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PubMed2025

Innovative strategies for mitochondrial dysfunction in myeloproliferative neoplasms a step toward precision medicine.

Myeloproliferative neoplasms (MPNs) are clonal disorders of hematopoietic stem cells characterized by aberrant proliferation of myeloid lineages, driven primarily by mutations in JAK2, CALR, and myeloproliferative leukemia, leading to constitutive activation of the JAK-STAT pathway. Emerging evidence highlights mitochondrial dysfunction as a key factor in MPN pathogenesis, contributing to increased reactive oxygen species production, mitochondrial DNA mutations, and dysregulated mitochondrial dynamics, which collectively promote clonal expansion and apoptosis resistance. Targeting mitochondrial pathways has gained attention as a therapeutic strategy, with approaches including mitochondria-targeted antioxidants, metabolic inhibitors, and modulation of mitophagy and mitochondrial fission/fusion dynamics. However, challenges such as drug delivery specificity, therapeutic resistance, and off-target effects remain significant. Recent advances in precision medicine, incorporating genomic, transcriptomic, and proteomic profiling, offer a more personalized approach to MPN treatment by tailoring interventions to individual mutation patterns. Additionally, novel therapeutic strategies, including gene editing technologies, RNA-based therapies, and nanoparticle-mediated drug delivery systems, hold promise for overcoming current treatment limitations. The integration of artificial intelligence in drug discovery and biomarker identification further enhances the potential for targeted therapies. Future research should focus on refining these strategies, developing reliable biomarkers for patient stratification, and exploring combination therapies that enhance treatment efficacy while minimizing adverse effects. By addressing mitochondrial dysfunction as an underlying driver of MPNs, these emerging approaches have the potential to improve disease management, extend patient survival, and enhance quality of life. Also, this new approach of precision medicine allows patient stratification and ensures that treatments are formed according to the individual disease biology of each patient, which results in overall better outcomes.

combination drug therapy↗
PubMed2026

Lipid-nanoparticle-mediated base editing of the trabecular meshwork rescues glaucoma in vivo.

Mutations in MYOC, the most common genetic cause of glaucoma, cause misfolded myocilin to accumulate in the endoplasmic reticulum (ER), leading to trabecular meshwork (TM) dysfunction, elevated intraocular pressure, and progressive vision loss. While gene editing offers curative potential, current delivery methods rely on viral vectors, which are limited by inflammation, off-target effects, and poor translatability. Here, we report a nonviral lipid nanoparticle (LNP) platform that enables selective in vivo delivery of mRNA encoding an adenine base editor and single guide RNA (LNP-ABE) to TM cells. A direct comparison of LNP-mCherry with lentiviral GFP revealed that LNPs outperform viral vectors, achieving markedly higher efficiency and greater selectivity for the TM without inducing ocular inflammation. In a Cre-inducible Tg.CreMYOCY437H glaucoma mouse model, LNP-Cre mRNA selectively induced mutant MYOC expression in the TM, faithfully recapitulating key disease features. A single administration of LNP-ABE achieved efficient on-target editing of mutant MYOC, reducing mutant myocilin protein by approximately 46%, decreasing aggregates, alleviating ER stress, and fully rescuing the glaucomatous phenotype in Tg.CreMYOCY437H mice. Importantly, no off-target editing or ocular toxicity was detected. These findings establish LNP-based mRNA delivery as a safe, efficient, and clinically translatable approach for TM-targeted genome editing with broad therapeutic potential in glaucoma.

Animals↗
PubMed2024

Aptazyme-directed A-to-I RNA editing.

As a promising therapeutic approach, the RNA editing process can correct pathogenic mutations and is reversible and tunable, without permanently altering the genome. RNA editing mediated by human ADAR proteins offers unique advantages, including high specificity and low immunogenicity. Compared to CRISPR-based gene editing techniques, RNA editing events are temporary, which can reduce the risk of long-term unintended side effects, making off-target edits less concerning than DNA-targeting methods. Moreover, ADAR-based RNA editing tools are less likely to elicit immune reactions because ADAR proteins are of human origin, and their small size makes them relatively easy to incorporate into gene therapy vectors, such as adeno-associated virus vectors (AAVs), which have limited space. Despite the promise of RNA editing as a therapeutic approach, precise temporal and spatial control of RNA editing is still lacking. Therefore, we have developed a small molecule-inducible RNA editing strategy by incorporating aptazymes into the guide RNA of the BoxB-λN-ADAR system. This chapter provides detailed protocols for targeted RNA editing by ADAR deaminases using aptazyme-based guide RNAs controlled by exogenous small molecules, marking the earliest use of aptazymes to regulate RNA editing strategies. Once small molecules are added or removed, aptazymes trigger self-cleavage to release the guide RNA, thus achieving small molecule-controlled RNA editing. To satisfy different RNA editing applications, we have realized the conditional activation and deactivation of A-to-I RNA editing of target mRNA using switch aptazymes. We provide step-by-step protocols for constructing guide RNA plasmids for regulatory purposes and conducting small molecule-induced RNA regulatory editing experiments in cells.

