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[Assessing abundance and specificity of different types of sgRNA targeting miRNA precursors].
CRISPR/Cas technology enables efficient and specific editing the genome. Since different bacterial sources or artificially modified Cas9, as well as Cpf1 and other nucleases, recognize different PAMs (protospacer adjacent motifs), different gene editing nucleases may use different types of sgRNAs (small guide RNA). MicroRNAs (miRNAs) are a class of regulatory small non-coding RNAs. To determine whether specific targets for sgRNAs in miRNA precursor exit, the abundance and specificity of 11 different types of sgRNA targeting 28 645 miRNA precursors were analyzed in the present study using the CRISPR-offinder, a bioinformatics software developed in our own laboratory. The CRISPR/Cas9 lentivirus technology was used to target the miR-302/367 cluster in a porcine cell line, and its knockout efficiency for the miRNA target was evaluated. The results show that there are about 8 different types of sgRNAs that can target individual miRNA precursors. By assessing the off-target effect, only 18.2% of the sgRNAs showed high specificity for targeting the porcine miRNA precursors. Lastly, using the miR-302/367 cluster target as an example, we showed that the CRISPR/Cas9 lentivirus technology was 40% efficient in successfully establishing correct knockout of the target miRNA in the porcine cell line. This present study provides an important resource for the use of CRISPR/Cas technology to target miRNAs for knockout studies.
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Engineering broad-spectrum resistance to cotton leaf curl disease by CRISPR-Cas9 based multiplex editing in plants.
Advances in genome editing technologies have tremendous potential to address the limitations of classical resistance breeding. CRISPR-Cas9 based gene editing has been applied successfully in plants to tolerate virus infections. In this study, we successfully tested CRISPR-Cas9 system to counteract cotton leaf curl disease (CLCuD) caused by whitefly transmitted cotton leaf curl viruses (CLCuVs). We also analyzed the ability of CLCuV to escape the Cas9 endonuclease activity. Targeting overlapping genes of most prevalent CLCuVs with three gRNAs resulted in virus interference, as validated by low virus titer. Furthermore, multiplex CRISPR-Cas9 construct simultaneously targeting six genes of CLCuV, was found more effective to interfere with virus proliferation compared to targeting single region individually. Additionally, transgenic N. benthamiana plants expressing multiple gRNAs simultaneously showed enhanced tolerance against CLCuV infection when compared to wild-type plants. T7 Endonuclease-I (T7EI) assay, showing indels in the CLCuV genome, confirmed the occurrence of double strand breaks (DSBs) in DNA at target sequence induced by Cas9 endonuclease. We observed that targeting CLCuV genome at multiple sites simultaneously resulted in better interference, also with inefficient recovery of altered virus molecules. Next, we tested multiplex construct in cotton to interfere CLCuV infection. We found significant decrease in virus accumulation in cotton leaves co-infiltrated with multiplex cassette and virus compared to cotton leaves infiltrated with virus only. The results demonstrate future use of CRISPR-Cas9 system for engineering virus resistance in crops. Moreover, our results also advocate that resistance to mixed virus infections can be engineered using multiplex genome editing.
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Wuschel2 enables highly efficient CRISPR/Cas-targeted genome editing during rapid de novo shoot regeneration in sorghum.
For many important crops including sorghum, use of CRISPR/Cas technology is limited not only by the delivery of the gene-modification components into a plant cell, but also by the ability to regenerate a fertile plant from the engineered cell through tissue culture. Here, we report that Wuschel2 (Wus2)-enabled transformation increases not only the transformation efficiency, but also the CRISPR/Cas-targeted genome editing frequency in sorghum (Sorghum bicolor L.). Using Agrobacterium-mediated transformation, we have demonstrated Wus2-induced direct somatic embryo formation and regeneration, bypassing genotype-dependent callus formation and significantly shortening the tissue culture cycle time. This method also increased the regeneration capacity that resulted in higher transformation efficiency across different sorghum varieties. Subsequently, advanced excision systems and "altruistic" transformation technology have been developed to generate high-quality morphogenic gene-free and/or selectable marker-free sorghum events. Finally, we demonstrate up to 6.8-fold increase in CRISPR/Cas9-mediated gene dropout frequency using Wus2-enabled transformation, compared to without Wus2, across various targeted loci in different sorghum genotypes.
