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Found: 26 179
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In vivo gene editing via homology-independent targeted integration for adrenoleukodystrophy treatment.
Adrenoleukodystrophy (ALD) is caused by various pathogenic mutations in the X-linked ABCD1 gene, which lead to metabolically abnormal accumulations of very long-chain fatty acids in many organs. However, curative treatment of ALD has not yet been achieved. To treat ALD, we applied two different gene-editing strategies, base editing and homology-independent targeted integration (HITI), in ALD patient-derived fibroblasts. Next, we performed in vivo HITI-mediated gene editing using AAV9 vectors delivered via intravenous administration in the ALD model mice. We found that the ABCD1 mRNA level was significantly increased in HITI-treated mice, and the plasma levels of C24:0-LysoPC (lysophosphatidylcholine) and C26:0-LysoPC, sensitive diagnostic markers for ALD, were significantly reduced. These results suggest that HITI-mediated mutant gene rescue could be a promising therapeutic strategy for human ALD treatment.
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A self-iterative orthogonal base-editing platform enables multiplex N-to-N diversification and genome-scale functional screening in Escherichia coli.
Base editing enables precise genome modification without double-strand breaks but remains limited by narrow editing windows, DNA repair pathway biases, and restricted nucleotide diversity. Here, we report MUTATOR, a MUlTiplexAble and self-iTerative ORthogonal base-editing platform that enables N-to-N diversification in Escherichia coli. MUTATOR combines CWBE and ABE with iterative editing on two complementary DNA strands, thereby overcoming endogenous DNA repair constraints and expanding A-to-N and C-to-N editing outcomes across both strands. This strategy substantially expands accessible nucleotide outcomes, codon variants, and amino-acid diversity within existing editing windows relative to conventional editors. Using four gRNAs, MUTATOR facilitated four-site editing of ompR, generating 84 distinct amino-acid combinations and 252 codon combinations, with the synonymous OmpR_P160P variant increasing isobutanol production by up to 56.2%. We further applied MUTATOR to a 151-gene library encompassing transcriptional regulators, translation factors, DNA repair proteins, ribosomal components, and NAD(P)H-associated metabolic genes, identifying single and combinatorial mutations that markedly enhanced cell growth and ethanol utilization when ethanol was used as the sole carbon source. Together, these results establish MUTATOR as a broadly applicable platform for genome-wide diversification, functional dissection, and rapid engineering of industrial microbial chassis.
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Expanding the genome-targeting scope and the site selectivity of high-precision base editors.
Base editors (BEs) are RNA-guided CRISPR-Cas-derived genome editing tools that induce single-nucleotide changes. The limitations of current BEs lie in their low precision (especially when multiple target nucleotides of the deaminase are present within the activity window) and their restriction to targets that are in proper distance from the PAM sequence. We have recently developed high-precision cytidine BEs by engineering CDA1 truncations and nCas9 fusions that predominantly edit nucleotide C-18 relative to the PAM sequence NGG. Here, by testing fusions with Cas9 variants that recognize alternative PAMs, we provide a series of high-precision BEs that greatly expand the versatility of base editing. In addition, we obtained BEs that selectively edit C-15 or C-16. We also show that our high-precision BEs can substantially reduce off-target effect. These improved base editing tools will be widely applicable in basic research, biotechnology and gene therapy.
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Adenine Base Editing System for Pseudomonas and Prediction Workflow for Protein Dysfunction via ABE.
Pseudomonas is a large genus that inhabits diverse environments due to its distinct metabolic versatility. Its applications range from environmental to industrial biotechnology. Molecular tools that allow precise and efficient genetic manipulation are required to understand and harness its full potential. Here, we report the development of a highly efficient adenine base editing system, i.e., dxABE-PS, for Pseudomonas species. The system allows A:T → G:C transition with up to 100% efficiency along a broad target spectrum because we use xCas9 3.7, which recognizes NG PAM. To enhance the dxABE-PS utility, we develop a prediction workflow for protein dysfunction using ABE, namely, DABE-CSP (dysfunction via ABE through CRISPOR-SIFT prediction). We applied DABE-CSP to inactivate several genes in Pseudomonas putida KT2440 to accumulate a nylon precursor, i.e., muconic acid from catechol with 100% yield. Moreover, we expanded the ABE to non-model Pseudomonas species by developing an nxABE system for P. chengduensisDY56-96, isolated from sediment samples from the seamount area in the West Pacific Ocean. Taken together, the establishment of the ABE systems along with DABE-CSP will fast-track research on Pseudomonas species.
