Rationally engineered Cas9 nucleases with improved specificity

Nickase fidelity drives EvolvR-mediated diversification in mammalian cells

In vivo genetic diversifiers have previously enabled efficient searches of genetic variant fitness landscapes for continuous directed evolution. However, existing genomic diversification modalities for mammalian genomic loci exclusively rely on deaminases to generate transition mutations within target loci, forfeiting access to most missense mutations. Here, we engineer CRISPR-guided error-prone DNA polymerases (EvolvR) to diversify all four nucleotides within genomic loci in mammalian cells. We demonstrate that EvolvR generates both transition and transversion mutations throughout a mutation window of at least 40 bp and implement EvolvR to evolve previously unreported drug-resistant MAP2K1 variants via substitutions not achievable with deaminases. Moreover, we discover that the nickase's mismatch tolerance limits EvolvR's mutation window and substitution biases in a gRNA-specific fashion. To compensate for gRNA-to-gRNA variability in mutagenesis, we maximize the number of gRNA target sequences by incorporating a PAM-flexible nickase into EvolvR. Finally, we find a strong correlation between predicted free energy changes underlying R-loop formation and EvolvR's performance using a given gRNA. The EvolvR system diversifies all four nucleotides to enable the evolution of mammalian cells, while nuclease and gRNA-specific properties underlying nickase fidelity can be engineered to further enhance EvolvR's mutation rates.

Gene Editing for Duchenne Muscular Dystrophy: From Experimental Models to Emerging Therapies

The CRISPR system has emerged as a ground-breaking gene-editing tool, offering promising therapeutic potential for Duchenne muscular dystrophy (DMD), a severe genetic disorder affecting approximately 1 in 5000 male births globally. DMD is caused by mutations in the dystrophin gene, which encodes a critical membrane-associated protein essential for maintaining muscle structure, function and repair. Patients with DMD experience progressive muscle degeneration, loss of ambulation, respiratory insufficiency, and cardiac failure, with most succumbing to the disease by their third decade of life. Despite the well-characterized genetic basis of DMD, curative treatments- such as exon skipping therapies, micro-dystrophin, and steroids- remain elusive. Recent preclinical studies have demonstrated the promise of CRISPR-based approaches in restoring dystrophin expression across various models, including human cells, murine systems, and large animal models. These advancements highlight the potential of gene editing to fundamentally alter the trajectory of the disease. However, significant challenges persist, including immunogenicity, off-target effects, and limited editing efficiency, which hinder clinical translation. This review provides a comprehensive analysis of the latest developments in CRISPR-based therapeutic strategies for DMD. It emphasizes the need for further innovation in gene-editing technologies, delivery systems, and rigorous safety evaluations to overcome current barriers and harness the full potential of CRISPR/Cas as a durable and effective treatment for DMD.

Current trends in gene therapy to treat inherited disorders of the brain

Gene therapy development, re-engineering, and application to patients hold promise to revolutionize medicine, including therapies for disorders of the brain. Advances in delivery modalities, expression regulation, and improving safety profiles are of critical importance. Additionally, each inherited disorder has its own unique characteristics as to regions and cell types impacted and the temporal dynamics of that impact that are essential for the design of therapeutic design strategies. Here, we review the current state of the art in gene therapies for inherited brain disorders, summarizing key considerations for vector delivery, gene addition, gene silencing, gene editing, and epigenetic editing. We provide examples from animal models, human cell lines, and, where possible, clinical trials. This review also highlights the various tools available to researchers for basic research questions and discusses our views on the current limitations in the field.

TOPO-seq reveals DNA topology-induced off-target activity by Cas9 and base editors

With the increasing use of CRISPR-Cas9, detecting off-target events is essential for safety. Current methods primarily focus on guide RNA (gRNA) sequence mismatches, often overlooking the impact of DNA topology in regulating off-target activity. Here we present TOPO-seq, a high-throughput and sensitive method that identifies genome-wide off-target effects of Cas9 and base editors while accounting for DNA topology. TOPO-seq revealed that topology-induced off-target sites frequently harbor higher mismatches than the relaxed DNA sequence, with over 50% of off-target sites containing six mismatches, which are usually overlooked using previous methods. Applying TOPO-seq to three therapeutic gRNAs in hematopoietic stem cells identified 47 bona fide off-target loci, six of which are specifically induced by DNA topology. These findings highlight DNA topology as a regulator of off-target editing rates, establish TOPO-seq as a robust method for capturing DNA topology-induced off-target events and underscore its importance in off-target detection for developing safe genome-editing therapies.

Hairpin Internal Nuclear Localization Signals in CRISPR-Cas9 Enhance Editing in Primary Human Lymphocytes

The incorporation of nuclear localization signal (NLS) sequences at one or both termini of CRISPR enzymes is a widely adopted strategy to facilitate genome editing. Engineered variants of CRISPR enzymes with diverse NLS sequences have demonstrated superior performance, promoting nuclear localization and efficient DNA editing. However, limiting NLS fusion to the CRISPR protein's termini can negatively impact protein yield via recombinant expression. Here we present a distinct strategy involving the installation of hairpin internal NLS sequences (hiNLS) at rationally selected sites within the backbone of CRISPR-Cas9. We evaluated the performance of these hiNLS Cas9 variants by editing genes in human primary T cells following the delivery of ribonucleoprotein enzymes via either electroporation or co-incubation with amphiphilic peptides. We show that hiNLS Cas9 variants can improve editing efficiency in T cells compared with constructs with terminally fused NLS sequences. Furthermore, many hiNLS Cas9 constructs can be produced with high purity and yield, even when these constructs contain as many as nine NLS. These hiNLS Cas9 constructs represent a key advance in optimizing CRISPR effector design and may contribute to improved editing outcomes in research and therapeutic applications.

CRISPR-Cas9 Targeting PCSK9: A Promising Therapeutic Approach for Atherosclerosis

CRISPR-Cas9 gene editing technology, as an innovative biomedical tool, holds significant potential in the prevention and treatment of atherosclerosis. By precisely editing key genes such as PCSK9, CRISPR-Cas9 offers the possibility of long-term regulation of low-density lipoprotein cholesterol (LDL-C), which may reduce the risk of cardiovascular diseases. Early clinical studies of gene editing therapies like VERVE-101 have yielded encouraging results, highlighting both the feasibility and potential efficacy of this technology. However, clinical applications still face challenges such as off-target effects, immunogenicity, and long-term safety. Future research should focus on enhancing the specificity and efficiency of gene editing, optimizing delivery systems, and improving personalized treatment strategies. Additionally, the establishment of ethical and legal regulatory frameworks will be critical for the safe adoption of this technology. With the continued advancement of gene editing technology, CRISPR-Cas9 may become an important tool for treating atherosclerosis and other complex diseases.

Dynamic basis of supercoiling-dependent DNA interrogation by Cas12a via R-loop intermediates

The sequence specificity and programmability of DNA binding and cleavage have enabled widespread applications of CRISPR-Cas12a in genetic engineering. As an RNA-guided CRISPR endonuclease, Cas12a engages a 20-base pair (bp) DNA segment by forming a three-stranded R-loop structure in which the guide RNA hybridizes to the DNA target. Here we use single-molecule torque spectroscopy to investigate the dynamics and mechanics of R-loop formation of two widely used Cas12a orthologs at base-pair resolution. We directly observe kinetic intermediates corresponding to a ~5 bp initial RNA-DNA hybridization and a ~17 bp intermediate preceding R-loop completion, followed by transient DNA unwinding that extends beyond the 20 bp R-loop. The complex multistate landscape of R-loop formation is ortholog-dependent and shaped by target sequence, mismatches, and DNA supercoiling. A four-state kinetic model captures essential features of Cas12a R-loop dynamics and provides a biophysical framework for understanding Cas12a activity and specificity.

Structural and Dynamic Impacts of Single-atom Disruptions to Guide RNA Interactions within the Recognition Lobe of Geobacillus stearothermophilus Cas9

The intuitive manipulation of specific amino acids to alter the activity or specificity of CRISPR-Cas9 has been a topic of great interest. As a large multi-domain RNA-guided endonuclease, the intricate molecular crosstalk within the Cas9 protein hinges on its conformational dynamics, but a comprehensive understanding of the extent and timescale of the motions that drive its allosteric function and association with nucleic acids remains elusive. Here, we investigated the structure and multi-timescale molecular motions of the recognition (Rec) lobe of GeoCas9, a thermophilic Cas9 from Geobacillus stearothermophilus. Our results provide new atomic details about the GeoRec subdomains (GeoRec1, GeoRec2) and the full-length domain in solution. Two rationally designed mutants, K267E and R332A, enhanced and redistributed micro-millisecond flexibility throughout GeoRec, and NMR studies of the interaction between GeoRec and its guide RNA showed that mutations reduced this affinity and the stability of the ribonucleoprotein complex. Despite measured biophysical differences due to the mutations, DNA cleavage assays reveal no functional differences in on-target activity, and similar specificity. These data suggest that guide RNA interactions can be tuned at the biophysical level in the absence of major functional losses but also raise questions about the underlying mechanism of GeoCas9, since analogous single-point mutations have significantly impacted on- and off-target DNA editing in mesophilic S. pyogenes Cas9. A K267E/R332A double mutant did also did not enhance GeoCas9 specificity, highlighting the robust tolerance of mutations to the Rec lobe of GeoCas9 and species-dependent complexity of Rec across Cas9 paralogs. Ultimately, this work provides an avenue by which to modulate the structure, motion, and guide RNA interactions at the level of the Rec lobe of GeoCas9, setting the stage for future studies of GeoCas9 variants and their effect on its allosteric mechanism.

Lymphoblastoid and Jurkat cell lines are useful surrogate in developing a CRISPR-Cas9 method to correct leukocyte adhesion deficiency genomic defect

Introduction: Leukocyte adhesion deficiency type 1 (LAD1) is a severe inborn error of immunity caused by mutations in the ITGB2 gene, which encodes the beta-2 integrin subunit (CD18). These mutations lead to the absence or deficiency of CD18/CD11a, b, and c heterodimers, crucial for leukocyte adhesion and immune function. CRISPR-Cas9 Gene editing technology represents a promising approach for correcting these genomic defects restore the stable expression of CD18 and reverse the disease. Methods: We developed a CRISPR-Cas9-based gene correction strategy using Jurkat cells and patient-derived lymphoblastoid cell lines as surrogates for hematopoietic progenitor cells. Three candidate gRNAs were first predicted in silico using CRISPOR and experimentally tested in wild-type ITGB2-expressing Jurkat cells to identify the gRNA with the highest genomic DNA cleavage efficiency. The most efficient gRNA was then paired with espCas9 and used alongside five homology-directed repair templates (HDRs) (single-stranded donor oligonucleotides, ssODNs) to repair ITGB2 defects in patient-derived lymphoblastoid cell lines. CD18 expression levels in edited cells were quantified via flow cytometry, and whole-genome sequencing (WGS) was conducted to assess off-target effects and insertion accuracy. Results: Among the three candidate gRNAs, 2-rev gRNA exhibited the highest genomic cleavage rate in Jurkat cells. Using this gRNA with espCas9 and HDR-2, we achieved a 23% restoration of CD18 expression in LAD1 patient-derived cells, a level sufficient to change the disease course from severe to moderate. Whole-genome sequencing confirmed the absence of off-target mutations or undesired DNA insertions, demonstrating high specificity and precision in gene correction. Discussion: This CRISPR-Cas9-based method provides a precise and effective approach for correcting ITGB2 mutations in LAD1 patients. The high-fidelity gene editing process, validated through WGS, supports its potential for future applications in CD34+ hematopoietic stem cell therapies. The approach can be further optimized for clinical translation, offering a path toward a stable and long-term cure for LAD1.

Engineering a New Generation of Gene Editors: Integrating Synthetic Biology and AI Innovations

CRISPR-Cas technology has revolutionized biology by enabling precise DNA and RNA edits with ease. However, significant challenges remain for translating this technology into clinical applications. Traditional protein engineering methods, such as rational design, mutagenesis screens, and directed evolution, have been used to address issues like low efficacy, specificity, and high immunogenicity. These methods are labor-intensive, time-consuming, and resource-intensive and often require detailed structural knowledge. Recently, computational strategies have emerged as powerful solutions to these limitations. Using artificial intelligence (AI) and machine learning (ML), the discovery and design of novel gene-editing enzymes can be streamlined. AI/ML models predict activity, specificity, and immunogenicity while also enhancing mutagenesis screens and directed evolution. These approaches not only accelerate rational design but also create new opportunities for developing safer and more efficient genome-editing tools, which could eventually be translated into the clinic.

Unlocking the potential of CRISPR-Cas9 for cystic fibrosis: A systematic literature review

CRISPR-Cas9 technology has revolutionized genetic engineering, offering precise and efficient genome editing capabilities. This review explores the application of CRISPR-Cas9 for cystic fibrosis (CF), particularly targeting mutations in the CFTR gene. CF is a multiorgan disease primarily affecting the lungs, gastrointestinal system (e.g., CF-related diabetes (CFRD), CF-associated liver disease (CFLD)), bones (CF-bone disease), and the reproductive system. CF, a genetic disorder characterized by defective ion transport leading to thick mucus accumulation, is often caused by mutations like ΔF508 in the CFTR gene. This review employs a systematic methodology, incorporating an extensive literature search across multiple academic databases, including PubMed, Web of Science, and ScienceDirect, to identify 40 high-quality studies focused on CRISPR-Cas9 applications for CFTR gene editing. The data collection process involved predefined inclusion criteria targeting experimental approaches, gene-editing outcomes, delivery methods, and verification techniques. Data analysis synthesized findings on editing efficiency, off-target effects, and delivery system optimization to present a comprehensive overview of the field. The review highlights the historical development of CRISPR-Cas9, its mechanism, and its transformative role in genetic engineering and medicine. A detailed examination of CRISPR-Cas9's application in CFTR gene correction emphasizes the potential for therapeutic interventions while addressing challenges such as off-target effects, delivery efficiency, and ethical considerations. Future directions include optimizing delivery systems, integrating advanced editing tools like prime and base editing, and expanding personalized medicine approaches to improve treatment outcomes. By systematically analyzing the current landscape, this review provides a foundation for advancing CRISPR-Cas9 technologies for cystic fibrosis treatment and related disorders.

