scholarly journals TALEN and CRISPR/Cas Genome Editing Systems: Tools of Discovery

Acta Naturae ◽  
2014 ◽  
Vol 6 (3) ◽  
pp. 19-40 ◽  
Author(s):  
A. A. Nemudryi ◽  
K. R. Valetdinova ◽  
S. P. Medvedev ◽  
S. M. Zakian

Precise studies of plant, animal and human genomes enable remarkable opportunities of obtained data application in biotechnology and medicine. However, knowing nucleotide sequences isnt enough for understanding of particular genomic elements functional relationship and their role in phenotype formation and disease pathogenesis. In post-genomic era methods allowing genomic DNA sequences manipulation, visualization and regulation of gene expression are rapidly evolving. Though, there are few methods, that meet high standards of efficiency, safety and accessibility for a wide range of researchers. In 2011 and 2013 novel methods of genome editing appeared - this are TALEN (Transcription Activator-Like Effector Nucleases) and CRISPR (Clustered Regulatory Interspaced Short Palindromic Repeats)/Cas9 systems. Although TALEN and CRISPR/Cas9 appeared recently, these systems have proved to be effective and reliable tools for genome engineering. Here we generally review application of these systems for genome editing in conventional model objects of current biology, functional genome screening, cell-based human hereditary disease modeling, epigenome studies and visualization of cellular processes. Additionally, we review general strategies for designing TALEN and CRISPR/Cas9 and analyzing their activity. We also discuss some obstacles researcher can face using these genome editing tools.

2019 ◽  
Vol 20 (16) ◽  
pp. 4045 ◽  
Author(s):  
Ali Razzaq ◽  
Fozia Saleem ◽  
Mehak Kanwal ◽  
Ghulam Mustafa ◽  
Sumaira Yousaf ◽  
...  

Increasing agricultural productivity via modern breeding strategies is of prime interest to attain global food security. An array of biotic and abiotic stressors affect productivity as well as the quality of crop plants, and it is a primary need to develop crops with improved adaptability, high productivity, and resilience against these biotic/abiotic stressors. Conventional approaches to genetic engineering involve tedious procedures. State-of-the-art OMICS approaches reinforced with next-generation sequencing and the latest developments in genome editing tools have paved the way for targeted mutagenesis, opening new horizons for precise genome engineering. Various genome editing tools such as transcription activator-like effector nucleases (TALENs), zinc-finger nucleases (ZFNs), and meganucleases (MNs) have enabled plant scientists to manipulate desired genes in crop plants. However, these approaches are expensive and laborious involving complex procedures for successful editing. Conversely, CRISPR/Cas9 is an entrancing, easy-to-design, cost-effective, and versatile tool for precise and efficient plant genome editing. In recent years, the CRISPR/Cas9 system has emerged as a powerful tool for targeted mutagenesis, including single base substitution, multiplex gene editing, gene knockouts, and regulation of gene transcription in plants. Thus, CRISPR/Cas9-based genome editing has demonstrated great potential for crop improvement but regulation of genome-edited crops is still in its infancy. Here, we extensively reviewed the availability of CRISPR/Cas9 genome editing tools for plant biotechnologists to target desired genes and its vast applications in crop breeding research.


2014 ◽  
Vol 80 (5) ◽  
pp. 1544-1552 ◽  
Author(s):  
Tao Xu ◽  
Yongchao Li ◽  
Joy D. Van Nostrand ◽  
Zhili He ◽  
Jizhong Zhou

ABSTRACTDevelopment of tools for targeted genome editing and regulation of gene expression has significantly expanded our ability to elucidate the mechanisms of interesting biological phenomena and to engineer desirable biological systems. Recent rapid progress in the study of a clustered, regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (Cas) protein system in bacteria has facilitated the development of newly facile and programmable platforms for genome editing and transcriptional control in a sequence-specific manner. The core RNA-guided Cas9 endonuclease in the type II CRISPR system has been harnessed to realize gene mutation and DNA deletion and insertion, as well as transcriptional activation and repression, with multiplex targeting ability, just by customizing 20-nucleotide RNA components. Here we describe the molecular basis of the type II CRISPR/Cas system and summarize applications and factors affecting its utilization in model organisms. We also discuss the advantages and disadvantages of Cas9-based tools in comparison with widely used customizable tools, such as Zinc finger nucleases and transcription activator-like effector nucleases.


