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PDE4DIP-Derived MMG8 Supports Proliferation, Migration, and Tumor Growth in Hepatocellular Carcinoma Models.

BACKGROUND: PDE4DIP encodes a scaffold protein that has been implicated in compartmentalized signaling and cytoskeletal organization, but the role of its myomegalin variant 8 (MMG8) isoform in hepatocellular carcinoma (HCC) remains unclear. To address this gap, we examined PDE4DIP expression in public HCC datasets and investigated the functional role of MMG8 in HCC models. METHODS: PDE4DIP expression was analyzed in The Cancer Genome Atlas Liver Hepatocellular Carcinoma (TCGA-LIHC) cohort and two Gene Expression Omnibus (GEO) cohorts (GSE14520, GSE36376). MMG8 function was assessed in Huh7 cells using siRNA-mediated knockdown and in Hepa1-6 cells using lentiviral Clustered Regularly Interspaced Short Palindromic Repeats - CRISPR-associated protein 9 (CRISPR-Cas9)-mediated knockout. Cell proliferation in MMG8-KD Huh7 cells and MMG8-KO Hepa1-6 cells was assessed using Cell Counting Kit-8 (CCK-8) assays, while Huh7 cell migration was evaluated using Transwell assays. Tumor growth was assessed using a murine subcutaneous tumor model. Immunohistochemical staining for Ki67 and cleaved caspase-3 was employed to assess tumor cell proliferation and apoptosis-associated changes, respectively. Gene set enrichment analysis was performed in TCGA-LIHC tumors stratified based on PDE4DIP expression. RESULTS: PDE4DIP expression differed between tumor and non-tumor tissues across HCC cohorts, although the directionality of this difference was not uniform. MMG8 knockdown in Huh7 cells reduced proliferation and migratory activity. A single-cell-derived MMG8-KO Hepa1-6 clone exhibited reduced proliferation in vitro and formed smaller tumors in vivo, with lower Ki67 positivity but no significant difference in cleaved caspase-3 positivity between groups. In tumors from the TCGA-LIHC cohort, PDE4DIP expression was associated with distinct transcriptional programs. Specifically, PDE4DIP-high tumors presented with positive normalized enrichment score (NES) values for several metabolic pathways, whereas adhesion/extracellular matrix (ECM), cell cycle/proliferation, and translation/ribosome-related pathways exhibited negative NES values. CONCLUSIONS: These findings support a functional contribution of MMG8 to proliferative, migratory, and tumor-growth phenotypes in the tested HCC models. Bulk gene-level PDE4DIP expression in human tumors was associated with context-dependent transcriptional states and should not be interpreted as a direct surrogate for MMG8 function.

Liver Neoplasms

Development and application of a fast and efficient CRISPR/Cas12f -based genetic toolkit in Bacillus cereus GW-01.

Bacillus cereus GW-01, an efficient degrader of β-cypermethrin (β-CY), has a high safety profile and probiotic potential for regulating intestinal flora and fermented foods, which is difficult to genetically engineer for modification due to its restrictive modification system. This study successfully developed a CRISPR/enCas12f-based genome editing system, first selecting the plcR gene for proof-of-concept validation with 100% knockout efficiency. Subsequently, this system was utilized to delete the virulence gene nheABC in GW-01, yielding a safer probiotic strain. Compared with the wild-type strain GW-01, the probiotic-related indicators of the ΔnheABC mutant, including cell surface hydrophobicity, auto-aggregation ability and biofilm formation ability, were 80%, 90% and 2.9 (OD₅₉₅), respectively. There were no significant differences in these indicators between the mutant and the wild type. Meanwhile, the ΔnheABC mutant still maintained a high β-cypermethrin degradation efficiency of 80% at the concentration of 30 μg/mL. This work facilitates functional genomic research and genetic modification of Bacillus cereus GW-01. The established CRISPR/enCas12f system enables targeted gene deletion to explore gene functions and phenotypic mechanisms, and paves the way for its development into safe probiotics and excellent microbial chassis.

Bacillus cereus

Cross-target and cell-preferential CRISPR-Cas9 inhibition with carbohydrate-tagged oligonucleotides.

