Ever since the amazing technology, famous as the ‘CRISPR’, has been introduced to the world, it has been revolutionizing the world of gene technology through its uses and applications.
CRISPR is also known as ‘Clustered Regularly Interspaced Short Palindromic Repeats’. It is a technology that allows the DNA of any genome to get easily read and then edited by a scientist who is working on them. This way, an organism’s DNA could be changed as required.
CRISPR gives a free hand to the scientist – they are free to change, add, or remove the setting or edit the DNA at any location where they want to on the given genome. It has now come to be known as one of the easiest and most convenient methods of genome editing, thus making research easier for genetic scientists.
What Is CRISPR – CAS9?
CRISPR-CAS9 or CRISPR-associated protein 9 is a naturally occurring DNA sequence that is most commonly found to occur in unicellular organisms such as archaea and bacteria. This DNA sequence plays an important role in providing immunity against viruses to the said organisms.
They do so through their ability to memorize and remember what type and strain of a given virus caused an infection and thus, to prevent it from ensuing, later on, they provide an ‘adaptive’ immune response to deal with the virus if it ever strikes back later on.
Mechanism of Action of CRISPR-CAS9:
The mechanism through which CRISPR-CAS9 remembers and recognizes a previous virus and caters immunity is overviewed as follows:
- It all begins when a virus has attacked a bacterial cell. The bacteria are smart and it directs a special protein called the ‘CAS9’ to act quickly and extract a small piece of the viral DNA.
- A guide RNA (gRNA) is used to direct the nuclease enzyme for chopping off the targeted DNA sequence.
- The spliced-off DNA fragment is then stored between the sequences of CRISPR and whenever there is an invasion the next time by the same virus, the body knows what to do next to eliminate it from the system altogether.
Practical Application and Uses of CRISPR-CAS9
As soon as the potential of the CRISPR-CAS9 was realized, scientists wanted to put its ability to good use and discover practical implementations, if any of them were possible.
So far, it has yielded a hopeful and positive response and is expected to do the same once more is found about it. However, some of the well-known practical applications of CRISPR-CAS9 are summarized as under:
Use In Cancer Immunotherapy:
Recently, CRISPR-CAS9 was applied in the treatment of metastatic lung cancer and multiple myeloma in patients. The mechanism of action proposed for doing this was this: the T-cells would be extracted from the patient.
Then, using the CRISPR-CAS9 system, the PD-1 gene would be thrown away. PD-1 belongs to one of those genes that downregulates the immune response of the T-cells in diseased patients. Afterward, these edited or ‘modified’ T-cells would then again be released into the bloodstream of the patient.
After conducting this experiment, it was found that the inhibition of just one gene PD-1 was successful in reducing the progression of the disease. This was a breakthrough discovery and can prove to be successful in prolonging the lives of cancer patients.
Generation of Animal and Cellular Models:
CRISPR-CAS9 has revamped traditional biological research by accelerating the development of transgenic animal and cellular models. These models would help scientists and researchers in studying the different roles of the genetic variations in a given organism at a given time.
Therefore, instead of just relying on the diseased models for studying the possible causative mutations, it would now be easier for the scientists to introduce or correct a given or prepared mutation of their choice for further research using CRISPR-CAS9.
For doing this, the CRISPR-CAS9 protein just needs to be injected directly into the zygote to stimulate the development of the so-called ‘heritable’ gene mutation.
Malaria and Other Infectious Diseases:
Malaria and other insect-borne diseases, such as the Zika virus, for example, have been wreaking havoc on humans for a long time now. Since these diseases are seen to be prevalent at a particular season, it was decided that resistance against the disease should be introduced into the bodies of the humans to better prepare them for fighting against these diseases and to also stop the disease from affecting these people now and then.
For preparing a disease-resistance gene drive, researchers packed CRISPR-CAS9 and gRNA into a single gene compact along with the other disease resistance genes. When these genes are transferred into the paternal chromosomes, approximately 99% of them are transferred onto the next generation.
These genes then help people in staying resistant against developing these diseases.
Role In Obesity:
The FTO (fat mass and obesity-associated) gene is an important gene that is found in obese people. FTO itself, along with several other related variants is found to induce effects such as heavyweight, extra body mass, and the development of obesity in people.
Therefore, using the CRISPR-CAS9 knock-in technique, the obesity-associated variants of the FTO genes could easily be converted into the normal, harmless variants of the FTO genes, which do not promote obesity. Moreover, the converted genes also showed an accelerated metabolism effect, which was hopeful in reducing the development of obesity in these individuals.
Genomic Screens:
The rapid editing of CRISPR makes it easier for researchers to alter their target genome of interest easily. This editing could effortlessly be applied to the entire genome instead of just a part of it and so, studying a particular gene for its resultant phenotype could be easily done.
Some research work is already being carried out to perform negative and positive selection screens in humans.
Conclusion:
As seen above, CRISPR-CAS9 is showing promising benefits in several fields of science and medicine alike. Using these applications in the daily life of everyone could prove to be a revolutionizing step for humanity as several impossible tasks and deadly diseases and conditions could easily get treated through the application of this technique.
Scientists and researchers are still on the hunt to discover more helpful applications of this wonderful technique and it is hoped that they would not be successful in finding more helpful applications this way.
References:
- Redman, M., King, A., Watson, C., & King, D. (2016). What is CRISPR/Cas9?. Archives of disease in childhood. Education and practice edition, 101(4), 213–215. https://doi.org/10.1136/archdischild-2016-310459
- El-Mounadi K, Morales-Floriano ML and Garcia-Ruiz H (2020) Principles, Applications, and Biosafety of Plant Genome Editing Using CRISPR-Cas9. Front. Plant Sci. 11:56. doi: 10.3389/fpls.2020.00056
- Hsu, P. D., Lander, E. S., & Zhang, F. (2014). Development and applications of CRISPR-Cas9 for genome engineering. Cell, 157(6), 1262–1278. https://doi.org/10.1016/j.cell.2014.05.010
- Karimian, A., Azizian, K., Parsian, H., Rafieian, S., Shafiei-Irannejad, V., Kheyrollah, M., Yousefi, M., Majidinia, M., & Yousefi, B. (2019). CRISPR/Cas9 technology as a potent molecular tool for gene therapy. Journal of cellular physiology, 234(8), 12267–12277. https://doi.org/10.1002/jcp.27972
- Sun, L., Lutz, B. M., & Tao, Y. X. (2016). The CRISPR/Cas9 system for gene editing and its potential application in pain research. Translational perioperative and pain medicine, 1(3), 22–33.