CRISPR: The Future of Gene-Editing
What does CRISPR stand for? CRISPR is an acronym that stands for Clustered Regularly Interspaced Short Palindromic Repeats.
What is CRISPR? CRISPR is a specialized region of DNA with nucleotide repeats and spacers, which are intersped among the repeated sequences. CRISPR is a family of DNA sequences found from prokaryotes. Through those DNA sequences, scientists can use CRISPR to edit and repair human genomes.
History of CRISPR In 1993, Francisco Mojica, a Spanish microbiologist and molecular biologist, first discovered the CRISPR locus. In other words, he described the complete gene sequence repeats in the archaeal organisms and studied their function. He also correctly hypothesized that CRISPR was an adaptive immune system.
In 2008, CRISPR was discovered to act on DNA. This went against the belief that CRISPR was parallel to RNA interference, also known as RNAi, which acts on RNA.
CRISPR in Bacteria CRISPR was discovered when scientists studied the bacterial immune system. Bacterial immune systems use CRISPR to cut specific strands of DNA using RNA. CRISPR works in bacteria by capturing a piece of the virus’s DNA and integrating it in itself. If the virus is ever present again, CRISPR uses the sequence that it previously integrated to identify and destroy the virus.
How does this gene-editing technology work? Cas 9 is a nuclease, which is a type of enzyme that can cut DNA. When a bacterial cell is invaded with a virus, two short strands of RNA, one of which contains some of the viral DNA sequence, forms a complex with Cas9. One of the RNA strands is called guide RNA.
When the guide RNA finds its target sequence in the viral genome, the Cas 9 enzyme cuts the target DNA to disable the virus. Future mutations caused by the cell trying to repair the cut allows for the disabling of the gene. This helps researchers understand gene function.
Researchers have found that CAS-9 could be engineered to cut any DNA sequence at a precisely chosen location by changing the guide RNA to match the target. This could be done within the nucleus of a living cell, not only a test tube.
CRISPR can also target many genes at once, allowing it to be more useful when working with complex diseases that involve multiple genes. CRISPR is helpful in research, drug development, agriculture, and treating human patients with genetic disorders.
Ethics Along with any new technology, there are many ethical concerns. This gene-editing technology is no exception to these concerns. CRISPR and its ability to alter human genomes of current and future generations poses a threat to the diversity and randomness that comes with genetics.
Applying CRISPR to somatic cells fixes genes in just one specific individual. However, applying CRISPR to germ-line cells would impact the inheritance patterns of humans. The ethics comes in because CRISPR and its ability to alter human genomes of current and future generations poses a threat to the diversity and randomness that comes with genetics.
The 2015 International Summit on Human Gene Editing, held in Washington D.C., concluded that CRISPR’s gene editing would proceed under FDA control only on somatic cells. However, human germline engineering was not to be pursued because of its impact on the human population.
BY: Richa Kuklani Sources: