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Engineered Transformer Base Editor with Enhanced Editing Efficiency.

Canonical cytosine base editors (CBEs) achieve precise C-to-T conversions without inducing DNA double-strand breaks (DSBs), yet their clinical potential remains hampered by substantial off-target (OT) mutations. The recently developed transformer base editor (tBE) significantly reduces both genomic and transcriptomic OT mutations by using a cleavable deoxycytidine deaminase inhibitor (dCDI) domain. However, the modest base editing efficiency limits its broader applications. Here, through rational deaminase engineering and fusion of a uracil DNA glycosylase inhibitor (UGI) domain, we developed the engineered tBE (etBE). The etBE exhibited substantially enhanced editing efficiencies compared with the parental tBE (up to 35.11-fold improvement), while maintaining high editing fidelity and background levels of OT mutations. As a therapeutic proof-of-concept, dual adeno-associated virus (AAV)-mediated delivery of etBE targeting proprotein convertase subtilisin/kexin type 9 (PCSK9), a well-established therapeutic target for cardiovascular diseases, was evaluated in a humanized mouse model. The treatment achieved efficient in vivo base editing (up to 35.13%), resulting in substantial reductions in plasma PCSK9 protein (24%) and low-density lipoprotein cholesterol (LDL-C) levels (33%), while inducing only minimal OT mutations. Collectively, etBE represents a highly efficient and specific base editing platform with enormous potential for both basic research and clinical applications.

CRISPR‐Cas9↗

Bacterial directed evolution of CRISPR base editors.

Base editing and other precision editing agents have transformed the utility and therapeutic potential of CRISPR-based genome editing. While some native enzymes edit efficiently with their nature-derived function, many enzymes require rational engineering or directed evolution to enhance the compatibility with mammalian cell genome editing. While many methods of engineering and directed evolution exist, plate-based discrete evolution offers an ideal balance between ease of use and engineering power. Here, we describe a detailed method for the bacterial directed evolution of CRISPR base editors that compounds technical ease with flexibility of application.

Gene Editing↗

Interactive graphic editor for analysis and enhancement of medical images.

We have developed an interactive graphic editor to define subregions within a volume of medical images arranged in serial sections. The editing methods include tracing and automatic growing of connected components defined by the gray level range. The editor performs a statistical analysis of the signal contained in each subvolume and is used in studies of magnetic resonance (MR) signal in medical images. The graphic editor is also used for creating 3D views from MR images based on the new volume-rendering algorithm. The editor transforms the volume of images by remapping their gray levels and by multiplanar cuts. The ability to suppress regions having the same signal intensity as the region of interest is important in generating an unobstructed view of the anatomical structures.

Brain↗

Transgene-free genome editing in citrus and poplar trees using positive and negative selection markers.

Transgene-free genome editing of the gene of interest in citrus and poplar has been achieved by co-editing the ALS gene via transient transgene expression of an efficient cytosine base editor. CRISPR-Cas genome editing systems have been widely used in plants. However, such genome-edited plants are nearly always transgenic in the first generation when Agrobacterium-mediated transformation is used. Transgene-free genome-edited plants are valuable for genetic analysis and breeding as well as simplifying regulatory approval. It can be challenging to generate transgene-free genome-edited plants in vegetatively propagated or perennial plants. To advance transgene-free genome editing in citrus and poplar, we investigated a co-editing strategy using an efficient cytosine base editor (CBE) to edit the ALS gene to confer herbicide resistance combined with transient transgene expression and potential mobile RNA-based movement of CBE transcripts to neighboring, non-transgenic cells. An FCY-UPP based cytotoxin system was used to select non-transgenic plants that survive after culturing on 5-FC containing medium. While the editing efficiency is higher in poplar than in citrus, our results show that the CBE-based co-editing strategy works in both citrus and poplar, albeit with low efficiency for biallelic edits. Unexpectedly, the addition of the TLS mobile RNA sequence reduced genome editing efficiency in both transgenic and non-transgenic plants. Although a small fraction of escaping plants is detected in both positive and negative selection processes, our data demonstrate a promising approach for generating transgene-free base-edited plants.

Populus↗

Efficient CRISPR/Cas-SF01 genome editing tools with high editing efficiency in allotetraploid oilseed rape.

CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-Cas9 has been widely utilized for plant genome editing, but the protospacer adjacent motif (PAM) requirement limits its editing scope. CRISPR/Cas12i3 belongs to the type-VI Cas system that has gained extensive attention due to its smaller size and less restricted canonical TTN PAM sequence. In this study, we explored the newly developed Cas-SF01 system (Cas12i3 variant) for genome editing in oilseed rape. We established an efficient protoplast transformation system in oilseed rape to compare editing efficiency between Cas-SF01 and Cas9. Cas-SF01 shows cleavage activities at the tested 5'-TTN-3' PAM sites with editing outcomes sharing considerable similarities with the CRISPR-Cas9 system in protoplast. Cas-SF01 also induces high efficiency mutagenesis for multiple target sites in stable transformed oilseed rape lines, generating mutants with multilocular silique and male sterile phenotypes. Furthermore, Cas-SF01-derived cytosine base editors (CBEs) were developed to produce targeted C-to-T base edits. Compared to SpCas9, Cas-SF01 has an expanded PAM range and effectively recognizes TTN PAMs, which has substantially broadened the scope of editable sites within the rapeseed genome. No mutations were identified at the putative off-target sites among the edited plants. This study developed a robust, first-of-its-kind Cas12 system in the allotetraploid Brassica napus, expanding the scope of editing and enriching genome-editing toolkits for biological research and genetic improvement.

Brassica napus↗

Transforming an industrial giant. Interview by Thomas A. Stewart and Louise O'Brien.

In his 12 years at the helm of Siemens, CEO Heinrich von Pierer designed and directed a major transformation. Taking this German icon from a technically superb but slow-moving industrial giantto a disciplined yet nimble multinational has posed enormous challenges. Since 1992, Siemens has revamped its portfolio of businesses, expanded its reach into 192 countries, and created a more local-market-driven culture, gaining recognition as one of the best-managed and most competitive companies in the world. In this edited interview with HBR editor Thomas A. Stewart and consulting editor Louise O'Brien, von Pierer describes the requirements for transformation and culture change and how he broke down historical barriers at Siemens. He shares his insights about portfolio restructuring, his lessons from competing with GE, and the pros and cons of being based in Europe versus America. He reflects on the true start of globalization after the fall of the Berlin wall and on how dramatically the company needed to change in order to counter the resulting pricing pressures across all of its businesses. He talks, too, about the biggest challenge on his successor's desk-"the particular challenge of China;" he says. Amid all these topics, von Pierer reiterates the importance of people: "We all talk about people as our most important resource, but as a matter of fact, who's really taking care of people?... We need [their] backing. We can't afford to run into a situation where people no longer accept what we do."

Administrative Personnel↗

Gene therapy for genodermatoses at the crossroads of innovation and clinical translation.

Inherited genodermatoses are a heterogeneous group of rare monogenic disorders. Among these, epidermolysis bullosa (EB) and ichthyoses represent paradigmatic disorders characterized by severe skin fragility and hyperkeratosis, respectively, and impaired barrier function, often with profound effects on quality of life and systemic health. Current management remains largely palliative, underscoring the urgent need for disease-modifying therapies. Over the past 2 decades, advances in epithelial stem cell biology, vector engineering and genome editing technologies have transformed the therapeutic landscape for genodermatoses. Ex vivo gene therapy has provided the first proof that genetically corrected epidermal stem cells can achieve long-term tissue regeneration in EB skin patients, establishing a new paradigm for regenerative medicine. In parallel, the emergence of programmable genome engineering platforms, including CRISPR/Cas nucleases, base editors and prime editors, have enabled increasingly precise strategies for mutation-specific correction in both recessive and dominant disorders. Furthermore, the development of in vivo topical approaches is expanding the possibility of directly targeting the skin. Despite these advances, substantial translational barriers continue to limit broad clinical implementation. Efficient and durable targeting of epidermal stem cells within a highly regenerative tissue, together with safe delivery across the skin barrier, stringent control of off-target activity, scalable manufacturing and demonstration of long-term safety, remain major challenges for the clinical translation of these approaches. In this Review, we discuss the current state of gene therapy for genodermatoses, highlighting key clinical milestones, emerging genome editing technologies and next-generation delivery systems. We further examine the biological and regulatory challenges that need to be overcome to bridge the gap between experimental innovation and clinically accessible therapies for patients with inherited skin diseases.

epidermolysis bullosa (EB)↗

Unraveling the Mystery of Pain: A Unique Clinical Encounter and Case Report.

