🧬 PubMed RNA Editing Daily Digest

Miniature CRISPR-Cas12f nucleases are attractive candidates for therapeutic genome editing because of their compact size and compatibility with adeno-associated virus (AAV) delivery. However, editing efficiencies in mammalian cells are lower than those of larger systems. The extensive phylogenetic diversity of Cas12f suggests unexplored mechanistic variation with the potential for optimization. Here we identify and characterize a naturally occurring Cas12f ortholog discovered through metagenomics, Alistipes sp. Cas12f (Al3Cas12f), which supports robust genome editing in human cells. Through structural, biochemical and kinetic analyses, we compare Al3Cas12f to two recently described orthologs, Oscillibacter sp. Cas12f and Ruminiclostridium herbifermentans Cas12f. These orthologs present divergent architectures and regulatory features governing protospacer-adjacent motif recognition, guide RNA (gRNA) binding, dimerization and DNA cleavage. Notably, Al3Cas12f achieves efficient R-loop formation through a stable dimer interface and a naturally optimized gRNA. Leveraging these structural insights, we generate an engineered Al3Cas12f variant (RKK) that increases editing and improves activity across several tested genomic loci. By overcoming locus-dependent variability and an apparent potency threshold, this engineered compact editor seems to expand the feasibility of low-dose, AAV-compatible therapeutic genome editing. Our results elucidate mechanistic determinants of Cas12f activity and offer a framework for engineering compact genome editors that may bear therapeutic potential.

Neurodegenerative diseases (NDs), including Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis (ALS), represent a growing global health challenge characterized by progressive neuronal loss and a lack of definitive disease-modifying treatments. This review explores the emerging potential of targeting non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and exosomal RNAs, to modulate pathogenic molecular pathways and address the underlying molecular origins of neurodegeneration. We evaluate the integration of advanced computational techniques for RNA structure prediction and gene regulatory network analysis, alongside chemical engineering strategies-such as Locked Nucleic Acids (LNAs) and phosphorothioate modifications-aimed at enhancing the stability and specificity of RNA-based molecules. Furthermore, we analyze cutting-edge delivery and editing technologies, including nanotechnology-driven solutions for precise neuronal targeting and the CRISPR/Cas13 system for direct ncRNA manipulation.The findings indicate that while challenges in delivery efficiency and long-term efficacy persist, the synergy of chemical engineering and computational modeling significantly improves the therapeutic profile of ncRNAs, with exosomal pathways offering a novel route for intercellular signaling modulation and biomarker discovery. Therapeutic interventions directed at specific clinical targets, such as miR-34a and BACE1-AS, demonstrate the capacity to influence protein aggregation and neuroinflammatory cascades. Although ncRNA-based therapies are currently in nascent stages, ongoing technological advancements in RNA editing and nanotechnology offer a transformative framework that could redefine the future of ND treatment and successfully halt disease progression rather than merely managing symptoms.

Rett syndrome is a rare X-linked neurodevelopmental disorder caused by mutations in MECP2, a gene critical for neuronal function, chromatin organization, and synaptic plasticity. After a period of apparently normal early development, individuals with Rett syndrome experience rapid regression followed by lifelong neurological impairment. Notably, preclinical studies have shown that restoration of MeCP2 expression can reverse established symptoms in adult mice, positioning Rett syndrome as a promising target for molecular therapies. However, MECP2 is extremely dosage sensitive and both insufficient and excessive expression are harmful, creating a narrow therapeutic window and a major challenge for treatment design. This review examines the evolving landscape of gene- and RNA-based therapies for Rett syndrome, with a focus on strategies that enable precise MeCP2 replacement, dosage control, and widespread central nervous system delivery. We discuss clinical-stage adeno-associated virus gene replacement programs, including TSHA-102 and NGN-401, highlighting their vector designs, regulatory elements, delivery approaches, and emerging clinical data. Advances in adeno-associated virus capsid engineering and vector optimization aimed at improving neuronal targeting while minimizing peripheral exposure and immune toxicity are also reviewed. Beyond gene supplementation, we explore approaches that restore endogenous MECP2 regulation, such as reactivation of the inactive X chromosome, as well as DNA and RNA editing strategies. Collectively, these advances reflect a shift toward precision-regulated therapies for Rett syndrome that may provide a model for treating other dosage-sensitive neurodevelopmental disorders.

Myocardial infarction results in irreversible cardiomyocyte loss and fibrotic remodeling in adult mammals, whereas some vertebrates retain the ability to regenerate cardiac tissue. Comparative studies suggest that immune responses critically influence repair outcomes, yet the immune programs associated with regeneration remain incompletely defined. Here, we investigate how immune modulation accelerates cardiac repair in the nonregenerative medaka (