What is CRISPR-Cas9 Gene Editing Technology?

Jennifer Doudna and Emmanuelle Charpentier developed the gene editing method that utilizes CRISPR-Cas9 to make changes within an organism’s genome.

CRISPR stands for clustered regularly interspersed short palindromic repeats. It is derived from the bacterial immune system. In nature, when bacteria are invaded by a bacteriophage (a virus that infects bacteria), they use this CRISPR-Cas9 system to find the viral DNA and ‘catalog’ it. Later, if the same type of bacteriophage attacks once more, the stored complementary version of the viral DNA is used by the CRISPR-Cas9 system to fight the viral infection.

Currently, the goal of many scientists in the study of the crispr-cas9 gene editing technology is to use it for targeted gene therapies. For example, scientists have been testing the effectiveness of the CRISPR technology against cancer by editing the genome of immune cells so they can target and eliminate cancer cells more efficiently. There are, however, still questions as to the potential long-term effects of gene editing as well as the ethics behind certain applications.

Even so, with the completion of the human genome project, the potential for the CRISPR-cas9 gene editing technology is vast. With the use of reverse genetics, comparative genomics, and other methods, scientists can gain a deeper understanding of the genomic components of various diseases and pave the way to utilizing this technology to its fullest potential.

This can be seen in gene therapy research being applied to hematopoietic diseases, cancer, cystic fibrosis, muscular dystrophy, and others. What all these diseases have in common is that they are genetically rooted and therefore, are great candidates in the exploration of the potential of CRISPR-Cas9 gene editing.

So, how exactly does CRISPR-Cas9 gene editing work? There are a couple of components that come together to create the overall CRISPR-Cas9 system. These are the Cas9 enzyme and single guide RNA (sgRNA). Within the sgRNA there is a scaffold region, which determines the structure of the sgRNA. This structure is what fits into the Cas9 enzyme. The sgRNA also contains a sequence complementary to the sequence of the target DNA. Once the CRISPR-Cas9 complex has been made, it scans the DNA for the PAM sequence required for the Cas9 enzyme to bind to and open the DNA so the sgRNA can bind. If the DNA sequence the SgRNA binds to is complementary, the Cas9 enzyme makes a double stranded brake. This is where scientists can make insertions (utilizing homologous or nonhomologous end joining), deletions, or translocations within the genome.

It will be interesting to see the journey CRiSPR-Cas9 gene editing technology takes as its uses continue to be investigated. Where will it end up commercially? Will the ethical concerns ever be satiated? What will the results of studies investigating the long-term effects of gene editing look like?

Only time will tell.

References

Gostimskaya, I. (2022). CRISPR–CAS9: A history of its discovery and ethical considerations of its use in genome editing. Biochemistry, 87(8), 777–788. https://doi.org/10.1134/s0006297922080090

How CRISPR is changing cancer research and treatment. (2020, July 27). Cancer.gov. https://www.cancer.gov/news-events/cancer-currents-blog/2020/crispr-cancer-research-treatment

What causes muscular dystrophy (MD)? (2020, November 9). https://www.nichd.nih.gov/. https://www.nichd.nih.gov/health/topics/musculardys/conditioninfo/causes

Lim, J. M., & Kim, H. H. (2022). Basic principles and clinical applications of CRISPR-Based Genome Editing. Yonsei Medical Journal/Yonsei Medical Journal, 63(2), 105. https://doi.org/10.3349/ymj.2022.63.2.105

Mungfali.com. (1970, January 1). CRISPR Cas9 Knockin. https://mungfali.com/post/EC386E43FAD195070244D9CC068C5E3244ED1006/CRISPR+Cas9+Knockin