BACKGROUND: The Clinical Pharmacogenetics Implementation Consortium published an updated guideline for opioids and CYP2D6, OPRM1, and COMT in December 2020. These guidelines include recommendations to avoid key opioids in patients who are ultrarapid or poor metabolizers of CYP2D6 to avoid toxicity and optimize efficacy. CASE REPORT: An older woman encountered a letter to the editor in a family magazine regarding genomically based responses to opioids. She reached out for more information and assistance, attesting to continued lack of analgesia to opioids prescribed during occasions of severe pain over the course of many years. A pharmacogenomic analysis proved to be the key to solving her mystery. CONCLUSION: Pharmacogenomic results may provide life-altering information transforming a patient's perspective on health care. Personalized medicine may be a key component in providing objective evidence for opioid treatment efficacy. There is a critical need for both provider and patient education to increase awareness of pharmacogenomics and how it can be applied to effective pharmacotherapy. Research is needed to explore appropriate, effective educational methods.

Humans↗

CRISPRoff epigenome editing for programmable gene silencing in human cell lines and primary T cells.

The advent of CRISPR-based technologies has enabled the rapid advancement of programmable gene manipulation in cells, tissues, and whole organisms. An emerging platform for targeted gene perturbation is epigenetic editing, the direct editing of chemical modifications on DNA and histones that ultimately results in repression or activation of the targeted gene. In contrast to CRISPR nucleases, epigenetic editors modulate gene expression without inducing DNA breaks or altering the genomic sequence of host cells. Recently, we developed the CRISPRoff epigenetic editing technology that simultaneously establishes DNA methylation and repressive histone modifications at targeted gene promoters. Transient expression of CRISPRoff and the accompanying single guide RNAs in mammalian cells results in transcriptional repression of targeted genes that is memorized heritably by cells through cell division and differentiation. Here, we describe our protocol for the delivery of CRISPRoff through plasmid DNA transfection, as well as the delivery of CRISPRoff mRNA, into transformed human cell lines and primary immune cells. We also provide guidance on evaluating target gene silencing and highlight key considerations when utilizing CRISPRoff for gene perturbations. Our protocols are broadly applicable to other CRISPR-based epigenetic editing technologies, as programmable genome manipulation tools continue to evolve rapidly.

Humans↗

Base editing for precision therapeutics.

Base editing (BE), the precise installation of single-nucleotide changes in DNA or RNA without inducing double-strand breaks, holds substantial therapeutic promise for correcting single-nucleotide variants, which constitute more than half of the known pathogenic genetic variants. Recent advances have improved base editor specificity, efficiency, and delivery, enabling clinically oriented procedures. Clinically, BE has shown early success or strong translational promise in sickle cell disease, β-thalassemia, leukemia (via CAR T and epitope engineering), hypercholesterolemia (PCSK9 and ANGPTL3), alpha-1-antitrypsin deficiency, and glycogen storage disease type Ia. Key remaining challenges include bystander editing within the activity window, residual off-target DNA and RNA editing, delivery constraints (payload size, tissue targeting, and redosing limits), immunogenicity, and the need for durable long-term safety evidence across relevant cell types and disease contexts. Continued technological refinements, careful preclinical validation, and rigorous clinical assessment will be essential to fully realize BE's transformative potential in precision medicine.

Humans↗

Homology between an endogenous viral LTR and sequences inserted in an activated cellular oncogene.

Recently, some of us reported the detection and molecular cloning of a rearranged cellular oncogene, designated rc-mos, from a non-virally-induced mouse myeloma, XRPC24. Recombinant lambda phage DNA containing the rc-mos gene was active in transforming NIH 3T3 cells in a transfection assay, whereas recombinant DNA containing the unrearranged c-mos gene was not. In rc-mos, coding sequences from the 5' end of c-mos were found to have been displaced by a novel cellular element whose nucleotide sequence was reported. We now document the fact that a 349-base pair (bp) segment of the novel DNA immediately adjacent to the retained c-mos sequences in rc-mos has close homology with the long terminal repeat (LTR) of a known intracisternal A-particle gene. This homology was mentioned in Nature recently after it had been brought to the attention of the editors (N. Hozumi and R. Hawley, personal communication).

Base Sequence↗

Prophylactic pharmacological treatment of chronic daily headache.

