Elvir Becirovic

Evolution guides biological systems to populate ecological niches, with viruses among the most successful examples of this principle. Viruses evolved over billions of years to efficiently transfer genetic information. Although viruses are highly diverse, most have converged towards remarkable similarity in the size and shape of their capsids ^1,2 . By contrast, generative models for protein design enable the creation of protein architectures that are absent from nature ^3–5 . Here we investigate whether protein assemblies designed by artificial intelligence can be functionalized to construct nucleic acid transport vehicles that are independent of evolutionary trajectories. By combining natural protein domains with synthetic protein assemblies, we create more than 100 bottom-up RNA transfer vehicles with unique sizes and shapes. These vehicles surpass the RNA transfer efficiency of widely used delivery vehicles by several orders of magnitude. In addition, we demonstrate that their tropism can be programmed by incorporation of computationally designed peptide binders and use them to deliver therapeutically relevant cargo RNAs into a wide range of cellular models. We show the in vivo biodistribution of one of these vehicles in a mouse at near-single-cell resolution, confirm its safety, and use it to perform a gene-editing treatment strategy for Duchenne muscular dystrophy in patient-derived cells and a pig. Our work demonstrates how proteins created by generative artificial intelligence can be harnessed for the rational engineering of RNA transport systems with the desired properties by overcoming the limitations of natural protein diversity.

Mutations in MYO7A result in the most severe subtype of Usher syndrome, the leading genetic cause of deafblindness. The large size of MYO7A requires dual adeno-associated virus (AAV) vectors for gene transfer or alternative methods to treat retinal defects. Here, we evaluated two treatment approaches: i) Supplementation of the human MYO7A gene via dual mRNA trans-splicing AAVs, and ii) CRISPR/Cas-mediated activation of the related murine Myo7b gene. Upon MYO7A supplementation, the transgenic MYO7A transcript and protein were expressed and correctly localized in retinal pigment epithelial (RPE) and photoreceptors of mice, pigs, and human retinal organoids. In RPE- and photoreceptor-specific Myo7a knockout mice, we could restore MYO7A expression and localization of melanosomes in RPE cells to wild-type levels. Myo7b activation led to partial restoration of melanosome localization, and the localization of MYO7B protein was largely comparable to MYO7A. These findings indicate that both approaches are in principle suitable for the therapy of Usher syndrome.

The Concise Guide to Pharmacology 2025/26 marks the seventh edition in this series of biennial publications in the British Journal of Pharmacology. Presented in landscape format, the guide provides a comparative overview of the pharmacology of drug target families. The concise nature of the Concise Guide refers to the style of presentation, being clear, accessible, and well‐structured, rather than the scope of the content, which spans approximately 500 pages. The Concise Guide summarises the key pharmacological properties of around 1900 human drug targets, and nearly 7000 interactions, involving around 4400 ligands. While the content is a substantially condensed version of the more detailed information and links available at the www.guidetopharmacology.org website, the printed guide serves as a permanent, citable, point‐in‐time record, that remains stable despite ongoing updates to the online database. The full contents of this publication can be found at https://bpspubs.onlinelibrary.wiley.com/doi/10.1111/bph.70231 . The Concise Guides provide expert‐curated recommendations of ‘Gold Standard’ selective pharmacological tools, available either commercially or as donations, which enable the identification of individual drug targets or families of drug targets. While the Concise Guide offers a more streamlined overview, more comprehensive information, including detailed pharmacological profiles and links to multiple online databases, is available through the Guide to Pharmacology website. The 2025/26 edition of the Concise Guide is based on material current as of mid‐2025, and supersedes all previous editions, including the 2023/24 Guide, and earlier Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC‐IUPHAR), and as such provides official IUPHAR classification and nomenclature for human drug targets, where applicable. Ion channels are one of the six major pharmacological targets into which the Guide is divided, with the others being: G protein‐coupled receptors, nuclear hormone receptors, catalytic receptors, enzymes and transporters. Each section includes nomenclature guidance, concise summaries, information of the best available pharmacological tools, key references, and suggestions for further reading.

