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Found: 26 174
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Abnormal expression pattern of knock-in marker in Eimeria tenella using CRISPR/Cas9.
Gene editing technology has been widely applied in the genetic manipulation of many organisms and is increasingly being utilized in eukaryotic pathogens. However, its efficiency often requires improvement. In our study using CRISPR/Cas9 to genetically manipulate Eimeria tenella, we aimed to insert a tag into a target gene locus via homologous recombination, but observed outcomes inconsistent with expectations. Whole-genome sequencing analysis of the integration sites revealed that the transgenic E. tenella did not exhibit correct targeted integration. These results indicate that creating double-strand breaks (DSB) at specific genomic sites to trigger homology-directed repair (HDR) for gene modification can lead to mislocalized expression. This study provides insights for utilizing CRISPR/Cas9 technology in genetic editing, particularly in E. tenella, and offers suggestions for improving strategies that employ the co-transfection of multiple plasmids, such as Cas9-gRNA and donor plasmids.
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Targeted genome editing in the rare actinomycete Actinoplanes sp. SE50/110 by using the CRISPR/Cas9 System.
The application of genome editing technologies, like CRISPR/Cas9 for industrially relevant microorganisms, is becoming increasingly important. Compared to other methods of genetic engineering the decisive factor is that CRISPR/Cas9 is relatively easy to apply and thus time and effort can be significantly reduced in organisms, which are otherwise genetically difficult to access. Because of its many advantages and opportunities, we adopted the CRISPR/Cas9 technology for Actinoplanes sp. SE50/110, the producer of the diabetes type II drug acarbose. The functionality of genome editing was successfully shown by the scarless and antibiotic marker-free deletion of the gene encoding the tyrosinase MelC, which catalyzes the formation of the dark pigment eumelanin in the wild type strain. The generated ΔmelC2 mutant of Actinoplanes sp. SE50/110 no longer produces this pigment and therefore the supernatant does not darken. Furthermore, it was shown that the plasmid containing the gene for the Cas9 protein was removed by increasing the temperature due to its temperature-sensitive replication. The precision of the intended mutation was proven and possible off-target effects caused by the genome editing system were ruled out by genome sequencing of several mutants.
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Generation of Genomic Deletions (of Rig-I GENE) in Goat Primary Cell Culture Using CRISPR/CAS9 Method.
CRISPR/Cas9 system is a natural immune system in prokaryotes protecting them from infectious viral or plasmid DNA invading the cells. This RNA-guided system can act as powerful tool for introducing genomic alterations in eukaryotic cells with high efficiency. In the present study, Rig-Igene is taken as model gene to study the efficiency of CRISPR/Cas9 system induced gene deletion in primary fibroblast cell culture. Rig-I(retinoic acid-inducible gene-1) is involved in regulating immune response in mammals. In this study, we optimized the CRISPR/Cas9 method for knocking out Rig-Igene in Goat primary fibroblasts by using a NHEJ pathway. Cells were screened for inactivation of the Rig-Igene and two positive clones were found out of thirty colonies screened. Thus, cells containing Rig-Igene inactivation could be achieved by CRISPR/Cas9 in goat fibroblast cells.
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CRISPR-Cas for genome editing: Classification, mechanism, designing and applications.
Clustered regularly interspersed short pallindromic repeats (CRISPR) and CRISPR associated proteins (Cas) system (CRISPR-Cas) came into light as prokaryotic defence mechanism for adaptive immune response. CRISPR-Cas works by integrating short sequences of the target genome (spacers) into the CRISPR locus. The locus containing spacers interspersed repeats is further expressed into small guide CRISPR RNA (crRNA) which is then deployed by the Cas proteins to evade the target genome. Based on the Cas proteins CRISPR-Cas is classified according to polythetic system of classification. The characteristic of the CRISPR-Cas9 system to target DNA sequences using programmable RNAs has opened new arenas due to which today CRISPR-Cas has evolved as cutting end technique in the field of genome editing. Here, we discuss about the evolution of CRISPR, its classification and various Cas systems including the designing and molecular mechanism of CRISPR-Cas. Applications of CRISPR-Cas as a genome editing tools are also highlighted in the areas such as agriculture, and anticancer therapy. Briefly discuss the role of CRISPR and its Cas systems in the diagnosis of COVID-19 and its possible preventive measures. The challenges in existing CRISP-Cas technologies and their potential solutions are also discussed briefly.
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Ribozyme-processed guide RNA enhances virus-mediated plant genome editing.
In virus-induced gene-editing system, subgenomic promoters have been used to express guide RNAs (gRNAs). However, the transcription initiation site of the subgenomic promoters remains elusive. Here, we examined the sequence of gRNAs expressed by subgenomic promoters and found the variable length of overhangs at 5'-end of gRNAs. The overhangs at 5'-end of gRNA decrease the cleavage activity of SpCas9. To overcome this problem, we inserted hammerhead ribozyme between the subgenomic promoter and gRNA and confirmed that gRNAs with a precise 5'-end increase the editing efficacy in wild tobacco. This system will be widely used for editing target genes in plants with high efficiency.
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Enhancing CRISPR/Cas-Mediated Gene Knockout With Short Non-Homologous Oligonucleotides.