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Targeted gene editing and near-universal cDNA insertion of CYBA and CYBB as a treatment for chronic granulomatous disease.
Chronic granulomatous disease (CGD) is a severe inborn error of immunity caused by NADPH oxidase defects. Here, we develop CRISPR/Cas9-based gene editing strategies for correction of variants in the CYBA and CYBB genes causing CGD. For X-linked CGD, we also develop a near-universal gene editing strategy by targeted integration of a truncated CYBB cDNA in CD34+ hematopoietic stem and progenitor cells (HSPCs). Throughout, off-target editing and chromosomal translocations are evident, which negatively impact the ability of gene-edited HSPCs to engraft in immunodeficient mice. However, by employing a high-fidelity Cas9 to minimize off-target editing, we demonstrate restoration of the multilineage engraftment potential of gene-edited HSPCs. Moreover, to further improve safety, we develop a D10A Cas9n editing approach with no detectable off-target activity or chromosomal translocations. Collectively, through risk assessments of different gene editing approaches, we present a D10A Cas9n-based strategy with improved safety, offering a potentially curative treatment for CGD patients.
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Key considerations in designing CRISPR/Cas9-carrying nanoparticles for therapeutic genome editing.
CRISPR-Cas9, the breakthrough genome-editing technology, has emerged as a promising tool to prevent and cure various diseases. The efficient genome editing technology strongly relies on the specific and effective delivery of CRISPR/Cas9 cargos. However, the lack of a safe, specific, and efficient non-viral delivery system for in vivo genome editing remains a major limit for its clinical translation. In this review, we will first briefly introduce the working mechanism of CRISPR/Cas9 and the patterns of CRISPR/Cas9 delivery. Furthermore, the physiological obstacles for the delivery process in vivo are elaborated. Finally, the key considerations will be deeply discussed in designing non-viral nanovectors for therapeutic CRISPR/Cas9 delivery in vivo, including the effective encapsulation of large-size macromolecules, targeting specific tissues and cells, efficient endosomal escape and safety concerns of the vector systems, in the hope of inviting more comprehensive studies on the development of safe, specific, and efficient non-viral nanovectors for delivering a CRISPR/Cas9 system.
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Genome Editing with Cas9 in Lactobacilli.
The bacterial genus Lactobacillus comprises a vast range of strains with varying metabolic and probiotic traits, with genome editing representing an essential tool to probe genotype-phenotype relationships and enhance their beneficial properties. Currently, one of the most effective means of genome editing in bacteria couples low-efficiency recombineering with high-efficiency counterselection by nucleases from CRISPR-Cas systems. In lactobacilli, several CRISPR-based genome editing methods exist that have shown varying success in different strains. Here, we detail a fast and simple approach using two shuttle vectors encoding a recombineering template as well as the Streptococcus pyogenes Cas9, a trans-activating RNA, and a CRISPR array. We provide a step-by-step procedure for cloning the shuttle vectors, sequentially transforming the vectors into lactobacilli, screening for the desired edit, and finally clearing the shuttle vectors from the mutant strain. As CRISPR-based genome editing in bacteria can fail for various reasons, we also lay out instructions for probing mechanisms of escape. Finally, we include practical notes along the way to facilitate each stage of genome editing, and we illustrate the technique using a representative edit in a strain of Lactobacillus plantarum. Overall, this method should serve as a complete guide to performing genome editing in lactobacilli.
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Development of a CRISPR/Cas9-degron system that enables in vivo specific gene depletion in leukemia models.