Author(s):  
Meliawati Meliawati ◽  
Christoph Schilling ◽  
Jochen Schmid

Abstract Clustered regularly interspaced short palindromic repeats (CRISPR)-mediated genome engineering and related technologies have revolutionized biotechnology over the last decade by enhancing the efficiency of sophisticated biological systems. Cas12a (Cpf1) is an RNA-guided endonuclease associated to the CRISPR adaptive immune system found in many prokaryotes. Contrary to its more prominent counterpart Cas9, Cas12a recognizes A/T rich DNA sequences and is able to process its corresponding guide RNA directly, rendering it a versatile tool for multiplex genome editing efforts and other applications in biotechnology. While Cas12a has been extensively used in eukaryotic cell systems, microbial applications are still limited. In this review, we highlight the mechanistic and functional differences between Cas12a and Cas9 and focus on recent advances of applications using Cas12a in bacterial hosts. Furthermore, we discuss advantages as well as current challenges and give a future outlook for this promising alternative CRISPR-Cas system for bacterial genome editing and beyond. Key points • Cas12a is a powerful tool for genome engineering and transcriptional perturbation • Cas12a causes less toxic side effects in bacteria than Cas9 • Self-processing of crRNA arrays facilitates multiplexing approaches


2020 ◽  
Vol 40 (4) ◽  
Author(s):  
Matthew P. Hirakawa ◽  
Raga Krishnakumar ◽  
Jerilyn A. Timlin ◽  
James P. Carney ◽  
Kimberly S. Butler

Abstract Genome editing technologies, particularly those based on zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and CRISPR (clustered regularly interspaced short palindromic repeat DNA sequences)/Cas9 are rapidly progressing into clinical trials. Most clinical use of CRISPR to date has focused on ex vivo gene editing of cells followed by their re-introduction back into the patient. The ex vivo editing approach is highly effective for many disease states, including cancers and sickle cell disease, but ideally genome editing would also be applied to diseases which require cell modification in vivo. However, in vivo use of CRISPR technologies can be confounded by problems such as off-target editing, inefficient or off-target delivery, and stimulation of counterproductive immune responses. Current research addressing these issues may provide new opportunities for use of CRISPR in the clinical space. In this review, we examine the current status and scientific basis of clinical trials featuring ZFNs, TALENs, and CRISPR-based genome editing, the known limitations of CRISPR use in humans, and the rapidly developing CRISPR engineering space that should lay the groundwork for further translation to clinical application.


