Sample Solution

in which competition with the endogenous pathways is problematic.

In addition to CRISPRi experiments, CRISPR-Cas9 can also be used to engineer epigenetic modifications. Fusing dCas9 to p300, a mammalian acetyltransferase, for example can induce the acetylation of histone H3 at lysine 2719. This mark opens associated DNA which will lead to increased gene activation19. However, gene activation or inactivation is only the surface of this technology which could include dCas9 fused to a variety of histone post-translational effectors. It is within the realm of possibility that dCas9 fused to domains that can control deacetylation, methylation, or phosphorylation of histones could also be of use to influence gene expression in eukaryotic cells19. As one can imagine, this type of application of CRISPR-Cas9 can be used in a multitude of different experiments involving gene expression and silencing.

A future direction of this tool that is currently attainable would be its application in conjunction with genome-wide association studies (GWAS). Such studies uncover SNPs that may be associated with particular diseases. GWAS studies have already uncovered many specific SNPs that are known to correlate with the onset and cause of certain diseases. CRISPR-Cas9 makes it possible to repair those particular SNPs in the genome and thus treat disease20. Therefore, CRISPR-Cas9 in combination with high throughput sequencing may be able to prevent disease in certain circumstances. This type of approach has major implications with regard to populations with a known history of a particular disease and its associated SNPs20. If they are able to be reverted using CRISPR-Cas9, and this is able to be transferred through generations, it may be possible to reverse diseases plaguing susceptible populations.

I believe once the mechanism and components of the CRISPR-Cas9 system are fully understood the system will become a household name. A couple questions that need to be answered regarding future improvements include: is there a way to harness this system without the use of a PAM sequence? Additionally, can we eliminate off-target attacks on DNA in vivo and make targeting near perfect? Once questions like these are answered we will be well on our way to making land breaking progress in the world of genome science.

Conclusion

There are many other potential uses and results that have been left out of this review of the CRISPR-Cas9 system. However, this paper provided insights into the simple two-component CRISPR-Cas9 system, using Watson-Crick base pairing by a guide RNA to identify target DNA sequences. There are many examples of how CRISPR-Cas9 is a versatile technology that has already stimulated innovative applications in biology and biotechnology. Furthermore, specific methods for delivering Cas9 and its guide RNA to cells and tissues should benefit the field of human gene therapy. For example, recent exper