CRISPR Journal最新文献

The silkworm (Bombyx mori) is a lepidopteran model insect that has been utilized for basic research and industrial applications. In this species, transcription activator-like effector nucleases (TALENs) have been found to function efficiently, and we previously developed a TALEN-mediated genome editing system for knockout and knock-in experiments using plasmids and single-stranded oligodeoxynucleotides (ssODNs) as donors. By contrast, clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9)-mediated genome editing, especially for gene integration, remains limited. In this study, we attempted to improve CRISPR-Cas systems to expand the utility of genome editing in the silkworm. Codon optimization of Cas9 improved genome editing efficiency, and single-guide RNA utilization also resulted in a higher genome editing efficiency than crRNA/tracrRNA when Cas9 messenger RNA (mRNA) was used. CRISPR-Cas12a-mediated genome editing and targeted sequence integration using ssODNs were both successfully performed. Overall, our study provides a robust technical platform that can facilitate basic and applied silkworm studies.

Cas9 must be localized to the nucleus to access the genome of mammalian cells. For most proteins, adding a single nuclear localization signal (NLS) is sufficient to promote nuclear entry. However, Cas9 nuclear entry appears to be inefficient as multiple NLSs are typically added to Cas9. Here, we found that three different Cas9 variants interact with the ribosome in HEK293T cells, and that this interaction is RNA mediated. Following immunoprecipitation-mass spectrometry of cytoplasmic-localized Cas9-0NLS and nuclear-localized Cas9-4NLS constructs, we identified novel Cas9 interactors in postmitotic neurons, including KEAP1 and additional ribosomal subunits, the latter were enriched in Cas9-0NLS samples. Collectively, our results suggest that Cas9 is sequestered in the cytoplasm of mammalian cells, in part, via interaction with the ribosome. Increasing the number of NLSs on Cas9 and/or increasing the amount of cytoplasmic guide RNA has the potential to outcompete ribosomal RNA binding and promote efficient nuclear localization of CRISPR-Cas9 variants.

Design of guide RNA (gRNA) with high efficiency and specificity is vital for successful application of the CRISPR gene editing technology. Although many machine learning (ML) and deep learning (DL)-based tools have been developed to predict gRNA activities, a systematic and unbiased evaluation of their predictive performance is still needed. Here, we provide a brief overview of in silico tools for CRISPR design and assess the CRISPR datasets and statistical metrics used for evaluating model performance. We benchmark seven ML and DL-based CRISPR-Cas9 editing efficiency prediction tools across nine CRISPR datasets covering six cell types and three species. The DL models CRISPRon and DeepHF outperform the other models exhibiting greater accuracy and higher Spearman correlation coefficient across multiple datasets. We compile all CRISPR datasets and in silico prediction tools into a GuideNet resource web portal, aiming to facilitate and streamline the sharing of CRISPR datasets. Furthermore, we summarize features affecting CRISPR gene editing activity, providing important insights into model performance and the further development of more accurate CRISPR prediction models.

The potato family includes a highly diverse cultivar repertoire and has a high potential for nutritional yield improvement and refinement but must in line with other crops be adapted to biotic and abiotic stresses, for example, accelerated by climate change and environmental demands. The combination of pluripotency, high ploidy, and relative ease of protoplast isolation, transformation, and regeneration together with clonal propagation through tubers makes potato highly suitable for precise genetic engineering. Most potato varieties are tetraploid having a very high prevalence of length polymorphisms and small nucleotide polymorphisms between alleles, often complicating CRISPR-Cas editing designs and strategies. CRISPR-Cas editing in potato can be divided into (i) characterization of target area and in silico-aided editing design, (ii) isolation and editing of protoplast cells, and (iii) the subsequent explant regeneration from single protoplast cells. Implementation of efficient CRISPR-Cas editing relies on efficient editing at the protoplast (cell pool) level and on robust high-throughput editing scoring methods at the cell pool and explant level. Gene and chromatin structure are additional features to optionally consider. Strategies and solutions for addressing key steps in genome editing of potato, including light conditions and schemes for reduced exposure to hormones during explant regeneration, which is often linked to somaclonal variation, are highlighted.

Characterizing biodiversity using environmental DNA (eDNA) represents a paradigm shift in our capacity for biomonitoring complex environments, both aquatic and terrestrial. However, eDNA biomonitoring is limited by biases toward certain species and the low taxonomic resolution of current metabarcoding approaches. Shotgun metagenomics of eDNA enables the collection of whole ecosystem data by sequencing all molecules present, allowing characterization and identification. Clustered regularly interspaced short palindromic repeats (CRISPR) and the CRISPR-associated proteins (Cas)-based methods have the potential to improve the efficiency of eDNA metagenomic sequencing of low-abundant target organisms and simplify data analysis by enrichment of target species or nontarget DNA depletion before sequencing. Implementation of CRISPR-Cas in eDNA has been limited due to a lack of interest and support in the past. This perspective synthesizes current approaches of CRISPR-Cas to study underrepresented taxa and advocate for further application and optimization of depletion and enrichment methods of eDNA using CRISPR-Cas, holding promise for eDNA biomonitoring.