Animals↗
PubMed2005

Crystallography for protein kinase drug design: PKA and SRC case studies.

Protein crystallography can be used throughout the drug discovery process to obtain diverse information critical for structure based drug design. At a minimum, a single target structure may be available. Optimally, and especially for protein kinases, a broad range of crystal structures should be obtained to characterize target flexibility, structure modulation via co-factor binding or posttranslational modification, ligand induced conformational changes, and off-target complex structures for selectivity optimization. The flexibility of the protein kinases is in contrast to the need for "crystallizable" constructs, that is, proteins that crystallize under varying conditions and in varying crystal packing arrangements. Strategies to produce crystallizable protein kinase constructs include truncation to the catalytic domain, co-crystallization with rigidifying ligands, crystallization of known rigid forms, and point mutation to improve homogeneity or mimic less crystallizable proteins. PKA, the prototypical serine/threonine protein kinase, and SRC, a tyrosine kinase and the first identified oncoprotein, provide multiple examples of these various approaches to protein kinase crystallography for drug design.

Animals↗
PubMed2004

Gene expression microarray technologies in the development of new therapeutic agents.

We review in detail how gene expression microarray technology is benefiting all phases of the discovery, development and subsequent use of new cancer therapeutics. Global gene expression profiling is valuable in cancer classification, elucidation of biochemical pathways and the identification of potential targets for novel molecular therapeutics. We exemplify the value in tissue culture and animal models of cancer, as well as in clinical studies. The power of expression profiling alongside gene knockout or knockdown methods such as RNA interference is illustrated. The use of basal or constitutive gene expression profiling to understand and predict drug sensitivity or resistance is described. The ability of expression profiling to define detailed molecular signatures of drug action is emphasised. The approach can identify on-target and off-target effects. It can be used to identify molecular biomarkers for proof of concept studies, pharmacodynamic endpoints and prognostic markers for predicting outcome and patient selection.

Animals↗
PubMed2026

CRISPR/Cas9-Mediated Site-Directed Mutagenesis of Genes in Klebsiella pneumoniae.

Constructing target-gene mutants with a common genetic background is crucial for elucidating gene function in antimicrobial resistance (AMR) research. Taking advantage of the single-guide RNA (sgRNA) and protospacer adjacent motif (PAM) sequence (3'-NGG) specificity of the Cas9 protein in the CRISPR/Cas9 (Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) system and codon degeneracy, the authors design a repair template that incorporates the desired point mutation while excluding the PAM sequence disrupted by a synonymous substitution, thereby preventing re-cleavage by CRISPR/Cas9. This method employs two available plasmids, pCasKP-apr and pSGKP-spe, offering straightforward operation and high screening specificity. As a result, the approach enables efficient generation of genetically defined mutant strains of Klebsiella pneumoniae (K. pneumoniae) and is readily adaptable to routine laboratory settings. Furthermore, the protocol minimizes off-target editing, shortens experimental timelines, reduces screening workload, and provides a reliable platform for investigating resistance mechanisms, validating candidate genes, and supporting functional genomics studies in clinically relevant bacterial pathogens.

Klebsiella pneumoniae↗
PubMed2006

Thorough validation of siRNA-induced cell death phenotypes defines new anti-apoptotic protein.

Loss-of-function by means of RNA interference in cultured human cells enables rapid pathway dissection on a genome-scale. Improved siRNA design and key validation protocols are required to eliminate falsely identified phenotypes resulting from potential off-target consequences. Here, we demonstrate a validation strategy involving several steps for verifying cell death phenotypes revealed during loss-of-function screening. First, from a set of 45 novel human genes we identified gene candidates that, when silenced, induce apoptosis in cultured HeLa cells. For those candidates, we performed more extensive validation with multiple effective siRNAs. In addition, we designed rescue experiments involving candidate genes delivered exogenously and containing silent mutations in the siRNA target regions. Rescue of the observed knockdown phenotype demonstrated an original and more stringent validation of the siRNA's selectivity and the phenotype specificity for the target gene. As a result, our data reveals an anti-apoptotic function for novel human breast adenocarcinoma marker BC-2, adding new depth to BC-2's description as a putative tumor marker involved in cancer related pathways.