Precise control of clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) activity is important for limiting off-target effects and chromosomal rearrangements. Existing inhibitors, including anti-CRISPR proteins and spacer-targeting oligonucleotides, can be constrained by immunogenicity, target-sequence dependence, or delivery challenges. Here, we developed single-stranded DNA oligonucleotides that target conserved regions of the Streptococcus pyogenes Cas9 single-guide RNA (sgRNA) scaffold rather than the variable spacer. Screening identified single-stranded DNA 7 (ssDNA7), which targets stem-loop-1 and the adjacent linker and inhibits Cas9 activity across multiple tested spacer sequences and genomic loci without redesigning the inhibitor. Carbohydrate conjugation improved oligonucleotide stability and preferentially enhanced inhibitory activity in selected liver-derived or cancer cell models. Amplicon sequencing confirmed inhibition of endogenous editing in multiple cell models and normal liver-derived organoids, and supported cell-preferential inhibition in matched cell comparisons. These findings establish sgRNA-scaffold targeting as a strategy for cross-target inhibition of Cas9 and show that carbohydrate conjugation can tune its cellular activity.

CRISPR-Cas9

Expanding the scope of precision editing in seaweeds through the application of a novel CRISPR-associated nuclease 12a-aligned CRISPR system in Ulva prolifera.

Seaweeds, such as the fast-growing green alga Ulva prolifera, can be harnessed as valuable marine crops. The lack of scalable genome-editing tools hampers functional genomics to explore and elucidate algal molecular pathways with industrial importance. Here, we expanded precision genome modification in seaweeds by successfully demonstrating gene editing with a transgene-free AT-rich-targeting CRISPR-associated protein (Cas) system in U. prolifera. By evaluating various delivery buffers, comparing different Cas systems, and optimizing incubation temperatures, we determined suitable conditions for more widespread applicability of a novel Cas12a-aligned ST8 editor. We obtained >50 ST8-mediated knockout mutants of a toxin-based endogenous marker gene, UpAPT, at 28 °C post-delivery incubations. Our work diversified the applicable genome-editing tools in seaweeds, advancing algal functional genomics and providing more strategies to precisely target unexplored seaweed resources.

Ulva

Heritable virus-induced germline editing in tomato.

Here, we report the successful implementation of heritable virus-induced genome editing (VIGE) in tomato (Solanum lycopersicum). We generated three transgenic tomato lines expressing Streptococcus pyogenes Cas9 (SpCas9) under the control of Cauliflower mosaic virus 35S (35S), S. lycopersicum ribosomal protein S5A (SlRPS5A), or S. lycopersicum YAO promoters (SlYAO). These three lines were tested for somatic and heritable editing using the tobacco rattle virus (TRV)-based system carrying guide RNAs (gRNAs) fused with mobile RNA sequences. TRV with gRNA targeted to Phytoene desaturase (SlPDS) and Downy mildew resistance 6 (SlDMR6) genes fused to mobile RNA sequences showed significant somatic editing efficiency in all three tomato lines expressing SpCas9. However, the progenies from the SlYAO promoter-driven SpCas9 tomato infected with TRV with gRNA targeted to SlDMR6 fused to the mobile RNA sequence resulted in monoallelic mutations with a frequency of 3%. Optimization of environmental conditions, such as reduced light intensity, significantly increased heritable editing frequencies, from 0% to 86% at the SlPDS and from 3% to 100% at the SlDMR6, including biallelic mutations. These findings underscore the use of appropriate promoters to express Cas nucleases and optimized environmental conditions to enhance heritable genome editing efficiency in tomato using VIGE. Furthermore, our method enables the generation of mutants without additional tissue culture or transformation once a SpCas9-expressing tomato line is established.

Solanum lycopersicum

A rapid CRISPR-based nanodroplet assay enables direct clinical identification of mycobacteria species.