Recent advances in therapeutic gene-editing technologies

The advent of gene-editing technologies, particularly CRISPR-based systems, has revolutionized the landscape of biomedical research and gene therapy. Ongoing research in gene editing has led to the rapid iteration of CRISPR technologies, such as base and prime editors, enabling precise nucleotide changes without the need for generating harmful double-strand breaks (DSBs). Furthermore, innovations such as CRISPR fusion systems with DNA recombinases, DNA polymerases, and DNA ligases have expanded the size limitations for edited sequences, opening new avenues for therapeutic development. Beyond the CRISPR system, mobile genetic elements (MGEs) and epigenetic editors are emerging as efficient alternatives for precise large insertions or stable gene manipulation in mammalian cells. These advances collectively set the stage for next-generation gene therapy development. This review highlights recent developments of genetic and epigenetic editing tools and explores preclinical innovations poised to advance the field.

Insights into the compact CRISPR-Cas9d system

Cas9d, the smallest known member of the Cas9 family, employs a compact domain architecture for effective target cleavage. However, the underlying mechanism remains unclear. Here, we present the cryo-EM structures of the Cas9d-sgRNA complex in both target-free and target-bound states. Biochemical assays elucidated the PAM recognition and DNA cleavage mechanisms of Cas9d. Structural comparisons revealed that at least 17 base pairs in the guide-target heteroduplex is required for nuclease activity. Beyond its typical role as an adaptor between Cas9 enzymes and targets, the sgRNA also provides structural support and functional regulation for Cas9d. A segment of the sgRNA scaffold interacts with the REC domain to form a functional target recognition module. Upon target binding, this module undergoes a coordinated conformational rearrangement, enabling heteroduplex propagation and facilitating nuclease activity. This hybrid functional module precisely monitors heteroduplex complementarity, resulting in a lower mismatch tolerance compared to SpyCas9. Moreover, structure-guided engineering in both the sgRNA and Cas9d protein led to a more compact Cas9 system with well-maintained nuclease activity. Altogether, our findings provide insights into the target recognition and cleavage mechanisms of Cas9d and shed light on the development of high-fidelity mini-CRISPR tools.

Engineering of SauriCas9 with enhanced specificity

SauriCas9 is a compact Cas9 nuclease showing promise for in vivo therapeutic applications. However, concerns about off-target effects necessitated improvements in specificity. We addressed this by introducing mutations to eliminate polar contacts between Cas9 and the target DNA, resulting in the SauriCas9-R253A variant with enhanced specificity. To validate its efficacy, we employed SauriCas9-R253A to disrupt three genes (B2M, TRAC, and PDCD1), a strategy integral to the development of allogeneic chimeric antigen receptor T cell (CAR-T) therapies. Our results demonstrated that the most efficient single-guide RNAs for SauriCas9-R253A exhibited comparable activity to SpCas9 and showed no detectable off-target effects in the disruption of these genes, highlighting its therapeutic potential.

DNA nanotechnology-based strategies for minimising hybridisation-dependent off-target effects in oligonucleotide therapies

Targeted therapy has emerged as a transformative breakthrough in modern medicine. Oligonucleotide drugs, such as antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs), have made significant advancements in targeted therapy. Other oligonucleotide-based therapeutics like clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein (Cas) systems are also leading a revolution in targeted gene therapy. However, hybridisation-dependent off-target effects, arising from imperfect base pairing, remain a significant and growing concern for the clinical translation of oligonucleotide-based therapeutics. These mismatches in base pairing can lead to unintended steric blocking or cleavage events in non-pathological genes, affecting the efficacy and safety of the oligonucleotide drugs. In this review, we examine recent developments in oligonucleotide-based targeted therapeutics, explore the factors influencing sequence-dependent targeting specificity, and discuss the current approaches employed to reduce the off-target side effects. The existing strategies, such as chemical modifications and oligonucleotide length optimisation, often require a trade-off between specificity and binding affinity. To further address the challenge of hybridisation-dependent off-target effects, we discuss DNA nanotechnology-based strategies that leverage the collaborative effects of nucleic acid assembly in the design of oligonucleotide-based therapies. In DNA nanotechnology, collaborative effects refer to the cooperative interactions between individual strands or nanostructures, where multiple bindings result in more stable and specific hybridisation behaviour. By requiring multiple complementary interactions to occur simultaneously, the likelihood of unintended partially complementary binding events in nucleic acid hybridisation should be reduced. And thus, with the aid of collaborative effects, DNA nanotechnology has great promise in achieving both high binding affinity and high specificity to minimise the hybridisation-dependent off-target effects of oligonucleotide-based therapeutics.

Protein family FAM241 in human and mouse

FAM241B was isolated in a genome-wide inactivation screen for generation of enlarged lysosomes. FAM241B and FAM241A comprise protein family FAM241 encoding proteins of 121 and 132 amino acid residues, respectively. The proteins exhibit 25% amino acid sequence identity and contain a domain of unknown function (DUF4605; pfam15378) that is conserved from primitive multicellular eukaryotes through vertebrates. Phylogenetic comparison indicates that duplication of the ancestral FAM241B gene occurred prior to the origin of fish. FAM241B has been deleted from the avian lineage. Fam241a and Fam241b are widely expressed in mouse tissues. Experimental knockout of mouse Fam241a, Fam241b, and the double knockout, did not generate a visible phenotype. Knockout of Fam241A and Fam241B did not exacerbate the phenotype of FIG4 null mice. RNAseq of brain RNA from double knockout mice detected reduced expression of several genes including Arke1e1 and RnaseL. The human variant p.Val115Gly in FAM241B was identified in a patient with developmental delay. Lysosome morphology in patient-derived fibroblasts was normal. In previous studies, FAM241A and FAM241B appeared to co-localize with proteins of the endoplasmic reticulum. The molecular function of this ancient protein family remains to be determined.

Improving adenine base editing precision by enlarging the recognition domain of CRISPR-Cas9

Domain expansion contributes to diversification of RNA-guided-endonucleases including Cas9. However, it remains unclear how REC domain expansion could benefit Cas9. In this study, we identify an insertion spot that is compatible with large REC insertion and succeeds in enlarging the non-catalytic REC domain of Streptococcus pyogenes Cas9. The natural-evolution-like giant SpCas9 (GS-Cas9) is created and shows substantially improved editing precision. We further discover that enlarging the REC domain could enable regulation of the N-terminal adenine deaminase TadA8e tethered to the Cas9 scaffold, which contributes to substantially reducing unexpected editing and improving the precision of the adenine base editor ABE8e. We provide proof of concept for evolution-inspired expansion of Cas9 and offer an alternative solution for optimizing gene editors. Our study also indicates a vast potential for engineering the topological malleability of RNA-guided endonucleases and base editors.

Applications of Gene Editing and Nanotechnology in Stem Cell-Based Therapies for Human Diseases

Stem cell research is a dynamic and fast-advancing discipline with great promise for the treatment of diverse human disorders. The incorporation of gene editing technologies, including ZFNs, TALENs, and the CRISPR/Cas system, in conjunction with progress in nanotechnology, is fundamentally transforming stem cell therapy and research. These innovations not only provide a glimmer of optimism for patients and healthcare practitioners but also possess the capacity to radically reshape medical treatment paradigms. Gene editing and nanotechnology synergistically enhance stem cell-based therapies' precision, efficiency, and applicability, offering transformative potential for treating complex diseases and advancing regenerative medicine. Nevertheless, it is important to acknowledge that these technologies also give rise to ethical considerations and possible hazards, such as inadvertent genetic modifications and the development of genetically modified organisms, therefore creating a new age of designer infants. This review emphasizes the crucial significance of gene editing technologies and nanotechnology in the progress of stem cell treatments, particularly for degenerative pathologies and injuries. It emphasizes their capacity to restructure and comprehensively revolutionize medical treatment paradigms, providing fresh hope and optimism for patients and healthcare practitioners.

