Week 8: CRISPR: Gene Editing and Beyond

CRISPR stands for “CRISPR-Cas9”, which is also called “clusters of regularly interspaced short palindromic repeats”. It is a specialized stretch of DNA which, with the associated Cas9 protein, is able to make gene editing possible. It is a simple but also helpful tool for gene deleting and inserting.

 

Figure 1: What is CRISPR?

 

Basically, the process of CRISPR gene editing starts with a guide RNA. The RNA can locate the area where an editing activity should take place, and thus guide the Cas9 protein to bind on the exact spot on the DNA chain where a cut is desired. The Cas9 protein then acts as a zipper which unzips the double-stranded DNA. After the DNA is unzipped, the guide RNA would be able to pair up with some regions on the DNA, while the Cas9 protein then cut both of the two strands of the DNA at some point. Noticing the breakage on the DNA chains, some cells will react to repair the breakage. While the cells are “gluing up” the breakage-which is a comparably sloppy process-one of the easiest things to happen includes the disabling of a gene due to mutation. Besides, this repair might also insert a new gene into the DNA chains. Sometimes, by creating a mutation from this process, scientists can gain new information about protein roles and/or genetic diseases.

 

Figure 2: How CRISPR works in a nutshell

 

As mentioned in the video shown in Thursday’s class, Chinese biologist Jiankui He used CRISPR to create a pair of genetically modified twins. He performed the DNA editing in hope of protecting the baby twins from HIV. His action, as expected, immediately brought up ethical problems and he went under a series of investigations. So, do CRISPR risks really outweigh the rewards?

Recently, new researches show that CRISPR can accidentally damage DNA during the editing process and/or unintentionally edit the non-targeted regions. While CRISPR technology has the potential of changing the way many problems are solved, gene editing is still at an early stage today. While more research is needed in the field, the biggest problem people are facing is that we do not have the advanced enough tools yet. The exploration of new ways to utilize CRISPR will not end, and we will definitely be getting more and more knowledge about how to best use CRISPR to better the community of humankind.

 

Figure 3: Do CRISPR Risks Outweigh Rewards?


References

1. “Do CRISPR Risks Outweigh Rewards?”. GEN: Genetic Engineering & Biotechnology News. Vol.38 No.19 November 1, 2018. https://www.genengnews.com/magazine/328/do-crispr-risks-outweigh-rewards/

2. Doudna, Jennifer A., and Emmanuelle Charpentier. "The new frontier of genome engineering with CRISPR-Cas9." Science346.6213 (2014): 1258096.

3. Plumer, Brad. “A Simple Guide to CRISPR, One of the Biggest Science Stories of the Decade”. Vox.com. Dec 27, 2018. https://www.vox.com/2018/7/23/17594864/crispr-cas9-gene-editing

4. Saey, H Tina. “Explainer: How CRISPR Works”. Science News for Students. Jul 31, 2017. https://www.sciencenewsforstudents.org/article/explainer-how-crispr-works

 

Figures

Figure 1: https://geneticliteracyproject.org/wp-content/uploads/2016/08/stock-photo-crispr-cas-system-for-editing-regulating-and-targeting-genomes-biotechnology-and-genetic-367760717.jpg

Figure 2: https://cdn.vox-cdn.com/thumbor/tL9QGldOG7mPzXv-EheZ-78Zyw8=/0x0:1886x1861/1200x0/filters:focal(0x0:1886x1861):no_upscale()/cdn.vox-cdn.com/uploads/chorus_asset/file/7724917/Artboard_1.jpg

Figure 3: https://www.genengnews.com/wp-content/uploads/2018/10/crispr-8-3-18.jpg