The global incidence and mortality of nontuberculous mycobacterial infections have risen sharply with population aging. In some regions, they are now surpassing Mycobacterium tuberculosis complex infections, imposing a substantial clinical and economic burden. Because nontuberous mycobacteria exhibit species-level heterogeneity and require prolonged culture for identification, their diagnosis remains slow and is frequently inaccurate. Here, we describe a multiplexed clustered regularly interspaced short palindromic repeats (CRISPR)-assisted nanodroplet differential identification (CANDI) diagnostic platform that integrates species-agnostic target amplification with species-specific CRISPR-associated protein 12a (Cas12a) detection in fluorescence-barcoded nanodroplets. By spatially compartmentalizing CRISPR reactions into color-encoded nanodroplets, CANDI overcomes the multiplexing limitations of conventional CRISPR diagnostics and enables simultaneous interrogation of multiple mycobacterial targets in a single assay. We designed a 16-plex panel that distinguishes 15 clinically relevant Mycobacterium species and subspecies. CANDI achieved high analytical sensitivity and accurate discrimination in samples containing coinfections with multiple species or subspecies. When applied to 230 clinical specimens, including sputum, tracheal aspirates, and other respiratory fluids, CANDI delivered subspecies-level results within 3.5 hours, achieving 97.08% sensitivity and 99.7% specificity relative to culture-based identification. By combining multiplexed, high-specificity CRISPR detection with scalable droplet-based engineering, CANDI has the potential to overcome the culture dependency of current diagnostics and enable species- and subspecies-level identification across the genetically complex Mycobacterium genus, offering a clinically adaptable framework for rapid, precision diagnosis of mycobacterial infections.

Humans

RT-RPA Assisted CRISPR/Cas12a Based One-Pot Rapid and Visual Detection of the Pan-Dengue Virus.

Globally ≤ 4 billion of the population are at potential risk of contracting dengue virus (DENV) infection. Seasonal outbreaks of dengue are frequently reported causing a high healthcare burden. Undiagnosed DENV can lead to severe morbidity and mortality. Early diagnosis of DENV relies on molecular methods, which are impractical in resource-constrained settings (RCSs). Dengue can be caused by any of the four distinct DENV serotypes. Therefore, a simple method for rapid diagnosis of Pan-DENV serotypes is of utmost importance at RCSs. A fluorescence detection platform for Pan-DENV using RT-RPA and CRISPR/Cas12a was developed targeting nonstructural 1 (NS1) gene for DENV-1, 2, and 3, and envelope (E) gene for DENV-2. Further, crRNA specific to DENV serotypes were designed to facilitate CRISPR/Cas12a detection. Analytical sensitivity was determined using synthetic RNA and DENV serotypes genome. Clinical validation of the assay was performed using RNA extracted from AES/AFI clinical samples. The developed CRISPR/Cas12a-based detection platform can detect all four serotypes of DENV viz 1-4 in a single pot using fluorescence detection. This assay showed the limit of detection ≥ 781 zg reaction- 1, ≥ 1.81 ag reaction-1, ≥ 62.5 fg reaction-1, and ≥ 2.5 pg reaction-1 for synthetic DENV-1, DENV-2, DENV-3, and DENV-4 template, respectively. Our assay demonstrated the analytic sensitivity of ≥ 10 ng reaction-1 for DENV-1 and DENV-4, and ≥ 0.5 ng reaction-1 for DENV-3 and DENV-4 genomes. This assay showed no cross-reactivity with other related etiologies tested causing AFI/AES. With 76 clinical samples (DENV PCR positive = 16, DENV PCR negative = 60), the assay demonstrated 93.7% sensitivity and 100% specificity with an overall accuracy of 98.7% for detection of the Pan-DENV serotypes. Our assay displayed comparable results to that of RT-PCR. The ease of interpretation and rapid detection of the Pan-DENV, represents the potential of the developed assay as an ideal point-of-care test. This assay upon field-deployment could help in reducing healthcare burden, provide differential diagnosis and support initiating early and prompt treatment to patients at RCS.

Dengue Virus

RT-RPA-Assisted CRISPR/Cas12a-Based Isothermal Detection of Chikungunya Virus.

Chikungunya virus (CHIKV) is transmitted through the bite of Aedes mosquitoes, specifically A. aegypti and A. albopictus. CHIKV belongs to the alphavirus with a positive-sense ssRNA genome of 11-12 kb size. The virus has been reported from various geographical regions across the globe. Chikungunya fever is an acute febrile illness, which, if left untreated, may develop into chronic arthralgia that may persist for several months or acute encephalitis syndrome. Therefore, early diagnosis of CHIKV is crucial to initiate prompt supportive treatment. Laboratory diagnosis of CHIKV typically relies on serological tests such as IgM antigen capture ELISA and molecular methods including RT-PCR or qRT-PCR. However, both these methods are not viable in peripheral settings. This chapter highlights recent advancements in molecular detection techniques for CHIKV, specifically isothermal detection methods that eliminate the requirement for complex instruments. The detection is facilitated by RT-RPA and CRISPR/Cas12a endonuclease. The assay offers advantages over existing methods such as rapid and early detection, and eliminates cross-over contamination, ultra-sensitivity, high specificity, and ease of result interpretation.

