chitinase A1 and Phospholipid transferase protein (pZmCTA1 and pZmPLTP) to drive Cas9 expression, and the target gene chosen for this study was the bZIP transcription factor Opaque2 (O2). The CRISPR/Cas9 system driven by the maize Ubiquitin promoter (pZmUbi) was employed as a comparative control. Editing efficiency analysis based on high-throughput tracking of mutations (Hi-TOM) showed that the CSC systems generated more target gene mutations than the ubiquitously expressed CRISPR/Cas9 (UC) system in calli. Transgenic plants were generated for the CSC and UC systems. We found that the CSC systems generated fewer target gene mutations than the UC system in the T0 seedlings but reduced the influence of somatic mutations. Nearly 100% of mutations in the T1 generation generated by the CSC systems were derived from the T0 plants. Only 6.3-16.7% of T1 mutations generated by the UC system were from the T0 generation. Our results demonstrated that the CSC system consistently produced more stable, heritable mutants in the subsequent generation, suggesting its potential application across various crops to facilitate the genetic breeding of desired mutations.
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Efficient Delivery of CRISPR-Cas9 RNP Complexes with Cyclodextrin-Based Nanosponges for Enhanced Genome Editing: TILD-CRISPR Integration.
The CRISPR-Cas9 system has transformed biomedical research by enabling precise genetic modifications. However, efficient delivery of CRISPR components remains a major hurdle for therapeutic applications. To address this, we employed a new modified cationic hyper-branched cyclodextrin-based polymer (Ppoly) system to deliver an integrating GFP gene using the TILD-CRISPR method, which couples donor DNA linearization with RNP complexes. The physicochemical properties, loading efficiency, and cellular uptake of RNP with Ppoly were studied. After transfection, antibiotic selection and single-cell cloning were performed. Junction PCR was then performed on the isolated clones, and we compared the knock-in efficiency of Ppoly with that of the commercial CRISPRMAX™ reagent (Thermo Fisher, Invitrogen™, Waltham, MA, USA). The results demonstrate the encapsulation efficiency of over 90% for RNP and Ppoly, and cell viability remaining above 80%, reflecting the minimal toxicity of this approach. These attributes facilitated successful GFP gene integration using the TILD-CRISPR with RNP delivered via cyclodextrin-based nanosponges. The present method achieved a remarkable 50% integration efficiency in CHO-K1 cells, significantly outperforming the 14% observed with CRISPRMAX™ while maintaining lower cytotoxicity. This study highlights a promising platform for precise and efficient genome editing, with strong potential for therapeutic and regenerative medicine applications.
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CRISPR/Cas-Based Modifications for Therapeutic Applications: A Review.
The CRISPR-Cas genome editing system is an intrinsic property of a bacteria-based immune system. This employs a guide RNA to detect and cleave the PAM-associated target DNA or RNA in subsequent infections, by the invasion of a similar bacteriophage. The discovery of Cas systems has paved the way to overcome the limitations of existing genome editing tools. In this review, we focus on Cas proteins that are available for gene modifications among which Cas9, Cas12a, and Cas13 have been widely used in the areas of medicine, research, and diagnostics. Since CRISPR has been already proven for its potential research applications, the next milestone for CRISPR will be proving its efficacy and safety. In this connection, we systematically review recent advances in exploring multiple variants of Cas proteins and their modifications for therapeutic applications.
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A novel recombinant CRISPR/Cas9 vector system for genome editing in plants.
Genome editing employing CRISPR/Cas9 systems has found widespread applications for knocking out targeted genes. In spite of exponential applications in plants for trait improvement, low editing efficiency in plants is a major concern. We report construction of a pCAMBIA2300 based binary vector cassette (pCR) harbouring novel recombinant CRISPR/Cas9 system for efficient genome editing in plants. The Cas9 cDNA with sequence encoding nuclear localization signals at the N-terminal and C-terminal ends had been codon optimized for better expression in plants. Undesirable internal restriction sites were removed. Small stretch of 5' UTR sequence of Rubisco small subunit (rcbS) of potato, harbouring in between potato granule bound starch synthase (GBSS) intron, was added at the 5' end of the Cas9 cDNA to function as 5' UTR. The recombinant Cas9 gene (rdCas9) was placed under the transcriptional control of CaMV 35S promoter and NOS terminator. The single guide RNA cassette (sgRNA) was comprised of Arabidopsis U6 promoter, 20-21 nucleotide (nt) spacer sequence, sgRNA scaffold sequence and potato U6 RNA Pol-III termination sequence. The 20-21 nt sgRNA spacer sequence could be added to the sgRNA construct by AarI or PaqCI digestion. The sgRNA construct had been designed in such a way so that single or multiplexed sgRNA could be cloned into the pCR vector cassette in a single step. Moreover, modular nature of this vector system can help to derive different combination of promoter, terminator with Cas9 and sgRNA constructs. The efficacy of the pCR vector system had been validated in Nicotiana tabacum and Solanum tuberosum by knocking out phytoene desaturase gene (PDS), through Agrobacterium-mediated transformation. The pCR binary vector system can be utilized as a versatile tool box for efficient genome editing of plant to improve agriculturally important traits.
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