🧬 PubMed RNA Editing Daily Digest

RNA plays a pivotal role in the regulation of gene expression, and its spatiotemporal dynamics are critical for elucidating fundamental biological processes and disease mechanisms. However, traditional RNA imaging methods, such as fluorescence in situ hybridization (FISH) and the MS2-GFP system, often require cell fixation, suffer from low labeling efficiency, or interfere with native RNA functionthus limiting their ability to monitor RNA behavior in living cells. In recent years, CRISPR technology has rapidly emerged as a powerful tool for live-cell RNA imaging due to its high target specificity, signal amplification capability, and excellent compatibility with living systems. This review provides a comprehensive overview of recent advances in CRISPR-based live-cell RNA imaging, highlighting its imaging principles, technical advantages, and representative applications.

Programmable A-to-I RNA editing using endogenous ADAR enzymes is emerging as a therapeutic strategy, but editability remains difficult to predict because ADAR recognition depends on double-stranded RNA geometry and stability rather than sequence alone. We present ADAREDIT, a structure-explicit graph-attention framework that represents each dsRNA substrate as a nucleotide graph with backbone and base-pair edges and augments this representation with typed interactions and a motif-sensitive sequence branch. We trained and evaluated the model on high-confidence inverted Alu duplexes (n = 905) with secondary structures predicted by RNAfold and editing levels measured across 8,603 GTEx RNA-seq samples spanning 47 tissues. Across five tissue contexts and comprehensive cross-tissue transfer experiments, ADAREDIT consistently outperformed sequence-only CNN, transformer, and RNA language model baselines and achieved strong discrimination on combined tissue data (AUROC/AUPRC = 0.96; F1 ≈ 0.90). The same graph representation transferred to evolutionarily distant non-Alu species (sea urchin, acorn worm, and octopus), indicating conserved principles of ADAR substrate recognition. Finally, attention profiles and in silico mutagenesis recapitulated known biochemical constraints, including suppression by an upstream guanosine, and revealed longer-range asymmetric structural influences on editing. The sources of this work are available at our repository: https://github.com/Scientific-Computing-Lab/AdarEdit.

The CRISPR/Cas9 gene-editing technology has been widely used in defining gene functions and crop improvement. However, some genes are essential for plant growth and development. Loss-of-function homozygous mutations in essential genes lead to plant death or sterility. Mutations in essential genes need to be maintained and propagated in heterozygous plants. CRISPR/Cas9 technology is highly efficient in generating homozygous or bi-allelic mutations at T0 generation in rice, making it difficult to generate useful genetic materials for essential genes using traditional gene editing technology. In this study, we designed Transgene-Killer CRISPR (TKC)-mediated mismatch-spacer targeting (TKC-M) to efficiently generate heritable heterozygous mutations in essential genes in rice. Leveraging our earlier transgenic offspring self-elimination TKC platform, TKC-M relied on timely self-elimination of Cas9 and engineered gRNA-target mismatches to enrich heritable heterozygous or mosaic incomplete-edited T0 mutants and heterozygous progeny. We found that the sensitivity of targets to spacer mismatch(es) varies. A single-base mismatch at gRNA positions 11 or 17 yielded abundant heritable heterozygotes in sensitive targets. For insensitive targets, dual mismatches at positions 8 and 15 maximised heritable heterozygotes. Co-transformation of rice with TKC vectors carrying gRNA without mismatches (G1), gRNA with a mismatch at position 11 (M11) and M8 + M15 spacers, termed TKC-M Cocktail (TKC-MC) significantly increased the incomplete-edited mutant ratio compared with using G1 alone. This work establishes a technical foundation for generating mutant libraries that cover every single gene in a plant genome and for in-depth research on essential genes.

Here, we present a protocol for marker-free genome editing in Saccharomyces cerevisiae by combining PCR-based selectable marker cassettes with CRISPR-Cas9. We describe steps for generating gene deletions using MX6 markers and excising the markers by introducing a reusable guide RNA (gRNA)-Cas9 plasmid and universal repair templates, allowing multiplex removal in a single step. Final verification by PCR yields marker-free strains that can be iteratively edited using the same selectable markers. For complete details on the use and execution of this protocol, please refer to Grissom et al.

Efficient genome writing in mammalian cells requires robust methods for integrating large DNA payloads. The previously described method mammalian Switching Antibiotic resistance markers Progressively for Integration (mSwAP-In) enables iterative, biallelic genome rewriting in mammalian stem cells with DNA payloads exceeding 100 kb. However, the lack of standardized vectors and certain technical constraints have limited its broader adoption. Here we present an improved plasmid toolkit designed to streamline the implementation of mSwAP-In. The toolkit includes two core vectors. pLP-TK (pCTC174) is a landing-pad plasmid compatible with Golden Gate assembly of genomic homology arms and supports both mSwAP-In and the recombinase-mediated cassette exchange method Big-IN. mSwAP-In MC2v2 (pKBA135) is a versatile Big DNA assembly and delivery vector that supports Gibson-based assembly and incorporates positive, negative, and fluorescent selection markers, as well as a backbone counterselection cassette to minimize unwanted plasmid integration. The vector architecture also enables propagation in yeast and bacterial hosts, inducible plasmid copy-number amplification in standard E. coli strains, and CRISPR/Cas9-mediated payload release through preinstalled guide RNA target sites. We further characterize the FCU1/5-FC counterselection system in mouse embryonic stem cells and define conditions that minimize its bystander toxicity. Finally, we provide a set of Cas9-gRNA expression plasmids optimized for common mSwAP-In applications. Together, these reagents constitute a standardized and experimentally validated toolkit that simplifies large-scale genome writing using mSwAP-In.