Chikungunya virus

Structure and evolution-guided design of minimal RNA-guided nucleases.

The design of RNA-guided nucleases with properties not limited by evolution can expand programmable genome-editing capabilities. However, generating diverse multidomain proteins with robust enzymatic properties remains challenging. Here, we use a protein design strategy that couples a structure-guided inverse-folding model with evolution-informed residue constraints to generate active, divergent variants of TnpB, a minimal CRISPR-Cas12-like nuclease, termed SynTnpBs. High-throughput screening of artificial intelligence-generated variants yielded editors that retained or exceeded wild-type activity in bacterial, plant, and human cells. Cryo-electron microscopy-based structure determination of the most divergent variant revealed stabilizing contacts in the RNA-DNA interfaces across conformations, demonstrating the design potential of this approach. Together, these results establish a strategy for creating non-natural RNA-guided nucleases and conformationally active nucleic acid binders, enlarging the designable protein space.

Humans

The SlGRAS9-SlMYC1 regulatory module controls glandular trichome formation and modulates resilience to pest in tomato.

Trichomes of aerial plant organs contribute to adaptive responses to abiotic and biotic stresses. In horticultural plants, increasing glandular trichome density is an effective breeding strategy to enhance resistance to herbivores through promoting the capacity to produce specialized metabolites. The regulatory mechanisms controlling multicellular trichome formation are only partially understood. In this study, we reveal that SlGRAS9 and SlMYC1 transcription factors form a regulatory module controlling glandular trichome formation in multiple tissues. Knockout of SlGRAS9 or overexpression of SlMYC1 in tomato leads to an increased number of type VI glandular trichomes and to higher terpenoid accumulation in leaves, petals, sepals, and fruits. Conversely, knockout of SlMYC1 results in reduced type VI glandular trichomes number and terpenoid levels. Promoter-binding and genetic interaction experiments revealed that SlGRAS9 negatively regulates the transcription of SlMYC1, indicating that the regulation of glandular trichome formation by SlGRAS9 is dependent, at least partly, on SlMYC1. Consistently, both SlGRAS9 knockout and SlMYC1 overexpression result in higher tolerance of tomato plants to spider mites and aphids. In addition to adding some of the missing components to the mechanisms controlling formation of type VI glandular trichome, our findings also uncover new targets for breeding strategies aimed at improving crop protection against pest invasion, thus ensuring crop yield resilience to climate change.

Trichomes

CRISPR-Cas regulates expression of embedded anti-phage defence systems.

Bacteria utilize diverse defence systems to protect against harmful foreign DNA such as bacteriophages1,2, but how these systems coordinate with each other remains poorly understood. Here we uncover CRISIS (CRISPR-supervised immune system), a widespread regulatory paradigm whereby type I CRISPR-Cas loci embed and transcriptionally modulate diverse innate defences. Small non-canonical CRISPR RNA (crRNA)-like RNAs guide the I-C CRISPR-associated complex for antiviral defence (Cascade) effector complex to inhibit promoters of diverse immune cassettes-including composite multi-system clusters-enabling their basal expression for antiviral activity while mitigating fitness costs associated with hyperactivation, such as host growth impairment or exclusion of beneficial plasmids. When CRISPR-Cas is compromised by mutation or anti-CRISPR proteins, there is a burst in transcription of these embedded defence systems, leading to higher-level innate immunity at the expense of host fitness. Together, adaptive CRISPR-Cas systems orchestrate diverse innate immune systems into a layered defence network, comprising a prokaryotic 'immunity guard' strategy.

Bacteriophages

Engineered virus-like particle-assembled Vegfa-targeting Cas9 ribonucleoprotein treatment alleviates neovascularization in wet age-related macular degeneration.