Chlamydomonas reinhardtii is a model green microalga that has great industrial potential as a sustainable bio-factory for recombinant protein and high-value chemical production. Efficient genome editing tools are required to redesign this organism for synthetic biology applications. CRISPR-Cas editing technologies have already been adapted for gene knockout, transgene knock-in, and precise gene editing in C. reinhardtii. However, the efficacy of CRISPR/Cas-mediated gene knockout (KO) is low, which hampers pathway engineering and functional genomic studies. Here we report that co-delivery of CRISPR-Cas gene editing reagents with short double-stranded non-homologous oligodeoxynucleotides (dsNHO) increases gene knockout efficacy up to 100-fold in C. reinhardtii. This phenomenon, referred to as non-homologous oligonucleotide enhancement (NOE), is heavily affected by the length, structure, and chemical modifications of dsNHO, and is largely mediated by the DNA double-stranded break sensor KU70/80 (KU) heterodimer in a Cas nuclease-, locus-, and strain-independent manner. Our data suggest that dsNHOs disrupt the cell's double-stranded break (DSB) sensing pathways, consequently shifting the balance of DNA repair from canonical non-homologous end joining (c-NHEJ) towards the more error-prone, microhomology-mediated end joining (MMEJ), which could be harnessed as a strategy for improving gene KO efficiency in Chlamydomonas and beyond.
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CRISPR/Cas9 for achieving postintervention HIV control.
PURPOSE OF REVIEW: Recent advances in gene therapy have led to the first clinically approved CRISPR/Cas9 therapy for β-thalassaemia and sickle cell disease. Gene therapy could play an important role in targeting HIV persistence and achieving postintervention HIV control. Here, we review recent updates in CRISPR/Cas9-based HIV gene therapy approaches, including CCR5-editing (protect), proviral targeting (excise or modify), and immune cell engineering (attack). RECENT FINDINGS: Recent studies provide additional safety data for use of CRISPR/Cas9-based gene therapies, however low in vivo editing efficiency highlights the need for improved delivery methods. This is particularly relevant for strategies requiring transfection of all HIV-infected cells containing intact proviruses, such as proviral excision. For ex vivo editing approaches, poor engraftment and durability of edited cells present additional challenges. Newer methods such as lipid nanoparticle delivery could provide a mechanism to overcome current limitations with ex vivo and in vivo delivery. Several studies have demonstrated proof-of-concept of combination gene therapy approaches, including gene editing strategies to generate HIV-resistant cells with immune effector functions, providing novel approaches to control and durably suppress viral replication. SUMMARY: Several studies have demonstrated feasibility of gene therapy approaches in achieving postintervention HIV control. Improvements in both ex vivo and in vivo delivery methods are required to progress current gene therapy approaches to the clinic.
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Applications of CRISPR technology in cellular immunotherapy.
CRISPR technology has transformed multiple fields, including cancer and immunology. CRISPR-based gene editing and screening empowers direct genomic manipulation of immune cells, opening doors to unbiased functional genetic screens. These screens aid in the discovery of novel factors that regulate and reprogram immune responses, offering novel drug targets. The engineering of immune cells using CRISPR has sparked a transformation in the cellular immunotherapy field, resulting in a multitude of ongoing clinical trials. In this review, we discuss the development and applications of CRISPR and related gene editing technologies in immune cells, focusing on functional genomics screening, gene editing-based cell therapies, as well as future directions in this rapidly advancing field.
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[Construction of a new isovalerylspiramycin I producing strain by CRISPR-Cas9 system].
Isovalerylspiramycin (ISP)Ⅰ, as a major component of bitespiramycin (BT), exhibits similar antimicrobial activities with BT and has advantages in quality control and dosage forms. It has been under preclinical studies. The existing ISPⅠ producing strain, undergoing three genetic modifications, carries two resistant gene markers. Thus, it is hard for further genetic manipulation. It is a time-consuming and unsuccessful work to construct a new ISPⅠ strain without resistant gene marker by means of the classical homologous recombination in our preliminary experiments. Fortunately, construction of the markerless ISPⅠ strain, in which the bsm4 (responsible for acylation at 3 of spiramycin) gene was replaced by the Isovaleryltansferase gene (ist) under control of the constitutive promoter ermEp*, was efficiently achieved by using the CRISPR-Cas9 gene editing system. The mutant of bsm4 deletion can only produce SPⅠ. Isovaleryltransferase coded by ist catalyzes the isovalerylation of the SPⅠat C-4" hydroxyl group to produce ISPⅠ. As anticipated, ISPⅠ was the sole ISP component of the resultant strain (ΔEI) when detected by HPLC and mass spectrometry. The ΔEI mutant is suitable for further genetic engineering to obtain improved strains by reusing CRISPR-Cas9 system.
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Genome Editing to Produce Knockout Mutations of Seed Dormancy Genes in Wheat.
Knockout mutants provide definitive information about the functions of genes related to agronomic traits, including seed dormancy. However, it takes many years to produce knockout mutants using conventional techniques in polyploid plants such as hexaploid wheat. Genome editing with sequence-specific nucleases is a promising approach for obtaining knockout mutations in all targeted homoeologs of wheat simultaneously. Here, we describe a procedure to produce a triple recessive mutant in wheat via genome editing. This protocol covers the evaluation of gRNA and Agrobacterium-mediated transformation to obtain edited wheat seedlings.
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