OBJECTIVE: To review all the prophylactic pharmacological treatments for chronic daily headache from the past decade. BACKGROUND: Chronic daily headache is among the most common diagnoses seen in specialized headache centers. Prior to 1988, there were no criteria for the diagnosis of chronic tension-type headache and chronic daily headache. An expanded chronic daily headache classification has been proposed. METHODS: A MEDLINE search was performed using the following key words: chronic daily headache, intractable headache, transformed migraine, chronic tension headache, and chronic tension-type headache. We limited our review to those studies published in English in the last decade, including published abstracts and letters to the editor. Double-blind studies carried out prior to 1988 were also included. RESULTS: Pharmacological treatments for chronic daily headache include antidepressants (tricyclics, tetracyclics, monoamine oxidase inhibitors, selective serotonin reuptake inhibitors), anticonvulsants, muscle relaxants, 5-HT1 agonists, ergots, 5-HT2 antagonists, antianxiety agents, and miscellaneous drugs. Many of these reports are anecdotal, and most are open rather than double-blind studies. CONCLUSIONS: There is a great variety of pharmacological treatments available for chronic daily headache. Only the antidepressants have been extensively studied. Other medications may be used if these fail. Recommendations based on our experience at the Headache Unit of the Montefiore Medical Center are outlined here.

Anticonvulsants↗

An automatized computer-method utilizing Procomm Plus and DataEase (4.2) PC and SAS (6.06) mainframe software for isolated, perfused guinea-pig heart studies.

A powerful, time sharing and automatized method of a comprehensive data analysis for isolated, perfused guinea-pig heart studies is described. Data are collected using DataEase PC software (version 4.2) into forms with data fields specified for vital parameters consistently recorded in isolated, perfused heart studies (HR, CBF, PEAKPRESSURE, DPDT, MVO2). After running, DataEase reports the data and information is uploaded to an IBM 3081D mainframe computer on each day of heart experiment and data collection. The uploading process, the data archival and the statistical analyses are automatized by Procomm Plus commands written in Aspect Source Program (.ASP) Files for logging, data transforming and file management procedures. The ASPCOMP.EXE compiler compiles these .ASP files into Aspect Script eXecutable (.ASX) programs, which run on the PC in our laboratory and activate WYLBUR (IBM 3081D Batch-job service and Command file processor) edited files in the mainframe's electronic devices then upload, backup and save data into these files. SAS EXE files containing program instructions for the data analyzing system are then forced by Procomm Plus to operate over the data just uploaded. SAS reads the DATA files by its INFILE facility and performs comprehensive statistical analyses and produces hard output including graphics and JOB reports of dose-response- and logaritmic scale curves for delivery to team members. This computerized and automatized method developed for isolated, perfused guinea-pig heart studies is capable of performing multiple file transfer, sophisticated statistical analyses and graphic procedures after one keystroke on the PC (Alt-F5 in Procomm Plus section) and also facilitates a consistent and convenient method for planning, controlling and standardizing experiments. The method is based on an interactive computer conversation between the PC in the laboratory and the remote's WYLBUR editor. No human presence is needed; however, in case of failure, Procomm Plus gives one of the team members supervising the system a phone call in order to get human help.

Animals↗

The down-regulation of HLA-DM gene expression in rheumatoid arthritis is not related to their promoter polymorphism.

HLA-DM molecule, a class II-like heterodimer, is a critical factor of HLA class II-dependent Ag presentation. It acts as a molecular chaperone and also functions as a peptide editor favoring the presentation of high-stability peptides. Thus, it appears to skew the peptide repertoire presented to T cells. Variation in HLA-DM expression has considerable effect on Ag presentation and regulation of these genes is likely to be a prerequisite to prevent autoimmunity. In this study, rheumatoid arthritis (RA) was chosen as a model of human autoimmune disease since its genetic susceptibility is known to be associated with the HLA-DR and -DM components. We described a limited nucleotide polymorphism in the HLA-DM promoters with functional impact on basal transcriptional activity and IFN-gamma induction as assessed in vitro. However, no difference of allele frequencies was found between controls and RA patients. Despite of this lack of association, expression of HLA-DM molecules was also investigated. Interestingly, an underexpression of HLA-DM transcripts and protein was shown in peripheral blood B cells from RA patients compared with controls or inflammatory arthritis patients. This underexpression does not affect HLA-DR genes and is responsible for a decrease of the DM:DR ratio in RA patients. This specific HLA-DM down-regulation is likely to have important consequences on Ag presentation and could participate in the autoimmune process in RA.

Arthritis, Rheumatoid↗