基因编辑,CRISPR-Cas9 z-bo 2020-09-24 412

　　In a new study, researchers from the Shaq Institute in the United States discovered that the holy grail of gene editing is the first to insert DNA into a non-dividing cell at a target site in the genome. Non-dividing cells account for the majority of adult organs and tissues. They confirmed that this technique can partially restore the visual response of blind rodents. It will open new avenues for basic research and a variety of treatments for diseases such as retinal diseases, heart diseases and neurological diseases.

　　Corresponding author of the paper, Professor Juan Carlos Izpisua Belmonte of the Gene Expression Laboratory of the Shaq Institute, said, "We are very excited about the technology we have discovered because it was not possible before. We were able to Target cells that have not divided and modify their DNA as you wish. The possible applications of this discovery are enormous."

　　Prior to this, technologies that modify DNA--such as the CRISPR-Cas9 system--have most effectively used the normal replication mechanism of dividing cells in these cells (such as those in the skin or intestine). Play a role. The new technology developed by the Shaq Institute is 10 times more efficient than other methods for integrating new DNA into dividing cells cultured in vitro, making it a promising tool for research and drug development. But, more importantly, this new technology represents the first time that scientists have successfully inserted a new gene into adult cells that no longer divide (such as those in the eyes, brain, pancreas, or heart). The precise DNA site provides new possibilities for therapeutic applications in these cells.

　　In order to do this, researchers are targeting a DNA repair cellular pathway called non-homologous end-joining (NHEJ), in which NHEJ rejoins the ends of DNA strands that have undergone regular breaks. Repair broken DNA. They used this process in combination with existing gene editing techniques to successfully insert new DNA into precise locations in non-dividing cells.

　　Keiichiro Suzuki, the co-first author of the paper and a senior researcher in the Izpisua Belmonte laboratory, said, “In terms of gene editing the genome of living adult organisms, the use of this NHEJ pathway to insert completely new DNA is revolutionary. Before that, there was no People do it."

　　For the first time, researchers optimized the NHEJ pathway for use in combination with CRISPR-Cas9, allowing DNA to be introduced into very precise locations in the genome. Researchers have constructed a customized insertion tool called homology-independent targeted integration (HITI) composed of a mixture of nucleic acids. They then used an inert virus to transport the genetic instructions carried by HITI to neurons produced by human embryonic stem cells.

　　Jun Wu, the co-first author of the paper, said, “This is the first time that HITI may play a role in non-dividing cells.” Based on this achievement, the researchers then successfully delivered this genetic instruction to the brains of adult mice. . Finally, in order to explore the possibility of using HITI in gene replacement therapy, they tested this in model rats suffering from retinitis pigmentosa, an inherited retinal degenerative disease that can cause blindness in humans. Kind of technology. This time, the researchers used HITI to deliver a functional copy of the Mertk gene into the eyes of 3-week-old rats, where Mertk is a gene damaged in retinitis pigmentosa. When these rats were 8 weeks old, their analysis showed that they were able to respond to light, and the results of several tests showed that their retinal cells were healing.

　　paper co-first author Reyna Hernandez-Benitez said, "We can improve the vision of these blind rats. This early success suggests that this technology is very promising."

　　The next step for the researchers will be to improve the delivery efficiency of HITI constructs. As with all genome editing technologies, obtaining enough cells to integrate new DNA is a major challenge. The beauty of HITI technology is that it can be adapted to any targeted genome editing system, not just CRISPR-Cas9. Therefore, as the safety and effectiveness of these systems improve, the effectiveness of HITI will also improve.

　　Izpisua Belmonte said, “Today, we have a technology that allows us to modify DNA in non-dividing cells to repair broken genes in the brain, heart, and liver. It allows us, for the first time, to imagine curing diseases that we could not cure before. It's exciting."