What is CRISPR-Cas9?
Although the existence of CRISPR clusters has been known since the 1980s, their role in the defense mechanism of living beings has been proven relatively recently. Since 2013, the technology of gene editing using the CRISPR-Cas9 system, which has been the center of attention of the entire scientific world, has been described by Science magazine as one of the fastest, most successful, cheapest and highly accurate methods of genome modification that humanity has discovered to date.
CRISPR (clustered regularly interspaced short palindromic repeats = clusters of regularly interspaced short palindromic repeats) /Cas9 (CRISPR-associated nuclease-9) are prokaryotic DNA segments containing short repeated base sequences. All archaea and half of bacteria have this system.
How does CRISPR-Cas9 work?
There are two important molecules that create the mutation:
– A Protospacer Adjacent Motif (PAM) must be present in the target gRNA.
– It enables the binding of the gRNA complex to DNA, which forms a ribonucleoprotein complex with the Cas9 enzyme via the PAM sequence.
– Cas9 follows the guide RNA to the appropriate location in the DNA and makes a cut in both strands of the DNA.
– At this stage, the cell realizes that the DNA has been damaged and tries to repair it.
– Thus, using the DNA repair mechanism, it can modify one or more genes of the cell of interest.
What does the future hold?
– It has high potential in the treatment of many diseases such as cancer, HIV, Parkinson’s, malaria, hepatitis, vision loss correction, which are very difficult to treat and whose mechanisms are unknown. To date, this system has been utilized in the treatment of diseases, albeit to a lesser extent.
– It is known to be much easier, faster and less costly than other gene editing systems.
– Since the possibility that changes to reproductive cells could be passed on from generation to generation would trigger ethical issues, it seems a long time before it can be used on humans.
– There are many efforts to eliminate “off-target” effects. Even though the system is specific, there is still the possibility that in some cases it may make a mistake by cutting at a different point instead of the targeted gene.
– The 2020 Nobel Prize in Chemistry has been awarded many prizes, including the Nobel Prize in Chemistry, but the success rate of the system has still not exceeded 30%.
Conclusion
CRISPR/Cas technology is becoming increasingly precise and efficient and will continue to be used as an effective tool for functional genomics studies and for improving the properties of products.