Apoptosis↗
PubMed2006

Inhibition of rho GTPases by RNA interference.

Selective down-modulation or silencing of individual members of the Rho-GTPase family is now practical using RNA interference. Transfection of mammalian cells with an individual siRNA duplex or siRNA pools can suppress expression of a specific isoform to understand its function. By adjusting the dose of siRNA, intermediate levels of suppression can be attained to test the biological role of different levels of a GTPase such as Rac. Nevertheless, there are significant potential pitfalls, including "off-target" effects of the siRNA on other genes. Besides demonstrating successful, noncytotoxic suppression of protein and activity levels of a specific GTPase, controls are essential to establish specificity. In this chapter, we provide methods for selective knockdown of expression by siRNA and confirmation of the effectiveness of Rho GTPase silencing, as well as descriptions and some examples of controls for specificity that include evaluations of dose-response, negative and positive controls, GTPase specificity, confirmation by using more than one siRNA for the same gene, rescue by a mutated siRNA-resistant cDNA encoding the target gene, and complementary supporting evidence. Selective silencing of specific Rho family GTPases should provide increasing insight into the regulatory and functional roles of each isoform in a wide variety of biological processes.

Cell Line↗
PubMed2024

Introducing a hemoglobin G-Makassar variant in HSCs by in vivo base editing treats sickle cell disease in mice.

Precise repair of the pathogenic mutation in hematopoietic stem cells (HSCs) represents an ideal cure for patients with sickle cell disease (SCD). Here, we demonstrate correction of the SCD phenotype by converting the sickle mutation codon (GTG) into a benign G-Makassar variant (GCG) using in vivo base editing in HSCs. We show successful production of helper-dependent adenoviral vectors expressing an all-in-one base editor mapping to the sickle mutation site. In HSC-enriched cells from SCD patients, transduction with the base editing vector in vitro resulted in 35% GTG > GCG conversion and phenotypic improvements in the derived red blood cells. After ex vivo transduction of HSCs from an SCD mouse model and subsequent transplantation, we achieved an average of 88% editing at the target site in transplanted mice. Importantly, in vivo HSC base editing followed by selection generated 24.5% Makassar variant in long-term repopulating HSCs of SCD mice. The treated animals demonstrated correction of disease hallmarks without any noticeable side effects. Off-target analyses at top-scored genomic sites revealed no off-target editing. This in vivo approach requires a single non-integrating vector, only intravenous/subcutaneous injections, and minimal in vivo selection. This technically simple approach holds potential for scalable applications in resource-limiting regions where SCD is prevalent.

Animals↗
PubMed2026

Application of compact CRISPR/Cas nucleases for citrus genome editing.

Gene editing technology continues to advance, and the range of available editing tools is steadily expanding. Recently, several compact and ultracompact systems have been developed, gaining considerable attention because their components can be efficiently packaged into viral vectors. To identify compact tools suitable for efficient genome editing in citrus, Casπ, CoCas9, along with their respective single guide RNAs, were synthesized, and CRISPR/Casπ and CRISPR/CoCas9 constructs were designed to assess their editing efficiency in 'Wanjincheng' orange (Citrus sinensis Osbeck). The Casπ was able to mediate genome editing in the citrus genome, although with low efficiency. In comparison, CoCas9 showed a transformation efficiency three times higher than that of the widely used SpCas9. Moreover, while the gene editing efficiency of CoCas9 was comparable to that of SpCas9, the significantly elevated transformation efficiency resulted in a significantly higher overall editing efficiency for CoCas9 relative to SpCas9. Mutation profiles generated by CoCas9 and SpCas9 were highly similar, and both nucleases displayed comparable target specificity at three potential off-target sites. These results indicate that Casπ is not suitable for application in citrus genome editing, whereas CoCas9 represents a promising alternative to SpCas9 for efficient and precise genome modification in citrus.

CRISPR-Cas Systems↗
PubMed2006

Exploring the mode-of-action of bioactive compounds by chemical-genetic profiling in yeast.