BACKGROUND: Age-related macular degeneration, particularly the wet form, is a leading cause of vision loss, characterized by vascular endothelial growth factor A (VEGFA) overproduction. Engineered virus-like particles (eVLPs) combine the efficiency of viral systems with the transient nature of non-viral platforms to offer a potential solution for delivering VEGFA-targeting genome editing enzymes in a safe and efficient manner. Here, we investigate the therapeutic efficacy of eVLPs for transient delivery of Vegfa-targeting Cas9 ribonucleoprotein in a laser-induced choroidal neovascularization mouse model of wet age-related macular degeneration. RESULTS: We find that Cas9-eVLPs enables efficient intracellular delivery in vitro, achieving up to 99% insertion and deletion frequency at Vegfa target locus and significant VEGFA protein downregulation in NIH/3T3 cells. A single subretinal injection of Cas9-eVLPs into the mouse retinal pigment epithelium effectively disrupts Vegfa expression, achieving an average indel efficiency of 16.7%. Compared to control groups, the laser-induced choroidal neovascularization mouse model exhibits significantly reduced choroidal neovascularization formation following Cas9-eVLPs intervention, and decreased VEGFA protein levels are detected in the retinal pigment epithelium. Furthermore, the retinal anatomical and functional toxicity are not affected after treatment. CONCLUSIONS: eVLPs exhibit the potential as a safe and efficient delivery platform for Cas9 ribonucleoproteins, achieving precise Vegfa downregulation and significant reduction in choroidal neovascularization in a mouse model of wet age-related macular degeneration. With transient delivery of gene editing enzymes, high editing efficiency, and minimal risk of genomic integration, eVLPs present a promising alternative to conventional delivery systems for advancing genome editing therapies in retinal diseases.

CRISPR-Associated Protein 9

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.

Gene Editing

Extracellular vesicles-mediated delivery of SpCas9 RNPs for therapeutic gene editing in Spinocerebellar Ataxia Type 3.

Spinocerebellar Ataxia Type 3 (SCA3) is a neurodegenerative dominantly-inherited disorder caused by an overexpansion of a CAG tract within the ATXN3 gene, conferring toxic properties to the ataxin-3 protein. Genome editing with CRISPR-Cas9 enzymes is a promising strategy to inactivate mutant ATXN3 alleles, however, in vivo delivery remains challenging. Extracellular vesicles (EVs) are promising delivery vehicles for Cas9 and single guide RNA (sgRNA) ribonucleoproteins that minimize genomic exposure to highly active endonucleases. In this study, we designed SpCas9 with a palmitoylation motif that enables SpCas9 and sgRNA enrichment into EVs. Introduction of a photocleavable linker - PhoCl - allowed the photo-inducible release of SpCas9 from the palmitoylation motif in EVs, increasing target engagement to ATXN3 in vitro. EVs loaded with SpCas9 ribonucleoproteins resulted in ATXN3 knockout in SCA3 patient-derived iPSCs and two SCA3 animal models. These findings highlight an innovative route for transient delivery of gene editing tools. This approach provides a promising therapeutic platform for the treatment of genetic diseases, including SCA3.

Humans

Engineering bubble structures as Cas12a activators for highly sensitive monitoring of WRN helicase function.

The Werner syndrome helicase (WRN) is a critical synthetic lethal target in microsatellite instability cancers, essential for resolving complex genomic structures like replication bubbles and R-loops. However, strategies to simultaneously discriminate WRN activity on DNA versus DNA-RNA substrates in living cells are lacking. Here, we developed a structure-specific CRISPR/Cas12a biosensing strategy to visualize WRN functional activity by engineering bubble-structure probes. These probes were rationally designed to structurally mimic DNA replication bubbles and R-loop associated DNA-RNA hybrids. Upon specific unwinding by WRN, the probes release a sequestered activator strand that triggers Cas12a trans-cleavage, effectively converting the unwinding event into an amplified fluorescent signal. This assay achieves low picomolar sensitivity (LODs: 5.6-6.0 pM) and exceptional selectivity against homologous RecQ helicases. Uniquely, this strategy enables the parallel quantification of WRN activity on both substrate types, providing insights into distinct WRN-mediated pathways for resolving genomic stress. We further demonstrated the strategy's utility by visualizing endogenous WRN dynamics in living cells and profiling the efficacy of small-molecule inhibitors. This work offers a powerful molecular toolkit for dissecting WRN biology and facilitating high-throughput drug screening in targeted cancer therapy.