Dynamic sampling of a surveillance state enables DNA proofreading by Cas9

CRISPR-Cas9 has revolutionized genome engineering applications by programming its single-guide RNA, where high specificity is required. However, the precise molecular mechanism underscoring discrimination between on/off-target DNA sequences, relative to the guide RNA template, remains elusive. Here, using methyl-based NMR to study multiple holoenzymes assembled in vitro, we elucidate a discrete protein conformational state which enables recognition of DNA mismatches at the protospacer adjacent motif (PAM)-distal end. Our results delineate an allosteric pathway connecting a dynamic conformational switch at the REC3 domain, with the sampling of a catalytically competent state by the HNH domain. Our NMR data show that HiFi Cas9 (R691A) increases the fidelity of DNA recognition by stabilizing this "surveillance state" for mismatched substrates, shifting the Cas9 conformational equilibrium away from the active state. These results establish a paradigm of substrate recognition through an allosteric protein-based switch, providing unique insights into the molecular mechanism which governs Cas9 selectivity.

General and robust sample preparation strategies for cryo-EM studies of CRISPR-Cas9 and Cas12 enzymes

Cas9 and Cas12 are RNA-guided DNA endonucleases derived from prokaryotic CRISPR-Cas adaptive immune systems that have been repurposed as versatile genome-engineering tools. Computational mining of genomes and metagenomes has expanded the diversity of Cas9 and Cas12 enzymes that can be used to develop versatile, orthogonal molecular toolboxes. Structural information is pivotal to uncovering the precise molecular mechanisms of newly discovered Cas enzymes and providing a foundation for their application in genome editing. In this chapter, we describe detailed protocols for the preparation of Cas9 and Cas12 enzymes for cryo-electron microscopy. These methods will enable fast and robust structural determination of newly discovered Cas9 and Cas12 enzymes, which will enhance the understanding of diverse CRISPR-Cas effectors and provide a molecular framework for expanding CRISPR-based genome-editing technologies.

Modulation of CRISPR-Cas9 Cleavage with an Oligo-Ribonucleoprotein Design

Clustered regularly interspaced short palindromic repeats (CRISPR) associated protein Cas9 system has been widely used for genome editing. However, the editing or cleavage specificity of CRISPR Cas9 remains a major concern due to the off-target effects. The existing approaches to control or modulate CRISPR Cas9 cleavage include engineering Cas9 protein and development of anti-CRISPR proteins. There are also attempts on direct modification of sgRNA, for example, structural modification via truncation or hairpin design, or chemical modification on sgRNA such as partially replacing RNA with DNA. The above-mentioned strategies rely on extensive protein engineering and direct chemical or structural modification of sgRNA. In this study, we proposed an indirect method to modulate CRISPR Cas9 cleavage without modification on Cas9 protein or sgRNA. An oligonucleotide was used to form an RNA-DNA hybrid structure with the sgRNA spacer, creating steric hindrance during the Cas9 mediated DNA cleavage process. We first introduced a simple and robust method to assemble the oligo-ribonucleoprotein (oligo-RNP). Next, the cleavage efficiency of the assembled oligo-RNP was examined using different oligo lengths in vitro. Lastly, we showed that the oligo-RNP directly delivered into cells could also modulate Cas9 activity inside cells using three model gene targets with reduced off-target effects.

Reduced SH3RF3 may protect against Alzheimer's disease by lowering microglial pro-inflammatory responses via modulation of JNK and NFkB signaling

Understanding how high-risk individuals are protected from Alzheimer's disease (AD) may illuminate potential therapeutic targets. We identified protective genetic variants in SH3RF3/POSH2 that delayed the onset of AD among individuals carrying the PSEN1 G206A mutation. SH3RF3 acts as a JNK pathway scaffold and activates NFκB signaling. While effects of SH3RF3 knockdown in human neurons were subtle, including decreased ptau S422, knockdown in human microglia significantly reduced inflammatory cytokines in response to either a viral mimic or oAβ42. This was associated with reduced activation of JNK and NFκB pathways in response to these stimuli. Pharmacological inhibition of JNK or NFκB signaling phenocopied SH3RF3 knockdown. We also found PSEN1 G206A microglia had reduced inflammatory response to oAβ42. Thus, further reduction of microglial inflammatory responses in PSEN1 G206A mutant carriers by protective variants in SH3RF3 might reduce the link between amyloid and neuroinflammation to subsequently delay the onset of AD.

Optimal SpCas9- and SaCas9-mediated gene editing by enhancing gRNA transcript levels through scaffold poly-T tract reduction

Ensuring sufficient gRNA transcript levels is critical for obtaining optimal CRISPR-Cas9 gene editing efficiency. The standard gRNA scaffold contains a sequence of four thymine nucleotides (4T), which is known to inhibit transcription from Pol III promoters such as the U6 promoter. Our study showed that using standard plasmid transfection protocols, the presence of these 4Ts did not significantly affect editing efficiency, as most of the gRNAs tested (55 gRNAs) achieved near-perfect editing outcomes. We observed that gRNAs with lower activity were T-rich and had reduced gRNA transcript levels. However, this issue can be effectively resolved by increasing transcript levels, which can be readily achieved by shortening the 4T sequences. In this study, we demonstrated this by modifying the sequences to 3TC. Although the 3TC scaffold modification did not improve editing efficiency for already efficient gRNAs when high vector quantities were available, it proved highly beneficial under conditions of limited vector availability, where the 3TC scaffold yielded higher editing efficiency. Additionally, we demonstrated that the 3TC scaffold is compatible with SpCas9 high-fidelity variants and ABEmax base editing, enhancing their editing efficiency. Another commonly used natural Cas9 variant, SaCas9, also benefited from the 3TC scaffold sequence modification, which increased gRNA transcription and subsequently improved editing activity. This modification was applied to the EDIT-101 therapeutic strategy, where it demonstrated marked improvements in performance. This study highlights the importance of shortening the 4T sequences in the gRNA scaffold to optimize gRNA transcript expression for enhanced CRISPR-Cas9 gene editing efficiency. This optimization is particularly important for therapeutic applications, where the quantity of vector is often limited, ensuring more effective and optimal outcomes.

Molecular insights and rational engineering of a compact CRISPR-Cas effector Cas12h1 with a broad-spectrum PAM

Cas12h1 is a compact CRISPR-associated nuclease from functionally diverse type V CRISPR-Cas effectors and recognizes a purine-rich protospacer adjacent motif (PAM) distinct from that of other type V Cas effectors. Here, we report the nickase preference of Cas12h1, which predominantly cleaves the nontarget strand (NTS) of a double-stranded DNA (dsDNA) substrate. In addition, Cas12h1 acts as a nickase in human cells. We further determined the cryo-EM structures of Cas12h1 in the surveillance, R-loop formation, and interference states, revealing the molecular mechanisms involved in the crRNA maturation, target recognition, R-loop formation, nuclease activation and target degradation. Cas12h1 notably recognizes a broad 5'-DHR-3' PAM (D is A, G, or T; H is A, C, or T; R is A or G) both in vitro and in human cells. In addition, Cas12h1 utilizes a distinct activation mechanism that the lid motif undergoes a "flexible to stable" transition to expose the catalytic site to the substrate. A high-fidelity nucleic acid detector, Cas12h1hf, was developed through rational engineering, which distinguishes single-base mismatches and retains comparable on-target activities. Our results shed light on the molecular mechanisms underlying Cas12h1 nickase, improve the understanding of type V Cas effectors, and expand the CRISPR toolbox for genome editing and molecular diagnosis.