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Implementation of an Undergraduate Laboratory-Based Mammalian Genome Editing Course.
Genome engineering methods can be utilized to perform complex genetic manipulations in living cells with remarkable efficiency and precision. Given the transformative potential of these enabling technologies, their applications are steadily expanding into most biology and biomedical fields where they play a central role in many experimental frameworks. For these reasons, in order to effectively prepare future generations of biologists and bioengineers for successful careers, there is a high need to incorporate courses teaching genome editing fundamentals into existing curricula. To accomplish this objective, lecture-based courses are rapidly integrating genome editing concepts; however, there are few laboratory courses that teach the practical skills needed to successfully perform genome editing experiments. Here, we describe the development and implementation of a semester-long laboratory course that teaches students not only the techniques needed to perform gene knockout, gene activation, gene repression, and base editing in mammalian cells but also prepares them to design and troubleshoot experiments, write scientific manuscripts, as well as prepare and deliver scientific presentations. Course evaluations demonstrate that this class effectively equips students with the knowledge and hands-on experience needed to succeed in careers related to genome engineering, cell and tissue engineering, and, more broadly, biology.
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Application of the modified cytosine base-editing in the cultured cells of bama minipig.
Bama minipig is a unique miniature swine bred from China. Their favorable characteristics include delicious meat, strong adaptability, tolerance to rough feed, and high levels of stress tolerance. Unfavorable characteristics are their low lean meat percentage, high fat content, slow growth rate, and low feed conversion ratio. Genome-editing technology using CRISPR/Cas9 efficiently knocked out the myostatin gene (MSTN) that has a negative regulatory effect on muscle production, effectively promoting pig muscle growth and increasing lean meat percentage of the pigs. However, CRISPR/Cas9 genome editing technology is based on random mutations implemented by DNA double-strand breaks, which may trigger genomic off-target effects and chromosomal rearrangements. The application of CRISPR/Cas9 to improve economic traits in pigs has raised biosafety concerns. Base editor (BE) developed based on CRISPR/Cas9 such as cytosine base editor (CBE) effectively achieve targeted modification of a single base without relying on DNA double-strand breaks. Hence, the method has greater safety in the genetic improvement of pigs. The aim of the present study is to utilize a modified CBE to generate MSTN-knockout cells of Bama minipigs. Our results showed that the constructed "all-in-one"-modified CBE plasmid achieved directional conversion of a single C·G base pair to a T·A base pair of the MSTN target in Bama miniature pig fibroblast cells. We successfully constructed multiple single-cell colonies of Bama minipigs fibroblast cells carrying the MSTN premature termination and verified that there were no genomic off-target effects detected. This study provides a foundation for further application of somatic cell cloning to construct MSTN-edited Bama minipigs that carry only a single-base mutation and avoids biosafety risks to a large extent, thereby providing experience and a reference for the base editing of other genetic loci in Bama minipigs.
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CRISPR-Cas12a Gene Editing of HBG1 and HBG2 Promoters to Treat Sickle Cell Disease.
