The rise and rise

Abstract

Over the last couple of years the press and scientific journals have been full of talk of a new super-technology in the genome editing world called CRISPR (clustered regularly interspaced short palindromic repeats). As a technology it has been taken up with enthusiasm by both the academic and industry sectors and is now being used to investigate a huge range of scientific problems from how to produce better food, to investigating early human development, to targeting infectious diseases. Helen Albert talks to three researchers, Rodolphe Barrangou, Fredrik Lanner and Marco Weinberg, about the rise of CRISPR technology, its pros and cons and their respective research in this area. The genome editing explosion Before 2002, when zinc-finger nucleases were first used to successfully edit DNA in Drosophila, the field of genome editing was fairly limited. While these techniques have continued to develop over the intervening period, including developments such as the advent of transcription activator-like effector nucleases (TALENs) in 2011, genome editing has only really taken off as a technique in a big way since the seminal paper by Jennifer Doudna (University of California, USA) and Emmanuelle Charpentier (Umeå University, Sweden and Max Planck Institute for Infection Biology, Berlin, Germany) on CRISPR-Cas9 was published in Science in 2012. CRISPRs are found in many bacteria and work as an immune system with Cas proteins to protect against infection from species such as bacteriophage. CRISPR elements produce short strands of RNA that are able to home-in on target sequences in the DNA of an organism. Travelling into the cell attached to these strands, the Cas9 protein acts as a molecular pair of scissors slicing the DNA at the target point. The key finding of Doudna and Charpentier and their team was that by engineering the two RNA strands into a single ‘guide RNA” of a chosen sequence, this natural phenomenon could be exploited and used along with Cas9 to cut any target DNA sequence. Since this technology was established it has been used successfully in many different species, including in human embryos. Another paper on gene editing in human and mouse cells using CRISPR-Cas9 was published by Feng Zhang (McGovern and Broad Institute, MIT, USA) and his team in Science early in 2013. Just before the publication of Doudna and Charpentier's paper in Science in 2012, Zhang had applied for a grant to study CRISPR-Cas9 as a tool for genome editing. He subsequently applied for a patent for the technology, which overlapped an earlier patent application by Doudna and colleagues. This has resulted in a patent dispute between the two groups that is still ongoing and is discussed in the ‘Who owns gene editing? Patents in the time of CRISPR” article on p26.