Structural basis for a dual-function type II-B CRISPR-Cas9

Cas9 from Streptococcus pyogenes (SpCas9) revolutionized genome editing by enabling programmable DNA cleavage guided by an RNA. However, SpCas9 tolerates mismatches in the DNA-RNA duplex, which can lead to deleterious off-target editing. Here, we reveal that Cas9 from Francisella novicida (FnCas9) possesses a unique structural feature-the REC3 clamp-that underlies its intrinsic high-fidelity DNA targeting. Through kinetic and structural analyses, we show that the REC3 clamp forms critical contacts with the PAM-distal region of the R-loop, thereby imposing a novel checkpoint during enzyme activation. Notably, F. novicida encodes a non-canonical small CRISPR-associated RNA (scaRNA) that enables FnCas9 to repress an endogenous bacterial lipoprotein gene, subverting host immune detection. Structures of FnCas9 with scaRNA illustrate how partial R-loop complementarity hinders REC3 clamp docking and prevents cleavage in favor of transcriptional repression. The REC3 clamp is conserved in type II-B CRISPR-Cas9 systems, pointing to a potential path for engineering precise genome editors or developing novel antibacterial strategies. These findings reveal the dual mechanisms of high specificity and virulence by FnCas9, with broad implications for biotechnology and therapeutic development.

Enhanced genome editing with a Streptococcus equinus Cas9

A large number of SpCas9 orthologs has been computationally identified, but their genome editing potential remains largely unknown. In this study, a GFP-activation assay was used to screen a panel of 18 SpCas9 orthologs, ten of which demonstrated activity in human cells. Notably, these orthologs had a preference for purine-rich PAM sequences. Four of the tested orthologs displayed enhanced specificity compared to SpCas9. Of particular interest is SeqCas9, which recognizes a simple NNG PAM and displays activity and specificity comparable to SpCas9-HF1. In addition, SeqCas9 exhibits superior base editing efficiency compared to SpCas9-NG and SpCas9-NRRH at multiple endogenous loci. This research sheds light on the diversity of SpCas9 orthologs and their potential for specific and efficient genome editing, especially in cases involving base editing.

Advancements in genome editing tools for genetic studies and crop improvement

The rapid increase in global population poses a significant challenge to food security, compounded by the adverse effects of climate change, which limit crop productivity through both biotic and abiotic stressors. Despite decades of progress in plant breeding and genetic engineering, the development of new crop varieties with desirable agronomic traits remains a time-consuming process. Traditional breeding methods often fall short of addressing the urgent need for improved crop varieties. Genome editing technologies, which enable precise modifications at specific genomic loci, have emerged as powerful tools for enhancing crop traits. These technologies, including RNA interference, Meganucleases, ZFNs, TALENs, and CRISPR/Cas systems, allow for the targeted insertion, deletion, or alteration of DNA fragments, facilitating improvements in traits such as herbicide and insect resistance, nutritional quality, and stress tolerance. Among these, CRISPR/Cas9 stands out for its simplicity, efficiency, and ability to reduce off-target effects, making it a valuable tool in both agricultural biotechnology and plant functional genomics. This review examines the functional mechanisms and applications of various genome editing technologies for crop improvement, highlighting their advantages and limitations. It also explores the ethical considerations associated with genome editing in agriculture and discusses the potential of these technologies to contribute to sustainable food production in the face of growing global challenges.

Engineering a bacterial toxin deaminase from the DYW-family into a novel cytosine base editor for plants and mammalian cells

Base editors are precise editing tools that employ deaminases to modify target DNA bases. The DYW-family of cytosine deaminases is structurally and phylogenetically distinct and might be harnessed for genome editing tools. We report a novel CRISPR/Cas9-cytosine base editor using SsdA, a DYW-like deaminase and bacterial toxin. A G103S mutation in SsdA enhances C-to-T editing efficiency while reducing its toxicity. Truncations result in an extraordinarily small enzyme. The SsdA-base editor efficiently converts C-to-T in rice and barley protoplasts and induces mutations in rice plants and mammalian cells. The engineered SsdA is a highly efficient genome editing tool.

A universal and wide-range cytosine base editor via domain-inlaid and fidelity-optimized CRISPR-FrCas9

CRISPR-based base editor (BE) offer diverse editing options for genetic engineering of microorganisms, but its application is limited by protospacer adjacent motif (PAM) sequences, context preference, editing window, and off-target effects. Here, a series of iteratively improved cytosine base editors (CBEs) are constructed using the FrCas9 nickase (FrCas9n) with the unique PAM palindromic structure (NNTA) to alleviate these challenges. The deaminase domain-inlaid FrCas9n exhibits an editing range covering 38 nucleotides upstream and downstream of the palindromic PAM, without context preference, which is 6.3 times larger than that of traditional CBEs. Additionally, lower off-target editing is achieved when incorporating high-fidelity mutations at R61A and Q964A in FrCas9n, while maintaining high editing efficiency. The final CBE, HF-ID824-evoCDA-FrCas9n demonstrates broad applicability across different microbes such as Escherichia coli MG1655, Shewanella oneidensis MR-1, and Pseudomonas aeruginosa PAO1. Collectively, this tool offers robust gene editing for facilitating mechanistic studies, functional exploration, and protein evolution in microbes.

Trisomic rescue via allele-specific multiple chromosome cleavage using CRISPR-Cas9 in trisomy 21 cells

Human trisomy 21, responsible for Down syndrome, is the most prevalent genetic cause of cognitive impairment and remains a key focus for prenatal and preimplantation diagnosis. However, research directed toward eliminating supernumerary chromosomes from trisomic cells is limited. The present study demonstrates that allele-specific multiple chromosome cleavage by clustered regularly interspaced palindromic repeats Cas9 can achieve trisomy rescue by eliminating the target chromosome from human trisomy 21 induced pluripotent stem cells and fibroblasts. Unlike previously reported allele-nonspecific strategies, we have developed a comprehensive allele-specific (AS) Cas9 target sequence extraction method that efficiently removes the target chromosome. The temporary knockdown of DNA damage response genes increases the chromosome loss rate, while chromosomal rescue reversibly restores gene signatures and ameliorates cellular phenotypes. Additionally, this strategy proves effective in differentiated, nondividing cells. We anticipate that an AS approach will lay the groundwork for more sophisticated medical interventions targeting trisomy 21.