BACKGROUND: Renizgamglogene autogedtemcel (reni-cel) is an investigational clustered regularly interspaced short palindromic repeats (CRISPR)-Cas12a gene-edited autologous hematopoietic stem-cell therapy. The therapy was designed to disrupt the BCL11A binding sites in the HBG1 and HBG2 promoters to reactivate fetal hemoglobin production for the treatment of sickle cell disease. METHODS: We conducted a phase 1-2, multicenter, open-label, single-group study involving patients with severe sickle cell disease who were 12 to 50 years of age and had had at least two severe vaso-occlusive events per year in the previous 2 years. The patients received a single infusion of reni-cel after myeloablative conditioning with busulfan. The patients were monitored for engraftment, hemoglobin-related measures, allelic editing levels, vaso-occlusive events, and adverse events over a 24-month period. The study was terminated early on the basis of the sponsor's reassessment of clinical development priorities. Results of an analysis that was not prespecified are reported. RESULTS: As of October 29, 2024, a total of 28 patients with severe sickle cell disease had been treated with reni-cel. The median duration of follow-up was 9.5 months (range, 0.7 to 25.2). Among 27 patients who had neutrophil and platelet engraftment by the data-cutoff date, neutrophil engraftment occurred after a median of 23 days (range, 14 to 29), and platelet engraftment occurred after a median of 25 days (range, 17 to 51). At month 6, among 18 patients with at least 6 months of available data, the mean (±SD) total hemoglobin level (9.8±1.7 g per deciliter at baseline) had increased to 13.8±1.9 g per deciliter, and the mean percentage of fetal hemoglobin (2.5±2.5% at baseline) had increased to 48.1±3.2%; both measures were maintained at or above these values thereafter. One patient had two severe vaso-occlusive events after infusion. Adverse events were consistent with those that occur after myeloablative busulfan-based conditioning and autologous hematopoietic stem-cell transplantation. CONCLUSIONS: Treatment with reni-cel led to normalization of the total hemoglobin level and an increase in the percentage of fetal hemoglobin, with no vaso-occlusive events occurring in 27 of 28 patients after infusion. These results support further investigation of this gene-editing approach in the treatment of severe sickle cell disease. (Funded by Editas Medicine; RUBY ClinicalTrials.gov number, NCT04853576.).
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Emerging Genome Engineering Tools in Crop Research and Breeding.
Recent advances in genome engineering are revolutionizing crop research and plant breeding. The ability to make specific modifications to a plant's genetic material creates opportunities for rapid development of elite cultivars with desired traits. The plant genome can be altered in several ways, including targeted introduction of nucleotide changes, deleting DNA segments, introducing exogenous DNA fragments and epigenetic modifications. Targeted changes are mediated by sequence specific nucleases (SSNs), such as zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and CRISPR (clustered regularly interspersed short palindromic repeats)-Cas (CRISPR associated protein) systems. Recent advances in engineering chimeric Cas nucleases fused to base editing enzymes permit for even greater precision in base editing and control over gene expression. In addition to gene editing technologies, improvement in delivery systems of exogenous DNA into plant cells have increased the rate of successful gene editing events. Regeneration of fertile plants containing the desired edits remains challenging; however, manipulation of embryogenesis-related genes such as BABY BOOM (BBM) has been shown to facilitate regeneration through tissue culture, often a major hurdle in recalcitrant cultivars. Epigenome reprogramming for improved crop performance is another possibility for future breeders, with recent studies on MutS HOMOLOG 1 (MSH1) demonstrating epigenetic-dependent hybrid vigor in several crops. While these technologies offer plant breeders new tools in creating high yielding, better adapted crop varieties, constantly evolving government policy regarding the cultivation of plants containing transgenes may impede the widespread adoption of some of these techniques. This chapter summarizes advances in genome editing tools and discusses the future of these techniques for crop improvement.
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Advances in genomics and genome editing for breeding next generation of fruit and nut crops.
Fruit tree crops are an essential part of the food production systems and are key to achieve food and nutrition security. Genetic improvement of fruit trees by conventional breeding has been slow due to the long juvenile phase. Advancements in genomics and molecular biology have paved the way for devising novel genetic improvement tools like genome editing, which can accelerate the breeding of these perennial crops to a great extent. In this article, advancements in genomics of fruit trees covering genome sequencing, transcriptome sequencing, genome editing technologies (GET), CRISPR-Cas system based genome editing, potential applications of CRISPR-Cas9 in fruit tree crops improvement, the factors influencing the CRISPR-Cas editing efficiency and the challenges for CRISPR-Cas9 applications in fruit tree crops improvement are reviewed. Besides, base editing, a recently emerging more precise editing system, and the future perspectives of genome editing in the improvement of fruit and nut crops are covered.
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Adenine base editors catalyze cytosine conversions in human cells.
Adenine base editors comprise an adenosine deaminase, evolved in vitro, and a Cas9 nickase. Here, we show that in addition to converting adenine to guanine, adenine base editors also convert cytosine to guanine or thymine in a narrow editing window (positions 5-7) and in a confined TC*N sequence context. Adenine base editor-induced cytosine substitutions occur independently of adenosine conversions with an efficiency of up to 11.2% and reduce the number of suitable targeting sites for high-specificity base editing.
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