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Treatment of Dyslipidemia Using CRISPR/Cas9 Genome Editing.
PURPOSE OF REVIEW: Clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated 9 (Cas9) has recently emerged as a top genome editing technology and has afforded investigators the ability to more easily study a number of diseases. This review discusses CRISPR/Cas9's advantages and limitations and highlights a few recent reports on genome editing applications for alleviating dyslipidemia through disruption of proprotein convertase subtilisin/kexin type 9 (PCSK9). RECENT FINDINGS: Targeting of mouse Pcsk9 using CRISPR/Cas9 technology has yielded promising results for lowering total cholesterol levels, and several recent findings are highlighted in this review. Reported on-target mutagenesis efficiency is as high as 90% with a subsequent 40% reduction of blood cholesterol levels in mice, highlighting the potential for use as a therapeutic in human patients. The ability to characterize and treat diseases is becoming easier with the recent advances in genome editing technologies. In this review, we discuss how genome editing strategies can be of use for potential therapeutic applications.
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Establishment of knockout adult sea urchins by using a CRISPR-Cas9 system.
Sea urchins are used as a model organism for research on developmental biology and gene regulatory networks during early development. Gene knockdown by microinjection of morpholino antisense oligonucleotide (MASO) has been used to analyze gene function in early sea urchin embryos. However, as the effect of MASO is not long lasting, it is impossible to perturb genes expressed during late development by MASO. Recent advances in genome editing technologies have enabled gene modification in various organisms. We previously reported genome editing in the sea urchin Hemicentrotus pulcherrimus using zinc-finger nuclease (ZFN) and transcription activator-like effector nuclease (TALEN); however, the efficiencies of these technologies were not satisfactory. Here, we applied clustered regularly interspaced short palindromic repeat (CRISPR)-CRISPR-associated nuclease 9 (Cas9) technology to knock out the Pks1 gene in H. pulcherrimus. When sgRNAs targeting Pks1, which is required for the biosynthesis of larval pigment, were microinjected into fertilized eggs with SpCas9 mRNA, high-efficiency mutagenesis was achieved within 24 hr post fertilization and SpCas9/sgRNA-injected pluteus larvae had an albino phenotype. One of the sgRNAs yielded 100% mutagenesis efficiency, and no off-target effect was detected. In addition, the albino phenotype was maintained in juvenile sea urchins after metamorphosis, and the knockout sea urchins survived for at least one year and grew to albino adult sea urchins. These findings suggest that knockout adult sea urchins were successfully established and the CRISPR-Cas9 system is a feasible method for analyzing gene functions from late developmental to adult stage.
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New Developments in CRISPR/Cas-based Functional Genomics and their Implications for Research Using Zebrafish.
INTRODUCTION: Genome editing using CRISPR/Cas9 has advanced very rapidly in its scope, versatility and ease of use. Zebrafish (Danio rerio) has been one of the vertebrate model species where CRISPR/Cas9 has been applied very extensively for many different purposes and with great success. In particular, disease modeling in zebrafish is useful for testing specific gene variants for pathogenicity in a preclinical setting. Here we describe multiple advances in diverse species and systems that can improve genome editing in zebrafish. OBJECTIVE: To achieve temporal and spatial precision of genome editing, many new technologies can be applied in zebrafish such as artificial transcription factors, drug-inducible or optogenetically-driven expression of Cas9, or chemically-inducible activation of Cas9. Moreover, chemically- or optogenetically- inducible reconstitution of dead Cas9 (catalytically inactive, dCas9) can enable spatiotemporal control of gene regulation. In addition to controlling where and when genome editing occurs, using oligonucleotides allows for the introduction (knock-in) of precise modifications of the genome. CONCLUSION: We review recent trends to improve the precision and efficiency of oligo-based point mutation knock-ins and discuss how these improvements can apply to work in zebrafish. Similarly to how chemical mutagenesis enabled the first genetic screens in zebrafish, multiplexed sgRNA libraries and Cas9 can enable the next revolutionary transition in how genetic screens are performed in this species. We discuss the first examples and prospects of approaches using sgRNAs as specific and effective mutagens. Moreover, we have reviewed methods aimed at measuring the phenotypes of single cells after their mutagenic perturbation with vectors encoding individual sgRNAs. These methods can range from different cell-based reporters to single-cell RNA sequencing and can serve as great tools for high-throughput genetic screens.
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Efficient genome editing of bovine in vitro derived zygotes via Cas9 RNP-electroporation using extended-stored bovine ovaries.
Bovine embryos serve as a relevant model for human preimplantation development and are increasingly used in genome editing research. Although CRISPR-Cas9 electroporation in zygotes offers a promising approach, challenges with respect to editing efficiency and mosaicism remain a challenge. However, traditional in vitro fertilization (IVF) workflows enforce highly inconvenient electroporation times of zygotes usually around midnight. This study therefore aimed to investigate the feasibility of using bovine zygotes derived from extended-stored slaughterhouse derived ovaries (Phosphate buffered saline, 14-18 °C, 20-22 h) with particular attention to the strength of the voltage field during electroporation and the Cas9-RNP concentration with respect to embryonic development and genome editing efficiency. Oocytes obtained under these conditions demonstrated in vitro developmental competence similar to those derived from fresh ovaries, with comparable cleavage and blastocyst formation rates. Electroporation conducted 10 h post-insemination at voltages of 15V, 20V, and 25V revealed that 25V yielded the highest blastocyst editing rate (40.7 %) while maintaining acceptable developmental rates. Increasing voltage to 30V and 35V further enhanced blastocyst editing rate (66.7 % and 67.9 %, respectively), with a greater proportion of blastocyst showing a full edit. While higher voltages reduced developmental rates, the optimal voltage for electroporation was found to be 30V for bovine zygotes derived from extended stored ovaries. Using that setting, contrasting Cas9-RNP concentrations (6 μM vs. 3 μM) were tested. A concentration of 6 μM resulted in higher editing rates compared to 3 μM (81.5 % vs. 60.0 %), although the distribution of monoallelic, biallelic, and mosaic modifications did not differ significantly. Taken together, this study confirmed for the first time that zygotes from extend-stored bovine ovaries are suitable for genome editing via CRISPR Cas9-RNP electroporation. Mosaicism, however, remained prevalent, underscoring the need for strategies to improve the precision and consistency of embryo editing.
