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CRISPR-Cas9-mediated efficient directed mutagenesis and RAD51-dependent and RAD51-independent gene targeting in the moss Physcomitrella patens.
The ability to address the CRISPR-Cas9 nuclease complex to any target DNA using customizable single-guide RNAs has now permitted genome engineering in many species. Here, we report its first successful use in a nonvascular plant, the moss Physcomitrella patens. Single-guide RNAs (sgRNAs) were designed to target an endogenous reporter gene, PpAPT, whose inactivation confers resistance to 2-fluoroadenine. Transformation of moss protoplasts with these sgRNAs and the Cas9 coding sequence from Streptococcus pyogenes triggered mutagenesis at the PpAPT target in about 2% of the regenerated plants. Mainly, deletions were observed, most of them resulting from alternative end-joining (alt-EJ)-driven repair. We further demonstrate that, in the presence of a donor DNA sharing sequence homology with the PpAPT gene, most transgene integration events occur by homology-driven repair (HDR) at the target locus but also that Cas9-induced double-strand breaks are repaired with almost equal frequencies by mutagenic illegitimate recombination. Finally, we establish that a significant fraction of HDR-mediated gene targeting events (30%) is still possible in the absence of PpRAD51 protein, indicating that CRISPR-induced HDR is only partially mediated by the classical homologous recombination pathway.
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The role of the CEBPB gene in porcine adipogenesis: a study using CRISPR/Cas9-edited mesenchymal stem cells.
Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 is a powerful tool for gene editing and the regulation of gene expression. It enables the introduction of targeted mutations, thereby facilitating functional studies of specific genes in various cellular processes. In this study, we aimed to generate a deletion in the promoter region of the CEBPB gene, which encodes a transcription factor involved in adipogenesis, and to evaluate the impact of this modification on the adipogenic differentiation potential of porcine mesenchymal stem cells (MSCs). A 575-bp deletion was introduced in the target region, resulting in the generation of both homozygous and heterozygous mutant cells. Adipogenic differentiation was assessed by quantifying transcript levels of adipocyte marker genes (GATA2, CEBPA, PPARG, and FABP4) at days 0, 4, 6, 8, and 10 of the differentiation process. Disruption of CEBPB expression led to the downregulation of these adipogenic markers, indicating impaired adipocyte differentiation. Additionally, to assess the proliferative capacity of the edited cells, the expression levels of proliferation-associated genes (CCND1, MCM2, and PCNA) were measured. A reduction in their transcript levels was observed in both homozygous and heterozygous mutant cells. These findings indicate that both homozygous and heterozygous deletions in the CEBPB promoter completely block adipogenesis and alter MSC proliferation, highlighting the pivotal role of CEBPB not only in adipogenic differentiation but also in the regulation of cell proliferation in porcine mesenchymal stem cells. These results provide new insights into the molecular mechanisms underlying adipose tissue development and have implications for pig breeding strategies aimed at optimizing carcass composition, as well as for biomedical research focused on adipose tissue biology.
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CRISPR-mediated knock-in of transgenes into the malaria vector Anopheles funestus.
The ability to introduce mutations, or transgenes, of choice to precise genomic locations has revolutionized our ability to understand how genes and organisms work. In many mosquito species that are vectors of various human diseases, the advent of CRISPR genome editing tools has shed light on basic aspects of their biology that are relevant to their efficiency as disease vectors. This allows a better understanding of how current control tools work and opens up the possibility of novel genetic control approaches, such as gene drives, that deliberately introduce genetic traits into populations. Yet for the Anopheles funestus mosquito, a significant vector of malaria in sub-Saharan Africa and indeed the dominant vector species in many countries, transgenesis has yet to be achieved. We describe herein an optimized transformation system based on the germline delivery of CRISPR components that allows efficient cleavage of a previously validated genomic site and preferential repair of these cut sites via homology-directed repair (HDR), which allows the introduction of exogenous template sequence, rather than end-joining repair. The rates of transformation achieved are sufficiently high that it should be able to introduce alleles of choice to a target locus, and recover these, without the need to include additional dominant marker genes. Moreover, the high rates of HDR observed suggest that gene drives, which employ an HDR-type mechanism to ensure their proliferation in the genome, may be well suited to work in A. funestus.
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Genome editing in plants using the compact editor CasΦ.
