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What does gene editing look like today?
Ruth Jean Ae Kim
When you hear the words “gene editing” what comes to mind?
As a movie buff myself, I think these movies are great outlets to reach mass audiences and create awareness of the latest technologies like “CRISPR” and ethical dilemmas associated with genetic modification.
However, the depictions of the science behind gene editing in fictional movies and other media are not necessarily accurate.
So what does gene editing look like in reality today?
These days in science and the media, the hottest technology in gene editing is called “CRISPR”.
CRISPR is an acronym that stands for Clustered Regularly Interspaced Palindromic Repeats. You can think of them as small groups of repeating DNA sequences. Originally derived from bacterial immune systems, CRISPR works with a protein called “Cas9” to find and cut invading DNA from pathogens.1,2,3
Scientists can now use the CRISPR-Cas9 system as a genome editing tool in many organisms ranging from humans to plants.
It took decades of research for scientists to discover the genome editing capabilities of CRISPR. Since the impact of the paper Jennifer Doudna7, Emmanuelle Charpentier, Martin Jinek published in Science in 2012 and the Feng Zheng paper in 2013, researchers across many fields have worked to improve and apply CRISPR technology in versatile ways.
How does CRISPR work?
CRISPR is carried by the guide RNA which identify sequences in the genome called a “PAM” sequence (usually 3 base pairs long). The attached Cas9 protein is like a pair of scissors which is attached to the guide RNA and makes a break or “cut” in the DNA near the PAM sequence.
Now that there is a cut in the DNA, our biological system wants to fix and repair the cut. This repair process can happen in two different ways. One way is called non-homologous end joining or “NHEJ” the other is called homology directed repair or “HDR”. While these natural processes are effective in putting the DNA back together, it is not perfect and there are errors that occur. During the process of repair, there can be deletions or insertions that can alter the original DNA sequence, this is what we call introducing a mutation.
What makes CRISPR such a “powerful tool”?
As a plant biologist, I use gene editing technologies in my research.
How do I use it?
In order to understand how a gene works, the best way is to get rid of its function. I use the CRISPR-cas9 system to knock out genes that might be important for temperature growth response in plants. Hopefully finding out the function of these genes we can use that knowledge to improve crops in the face of climate change.
Additionally, there are many other ways to use CRISPR and that potential is what makes it such a breakthrough. Targeted gene editing and manipulations have been around since the 1970s in the scientific field.6
CRISPR is unique compared to previous methods not only because it is easy to use and low in cost, but also because it has high efficiency and precision in making edits.
In the realm of agriculture, using CRISPR is a faster alternative to regular breeding practices where farmers selected crops with desirable traits and crossed them with other varieties for many generations. Companies and researchers are now taking steps to use CRISPR to discover new beneficial genes in crops, edit genes or insert genes that make crops more productive, survive disease, or even be drought resistant.4,5,6
CRISPR can also be used in medicine as a form of gene therapy to edit genes that are responsible for diseases. Researchers have also been working on CRISPR as a tool to rid the world of malaria by controlling the gene drive of mosquitos.4,6 The culmination of these applications and many more ideas are what make the technology potentially broad and highly impactful in the future.
It is important to note however, that the technology is still new and there are many things that are unknown. There is still a lot research to be done about the effects of editing and possible off-targeting effects of CRISPR. There are also unknown long term effects when you consider whether editing a genome will have other effects on other molecular pathways within an organisms we have yet to discover or for the evolutionary fitness it will have on the population later on.
Overall, there is still a lot of work to be done to understand CRISPR and its impact on society. There is still a long way to go before science fiction as seen in the movies or media becomes a reality and in some cases, they are probably not possible. On the other hand, there is no doubt that it is an exciting time for the field and hopefully in the future CRISPR will be used as a technology that has opened many possibilities in solving the world’s problems.