There is no limit to perfection?
The CRISPR system is often referred to as genetic scissors. The principle of its operation is similar to the process of editing a newspaper article: you can cut out words, but it is difficult to cut out individual letters, and it is impossible to immediately understand how the changes will affect the meaning of the entire text. The purpose of CRISPR is to remove unwanted genes responsible for a particular disease, but it is not yet possible to achieve a sufficient level of accuracy.
A group of researchers from Stanford University (Stanford University) in collaboration with colleagues from the National Institute of Standards and Technology (NIST) have developed a way to improve the accuracy of CRISPR. They called the modification MAGESTIC – high-precision genome editing with short, Traceable, integrated cellular barcodes (Multiplexed Accurate Genome Editing with Short, Trackable, Integrated Cellular barcodes). If we continue the analogy with text editing, then MAGESTIC, according to the authors, can be compared to working in a text editor using keyboard shortcuts to quickly search, cut and paste a fragment.
The main disadvantage of CRISPR is the high risk of uncontrolled mutations in genes located at the boundaries of the cut of DNA strands. Many cells do not survive after the intervention at all. Therefore, the predictions after genome editing are rather approximate.
To solve this problem, it is necessary to program the CRISPR mechanism for more precise targeting of the target gene, and then provide the edited DNA with a so-called template in the form of donor DNA, copying which, the thread would be restored without unwanted mutations. The MAGESTIC system is designed to cope with these tasks. It facilitates the search for the right gene, and also delivers artificial DNA directly to the incision site. The use of MAGESTIC made it possible to increase cell survival seven times.
The main difference between MAGESTIC and classical editing is a new type of cellular barcodes. Traditionally, small DNA rings (plasmids) are used for the expression of guide RNAs and for storing barcodes, which can then be used to track the changes made. At the same time, there may be from 10 to 40 plasmids in one cell, and during division they may be unevenly distributed between daughter cells. In the new technique, tags are integrated into chromosomes, so they can be easily found and identified.
Despite the rapid progress of technology, scientists still do not know the purpose of some genes. MAGESTIC can eliminate "white spots" in understanding the functions of the genome, allowing you to delete the gene of interest and observe the changes occurring with the cell. In addition, the MAGESTIC system is able to work simultaneously with a large number of cells, saving time and effort of researchers.
Article by K. R. Roy at al. Multiplexed precision genome editing with trackable genomic barcodes in yeast is published in Nature Biotechnology.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on NIST materials: From Clipping Scissors to Word Processor.