Author(s):  
Anuradha Bhardwaj ◽  
Vikrant Nain

Abstract Background Genome of an organism has always fascinated life scientists. With the discovery of restriction endonucleases, scientists were able to make targeted manipulations (knockouts) in any gene sequence of any organism, by the technique popularly known as genome engineering. Though there is a range of genome editing tools, but this era of genome editing is dominated by the CRISPR/Cas9 tool due to its ease of design and handling. But, when it comes to clinical applications, CRISPR is not usually preferred. In this review, we will elaborate on the structural and functional role of designer nucleases with emphasis on TALENs and CRISPR/Cas9 genome editing system. We will also present the unique features of TALENs and limitations of CRISPRs which makes TALENs a better genome editing tool than CRISPRs. Main body Genome editing is a robust technology used to make target specific DNA modifications in the genome of any organism. With the discovery of robust programmable endonucleases-based designer gene manipulating tools such as meganucleases (MN), zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats associated protein (CRISPR/Cas9), the research in this field has experienced a tremendous acceleration giving rise to a modern era of genome editing with better precision and specificity. Though, CRISPR-Cas9 platform has successfully gained more attention in the scientific world, TALENs and ZFNs are unique in their own ways. Apart from high-specificity, TALENs are proven to target the mitochondrial DNA (mito-TALEN), where gRNA of CRISPR is difficult to import. This review talks about genome editing goals fulfilled by TALENs and drawbacks of CRISPRs. Conclusions This review provides significant insights into the pros and cons of the two most popular genome editing tools TALENs and CRISPRs. This mini review suggests that, TALENs provides novel opportunities in the field of therapeutics being highly specific and sensitive toward DNA modifications. In this article, we will briefly explore the special features of TALENs that makes this tool indispensable in the field of synthetic biology. This mini review provides great perspective in providing true guidance to the researchers working in the field of trait improvement via genome editing.


2021 ◽  
Vol 2 ◽  
pp. 4
Author(s):  
Seema Dua ◽  
Kamlesh Kumari Bajwa ◽  
Atul Prashar ◽  
Sonu Bansal ◽  
Madhuri Beniwal ◽  
...  

To cater the exponential growth of human population, need to improve food production and quality through modern biotechnology with limited recourses in a way that has minimal impact on the environment. The selective breeding and genomic selection have attended the momentum gain in livestock productivity. Recent advancement in genome-editing technologies offers exciting prospects for the production of healthy and prolific livestock. Genome editing involves altering genetic material by manipulation, addition, or removal of certain deoxyribonucleic acid (DNA) sequences at a specific locus in a way that does not occur naturally. The major genome editors are zinc finger nucleases, transcription-activator-like endonucleases, and clustered regularly interspaced short palindromic repeats associated protein nine systems which are proficient of cutting the nuclear DNA precisely at a predetermined position. This review provides an update on the use of genome editing systems to modify the genes related to reproduction of farm animal vis-à-vis human, update knowledge on the underlying mechanism and discusses new opportunities to produce genetically modified farm animals.


mSphere ◽  
2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Peter B. Otoupal ◽  
Masakazu Ito ◽  
Adam P. Arkin ◽  
Jon K. Magnuson ◽  
John M. Gladden ◽  
...  

ABSTRACT Microbial production of biofuels and bioproducts offers a sustainable and economic alternative to petroleum-based fuels and chemicals. The basidiomycete yeast Rhodosporidium toruloides is a promising platform organism for generating bioproducts due to its ability to consume a broad spectrum of carbon sources (including those derived from lignocellulosic biomass) and to naturally accumulate high levels of lipids and carotenoids, two biosynthetic pathways that can be leveraged to produce a wide range of bioproducts. While R. toruloides has great potential, it has a more limited set of tools for genetic engineering relative to more advanced yeast platform organisms such as Yarrowia lipolytica and Saccharomyces cerevisiae. Significant advancements in the past few years have bolstered R. toruloides’ engineering capacity. Here we expand this capacity by demonstrating the first use of CRISPR-Cas9-based gene disruption in R. toruloides. Transforming a Cas9 expression cassette harboring nourseothricin resistance and selecting transformants on this antibiotic resulted in strains of R. toruloides exhibiting successful targeted disruption of the native URA3 gene. While editing efficiencies were initially low (0.002%), optimization of the cassette increased efficiencies 364-fold (to 0.6%). Applying these optimized design conditions enabled disruption of another native gene involved in carotenoid biosynthesis, CAR2, with much greater success; editing efficiencies of CAR2 deletion reached roughly 50%. Finally, we demonstrated efficient multiplexed genome editing by disrupting both CAR2 and URA3 in a single transformation. Together, our results provide a framework for applying CRISPR-Cas9 to R. toruloides that will facilitate rapid and high-throughput genome engineering in this industrially relevant organism. IMPORTANCE Microbial biofuel and bioproduct platforms provide access to clean and renewable carbon sources that are more sustainable and environmentally friendly than petroleum-based carbon sources. Furthermore, they can serve as useful conduits for the synthesis of advanced molecules that are difficult to produce through strictly chemical means. R. toruloides has emerged as a promising potential host for converting renewable lignocellulosic material into valuable fuels and chemicals. However, engineering efforts to improve the yeast’s production capabilities have been impeded by a lack of advanced tools for genome engineering. While this is rapidly changing, one key tool remains unexplored in R. toruloides: CRISPR-Cas9. The results outlined here demonstrate for the first time how effective multiplexed CRISPR-Cas9 gene disruption provides a framework for other researchers to utilize this revolutionary genome-editing tool effectively in R. toruloides.


