Deaminase is attached by a linker to nuclease-deficient CRISPR/Cas9. Guide RNA recognizes the DNA sequence of target genome and the deaminase modifies the base of the unwound DNA. (Photo : Kobe University)
Target-AID, a new genome editing technique that doesn't cleave DNA unlike CRISPR/Cas9, has been successfully developed by a team involving Kobe University researchers.
Using a high-level editing operation, the technique offers a method that addresses existing issues in genome editing. Scientists expect the technique will be applied to gene therapy in the future.
The technique might also provide a powerful tool for breeding useful organisms and conducting disease and drug-discovery research. The findings were published online in the journal, Science.
Genome editing has seen rapid progress in recent years and is gradually becoming a revolutionary tool in fields ranging from life sciences to advanced medical research. This process can directly manipulate the genome information of various organisms without leaving an artificial strand.
Known to be highly effective, genome editing using artificial nuclease aims to cut the DNA at the target point and modify the gene while it's repaired.
As this method is effective in biological materials for which genetic operation is difficult, it's been used mainly for higher eukaryotes such as animals and plants.
A major issue with this method, however, is the uncertainty of inducing the intended mutation. There's also the problem of cytotoxicity caused by splitting of chromosomes.
In the Tokyo study, researchers demonstrated it's possible to modify genetic function by inducing target point mutation at a highly efficient rate.
The point mutation was induced by forming a synthetic complex through removal of nuclease activity from the CRISPR system, a technique using artificial nuclease and the addition of deaminase, a deaminizing (base-modifying) enzyme, and then expressing it in yeasts and mammalian cells.
It was confirmed that compared to previous nuclease models, cytotoxicity is significantly reduced by modifying the DNA without cutting.
The present technique can realize a more diverse, higher-level genome editing operation as it can efficiently conduct intended modification in a way that doesn't put significant burden on the cells.
It's expected the new technique will be applied to gene therapy in the future. It will also be a powerful tool for breeding useful organisms and conducting disease and drug-discovery research.
The team consists of Project Associate Professor Nishida Keiji and Professor Kondo Akihiko (Graduate School of Science, Technology and Innovation, Kobe University), as well as Associate Professor Yachie Nozomu (Synthetic Biology Division, Research Center for Advanced Science and Technology, the University of Tokyo) and Professor Hara Kiyotaka (Department of Environmental Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka).