Clustered regularly interspaced short palindromic repeats and CRISPR-associated proteins (CRISPR-Cas) systems have been developed as important tools for plant genome engineering. Here, we demonstrate that the hypercompact CasΦ nuclease is able to generate stably inherited gene edits in Arabidopsis, and that CasΦ guide RNAs can be expressed with either the Pol-III U6 promoter or a Pol-II promoter together with ribozyme mediated RNA processing. Using the Arabidopsis fwa epiallele, we show that CasΦ displays higher editing efficiency when the target locus is not DNA methylated, suggesting that CasΦ is sensitive to chromatin environment. Importantly, two CasΦ protein variants, vCasΦ and nCasΦ, both showed much higher editing efficiency relative to the wild-type CasΦ enzyme. Consistently, vCasΦ and nCasΦ yielded offspring plants with inherited edits at much higher rates compared to WTCasΦ. Extensive genomic analysis of gene edited plants showed no off-target editing, suggesting that CasΦ is highly specific. The hypercompact size, T-rich minimal protospacer adjacent motif (PAM), and wide range of working temperatures make CasΦ an excellent supplement to existing plant genome editing systems.
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Curing Sickle Cell Disease by Allogeneic Hematopoietic Stem Cell (HSC) Transplantation Toward In Vivo HSC Gene Therapy.
Sickle cell disease comprises a group of prevalent inherited disorders defined by an underlying sickle cell allele that forms sickle hemoglobin. The incidence of this disease is rising, with more than 500,000 children born with it globally. The disease carries significant morbidity and mortality. Its only curative treatment was an allogeneic hematopoietic stem cell (HSC) transplant (HSCT) until late 2023, when two one-time gene therapies were approved for treating patients aged 12 years or older with severe sickle cell disease. This work aims to inform readers about these two gene therapies: one lentiviral-based and the other nonviral. The latter is based on the Nobel Prize-winning discovery of clustered, regularly interspaced, short, palindromic repeats (CRISPR)/CRISPR-associated (Cas)9 proteins and single-guide RNA (sgRNA)-based genome editing. Both approved gene therapies require an autologous HSCT with ex vivo genetically edited autologous hematopoietic stem and progenitor cells. Therefore, access to these gene therapies is limited to specialized centers with expertise in HSCTs. This review is meant for students, researchers, and clinical practitioners. It explains the basis for both approved gene therapies, their mechanisms of action, differences, risks, and other lentiviral-based and CRISPR-Cas9-based ex vivo gene therapies for sickle cell disease in clinical development. Additionally, it discusses the current state of preclinical studies for in vivo HSC gene therapy for sickle cell disease, which utilize advanced genome editing technologies developed after CRISPR-Cas9-sgRNA-based genome editing. In vivo HSC gene therapy, after it is clinically developed, would eliminate the need for an HSCT in receiving gene therapy and vastly increase access for numerous patients worldwide, even in low-income countries with the most significant disease burden.
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CRISPR-Cas based plasmid design for multidrug-resistant Klebsiella pneumoniae isolates.
Antimicrobial resistance is a major global health concern that requires innovative therapeutic strategies. This study aimed to address this challenge by designing Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-associated protein (CRISPR-Cas)-based plasmid systems for potential genome editing applications in multidrug-resistant (MDR) Klebsiella pneumoniae clinical isolates. Minimum inhibitory concentrations (MICs) of imipenem, meropenem, and ertapenem were determined according to European Committee on Antimicrobial Susceptibility Testing guidelines. All isolates (n = 5) were resistant, with MIC ranges of 4-128 μg/ml for imipenem, 8-64 μg/ml for meropenem, and 8-256 μg/ml for ertapenem. Resistance gene analysis revealed blaOXA-48-like and blaCTX-M-15 in all isolates, while blaNDM-1 was detected in one isolate. Two CRISPR-based plasmid systems, CRISPR-Cas9 and CRISPR-assisted cytidine deaminase, were designed. Target genes were amplified by polymerase chain reaction, and guide RNA (gRNA) sequences were designed from selected regions. Apramycin (50 μg/ml) was identified as a suitable selection marker. The pSGKP-AmpR(Pro)-ApmR plasmid was successfully constructed, whereas Cas9 and APOBEC constructs could not be cloned. Overall, this study highlights technical challenges in developing CRISPR-based tools for MDR K. pneumoniae and emphasizes the need for isolate-specific plasmid design and gRNA optimization.
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Genome editing in maize and sorghum: A comprehensive review of CRISPR/Cas9 and emerging technologies.
The increasing changes in the climate patterns across the globe have deeply affected food systems where unparalleled and unmatched challenges are created. This jeopardizes food security due to an ever-increasing population. The extreme efficiency of C4 crops as compared to C3 crops makes them incredibly significant in securing food safety. C4 crops, maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench) in particular, have the ability to withstand osmotic stress induced by oxidative stress. Osmotic stress causes a series of physical changes in a plant thus facilitating reduced water uptake and photosynthesis inhibition, such as membrane tension, cell wall stiffness, and turgor changes. There has been a great advancement in plant breeding brought by introduction of clustered regularly interspaced short palindromic repeats (CRISPR) gene editing technology. This technology offers precise alterations to an organism's DNA through targeting specific genes for desired traits in a wide number of crop species. Despite its immense opportunities in plant breeding, it faces limitations such as effective delivery systems, editing efficiency, regulatory concerns, and off-target effects. Future prospects lie in optimizing next-generation techniques, such as prime editing, and developing novel genotype-independent delivery methods. Overall, the transformative role of CRISPR/Cas9 in sorghum and maize breeding underscores the need for responsible and sustainable utilization to address global food security challenges.