Cyclic nucleotide-gated (CNG) channels are responsible for signalling in the primary sensory cells of the vertebrate visual and olfactory systems. CNG channels are voltage-independent cation channels formed as tetramers. Each subunit has 6TM, with the pore-forming domain between TM5 and TM6. CNG channels were first found in rod photoreceptors [83, 120], where light signals through rhodopsin and transducin to stimulate phosphodiesterase and reduce intracellular cyclic GMP level. This results in a closure of CNG channels and a reduced ‘dark current’. Similar channels were found in the cilia of olfactory neurons [181] and the pineal gland [71]. The cyclic nucleotides bind to a domain in the C terminus of the subunit protein: other channels directly binding cyclic nucleotides include hyperpolarisation-activated, cyclic nucleotide-gated channels (HCN), ether-a-go-go and certain plant potassium channels.The HCN channels are cation channels that are activated by hyperpolarisation at voltages negative to ~-50 mV. The cyclic nucleotides cyclic AMP and cyclic GMP directly bind to the cyclic nucleotide-binding domain of HCN channels and shift their activation curves to more positive voltages, thereby enhancing channel activity. HCN channels underlie pacemaker currents found in many excitable cells including cardiac cells and neurons [65, 192]. In native cells, these currents have a variety of names, such as Ih, Iq and If. The four known HCN channels have six transmembrane domains and form tetramers. It is believed that the channels can form heteromers with each other, as has been shown for HCN1 and HCN4 [2]. High resolution structural studies of CNG and HCN channels has provided insight into the gating processes of these channels [139, 146, 140]. A standardised nomenclature for CNG and HCN channels has been proposed by the NC-IUPHAR Subcommittee on voltage-gated ion channels [108].

Many patients suffering from inherited diseases do not receive a genetic diagnosis and are therefore excluded as candidates for treatments, such as gene therapies. Analyzing disease gene transcripts from patient cells holds potential for detection and interpretation of causative variants, but may be complicated by unavailability of affected tissue and/or lack of expression of the respective genes in blood or other easily accessible tissues. Using CRISPR/Cas-mediated transcriptional activation (CRISPRa), we developed a robust and efficient approach to activate genes in skin-derived fibroblasts and in freshly isolated peripheral blood mononuclear cells (PBMCs) from healthy individuals. This approach was successfully applied to blood samples from patients with inherited retinal dystrophies (IRDs). We were able to efficiently activate several IRD genes and detect their transcript isoforms using different diagnostically relevant methods such as RT-(q)PCR and long- and short-read RNA sequencing. CRISPRa-mediated transcriptional activation in PBMCs and fibroblasts will contribute to closing the critical gap in the genetic diagnosis of patients with IRD or other inherited diseases.

Despite their limited cargo capacity (<5 kb), adeno-associated viral (AAV) vectors remain the gold standard for in vivo delivery of therapeutic genes. Dual AAV vectors have emerged as a valuable tool for delivering large therapeutic genes and CRISPR tools to overcome this limitation. Here we provide a detailed protocol for the design, production and evaluation of dual AAV vectors. We offer guidelines for selecting a suitable dual AAV strategy, designing and cloning the genes to be delivered, and conducting in vitro evaluations of expression efficiency. In addition, we detail the production of dual AAVs and their assessment in human cellular models, such as induced pluripotent stem cell-derived retinal organoids. Finally, we outline the administration of dual AAVs via different routes in mice and the assessment of transgene-derived RNA and protein expression in various tissues. Overall, the instructions in this Protocol will aid in the efficient in vivo delivery of large DNA fragments using dual AAVs. This Protocol is adaptable to a wide range of model organisms as well as to human organoid cultures and, depending on the application, can be completed in 15–44 weeks.

