제 9 호 Genetic Scissors, Agree or Disagree?
Kicker: DEBATE (SCIENCE)
Genetic Scissors, Agree or Disagree?
A Tool for Rewriting the Code of Life
By Sol-Hyang Park, Reporter
The 2020 Nobel Prize in Chemistry was awarded to Emmanuelle Charpentier (Max Planck Unit for the Science of Pathogens, Berlin, Germany) and Jennifer A. Doudna (University of California, Berkeley, USA), for the development of new genetic scissors : CRISPR
<The 2020 Nobel Prize Winners in Chemistry>
What Is Genetic Scissors?
Genetic scissors is literally a genetic editing technique, cutting and pasting DNA. It recognizes a particular genome sequence of human, animal and plant cells and finely cuts DNA in that area. Simply put, it is a “genetic patchwork” that removes the torn clothing (specific genes causing trouble) and coverts it into a new cloth.
It is known as a “Magic Wand” in the life sciences industry because using this technology, it can not only treat genetic diseases known as incurable diseases but also can produce plants or animal varieties that are strong against certain germs.
The History of Genetic Scissors
The genetic scissors have developed in order - ZFNs (Zinc Finger Nucleases,) TALENs (Transcription Activator-Like Effector Nucleases,) and CRISPR (CRISPR/Cas9.) Especially, after the CRISPR was developed in 2012, the field of genetic editing technology has been revolutionizing.
The first generation of genetic scissors is ZFNs developed in the mid 1980s. When finger-shaped bumps in proteins containing Zinc (Zinc Finger) recognize certain DNA, the FOKI (restriction enzyme that identify and cut a particular sequence of bases) cut them.
The second generation, TALENs introduced in 2011, also operates in a similar way. It’s also a protein that binds to DNA and uses FOKI to cut DNA. The DNA binding part is replaced by the Tale protein, and it can recognize many more DNA bases at once and is more accurate than ZFNs.
<Principle of ZFNs & TALENs>
However, both are not suitable for actual use because their production and utilization are complicated – need much time and money. Besides, they are not accurate enough, so there is the possibility of off-target cuts (error) that are potentially dangerous. Thus, the first and second generation of genetic scissors are recognized only for research purposes.
The Discovery of the CRISPR
The CRISPR is the third-generation genetic scissors that complements the problems of the first and second-generation genetic scissors. CRISPR is a unique sequence of bacterial genomes discovered in colonbacillus by a Japanese research team in 1987, which stands for "clustered regularly interspaced short palindromic refits.” Later, in 2007, it was revealed that the sequence was involved in the adaptive immunity of bacteria, but there was no noticeable technology but only theory, so the CRISPR sequence had gradually been forgotten.
Meanwhile, in 2012, professors Emmanuelle Charpentier and Jennifer A. Doudnadiscovered one of gene technology’s sharpest tools: the CRISPR genetic scissors. During Emmanuelle Charpentier’s studies, she discovered that a previously unknown molecule, tracrRNA, is part of bacteria’s ancient immune system, CRISPR, that disarms viruses by cleaving DNA. Then she collaborated with Jennifer Doudna, a biochemist expert in RNA. Together, they succeeded in reprogramming the bacteria’s genetic scissors. Originally, the scissors recognize DNA from viruses, but the two scientists proved that they could be controlled to cut any DNA at a predetermined site.
The CRISPR consists of guide RNA which finds the target gene to be cut and Cas9 protein which transforms DNA. They are each paired to effectively correct DNA. When the guide RNA finds a specific DNA sequence that needs to be cut, the Cas9 protein binds to the target and cuts the DNA. New strands of DNA combine, and then the DNA edit is finally done.
<Principle of the CRISPR>
Using this, we can edit the number of genes in only several days at a relatively low cost, and repair multiple genes at the same time. Thus, we can treat genetic diseases such as AIDS or hemophilia. Furthermore, since it is easy to improve the genetic quality of crops, the Crispr is a rising alternative to GMO(geneticallymodifiedorganism.)This technology is now the most widely used genetic scissors – it has had a revolutionary impact on the life sciences. In recognition of their work, Charpentier and Doudna won the 2020 Nobel Prize in Chemistry.
Ethical Controversy of the CRISPR
However, there are concerns over the ethical issue of ecosystem destruction and customized babies. Using the genetic scissors, it is possible to make babies to our taste. In fact, in 2018, one Chinese scientist, He Jianku, made the world’s first babies using the Crispr - giving birth to twins by removing certain genes to prevent the HIV virus from AIDS. About this case, some experts say that it is invading the realm of God to modify genes that we naturally possess from the birth of human beings.
On the other hand, some point out that it is unreasonable to call it “manipulation” or “editing” over only one or two variations of more than 3.2 billion pairs of bases. Besides, this tool has contributed to many important discoveries. We would be able to develop crops that withstand pests and drought. In medicine, new therapies of inherited diseases and cancer are about to come true. These genetic scissors have taken the life sciences into a new epoch.
It’s clear that the development of genetic scissors technology is remarkable. In some respects, it will bring the greatest benefits to humankind. On the contrary, making a customized baby can also be considered “unethical.” Moreover, we cannot ignore that scientific side effects difficult to predict can occur, and some may abuse it. However, many experiments using the CRISPR have been conducted, and, furthermore, the next generation of gene scissors, "prime editing", is also under development. With advances in scientific technology, genetic scissors may be soon popularized. Social consensus on this controversy is still continuing. What do you think?
Sources :
https://www.goeonair.com/news/article.html?no=19089
https://www.nobelprize.org/prizes/chemistry/2020/press-release/
https://terms.naver.com/entry.nhn?docId=2843439&cid=43667&categoryId=43667
https://terms.naver.com/entry.nhn?docId=5781823&cid=62861&categoryId=62861
https://terms.naver.com/entry.nhn?docId=5141671&cid=60266&categoryId=60266