Discovering target and off-target effects of specific compounds is critical to drug discovery and development. We generated a compendium of "chemical-genetic interaction" profiles by testing the collection of viable yeast haploid deletion mutants for hypersensitivity to 82 compounds and natural product extracts. To cluster compounds with a similar mode-of-action and to reveal insights into the cellular pathways and proteins affected, we applied both a hierarchical clustering and a factorgram method, which allows a gene or compound to be associated with more than one group. In particular, tamoxifen, a breast cancer therapeutic, was found to disrupt calcium homeostasis and phosphatidylserine (PS) was recognized as a target for papuamide B, a cytotoxic lipopeptide with anti-HIV activity. Further, the profile of crude extracts resembled that of its constituent purified natural product, enabling detailed classification of extract activity prior to purification. This compendium should serve as a valuable key for interpreting cellular effects of novel compounds with similar activities.

Antineoplastic Agents, Hormonal↗
PubMed2026

Enhanced CRISPR-Cas3-mediated genome editing using circularized crRNAs.

Type I-E CRISPR-Cas3 represents a genome-editing technology in which large deletions averaging several kilobases are introduced in target regions. However, its genome-editing efficiency varies considerably across targets and cell types, making it difficult to achieve consistent results. Here, we investigated the efficacy and stability of circularized CRISPR RNAs (ccrRNAs) to enhance CRISPR-Cas3-mediated genome editing in human cells. Using in vitro single-strand DNA cleavage assays, we demonstrated that ccrRNA induces Cascade complex formation. Significant genome-editing activity targeting the EMX1 and B2M genes was observed in cellular assays using K562 cells. Long-read sequencing identified large-scale deletion mutations at the target loci and no detectable off-target effects using ccrRNA. Furthermore, ccrRNAs exhibited extended intracellular stability compared with that for linear crRNAs, resulting in an enhanced editing efficiency. These results demonstrate that ccrRNAs enable stable, efficient, and highly specific genome editing and support the broader application of the long-range deletion system.

CRISPR-Cas3↗
PubMed2026

Targeted insertion of an optimized donor DNA is effective in a humanized mouse model of dominant retinitis pigmentosa.

Retinitis pigmentosa (RP) affects 1 in 3,000 individuals worldwide, with 30%-40% of cases inherited as autosomal dominant (AD). Mutations in RHO (RP4) are the most common cause of ADRP. Because most RHO mutations exert gain-of-function or dominant-negative effects, conventional gene supplementation is insufficient, requiring mutant allele inactivation. Allele-specific editing is impractical, as each mutation requires a unique therapeutic strategy. We present a mutation-agnostic, RHO-specific approach using adeno-associated viral vector-mediated homology-independent targeted integration (AAV-HITI). Optimized donor DNA design enables targeted integration and efficient transgene expression from the endogenous RHO locus. In a humanized RP4 mouse model harboring the RHO P23H mutant allele alongside an endogenous wild-type mouse Rho allele, AAV-HITI significantly improves retinal structure, function, and visual acuity up to 1 year post-treatment. Comprehensive molecular analyses characterize on-target editing in mouse retina and off-target editing in a human cell line. These findings establish an effective, human-centric AAV-HITI platform for RP4 and support its evaluation in this and other dominant genetic conditions.

AAV↗
PubMed2025

A streamlined base editor engineering strategy to reduce bystander editing.

Base editing (BE) can permanently correct over half of known human pathogenic genetic variants without requiring a repair template, thus serving as a promising therapeutic tool to treat a broad spectrum of genetic diseases. However, the broad activity windows of current base editors pose a major challenge to their therapeutic application. Here, we show that integrating a naturally occurring oligonucleotide binding module into the deaminase active center of TadA-8e, a highly active deoxyadenosine deaminase, enhances its editing specificity. When conjugated with a Cas9 nickase or alternative PAM Cas9 variants, the engineered TadA variant-TadA-NW1-consistently achieves robust A-to-G editing efficiencies within an editing window consisting of four nucleotides, substantially narrower than the 10-bp editing window of the TadA-8e-derived ABEs. Moreover, compared to ABE8e, ABE-NW1 shows significantly decreased Cas9-dependent and -independent off-target activity while maintaining similar on-target editing efficiency. Further, TadA-NW1 can be reprogrammed to perform desired cytidine deamination and adenine transversion within a restricted editing window. Finally, in a cystic fibrosis (CF) cell model, ABE-NW1 outperforms existing ABEs in accurately and efficiently correcting the CFTR W1282X variant, one of the most common CF-causing mutations. In all, we engineered a suite of base editors with refined activity windows, enabling more precise base editing. Importantly, this study presents a streamlined genome editor re-engineering strategy to accelerate the development of therapeutic base editing.

