A New Effective and Accurate New Technology to Edit genome was Found by MIT and Published on Science Online
On the online edition of Science, you will find a report said that researchers from MIT, the Broad Institute and Rockefeller University have developed a new technique for precisely altering the genomes of living cells by adding or deleting genes. This will benefit any research that correlates with genes.
History Since 1970s, scientists have begun to research genome editing when created the first genetically altered mice by adding small pieces of DNA to mouse embryonic cells. This method is now widely used to create transgenic mice for the study of human disease. But it’s not perfect because the randomly inserted DNA in the genome can't allow researchers targeting the newly delivered genes to replace existing ones. In recent years with science advance, scientists have sought more precise ways, for example, the homologous recombination but with low success rate. Then scientists made some improvement by adding enzymes called nucleases, which can cut DNA. Zinc fingers are commonly used to deliver the nuclease to a specific location, but zinc finger arrays can't target every possible sequence of DNA, limiting their usefulness. Furthermore, assembling the proteins is a labor-intensive and expensive process, transcription activator-like effector nucleases (TALENs).
The New Approach Making use of naturally occurring bacterial protein-RNA systems that recognize and snip viral DNA, the researchers can create DNA-editing complexes that include a nuclease called Cas9 bound to short RNA sequences. These sequences are designed to target specific locations in the genome; when they encounter a match, Cas9 cuts the DNA. This approach can be used either to disrupt the function of a gene or to replace it with a new one. To replace the gene, the researchers must also add a DNA template for the new gene, which would be copied into the genome after the DNA is cut. Each of the RNA segments can target a different sequence. While it’s precision is embodied in that if there is a single base-pair difference between the RNA targeting sequence and the genome sequence, Cas9 is not activated. This is not the case for zinc fingers or TALEN. The new system also appears to be more efficient than TALEN, and much less expensive.
The research team has deposited the necessary genetic components with a nonprofit called Addgene, making the components widely available to other researchers who want to use the system. The researchers have also created a website with tips and tools for using this new technique.
The new technology helps to biofuels, to design animal models to study human disease, to develop new therapies and other potential applications. Among other possible applications, this system might be useful for treating HIV by removing patients' lymphocytes and mutating the CCR5 receptor, through which the virus enters cells. After being put back in the patient, such cells would resist infection.