Engineering Base Changes and Epitope-Tagged Alleles in Mice Using Cas9 RNA-Guided Nuclease

Mice carrying patient-associated base changes are powerful tools to define the causality of single-nucleotide variants to disease states. Epitope tags enable immuno-based studies of genes for which no antibodies are available. These alleles enable detailed and precise developmental, mechanistic, and translational research. The first step in generating these alleles is to identify within the target sequence-the orthologous sequence for base changes or the N or C terminus for epitope tags-appropriate Cas9 protospacer sequences. Subsequent steps include design and acquisition of a single-stranded oligonucleotide repair template, synthesis of a single guide RNA (sgRNA), collection of zygotes, and microinjection or electroporation of zygotes with Cas9 mRNA or protein, sgRNA, and repair template followed by screening born mice for the presence of the desired sequence change. Quality control of mouse lines includes screening for random or multicopy insertions of the repair template and, depending on sgRNA sequence, off-target sequence variation introduced by Cas9. © 2025 The Author(s). Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Single guide RNA design and synthesis Alternate Protocol 1: Single guide RNA synthesis by primer extension and in vitro transcription Basic Protocol 2: Design of oligonucleotide repair template Basic Protocol 3: Preparation of RNA mixture for microinjection Support Protocol 1: Preparation of microinjection buffer Alternate Protocol 2: Preparation of RNP complexes for electroporation Basic Protocol 4: Collection and preparation of mouse zygotes for microinjection or electroporation Basic Protocol 5: Electroporation of Cas9 RNP into zygotes using cuvettes Alternate Protocol 3: Electroporation of Cas9 RNP into zygotes using electrode slides Basic Protocol 6: Screening and quality control of derived mice Support Protocol 2: Deconvoluting multiple sequence chromatograms with DECODR.

Direct repeat region 3' end modifications regulate Cas12a activity and expand its applications

CRISPR-Cas12a technology has transformative potential, but as its applications grow, enhancing its inherent functionalities is essential to meet diverse demands. Here, we reveal a regulatory mechanism for LbCas12a through direct repeat (DR) region 3' end modifications and de-modifications, which can regulate LbCas12a's cis- and trans-cleavage activities. We extensively explored the effects of introducing phosphorylation, DNA, photo-cleavable linker, DNA modifications at the DR 3' end on LbCas12a's functionality. We find that the temporary inhibitory function of Cas12a can be reactivated by DR 3' end modification corresponding substances, such as alkaline phosphatase (ALP), immunoglobulin G (IgG), alpha-fetoprotein (AFP), DNA exonucleases, ultraviolet radiation, and DNA glycosylases, which greatly expand the scope of application of Cas12a. Clinical applications demonstrated promising results in ALP, AFP, and trace Epstein-Barr virus detection compared to gold standard methods. Our research provides valuable insights into regulating LbCas12a activity through direct modification of DR and significantly expands its potential clinical detection targets, paving the way for future universal clustered regularly interspaced short palindromic repeats (CRISPR) diagnostic strategies.

Phospholipase C epsilon 1 as a therapeutic target in cardiovascular diseases

BACKGROUND

Phospholipase C epsilon 1 (PLCε1) can hydrolyze phosphatidylinositol-4,5-bisphosphate and phosphatidylinositol-4-phosphate at the plasma membrane and perinuclear membrane in the cardiovascular system, producing lipid-derived second messengers. These messengers are considered prominent triggers for various signal transduction processes. Notably, diverse cardiac phenotypes have been observed in cardiac-specific and global Plce1 knockout mice under conditions of pathological stress. It is well established that the cardiac-specific Plce1 knockout confers cardioprotective benefits. Therefore, the development of tissue/cell-specific targeting approaches is critical for advancing therapeutic interventions.

AIM OF REVIEW

This review aims to distill the foundational biology and functional significance of PLCε1 in cardiovascular diseases, as well as to explore potential avenues for research and the development of novel therapeutic strategies targeting PLCε1.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Cardiovascular diseases remain the leading cause of morbidity and mortality worldwide, with incidence rates escalating annually. A comprehensive understanding of the multifaceted role of PLCε1 is essential for enhancing the diagnosis, management, and prognostic assessment of patients suffering from cardiovascular diseases.

Treating genetic blood disorders in the era of CRISPR-mediated genome editing

In the setting of monogenic disease, advances made in genome editing technologies can, in principle, be deployed as a therapeutic strategy to precisely correct a specific gene mutation in an affected cell type and restore functionality. Using the β-hemoglobinopathies and hemophilia as exemplars, we review recent experimental breakthroughs using CRISPR-derived genome editing technology that have translated to significant improvements in the management of inherited hematologic disorders. Yet there are also challenges facing the use of CRISPR-mediated genome editing in these patients; we discuss possible ways to obviate those issues for furtherance of clinical benefit.

Progress on long non-coding RNAs in calcific aortic valve disease

Calcific aortic valve disease (CAVD) is a common cardiovascular condition in the elderly population. The aortic valve, influenced by factors such as endothelial dysfunction, inflammation, oxidative stress, lipid metabolism disorders, calcium deposition, and extracellular matrix remodeling, undergoes fibrosis and calcification, ultimately leading to stenosis. In recent years, long non-coding RNAs (lncRNAs) have emerged as significant regulators of gene expression, playing crucial roles in the occurrence and progression of various diseases. Research has shown that lncRNAs participate in the pathological process underlying CAVD by regulating osteogenic differentiation and inflammatory response of valve interstitial cells. Specifically, lncRNAs, such as H19, MALAT1, and TUG1, are closely associated with CAVD. Some lncRNAs can act as miRNA sponges, form complex regulatory networks, and modulate the expression of calcification-related genes. In brief, this review discusses the mechanisms and potential therapeutic targets of lncRNAs in CAVD.

Precision genome editing using combinatorial viral vector delivery of CRISPR-Cas9 nucleases and donor DNA constructs

Genome editing based on programmable nucleases and donor DNA constructs permits introducing specific base-pair changes and complete transgenes or live-cell reporter tags at predefined chromosomal positions. A crucial requirement for such versatile genome editing approaches is, however, the need to co-deliver in an effective, coordinated and non-cytotoxic manner all the required components into target cells. Here, adenoviral (AdV) and adeno-associated viral (AAV) vectors are investigated as delivery agents for, respectively, engineered CRISPR-Cas9 nucleases and donor DNA constructs prone to homologous recombination (HR) or homology-mediated end joining (HMEJ) processes. Specifically, canonical single-stranded and self-complementary double-stranded AAVs served as sources of ectopic HR and HMEJ substrates, whilst second- and third-generation AdVs provided for matched CRISPR-Cas9 nucleases. We report that combining single-stranded AAV delivery of HR donors with third-generation AdV transfer of CRISPR-Cas9 nucleases results in selection-free and precise whole transgene insertion in large fractions of target-cell populations (i.e. up to 93%) and disclose that programmable nuclease-induced chromosomal breaks promote AAV transduction. Finally, besides investigating relationships between distinct AAV structures and genome-editing performance endpoints, we further report that high-fidelity CRISPR-Cas9 nucleases are critical for mitigating off-target chromosomal insertion of defective AAV genomes known to be packaged in vector particles.

Exploring CRISPR-Cas9 HNH-Domain-Catalyzed DNA Cleavage Using Accelerated Quantum Mechanical Molecular Mechanical Free Energy Simulation

The target DNA (tDNA) cleavage catalyzed by the CRISPR Cas9 enzyme is a critical step in the Cas9-based genome editing technologies. Previously, the tDNA cleavage from an active SpyCas9 enzyme conformation was modeled by Palermo and co-workers (Nierzwicki et al., Nat. Catal. 2022 5, 912) using ab initio quantum mechanical molecular mechanical (ai-QM/MM) free energy simulations, where the free energy barrier was found to be more favorable than that from a pseudoactive enzyme conformation. In this work, we performed ai-QM/MM simulations based on another catalytically active conformation (PDB 7Z4J) of the Cas9 HNH domain from cryo-electron microscopy experiments. For the wildtype enzyme, we acquired a free energy profile for the tDNA cleavage that is largely consistent with the previous report. Furthermore, we explored the role of the active-site K866 residue on the catalytic efficiency by modeling the K866A mutant and found that the K866A mutation increased the reaction free energy barrier, which is consistent with the experimentally observed reduction in the enzyme activity.

