Scientists working on gene editing need to talk about the responsible use of such techniques, geneticist Jennifer Doudna said ina lecture on Monday.
Doudna, one of the key players behind the discovery of the CRISPR-Cas9 genome editing technique, said that in early 2014 a lab in China published a paper about their use of this technique in monkey embryos. In the study, researchers implanted edited embryos in female monkeys.
“It made me wonder how long it would be until we began to work on human embryos, so I was encouraged to step out of the lab and begin to talk about the prudent path forward for genomic engineering,” she said.
In March 2015, Doudna and several other scientists published a paper titled "A prudent path forward for genomic engineering and germline gene modification," which led to the prompting of an International Summit on Human Gene Editing in Washington, DC in December 2015.
This conference was attended by representatives from the United Kingdom, China and the United States, Doudna explained, and many emphasized the pressing need for discussions on genome editing.
Doudna said that the CRISPR-Cas9 system was naturally found in bacterial cells to provide immunity against viruses. She explained that some bacterial genomes were found to have highly repetitive sequences of DNA. These repetitive sequences were interrupted by unique segments that matched the DNA of viruses that infect the bacteria. This finding ultimately led to the discovery of the CRISPR-Cas9 system.
The protein that acts as this "molecular scalpel," the Cas9 protein, has two pieces of RNA that guide its activity, one that recognizes the viral DNA sequence and another that helps the protein bind to the DNA helix, she added.
Scientists then realized that this protein could be harnessed as a technology that could search for a specific sequence in the genome, bind to it and then create a precise double-stranded break, she explained.
Because the protein exists in a natural system, it has evolved to be capable of rapid, accurate DNA target recognition, making it ideal for gene editing, Doudna said.
“The Cas9 protein is remarkably malleable, because it’s easy to deactivate it so that it only binds to a sequence instead of cutting. We can tag it with other protein activities and program it with multiple RNAs so that it can make multiple changes to the genome in a single shot,” she noted, highlighting the strengths of this technique.
Doudna explained that this discovery, which has been labeled one of the three biggest revolutions in biology in the recent past, came out of mainly curiosity-driven science with little funding.
“When we started looking at these strange bits of DNA in bacteria, no one could have predicted we would end up here,” she said.
Doudna, professor of chemistry, biophysics and structural biology at the University of California, Berkeley,added that the entire effort was highly collaborative, involving researchers and students from across the country and the world, from academic labs to commercial ones.
The lecture, titled ‘The Science and Bioethics of Editing our Genes,” took place at 6 p.m. on Wednesday in McCosh 50.
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