Gene Editing↗
PubMed2005

A systematic analysis of the silencing effects of an active siRNA at all single-nucleotide mismatched target sites.

The specificity of small interfering RNA (siRNA)-mediated gene silencing is a critical consideration for the application of RNA interference (RNAi). While the discovery of potential off-target effects by siRNAs is of concern, no systematic analysis has been conducted to explore the specificity of RNAi. Here, we present a study where a functionally validated siRNA (siCD46) was examined for silencing specificity on all possible 57 permutated target sites, each carrying a single-nucleotide mutation that would generate a mismatch when paired with siRNA antisense strand. We found that it was not only the position of the mismatched base pair, but also the identity of the nucleotides forming the mismatch that influenced silencing. Surprisingly, mismatches formed between adenine (A) and cytosine (C), in addition to the G:U wobble base pair, were well tolerated and target sites containing such mismatches were silenced almost as efficiently as its fully matched counterpart by siCD46. Northern blots showed that the silencing of fusion genes harboring the mutated target sites involved target mRNA degradation. This study provides direct evidence that the target recognition of siRNA is far more degenerative than previously considered. This finding is instrumental in the understanding of RNAi specificity and may aid the computational prediction of RNA secondary structure.

Base Pair Mismatch↗
PubMed2006

siVirus: web-based antiviral siRNA design software for highly divergent viral sequences.

siVirus (http://siVirus.RNAi.jp/) is a web-based online software system that provides efficient short interfering RNA (siRNA) design for antiviral RNA interference (RNAi). siVirus searches for functional, off-target minimized siRNAs targeting highly conserved regions of divergent viral sequences. These siRNAs are expected to resist viral mutational escape, since their highly conserved targets likely contain structurally/functionally constrained elements. siVirus will be a useful tool for designing optimal siRNAs targeting highly divergent pathogens, including human immunodeficiency virus (HIV), hepatitis C virus (HCV), influenza virus and SARS coronavirus, all of which pose enormous threats to global human health.

Anti-HIV Agents↗
PubMed2006

Validation of RNAi silencing specificity using synthetic genes: salicylic acid-binding protein 2 is required for innate immunity in plants.

RNA interference (RNAi) is widely used to specifically silence the expression of any gene to study its function and to identify and validate therapeutic targets. Despite the popularity of this technology, recent studies have shown that RNAi may also silence non-targeted genes. Here we demonstrate the utility of a quick, efficient and robust approach to directly validate the specificity of RNAi as an alternative to indirect validation of RNAi through gene expression profiling. Our approach involves reversing (complementing) the RNAi-induced phenotype by introducing a synthetic version of the target gene that is designed to escape silencing. This synthetic gene complementation approach can also be used for mutational analysis of the target gene, or to provide a functional version of a defective protein after silencing the defective gene by RNAi. Using this approach we demonstrate that the loss of systemic acquired resistance, a form of innate immunity in plants, is indeed due to the silencing of salicylic acid-binding protein 2 rather than to off-target effects.

Esterases↗
PubMed2026

Advances in CRISPR Base Editing: From Molecular Evolution to Therapeutic Applications in Genomic Medicine.

CRISPR-Cas9 systems revolutionized gene editing, but inherent drawbacks, namely DNA double-strand breaks (DSBs) and the difficulty of achieving precise repairs (due to low HDR efficiency), led researchers to invent new, more accurate gene editing tools. Base editing represents a significant leap forward, enabling targeted single-nucleotide conversions directly on the DNA without DSBs or donor templates. The core technology involves fusing catalytically dead or nickase Cas proteins to DNA deaminase enzymes. Cytosine base editors (CBEs) convert C•G to T•A pairs, while adenine base editors (ABEs) change A•T to G•C. These editors exploit the deaminase function within the R-loop structure formed by Cas binding and co-opt endogenous DNA repair mechanisms for precision. While offering improved efficiency and editing precision, base editing faces persistent challenges, such as off-target effects, bystander edits, delivery and ethical concerns. Continuous engineering efforts have refined these tools, enhancing accuracy, expanding targetability and reducing unwanted edits. The base editing arsenal has also broadened to include C-to-G base editors (CGBEs), dual A&C editors and versions targeting organelles. Successful preclinical studies demonstrating the correction of mutations responsible for the disease have paved the way for clinical trials, which are now testing therapies for conditions like sickle cell disease, β-thalassaemia and hypercholesterolemia using various delivery systems. This review explores CRISPR base editing's origins, mechanisms of action, potential therapies and current restrictions, pointing to its broadening impact on medical genetics.

Humans↗