CRISPR/Cas-mediated genome editing is an effective and attractive tool for the treatment of diseases or genes that cannot be adequately covered by gene replacement strategies. The first FDA-approved AAV-vector- and CRISPR/Cas-based clinical trials were each designed for the treatment of a subtype of an inherited retinal dystrophy, underscoring the importance of ophthalmic diseases in the field of gene (editing) therapies. This and most other pre-clinical therapeutic CRISPR/Cas approaches are typically designed for the treatment of single mutations. For the treatment of larger patient cohorts, however, mutation- or ideally gene-independent approaches appear to be more suitable. CRISPR/Cas-mediated transcriptional activation of genes (CRISPRa) is a promising approach to achieve these ambitious goals. In this minireview, focusing on inherited retinal dystrophies, we will discuss recent developments, advantages and limitations, and future prospects of CRISPRa as a therapeutic tool.

Many patients suffering from inherited diseases do not receive a genetic diagnosis and are therefore excluded as candidates for treatments, such as gene therapies. Analyzing disease-related gene transcripts from patient cells would improve detection of mutations that have been missed or misinterpreted in terms of pathogenicity during routine genome sequencing. However, the analysis of transcripts is complicated by the fact that a biopsy of the affected tissue is often not appropriate, and many disease-associated genes are not expressed in tissues or cells that can be easily obtained from patients. Here, using CRISPR/Cas-mediated transcriptional activation (CRISPRa) we developed a robust and efficient approach to activate genes in skin-derived fibroblasts and in freshly isolated peripheral blood mononuclear cells (PBMCs) from healthy individuals. This approach was successfully applied to blood samples from patients with inherited retinal dystrophies (IRD). We were able to efficiently activate several IRD-linked genes and detect the corresponding transcripts using different diagnostically relevant methods such as RT-qPCR, RT-PCR and long- and short-read RNA sequencing. The detection and analysis of known and unknown mRNA isoforms demonstrates the potential of CRISPRa-mediated transcriptional activation in PBMCs. These results will contribute to ceasing the critical gap in the genetic diagnosis of patients with IRD or other inherited diseases. Graphical

Evolution guides biological systems to populate ecological niches, with viruses being one of the most successful examples of that principle. Viruses evolved over billions of years for the efficient transfer of nucleic acids. Although highly diverse, most viruses converged toward a remarkable similarity in the size and shape of their capsids. In contrast, generative models for protein design enable the creation of protein architectures that are absent in nature. Here, we investigate whether AI-designed protein assemblies can be functionalized to construct nucleic acid transport vehicles that are independent of evolutionary trajectories. By combining natural protein domains with synthetic protein assemblies, we create more than a hundred bottom-up RNA transfer vehicles with unique sizes and shapes. These novel vehicles surpass the RNA transfer efficiency of widely used delivery vehicles by several orders of magnitude. Additionally, we demonstrate that their tropism can be programmed by incorporating computationally designed peptide binders and apply them to deliver various therapeutically relevant cargo RNAs, such as Gene Editors, into a wide range of cellular models. We show the in vivo biodistribution of one of these vehicles in a mouse with close to single-cell resolution and use it to perform a gene editing strategy for Duchenne muscular dystrophy in a pig. Our work demonstrates how proteins created by generative AI can be harnessed for the rational engineering of biological systems with desired properties by overcoming the limitations of natural protein diversity.

Large genes including several CRISPR-Cas modules like gene activators (CRISPRa) require dual adeno-associated viral (AAV) vectors for an efficient in vivo delivery and expression. Current dual AAV vector approaches have important limitations, e.g., low reconstitution efficiency, production of alien proteins, or low flexibility in split site selection. Here, we present a dual AAV vector technology based on reconstitution via mRNA trans-splicing (REVeRT). REVeRT is flexible in split site selection and can efficiently reconstitute different split genes in numerous in vitro models, in human organoids, and in vivo. Furthermore, REVeRT can functionally reconstitute a CRISPRa module targeting genes in various mouse tissues and organs in single or multiplexed approaches upon different routes of administration. Finally, REVeRT enabled the reconstitution of full-length ABCA4 after intravitreal injection in a mouse model of Stargardt disease. Due to its flexibility and efficiency REVeRT harbors great potential for basic research and clinical applications.