Structural basis of Cas9 DNA interrogation with a 5' truncated sgRNA

The efficiency and accuracy of CRISPR-Cas9 targeting varies considerably across genomic targets and remains a persistent issue for using this system in cells. Studies have shown that the use of 5' truncated single guide RNAs (sgRNAs) can reduce the rate of unwanted off-target recognition while still maintaining on-target specificity. However, it is not well-understood how reducing target complementarity enhances specificity or how truncation past 15 nucleotides (nts) prevents full Cas9 activation without compromising on-target binding. Here, we use biochemistry and cryogenic electron microscopy to investigate Cas9 structure and activity when bound to a 14-nt sgRNA. Our structures reveal that the shortened path of the displaced non-target strand (NTS) sterically occludes docking of the HNH L1 linker and prevents proper positioning of the nuclease domains. We show that cleavage inhibition can be alleviated by either artificially melting the protospacer adjacent motif (PAM)-distal duplex or providing a supercoiled substrate. Even though Cas9 forms a stable complex with its target, we find that plasmid cleavage is ∼1000-fold slower with a 14-nt sgRNA than with a full-length 20-nt sgRNA. Our results provide a structural basis for Cas9 target binding with 5' truncated sgRNAs and underline the importance of PAM-distal NTS availability in promoting Cas9 activation.

Gene-editing in patient and humanized-mice primary muscle stem cells rescues dysferlin expression in dysferlin-deficient muscular dystrophy

Dystrophy-associated fer-1-like protein (dysferlin) conducts plasma membrane repair. Mutations in the DYSF gene cause a panoply of genetic muscular dystrophies. We targeted a frequent loss-of-function, DYSF exon 44, founder frameshift mutation with mRNA-mediated delivery of SpCas9 in combination with a mutation-specific sgRNA to primary muscle stem cells from two homozygous patients. We observed a consistent >60% exon 44 re-framing, rescuing a full-length and functional dysferlin protein. A new mouse model harboring a humanized Dysf exon 44 with the founder mutation, hEx44mut, recapitulates the patients' phenotype and an identical re-framing outcome in primary muscle stem cells. Finally, gene-edited murine primary muscle stem-cells are able to regenerate muscle and rescue dysferlin when transplanted back into hEx44mut hosts. These findings are the first to show that a CRISPR-mediated therapy can ameliorate dysferlin deficiency. We suggest that gene-edited primary muscle stem cells could exhibit utility, not only in treating dysferlin deficiency syndromes, but also perhaps other forms of muscular dystrophy.

Quantifying Protein-Nucleic Acid Interactions for Engineering Useful CRISPR-Cas9 Genome-Editing Variants

Numerous high-specificity Cas9 variants have been engineered for precision genome editing. These variants typically harbor multiple mutations designed to alter the Cas9-single guide RNA (sgRNA)-DNA complex interactions for reduced off-target cleavage. By dissecting the contributions of individual mutations, we attempt to derive principles for designing high-specificity Cas9 variants. Here, we computationally modeled the specificity harnessing mutations of the widely used Cas9 isolated from Streptococcus pyogenes (SpCas9) and investigated their individual mutational effects. We quantified the mutational effects in terms of energy and contact changes by comparing the wild-type and mutant structures. We found that these mutations disrupt the protein-protein or protein-DNA contacts within the Cas9-sgRNA-DNA complex. We also identified additional impacted amino acid sites via energy changes that constitute the structural microenvironment encompassing the focal mutation, giving insights into how the mutations contribute to the high-specificity phenotype of SpCas9. Our method outlines a strategy to evaluate mutational effects that can facilitate rational design for Cas9 optimization.

Genome editing in Sub-Saharan Africa: a game-changing strategy for climate change mitigation and sustainable agriculture

Sub-Saharan Africa's agricultural sector faces a multifaceted challenge due to climate change consisting of high temperatures, changing precipitation trends, alongside intensified pest and disease outbreaks. Conventional plant breeding methods have historically contributed to yield gains in Africa, and the intensifying demand for food security outpaces these improvements due to a confluence of factors, including rising urbanization, improved living standards, and population growth. To address escalating food demands amidst urbanization, rising living standards, and population growth, a paradigm shift toward more sustainable and innovative crop improvement strategies is imperative. Genome editing technologies offer a promising avenue for achieving sustained yield increases while bolstering resilience against escalating biotic and abiotic stresses associated with climate change. Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated protein (CRISPR/Cas) is unique due to its ubiquity, efficacy, alongside precision, making it a pivotal tool for Sub-Saharan African crop improvement. This review highlights the challenges and explores the prospect of gene editing to secure the region's future foods.

State of the art CRISPR-based strategies for cancer diagnostics and treatment

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) technology is a groundbreaking and dynamic molecular tool for DNA and RNA "surgery". CRISPR/Cas9 is the most widely applied system in oncology research. It is a major advancement in genome manipulation due to its precision, efficiency, scalability and versatility compared to previous gene editing methods. It has shown great potential not only in the targeting of oncogenes or genes coding for immune checkpoint molecules, and in engineering T cells, but also in targeting epigenomic disturbances, which contribute to cancer development and progression. It has proven useful for detecting genetic mutations, enabling the large-scale screening of genes involved in tumor onset, progression and drug resistance, and in speeding up the development of highly targeted therapies tailored to the genetic and immunological profiles of the patient's tumor. Furthermore, the recently discovered Cas12 and Cas13 systems have expanded Cas9-based editing applications, providing new opportunities in the diagnosis and treatment of cancer. In addition to traditional cis-cleavage, they exhibit trans-cleavage activity, which enables their use as sensitive and specific diagnostic tools. Diagnostic platforms like DETECTR, which employs the Cas12 enzyme, that cuts single-stranded DNA reporters, and SHERLOCK, which uses Cas12, or Cas13, that specifically target and cleave single-stranded RNA, can be exploited to speed up and advance oncological diagnostics. Overall, CRISPR platform has the great potential to improve molecular diagnostics and the functionality and safety of engineered cellular medicines. Here, we will emphasize the potentially transformative impact of CRISPR technology in the field of oncology compared to traditional treatments, diagnostic and prognostic approaches, and highlight the opportunities and challenges raised by using the newly introduced CRISPR-based systems for cancer diagnosis and therapy.

Highly sequence-specific, timing-controllable m6A demethylation by modulating RNA-binding affinity of m6A erasers

Recent advancements in tools using programmable RNA binding proteins and m6A-erasers enable sequence-selective and timing-controllable m6A demethylation. However, off-target effects are still a concern. This study addresses the problem by reducing the RNA-binding ability of m6A-erasers. The modulated m6A-erasers achieved sequence-specific and timing-controllable m6A demethylation with minimal off-target activity.

