CRISPR-Cas was first discovered by Yoshizumi Ishino and colleagues in Osaka University in 1987, although the term itself was coined in 2002.
“Revolution” is the word that is frequently brought up whenever this technology is mentioned.
CRISPR-Cas systems offer geneticists the ability to do quick and precise DNA cuts and modifications, all at low-cost. This gene editing tool can serve a multitude of potential applications ranging from cancer treatment, to lab-grown meat, and the creation of gene-edited babies.
In general, we might be more familiar with CRISPR-Cas9 that came in 2012 and has since been attracting research and media buzz.
But in recent years, CRISPR has transformed into many iterations that, while sharing the same principles, were designed for specific uses. Currently, CRISPR-Cas systems come in two classes, six types, and 19 subtypes.
Now, a new type of the CRISPR family has arrived, and it doesn’t act like molecular scissors.
CRISPR-Cas3: The Genetic Shredder
Sometimes, biologists and geneticists don’t want to make DNA cuts, which CRISPR-Cas9 is used for, but instead, remove entire DNA sequences.
This is exactly what a new CRISPR-Cas tool was designed for.
Called CRISPR-Cas3, this technique allows for the wiping out of “long stretches of DNA from a targeted site in the human genome, a capability not easily attainable in more traditional CRISPR-Cas9 systems.”
Ailong Ke is a molecular biologist and geneticist at Cornell University who’s spent the last decade in his lab trying to figure out how to make such a tool work.
Now, Ke and his labmates have published a paper, in the journal Molecular Cell, where they discuss CRISPR-Cas3’s ability to erase some viruses like herpes simplex, Epstein-Barr, and hepatitis B, which pose serious public health challenges.
“I am thrilled that my colleagues and I finally demonstrated [CRISPR-Cas3] genome editing activity in human cells,” said Ke. “Our tools can be made to target these viruses very specifically and then erase them very efficiently. In theory, it could provide a cure for these viral diseases.”
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Per researchers, this novel genome editing tool can screen the genome and erase long sequences of DNA to determine the role of specific genetic elements.
To locate specific target sites in the genome, CRISPR-Cas3 uses the same mechanism as CRISPR-Cas9, but rather than cutting DNA in half, it can erase up to 100 kilobase-long stretches of targeted DNA.
Yan Zhang, assistant professor in biological chemistry at University of Michigan who led the research, calls the Cascade-Cas3 system a “DNA shredder with a motor”, unlike CRISPR-Cas9’s molecular scissor that “goes where you want it and snips once.”
“Cas3 goes where you want it, travels along the chromosome, and makes a spectrum of deletions tens of kilobases long,” says Zhang. “This could make it a powerful screening tool to determine what large areas of DNA are most important for a particular disease.”
Amazing, the next generation is going to be pretty cool. When gene edited would it be permanent?