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Highly efficient biallelic genome editing of human ES/iPS cells using a CRISPR/Cas9 or TALEN system.
Genome editing research of human ES/iPS cells has been accelerated by clustered regularly interspaced short palindromic repeats/CRISPR-associated 9 (CRISPR/Cas9) and transcription activator-like effector nucleases (TALEN) technologies. However, the efficiency of biallelic genetic engineering in transcriptionally inactive genes is still low, unlike that in transcriptionally active genes. To enhance the biallelic homologous recombination efficiency in human ES/iPS cells, we performed screenings of accessorial genes and compounds. We found that RAD51 overexpression and valproic acid treatment enhanced biallelic-targeting efficiency in human ES/iPS cells regardless of the transcriptional activity of the targeted locus. Importantly, RAD51 overexpression and valproic acid treatment synergistically increased the biallelic homologous recombination efficiency. Our findings would facilitate genome editing study using human ES/iPS cells.
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Modeling common and rare genetic risk factors of neuropsychiatric disorders in human induced pluripotent stem cells.
Recent genome-wide association studies (GWAS) and whole-exome sequencing of neuropsychiatric disorders, especially schizophrenia, have identified a plethora of common and rare disease risk variants/genes. Translating the mounting human genetic discoveries into novel disease biology and more tailored clinical treatments is tied to our ability to causally connect genetic risk variants to molecular and cellular phenotypes. When combined with the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated (Cas) nuclease-mediated genome editing system, human induced pluripotent stem cell (hiPSC)-derived neural cultures (both 2D and 3D organoids) provide a promising tractable cellular model for bridging the gap between genetic findings and disease biology. In this review, we first conceptualize the advances in understanding the disease polygenicity and convergence from the past decade of iPSC modeling of different types of genetic risk factors of neuropsychiatric disorders. We then discuss the major cell types and cellular phenotypes that are most relevant to neuropsychiatric disorders in iPSC modeling. Finally, we critically review the limitations of iPSC modeling of neuropsychiatric disorders and outline the need for implementing and developing novel methods to scale up the number of iPSC lines and disease risk variants in a systematic manner. Sufficiently scaled-up iPSC modeling and a better functional interpretation of genetic risk variants, in combination with cutting-edge CRISPR/Cas9 gene editing and single-cell multi-omics methods, will enable the field to identify the specific and convergent molecular and cellular phenotypes in precision for neuropsychiatric disorders.
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Precision prime editing of TP53 mutations for functional tumor suppression in colorectal cancer.
BACKGROUND: Colorectal cancer (CRC) is a major global health concern, with high mortality due to genetic heterogeneity and resistance to treatment. Tumor Protein p53 (TP53) mutations are also among the most important molecular changes that can disrupt genomic stability and facilitate tumor progression, so it is a critical target for precision-based interventions. AIM: This review aims to discuss the future potential of prime editing as a new generation of genome engineering to identify precise approaches to correct TP53 mutations in colorectal cancer. METHOD: A focused literature review was conducted on PubMed, Scopus, Web of Science, and Google Scholar for articles published between the years of 2010 and 2026. The keywords used in the search were CRC, TP53 mutation, prime editing, Prime Editing Guide RNA (pegRNA), CRISPR-Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-associated protein 9), and precision oncology. Studies were screened for experimental, mechanistic, and translational, and the focus was on mutation-specific editing, delivery platforms, organoid validation, clinically relevant barriers, etc. RESULTS/DISCUSSION: Prime editing is a programmable search-and-replace method that does not involve two single-stranded Deoxyribonucleic Acid (DNA) breaks, resulting in fewer Insertions/deletions (indels) and greater precision compared with traditional CRISPR-Cas9 approaches. Recent systems like Prime Editor Max (PEmax), PE5/PE5max, engineered pegRNAs, twin prime editors, PrimeDel, and PASTE have enhanced the efficiency, range, and flexibility. Hotspot and organoid studies suggest that variants of TP53, particularly R175H, R248Q/W, R273 H/C, and R282W, can be repaired. But cargo size, delivery specificity, tumor heterogeneity, varying cargo editing efficiency, cargo recognition by the immune system, and off-target risk are all barriers to clinical translation. CONCLUSION: Precision oncology with prime editing has the potential to be a useful tool for CRC, though optimized delivery, thorough preclinical testing, and safety monitoring will be required for therapeutic adoption. ORIGINALITY: This review combines TP53 hotspot biology, recent breakthroughs in prime editing technology, and CRC-specific translational challenges, and provides a step-by-step approach to its clinical application in a unique way.
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