The Canada Gairdner Awards are medical awards which recognize the research and achievements of the world’s leading biomedical researchers. Since 1959, the Gairdner Foundation has awarded over 320 awards, and many of the recipients have gone on to receive Nobel Prizes in Medicine.
This year, the Gairdner Awards largely recognised researchers involved in developing the CRISPR technique, which is a rapidly expanding field involving gene editing. The 2016 Gairdner award recipients were Jennifer Doudna (a professor of molecular
and cell biology, as well as chemistry, at
UC Berkeley), Emmanuelle Charpentier (a professor at the Swedish Umeå University), Feng Zhang (a professor at MIT and the Broad Institute), Anthony Fauci (the director of the US National Institute of Allergy and Infectious Diseases and National Institutes of Health), Rudolphe Barrangou (an associate professor at the North Carolina State University) and Phillipe Horvath (a senior scientist at the French company DuPont).
Every October, previous and current recipients visit Canada and share their research with both students and faculty across the country. Last week, a general lecture (“2016 Canada Gairdner Awardees’ Lectures) and a one-day symposium (“Gene Editing: Bacterial Immunity to Global Impact”) were held on Thursday and Friday respectively, at the Macleod Auditorium, on the U of T St. George campus.
What is CRISPR?
The Clustered Random Interspaced Short Palindromic Repeats technique originates from the bacterial immune system.
Karen Maxwell, a member of U of T’s Terrence Donnelly Centre for Cellular and Biomedical Research, mentioned in her opening remarks on Friday’s event that, “Bacteria, like humans, can be attacked by viruses that infect and kill them.”
One of the seminal discoveries was in 2007. The work done by Rudolphe Barrangou and Phillipe Horvath […] as well as Sylvain Moineau […] was that bacteria have an immune system that helps to protect them from being killed by these viruses. It was only about half a dozen years ago actually that Moineau then showed that this immunity that these bacteria have is provided by a protein that causes double-stranded breaks in the DNA. When the virus infects the bacterial cell, the bacteria has a way in which it can chew up the DNA and kill the virus,” said Maxwell.
Today, the CRISPR technique can be used to edit genomes for any organism, including humans, with high precision and efficiency.
“In the few years after the discovery from Moineau’s lab, there were a lot of rapid advances in the field of CRISPR. […] They took this technology and ran with it, and have been using it to develop tools for gene editing in human cells, bacterial cells, and all different kind of cells. In the last couple of years, the technology has really exploded. There are hundreds of labs all around the world who are using this technology to edit human genomes, to invent new anti-microbials and so on. From the initial beginnings, we could have never predicted where this technology was going to go.”
Dr. Moineau, a microbiology professor at the Université Laval based in Québec, emphasized the incredible spread of the CRISPR technique. “If you have been working in biological sciences and you have not been working in a cavern for a while, you should know that this is a pretty hot topic right now.”
Moineau also presented a screenshot which demonstrated the rising number of CRISPR-related publications in the last few years. “When I show this slide to my students, I tell them that this is what you call a career opportunity,” joked Moineau. “If you’re not using the technology, you should get on board, because it is very exciting.”
How does it work?
With the last few years of research, the CRISPR system has been reduced to the following components: the gene of interest that is to be modified, a guide RNA, a nearby Protospacer Adjacent Motif site, a donor DNA, (if a specific gene is to be inserted) and the enzyme Cas9.
The guide RNA will recognise the target sequence and bind to the gene of interest. If there is sufficient similarity between the guide RNA and the target sequence, as well as a nearby PAM site, the Cas9 enzyme will be able to introduce a double-stranded break. The cell will then detect this break in the DNA and attempt to repair it, either through an end-joining pathway or through homology-directed repair, resulting in gene disruption and specific gene insertions, respectively.
“That’s really how simple it is—that is why the technology is used around the world today,” said Moineau.
How can it be used?
The applications of the CRISPR technique are extensive—and a few of these applications were discussed during Friday’s symposium.
“This is clearly one of these things where you’re standing on the giants— this work is made possible by the pioneering efforts of the people we’ve heard here at the Gairdner Awardees’ lecture,” commented Dr. Anthony James, a microbiology and molecular genetics professor at the University of California Irvine.
James’ talk, titled “Synthetic Biology and Malaria”, focused on how CRISPR can be used to engineer mosquitoes with genes to prevent malaria parasite transmission.
While malaria is caused by plasmodium parasites, the disease itself is spread through humans by the female Anopheles mosquitoes. According to the World Health Organisation, in 2015, 95 countries and territories had cases of malaria, and approximately 3.2 billion people are at risk of catching the disease. While the incidence of malaria has fallen by 37 percent from 2000 to 2015, it is still an important concern.
“So how do we get to malaria eradication? [..] We start with control of the disease. These aren’t steps—they’re defined by the WHO. But the idea here is to get the number of cases down to a certain amount, so that you have a low amount of infections every year,” said James. “With extra effort, we can get local elimination, and the idea here is that you can locally eliminate malaria everywhere in the world.”
Using the CRISPR technique, James proposes that the genetic manipulation of mosquitoes occur within laboratories, which can then be used to introduce genes in nature.
“Here, we’re actually changing the ability of the mosquito to actually transmit the pathogen,” said James.
“We think that we can have a sustainable impact on malaria. […] If we can go to an area and clear it of malaria with this specific technology, you can move to a new area to work with some confidence that the areas you cleared of malaria will remain so. If you do that today with existing tools, and you stop your intervention, it’s highly likely that either the mosquitoes will come back or the parasites will come back. You will get a re-emergence of the disease.”