CRISPR Journal最新文献

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.

CRISPR-Cas9 genome editing holds tremendous potential for accelerating genetic improvements in aquaculture. The success of the CRISPR-Cas9 system relies on the specificity and efficiency of engineered single-guide RNAs (sgRNAs). In this study, we optimized an in vitro validation protocol for sgRNAs to streamline the gene editing process, capitalizing on the limited breeding season of the Pacific oyster (Crassostrea gigas). We evaluated the efficiency of 11 sgRNAs targeting four genes both in vitro and in vivo in C. gigas. In addition, we found that Cas9 protein differs from Cas9 mRNA in gene editing efficiency at various stages of early development. Cas9 protein proved particular efficacy in achieving early and efficient gene knockout, functioning effectively during the first cell division and facilitating biallelic gene knockouts. Statistical analysis showed that in the protein group, the biallelic editing frequency ranged from 12.5% to 57.8%, and the overall editing frequency reached as high as 75-90.6%. The mRNA group exhibited a biallelic editing frequency of 3.1-14.0% and the overall editing frequency spanning 65.6-78.1%. Contrary to expectations, low-temperature incubation (20°C) of oyster embryos prolonged the time window for the first cell division but did not improve gene editing efficiency, likely due to the high temperature sensitivity of Cas9 enzyme activity. Together, this study provides a comprehensive analysis of factors affecting the efficiency of CRISPR-Cas9 gene editing in C. gigas, providing a robust framework for future gene editing endeavors in mollusks and other marine invertebrates.

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.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in either the TSC1 or TSC2 genes. Though TSC causes the formation of nonmalignant tumors throughout multiple organs, the most frequent causes of mortality and morbidity are due to neurological complications. In two-thirds of cases, TSC occurs sporadically and TSC2 pathogenic variants are approximately three times more prevalent than TSC1 pathogenic variants. Here, we utilized CRISPR-Cas9-mediated homology directed repair in patient induced pluripotent stem cells (iPSCs) to correct two types of TSC2 pathogenic variants generating two isogenic lines. In one line, we corrected a splice acceptor variant (c.2743-1G>A), which causes the skipping of coding exon 23 and subsequent frameshift and introduction of a stop codon in coding exon 25. In the second line, we corrected a missense variant in coding exon 40 within the GTPase-activating protein domain (c.5228G>A, p.R1743Q). The generation of TSC2 patient iPSCs in parallel with their corresponding CRISPR-corrected isogenic lines will be an important tool for disease modeling applications and for developing therapeutics.

Flax is an important crop used for oil and fiber production. Although genetic engineering has been possible in flax, it is not commonly used to produce cultivars. However, the use of genome editing technology, which can produce site-specific mutations without introducing foreign genes, may be a valuable tool for creating elite cultivars that can be easily cultivated. The purpose of this study was to investigate the potential of genome editing in flax by establishing the clustered regularly interspaced short palindromic repeats (CR ISPR)-CRISPR-associated protein 9 (CRISPR-Cas9) genome editing system using the phytoene desaturase (PDS) gene, which produces albino mutants that are easily identifiable. Four sgRNAs were designed from two PDS genes of Flax (LuPDS1 and LuPDS2), and CRISPR-Cas9 genome editing vectors were constructed. After gene transformation, albino phenotypes were observed in transformed callus and regenerated plantlets on selection media. Polymerase chain reaction (PCR) amplification and sequencing of the PDS genes revealed deletions and insertions in the albino tissues, indicating successful editing of the PDS genes. Potential off-target sites were analyzed, but no off-target mutations were found, indicating the specificity of the CRISPR-Cas9 system. The establishment of a flax genome editing system using the CRISPR-Cas9 technology opens up new possibilities for the genetic engineering of flax. This study demonstrates the potential of genome editing in creating elite cultivars that can be easily cultivated, which can have significant implications for the flax industry.

In mice, naturally occurring and induced mutations in the suppressor of cytokine signaling-2 (Socs2) gene are associated with a high growth phenotype characterized by rapid post-weaning weight gain and 30-50% heavier mature body weight. In this work, we demonstrate an electroporation-based method of producing SOCS2 knock-out (KO) sheep. Electroporation of dual-guide CRISPR-Cas9 ribonucleoprotein complexes targeting SOCS2 was performed 6 h post-fertilization in sheep zygotes. Fifty-two blastocysts were transferred to 13 estrus-synchronized recipients, yielding five live lambs and one stillborn. These lambs all carried mutations predicted to result in SOCS2 KO. Three carried large deletion alleles which evaded detection in initial PCR screening. Off-target analysis using whole genome sequencing comparing the frequency of mutations in regions within 100 bp of possible sgRNA binding sites (up to 4 bp mismatches) and elsewhere in the genome showed no significant difference when comparing unedited control sheep to edited animals (p = 0.71). In conclusion, electroporation of zygotes with dual-guide CRISPR-Cas9 RNPs was effective at generating knock-out sheep with no substantial off-target activity.