An ILK/STAT3 pathway controls glioblastoma stem cell plasticity

Glioblastoma (GBM) is driven by malignant neural stem-like cells that display extensive heterogeneity and phenotypic plasticity, which drive tumor progression and therapeutic resistance. Here, we show that the extracellular matrix-cell adhesion protein integrin-linked kinase (ILK) stimulates phenotypic plasticity and mesenchymal-like, invasive behavior in a murine GBM stem cell model. ILK is required for the interconversion of GBM stem cells between malignancy-associated glial-like states, and its loss produces cells that are unresponsive to multiple cell state transition cues. We further show that an ILK/STAT3 signaling pathway controls the plasticity that enables transition of GBM stem cells to an astrocyte-like state in vitro and in vivo. Finally, we find that ILK expression correlates with expression of STAT3-regulated proteins and protein signatures describing astrocyte-like and mesenchymal states in patient tumors. This work identifies ILK as a pivotal regulator of multiple malignancy-associated GBM phenotypes, including phenotypic plasticity and mesenchymal state.

Single-cell synaptome mapping: its technical basis and applications in critical period plasticity research

Our brain adapts to the environment by optimizing its function through experience-dependent cortical plasticity. This plasticity is transiently enhanced during a developmental stage, known as the "critical period," and subsequently maintained at lower levels throughout adulthood. Thus, understanding the mechanism underlying critical period plasticity is crucial for improving brain adaptability across the lifespan. Critical period plasticity relies on activity-dependent circuit remodeling through anatomical and functional changes at individual synapses. However, it remains challenging to identify the molecular signatures of synapses responsible for critical period plasticity and to understand how these plasticity-related synapses are spatiotemporally organized within a neuron. Recent advances in genetic tools and genome editing methodologies have enabled single-cell endogenous protein labeling in the brain, allowing for comprehensive molecular profiling of individual synapses within a neuron, namely "single-cell synaptome mapping." This promising approach can facilitate insights into the spatiotemporal organization of synapses that are sparse yet functionally important within single neurons. In this review, we introduce the basics of single-cell synaptome mapping and discuss its methodologies and applications to investigate the synaptic and cellular mechanisms underlying circuit remodeling during the critical period.

Graph theory approaches for molecular dynamics simulations

Graph theory, a branch of mathematics that focuses on the study of graphs (networks of nodes and edges), provides a robust framework for analysing the structural and functional properties of biomolecules. By leveraging molecular dynamics (MD) simulations, atoms or groups of atoms can be represented as nodes, while their dynamic interactions are depicted as edges. This network-based approach facilitates the characterization of properties such as connectivity, centrality, and modularity, which are essential for understanding the behaviour of molecular systems. This review details the application and development of graph theory-based models in studying biomolecular systems. We introduce key concepts in graph theory and demonstrate their practical applications, illustrating how innovative graph theory approaches can be employed to design biomolecular systems with enhanced functionality. Specifically, we explore the integration of graph theoretical methods with MD simulations to gain deeper insights into complex biological phenomena, such as allosteric regulation, conformational dynamics, and catalytic functions. Ultimately, graph theory has proven to be a powerful tool in the field of molecular dynamics, offering valuable insights into the structural properties, dynamics, and interactions of molecular systems. This review establishes a foundation for using graph theory in molecular design and engineering, highlighting its potential to transform the field and drive advancements in the understanding and manipulation of biomolecular systems.

Rationally designed Campylobacter jejuni Cas9 enables efficient gene activation and base editing

Compact and adaptable CRISPR-Cas systems enable genome engineering applications in various contexts via high-efficiency delivery. The adeno-associated virus (AAV) is a widely used delivery system. One of the most compact type II-C Cas9 orthologs-CjCas9, derived from Campylobacter jejuni, is particularly appealing for AAV delivery. However, the editing efficiency of CjCas9 limits its applications. In this study, we used structure-guided protein engineering to improve the editing efficiency of CjCas9. Subsequently, we developed a miniature transcriptional activator (LDE-CjCas9-VPR) and base editors engineered from CjCas9 (LDE-CjABE and LDE-CjCBE). LDE-CjABE effectively induced genome editing in human and mouse cells. Through AAV delivery, LDE-CjABE enhanced the on-target editing efficiency, and off-target editing was not detected in the mouse retina. Therefore, the compact size and high editing efficiency of LDE-CjCas9 broadens the target scope of transcription activation and base editing toolsets for therapeutic applications.

The Role of CRISPR/Cas9 in Revolutionizing Duchenne's Muscular Dystrophy Treatment: Opportunities and Obstacles

Duchenne's muscular dystrophy (DMD) is a severe X-linked disorder characterized by progressive muscle degeneration, leading to loss of ambulation, respiratory failure, and premature death. It affects approximately 1 in 3,500 live male births and is caused by mutations in the dystrophin gene, which impairs muscle fiber stability. Current treatments are limited to managing symptoms and slowing disease progression, with no curative therapies available. The advent of CRISPR/Cas9 gene-editing technology has introduced a promising approach for directly correcting the genetic mutations responsible for DMD. This review explores the potential of CRISPR/Cas9 as a transformative therapy for DMD, highlighting its successes in preclinical models, the challenges associated with its delivery, and the obstacles to its clinical application. While preclinical studies demonstrate the efficacy of CRISPR/Cas9 in restoring dystrophin expression and improving muscle function, significant hurdles remain, including optimizing delivery methods and ensuring long-term safety.

Biology and applications of CRISPR-Cas12 and transposon-associated homologs

CRISPR-associated Cas12 proteins are a highly variable collection of nucleic acid-targeting proteins. All Cas12 variants use RNA guides and a single nuclease domain to target complementary DNA or, in rare cases, RNA. The high variability of Cas12 effectors can be explained by a series of independent evolution events from different transposon-associated TnpB-like ancestors. Despite basic structural and functional similarities, this has resulted in unprecedented variation of the Cas12 effector proteins in terms of size, domain composition, guide structure, target identity and interference strategy. In this Review, we compare the unique molecular features of natural and engineered Cas12 and TnpB variants. Furthermore, we provide an overview of established genome editing and diagnostic applications and discuss potential future directions.

Deciphering Cas9 specificity: Role of domain dynamics and RNA:DNA hybrid interactions revealed through machine learning and accelerated molecular simulations

CRISPR/Cas9 technology is widely used for gene editing, but off-targeting still remains a major concern in therapeutic applications. Although Cas9 variants with better mismatch discrimination have been developed, they have significantly lower rates of on-target DNA cleavage. This study compares the dynamics of the highly specific Cas9 from Francisella novicida (FnCas9) to the commonly used SpCas9. Using long-scale atomistic Gaussian accelerated molecular dynamic simulations and machine learning techniques, we deciphered the structural factors behind FnCas9's higher specificity in native and off-target forms. Our analysis revealed that Cas9's cleavage specificity relies more on its domain rearrangement than on RNA:DNA heteroduplex shape, with significant conformational variations in Cas9 domains among off-target forms, while the RNA:DNA hybrid showed minimal changes, especially in FnCas9 compared to SpCas9. REC1-REC3 domains contacts with the RNA:DNA hybrid in FnCas9 acted as critical discriminator of off-target effects playing a pivotal role in influencing specificity. In FnCas9, allosteric signal transmission involves the REC3 and HNH domain, bypassing REC2, leading to a superior efficiency in information transmission. This study offers a quantitative framework for understanding the structural basis of elevated specificity, paving the way for the rational design of Cas9 variants with improved precision and specificity in genome editing applications.