2021 ◽  
Vol 22 (20) ◽  
pp. 10985
Author(s):  
Juliët Schreurs ◽  
Claudia Sacchetto ◽  
Robin M. W. Colpaert ◽  
Libero Vitiello ◽  
Alessandra Rampazzo ◽  
...  

In the past two decades, genome editing has proven its value as a powerful tool for modeling or even treating numerous diseases. After the development of protein-guided systems such as zinc finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs), which for the first time made DNA editing an actual possibility, the advent of RNA-guided techniques has brought about an epochal change. Based on a bacterial anti-phage system, the CRISPR/Cas9 approach has provided a flexible and adaptable DNA-editing system that has been able to overcome several limitations associated with earlier methods, rapidly becoming the most common tool for both disease modeling and therapeutic studies. More recently, two novel CRISPR/Cas9-derived tools, namely base editing and prime editing, have further widened the range and accuracy of achievable genomic modifications. This review aims to provide an overview of the most recent developments in the genome-editing field and their applications in biomedical research, with a particular focus on models for the study and treatment of cardiac diseases.


2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Felix Radford ◽  
Shane D. Elliott ◽  
Alanna Schepartz ◽  
Farren J. Isaacs

AbstractGenome editing technologies introduce targeted chromosomal modifications in organisms yet are constrained by the inability to selectively modify repetitive genetic elements. Here we describe filtered editing, a genome editing method that embeds group 1 self-splicing introns into repetitive genetic elements to construct unique genetic addresses that can be selectively modified. We introduce intron-containing ribosomes into the E. coli genome and perform targeted modifications of these ribosomes using CRISPR/Cas9 and multiplex automated genome engineering. Self-splicing of introns post-transcription yields scarless RNA molecules, generating a complex library of targeted combinatorial variants. We use filtered editing to co-evolve the 16S rRNA to tune the ribosome’s translational efficiency and the 23S rRNA to isolate antibiotic-resistant ribosome variants without interfering with native translation. This work sets the stage to engineer mutant ribosomes that polymerize abiological monomers with diverse chemistries and expands the scope of genome engineering for precise editing and evolution of repetitive DNA sequences.


Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1312 ◽  
Author(s):  
Joffrey Mianné ◽  
Chloé Bourguignon ◽  
Chloé Nguyen Van ◽  
Mathieu Fieldès ◽  
Amel Nasri ◽  
...  

Recent advances in genome engineering based on the CRISPR/Cas9 technology have revolutionized our ability to manipulate genomic DNA. Its use in human pluripotent stem cells (hPSCs) has allowed a wide range of mutant cell lines to be obtained at an unprecedented rate. The combination of these two groundbreaking technologies has tremendous potential, from disease modeling to stem cell-based therapies. However, the generation, screening and molecular characterization of these cell lines remain a cumbersome and multi-step endeavor. Here, we propose a pipeline of strategies to efficiently generate, sub-clone, and characterize CRISPR/Cas9-edited hPSC lines in the function of the introduced mutation (indels, point mutations, insertion of large constructs, deletions).


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