CRISPR, Clustered Regularly Interspaced Short Palindromic Repeats, is a family of DNA sequences found in genomes of the prokaryotes. CRISPR-Cas9 has become a buzz word in the research community lately. It is a gene editing tool being used currently in the laboratories for research purposes which has been adapted from the naturally occurring genome editing system of the bacteria. It is based on the principle that bacteria capture DNA snippets of the virus invading in the bacteria and use them to form CRISPR arrays, which then helps bacteria to remember the virus, if in future that virus attacks the bacteria then it produces RNA segments from the arrays to target viral DNA by using the Cas9 and disables the virus. It can be said that the CRISPR gene editor uses RNA molecules that act as guides for Cas9 proteins, which are like enzymatic scissors, to a particular location in the genome for making a cut. CRISPR-Cas9 system consists of 2 components: a single-stranded guide RNA (sgRNA) and a Cas9 endonuclease. This system makes it easier to manipulate different genes in a cell line, plant or animal quickly, hence reducing the time from years to weeks. This system is not species specific so can be used on organisms previously resistant to genetic engineering.
The CRISPR?Cas system is based on the structural variation of the Cas genes and their organization is divided into 2 types: Class 1 that consists of multiprotein effector complexes, while Class 2 has only single effector protein. At present 29 subtypes have been reported and the list goes on expanding with increase in the research. The Type II CRISPR/Cas9 system is the most frequently used subtypes that are based on single Cas protein from Streptococcus pyogenes (SpCas9) targeting particular DNA sequences.
Gene Editing is of great interest in the field of human healthcare and diseases. CRISPR-Cas9 is used to make transgenic animal models and cell systems for studying the role of genes involved in various disease development and progression. It has been used in the field of Cancer, cardiovascular disease, neurodegenerative disease, hereditary eye disease, viral diseases and metabolic diseases etc. It is also being used to genetically modify insects to wipe out insect borne diseases like malaria and lyme disease. It is also being investigated in conjunction with pluripotent stem cells to provide human organs from transgenic pigs which will reduce the problems associated with organ transplant operations like graft versus host disease. With all the advantages keeping in mind researchers have tried creating a miniature tool: CasMINI. And after testing a variety of genes over years, they concluded that this miniature works really well and has the potential to be used in clinical studies. This is very new hence much more work needed for a breakthrough research landmark!!!!