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Genetic transformation and CRISPR/Cas12a-mediated gene editing of European beech (Fagus sylvatica L.) employing a transient protoplast system.
Fagus sylvatica L. (European beech) is a dominant hardwood forest tree species across Central Europe, supporting diverse ecosystem services and forming the basis of a significant market for high-value timber. However, climate change increasingly threatens beech vitality and productivity, making molecular insights into its stress resilience and functional validation of underlying genes urgently needed. Here, we report a protocol for protoplast isolation from seedling leaves and demonstrate transient genetic transformation and CRISPR/Cas-mediated genome editing in F. sylvatica. PEG-mediated transformation was sequentially optimized, achieving efficiencies of 59 ± 6.19% within distinct seasonal windows. Protoplast yield and transformation efficiency showed pronounced temporal variation throughout the year, indicating a strong seasonal influence on reproducibility of the workflow despite controlled growth conditions. A basic molecular toolkit for functional genomics and future biotechnological applications was established by testing a set of promoters and reporters. For proof-of-concept genome editing, we achieved 4.75 to 32.69% editing efficiencies in the PHYTOENE DESATURASE gene (FsPDS) using temperature-tolerant LbCas12a (ttLbCas12a). Although further optimization of transformation reproducibility and regeneration systems remains necessary, the presented protoplast platform provides a valuable foundation for transient functional assays and genome editing studies in this non-model tree species.
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In recognition of the Spanish origin of CRISPR/Cas9. Implications for the treatment of familial heart disease.
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Shock greets claim of CRISPR-edited babies.
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Generation of Mutants of Nuclear-Encoded Plastid Proteins Using CRISPR/Cas9 in the Diatom Phaeodactylum tricornutum.
Genome modifications in microalgae are becoming a widespread and mandatory tool for research in both fundamental and applied biology. Among genome editing methods in these photosynthetic organisms, CRISPR/Cas9 offers a specific, powerful and efficient tool for genome engineering by inducing mutations in targeted regions of the genome. Here we described a protocol that allows the generation of knockout mutants by CRISPR/Cas9 in the diatom Phaeodactylum tricornutum using biolistic transformation.
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A Dual CRISPR-Cas/Cre-loxP Genome Engineering Strategy for Stable Uricase Expression in Food-Grade Probiotics.
The development of robust, food-grade microbial chassis with tailored metabolic functions is critical for advancing synthetic biology applications in health and nutrition. Here, we report a dual genome engineering strategy that integrates CRISPR-Cas9-mediated knock-in with Cre/loxP-driven genome reduction to streamline the genome of Lactococcus lactis NZ9000 and enable stable expression of a high-activity uricase variant. The resulting strain, NZ9000::UAT-ΔD6, demonstrated enhanced enzymatic performance in vitro, achieving 2.34 U/mL activity and complete degradation of ∼500 μM urate within 20 h. Beyond improved catalytic output, this dual-system approach established a genetically stable and biosafe probiotic chassis with moderate colonization capacity in the murine gut. The integration of CRISPR-Cas and Cre/loxP techniques in this work is intended to enhance the expression of heterologous genes in the chassis strain, while providing a versatile platform for the rational design of food-grade probiotics and offering a general strategy for constructing living biotherapeutic agents with targeted metabolic activities.
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Dissecting Tissue-Specific Super-Enhancers by Integrating Genome-Wide Analyses and CRISPR/Cas9 Genome Editing.
Recent advances in genome-wide sequencing technologies have provided researchers with unprecedented opportunities to discover the genomic structures of gene regulatory units in living organisms. In particular, the integration of ChIP-seq, RNA-seq, and DNase-seq techniques has facilitated the mapping of a new class of regulatory elements. These elements, called super-enhancers, can regulate cell-type-specific gene sets and even fine-tune gene expression regulation in response to external stimuli, and have become a hot topic in genome biology. However, there is scant genetic evidence demonstrating their unique biological relevance and the mechanisms underlying these biological functions. In this review, we describe a robust genome-wide strategy for mapping cell-type-specific enhancers or super-enhancers in the mammary genome. In this strategy, genome-wide screening of active enhancer clusters that are co-occupied by mammary-enriched transcription factors, co-factors, and active enhancer marks is used to identify bona fide mammary tissue-specific super-enhancers. The in vivo function of these super-enhancers and their associated regulatory elements may then be investigated in various ways using the advanced CRISPR/Cas9 genome-editing technology. Based on our experience targeting various mammary genomic sites using CRISPR/Cas9 in mice, we comprehensively discuss the molecular consequences of the different targeting methods, such as the number of gRNAs and the dependence on their simultaneous or sequential injections. We also mention the considerations that are essential for obtaining accurate results and shed light on recent progress that has been made in developing modified CRISPR/Cas9 genome-editing techniques. In the future, the coupling of advanced genome-wide sequencing and genome-editing technologies could provide new insights into the complex genetic regulatory networks involved in mammary-gland development.
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