Gene editing , also sometimes known as genome editing, is a method of altering or ‘editing’ the DNA of an organism through the help of technology. Through this, genetic material can be inserted, removed, or changed in composition to make changes in the genome. There have been various different ways scientists and researchers have tried this. One of the most recent technologies to be developed in the CRISPR-Cas9. The word CRISPR stands for ‘Clustered Regularly Interspaced short palindrome repeats’ which are a type of bacterial defence system that makes CRISPR technology possible. CRISPRs were initially discovered in archaea and later in bacteria, and were assumed to be defending bacteria from viral attacks. CRISPR consists of repeated sequences of genetic code that are interrupted by remains of genetic codes of prior invaders, called ‘spacer’ sequences.
The basic operation of CRISPR is simple: It locates a certain specific length of DNA inside a cell and then either alters it.
A CRISPR ‘spacer’ sequence is said to be transcribed into short sequences of RNA. These RNA help guide the system to matching sequences of DNA. After locating the DNA, an enzyme produced by CRISPR known as ‘Cas9’ attaches itself to The strand of DNA and cuts it. This effectively shuts down the desired gene.
CRISPR as an adaptive Immune system was discovered in the year 1987 after which three types of CRISPR technological systems were developed, namely – Cas3 (type I system), Cas9 (type II system) and Cas10 (type III system). The development of these systems is said to have begun around 2002, and was unveiled in 2012. Prior to this, the method of editing plant or animal genomes costed hundreds of thousands of dollars. CRISPR made it possible to carry out this process for much cheaper.
CRISPR is used abundantly in scientific research. There is a very real possibility that we may have plants or animals that have had gene alteration done by CRISPR in the near future.CRISPR also potentially possesses the ability to help create medicines that may prevent many diseases.
The ‘Cas’ protein found in bacteria to be the defenders against viruses. ‘Cas9’ is one of these proteins that have been researched and widely used by scientists. This protein is said to be easily programmed to locate and bind to nearly any required sequence. The CRISPR Cas9 protein, when introduced into a cell, allows the protein to attach to the guide RNA and travel throughout the length of the DNA until it locates and attaches itself to that part of the DNA.
In its initial stages, CRISPR Cas9 was first tried out in 2008 to improve the immunity of bacteria against viruses. This experiment helped food manufacturers to produce cheese and yoghurt. Further on, this system was used by Scientists to try and alter genes of animals such as mice, rats, pigs and zebrafish. Scientists even reported successful use of this technology on mice to eliminate muscular dystrophy and cure a rare liver disease. There is ongoing research and investigation to genetically modify insects so that insect-borne diseases such as malaria and lyme disease can be stopped. Similarly, it opens up the possibility of creating cures for high cholesterol, HIV, Huntington’s disease and more.
Although there are numerous advantages, applications and possible benefits of the CRISPR technologies, there are some issues that come up as well. For example, there has been an attempt to use this technology to alter human embryos, which has caused a debate about how ‘ethical’ this highly advanced method of gene modification is. Moreover, comes the question of how safe this technology is. Although by far the most advance, CRISPR is still in its very early stages. It is believed by scientists that altering one part of the genome may sometimes automatically trigger a change in a different part. Such an issue has to be tackled before even thinking of applications toward human cells.
The areas of applications are truly limitless when it comes to genome editing thanks to CRISPR. It has single handedly made research areas that were previously nearly impossible to explore very easy and cheap to explore. But will it always lead to progress in medical sciences or will it create trouble? Only time can tell.