Abstract
Since its discovery CRISPR/Cas9 (Clustered regularly interspaced short palindromic repeat) has been widely used in gene editing. The associated protein- Cas9 has abled this coupled system to make very specific DNA modification. Earlier discovered gene editing methods like knock-in methods showed low efficiency in specific targeting. Here we review the principles and recent advancements in the CRISPR- Cas9 system.
Introduction
CRISPR is a method that is utilized for gene editing using the protein Cas9 and guide RNAs to insert a sequence of interest into DNA to make modifications. CRISPR was first found to be working in bacteria as an defense system against viruses that could attack bacteria ,now CRISPR is used for genetic engineering. CRISPR is also the cheapest methods available in the market for gene editing. This system only needs 20 nucleotide targets site which makes it very simple to design and use
Application
CRISPR has shown excellent results for treating diseases and also had several benefication agricultural applications.
- CRISPR can be used to prevent and treat HIV,cancer, sickle cell diseases, Alzheimer’s, muscular dystrophy and many more. Almost any genetic disease can be treated with the help of gene therapy.
- It can be used to increase the self life of food, increase resistance of crops to pests and diseases and also increase the nutritional value of the crop and even their yield
- This technology can also be used to bring back extinct species such as wooly mammoths and even perhaps dinosaurs
- It can also make insects such as the mosquito resistant to Plasmodium falciparum parasite that causes malaria
Mechanism of CRISPR
The Cas9 protein acts as a pair of highly specific molecular scissors that can be directed to cut and also edit almost any gene.
To edit a genome scientists introduce the cas 9 protein into the guide DNA with a specific sequence that will direct the protein to where it will make a cut. Cas9 then binds with the guide RNA and scans the DNA looking for that specific DNA recognition sequence. When it finds Cas9 will open up the double helix and check if the adjacent sequence is complimentary, if not it will continue scanning, if it finds the sequence Cas9 will cut both the strands of that DNA.
Advantages
One of the biggest advantages of CRISPR technology is its simplicity and efficiency. This technology can directly be applied in embryo, it also decreases the time required to modify the genes compared to other gene editing techniques
CRISPR can correct genetic errors to prevent serious diseases such as Hypertrophic cardiomyopathy which is a heart condition.
CRISPR can help develop new drugs. Pharmaceutical companies such as Bayer AG are investing hundreds of millions of dollars to develop CRISPR-based drugs to treat heart disease, blood disorders, and blindness. It can also help develop new cancer treatments. CRISPR can modify immune cells to make them more effective at targeting and destroying cancer cells. CRISPR can also be used evaluate how genes can be studied to determine their sensitivity to new anti cancer drug thereby developing a personalized treatment plan with the best possibility of success. It can reduce our need for plastic. CRISPR can be used to manipulate a type of yeast that transforms sugars into hydrocarbons, which can be used to make plastic—greatly reducing the need to rely on petroleum-based resources for plastics, easing stress on the environment. CRISPR has the distinct ability to alter the course of human evolution—to improve society for the greater good or, in the wrong hands, to diminish the human experience. Most genetic engineers agree that they must proceed with caution and good governance.
Limitations
The method used to insert the DNA fragment is achieved by DNA repair machinery activated by the cut in the double helical structure induced by Cas9. As the task of the system is not to insert DNA fragments in the genome, targeted alleles often carry additional modifications, such as deletions, partial or multiple integrations of the targeting vector, and even duplications.
2020-1-8-1578462647