The CRISPR/Cas9 system has transformed genome editing, yet precise temporal control of Cas9 activity remains challenging. We developed a Cas9-degron platform that couples degron-tagged Cas9 with a dTAG-based chemical degradation strategy. In the presence of dTAG, Cas9 is rapidly and near-completely degraded, preventing editing; upon dTAG withdrawal, Cas9 activity is restored, enabling precise temporal control. Using this system, we achieved selective in vivo gene depletion in acute myeloid leukemia (AML) models and confirmed that SETDB1, a histone H3K9 methyltransferase, is essential for the in vivo growth of both human (MOLM13) and murine (cSAM) AML cells. By maintaining SETDB1 intact prior to transplantation and depleting it afterward, we avoided culture-induced pre-selection bias inherent to sgRNA transduction and validated its critical role in AML progression within the in vivo context. The Cas9-degron retains activity and delivery efficiency comparable to conventional Cas9 in the absence of dTAG. Thus, this versatile system provides a superior alternative to conventional Cas9 and a powerful platform for in vivo CRISPR screening, gene function studies, and potentially temporally controlled gene therapy.
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Non-surgical deep uterine embryo transfer combined with electroporation-based genome editing enables scalable production of CD163-Knockout pigs.
Porcine reproductive and respiratory syndrome (PRRS) remains the most economically devastating viral disease in the global swine industry, causing annual losses exceeding $600 million in the United States alone. While CD163-knockout (KO) pigs have demonstrated complete resistance to the PRRS virus (PRRSV) infection, conventional production methods relying on microinjection-based genome editing and surgical embryo transfer present significant bottlenecks for industrial-scale application. Here, we demonstrate that the integration of electroporation-based CRISPR-Cas9 delivery with non-surgical deep intrauterine embryo transfer enables scalable production of CD163-KO pigs. Our approach achieved successful pregnancies and live births of genome-edited piglets without requiring surgical intervention or specialized microinjection expertise. Genotyping analysis revealed complete biallelic KOs in a subset of offspring, while others exhibited mosaic patterns reflecting the stochastic nature of electroporation-mediated editing. These findings establish a technically accessible and scalable pipeline for producing gene-edited pigs. By eliminating the need for complex surgical facilities and specialized microinjection equipment, this approach provides a practical and field-applicable strategy that can be readily implemented in standard commercial swine farms, representing a critical step toward the widespread deployment of genome-edited livestock in global agriculture.
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High-throughput Genetically Modified Animal Experiments Achieved by Next-generation Mammalian Genetics.
Animal models are essential tools for modern scientists to conduct biological experiments and investigate their hypotheses in vivo. However, for the past decade, raising the throughput of such animal experiments has been a great challenge. Conventionally, in vivo high-throughput assay was achieved through large-scale mutagen-driven forward genetic screening, which took years to find causal genes. In contrast, reverse genetics accelerated the causal gene identification process, but its throughput was also limited by 2 barriers, that is, the genome modification step and the time-consuming crossing step. Defined as genetics without crossing, next-generation genetics is able to produce gene-modified animals that can be analyzed at the founder generation (F0). This method is or can be accomplished through recent technological advances in gene editing and virus-based efficient gene modifications. Notably, next-generation genetics has accelerated the process of cross-species studies, and it will be a useful technique during animal experiments as it can provide genetic perturbation at an individual level without crossing. In this review, we begin by introducing the history of animal-based high-throughput analysis, with a specific focus on chronobiology. We then describe ways that gene modification efficiency during animal experiments was enhanced and why crossing remained a barrier to reaching higher efficiency. Moreover, we mention the Triple CRISPR as a critical technique for achieving next-generation genetics. Finally, we discuss the potential applications and limitations of next-generation mammalian genetics.
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A boronic acid-rich dendrimer with robust and unprecedented efficiency for cytosolic protein delivery and CRISPR-Cas9 gene editing.
Cytosolic protein delivery is of central importance for the development of protein-based biotechnologies and therapeutics; however, efficient intracellular delivery of native proteins remains a challenge. Here, we reported a boronic acid-rich dendrimer with unprecedented efficiency for cytosolic delivery of native proteins. The dendrimer could bind with both negatively and positively charged proteins and efficiently delivered 13 cargo proteins into the cytosol of living cells. All the delivered proteins kept their bioactivities after cytosolic delivery. The dendrimer ensures efficient intracellular delivery of Cas9 protein into various cell lines and showed high efficiency in CRISPR-Cas9 genome editing. The rationally designed boronic acid-rich dendrimer permits the development of an efficient platform with high generality for the delivery of native proteins.
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