Werner Syndrome Helicase

Strategic targeting of Cas9 nickase induces large segmental duplications.

Gene/segmental duplications play crucial roles in genome evolution and variation. Here, we introduce paired nicking-induced amplification (PNAmp) for their experimental induction. PNAmp strategically places two Cas9 nickases upstream and downstream of a replication origin on opposite strands. This configuration directs the sister replication forks initiated from the origin to break at the nicks, generating a pair of one-ended double-strand breaks. If homologous sequences flank the two break sites, then end resection converts them to single-stranded DNAs that readily anneal to drive duplication of the region bounded by the homologous sequences. PNAmp induces duplication of segments as large as ∼1 Mb with efficiencies exceeding 10% in the budding yeast Saccharomyces cerevisiae. Furthermore, appropriate splint DNAs allow PNAmp to duplicate/multiplicate even segments not bounded by homologous sequences. We also provide evidence for PNAmp in mammalian cells. Therefore, PNAmp provides a prototype method to induce structural variations by manipulating replication fork progression.

Saccharomyces cerevisiae

Leveraging protein language models for cross-variant CRISPR/Cas9 sgRNA activity prediction.

MOTIVATION: Accurate prediction of single-guide RNA (sgRNA) activity is crucial for optimizing the CRISPR/Cas9 gene-editing system, as it directly influences the efficiency and accuracy of genome modifications. However, existing prediction methods mainly rely on large-scale experimental data of a single Cas9 variant to construct Cas9 protein (variants)-specific sgRNA activity prediction models, which limits their generalization ability and prediction performance across different Cas9 protein (variants), as well as their scalability to the continuously discovered new variants. RESULTS: In this study, we proposed PLM-CRISPR, a novel deep learning-based model that leverages protein language models to capture Cas9 protein (variants) representations for cross-variant sgRNA activity prediction. PLM-CRISPR uses tailored feature extraction modules for both sgRNA and protein sequences, incorporating a cross-variant training strategy and a dynamic feature fusion mechanism to effectively model their interactions. Extensive experiments demonstrate that PLM-CRISPR outperforms existing methods across datasets spanning seven Cas9 protein (variants) in three real-world scenarios, demonstrating its superior performance in handling data-scarce situations, including cases with few or no samples for novel variants. Comparative analyses with traditional machine learning and deep learning models further confirm the effectiveness of PLM-CRISPR. Additionally, motif analysis reveals that PLM-CRISPR accurately identifies high-activity sgRNA sequence patterns across diverse Cas9 protein (variants). Overall, PLM-CRISPR provides a robust, scalable, and generalizable solution for sgRNA activity prediction across diverse Cas9 protein (variants). AVAILABILITY AND IMPLEMENTATION: The source code can be obtained from https://github.com/CSUBioGroup/PLM-CRISPR.

CRISPR-Cas Systems

CasY7: An optimized Cas12i system for enhanced genome editing in monocot crops.

The CRISPR-Cas12 family nucleases, particularly the Cas12i subtypes, are considered promising alternatives to Cas9 for genome editing in plants. We previously developed a new Cas12i variant, CasY7, which has been successfully applied in clinical trials; its performance in plants remains to be investigated. Initial testing in stable transgenic maize and rice showed that the codon-optimized CasY7 (pCasY7e1) achieved average editing efficiencies of 58.7% and 62.3% across five target sites, respectively, outperforming the typical Cpf1 (pCpf1) control that targets the same sites. To further enhance activity, we fused T5 exonuclease to CasY7 (pCasY7e2), which shifted mutation profiles toward larger deletions, and subsequently integrated an MS2 aptamer into the crRNA scaffold (pCasY7e3). The optimized pCasY7e3 system increased editing efficiencies to 87.7% in maize and 82.9% in rice-approximately 2.7-fold higher than pCpf1. We further demonstrated multiplexed editing in maize, generating biallelic dwarf mutants, and validated functionality in hexaploid wheat with editing efficiencies up to 58.8%. Overall, our comprehensive validation across 942 transgenic plants confirmed robust editing in maize, rice, and wheat, establishing CasY7 as a high-efficiency addition to the CRISPR toolkit.

Zea mays