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Review
. 2021 Mar 24;22(7):3327.
doi: 10.3390/ijms22073327.

Novel CRISPR-Cas Systems: An Updated Review of the Current Achievements, Applications, and Future Research Perspectives

Sweta Nidhi  1 , Uttpal Anand  2 , Patrik Oleksak  3 , Pooja Tripathi  4 , Jonathan A Lal  5 , George Thomas  5 , Kamil Kuca  3 , Vijay Tripathi  5
Affiliations
Review

Novel CRISPR-Cas Systems: An Updated Review of the Current Achievements, Applications, and Future Research Perspectives

Sweta Nidhi et al. Int J Mol Sci. .

Abstract

According to Darwin's theory, endless evolution leads to a revolution. One such example is the Clustered Regularly Interspaced Palindromic Repeats (CRISPR)-Cas system, an adaptive immunity system in most archaea and many bacteria. Gene editing technology possesses a crucial potential to dramatically impact miscellaneous areas of life, and CRISPR-Cas represents the most suitable strategy. The system has ignited a revolution in the field of genetic engineering. The ease, precision, affordability of this system is akin to a Midas touch for researchers editing genomes. Undoubtedly, the applications of this system are endless. The CRISPR-Cas system is extensively employed in the treatment of infectious and genetic diseases, in metabolic disorders, in curing cancer, in developing sustainable methods for fuel production and chemicals, in improving the quality and quantity of food crops, and thus in catering to global food demands. Future applications of CRISPR-Cas will provide benefits for everyone and will save countless lives. The technology is evolving rapidly; therefore, an overview of continuous improvement is important. In this review, we aim to elucidate the current state of the CRISPR-Cas revolution in a tailor-made format from its discovery to exciting breakthroughs at the application level and further upcoming trends related to opportunities and challenges including ethical concerns.

Keywords: CRISPR/Cas9; agricultural production; genome editing; industrial applications; livestock; therapeutics.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Figure 1
Figure 1
Timeline of the Clustered Regularly Interspaced Palindromic Repeats (CRISPR)–Cas system with important milestones; figure created with BioRender.com (accessed on 15 February 2021).
Figure 2
Figure 2
Left side: CRISPR adaptation step [2,9,10,14]. Right side: Generalized genomic organization in class 1 and class 2 systems. A dashed outline indicates that the gene is dispensable or missing in some subtypes or variants [14]. The figure was created with BioRender.com (accessed on 20 March 2021).
Figure 3
Figure 3
CRISPR expression and interference step in type I (top), type II (middle), and type III (bottom) systems. The figure was created with BioRender.com (accessed on 15 February 2021).
Figure 4
Figure 4
Selected multiprotein effector complexes of CRISPR class 1 systems. Figure was created with BioRender.com (accessed on 15 February 2021).
Figure 5
Figure 5
Selected single effector complexes of class 2. The figure was created with BioRender.com, accessed on 15 February 2021.
Figure 6
Figure 6
(A) General structure of the CRISPR RNA (crRNA)–trans-activating CRISPR RNA (tracrRNA) complex and artificial single-guide RNA (sgRNA). (B) CRISPR–Cas-assisted gene editing. The figure was created with BioRender.com (accessed on 15 February 2021).
Figure 7
Figure 7
Top: Diagram represents the ratio of world cropland area planted with genome-edited crops (red column) and conventional crops (green column) since 1996. The numbers above the green columns represent a total world cropland area (sum of red and green column) in million hectares (Mha) in the corresponding year. The numbers above the red columns represent the percentage of world cropland area planted with genome-edited crops in the corresponding year. Due to absence of data for 2019 (total world cropland area), numeral values (colored gray and marked with an asterisk) are calculated according to the data of the total world cropland area in 2018. Bottom: Number of publications on PubMed with the keywords in their title/abstract. The following keywords were used: “meganuclease”, “ZFN”, “TALEN”, and “CRISPR” [250,251,252].
Figure 8
Figure 8
Applications of the CRISPR–Cas technology in various fields.
See this image and copyright information in PMC

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