Twin cells
A group of researchers from Kyoto University has developed a completely accurate method for studying gene polymorphism.
The uniqueness of the technique lies in the fact that the regenerative mechanisms of the cell itself are directed in the right direction, an exact copy of the cell is created to study diseases associated with mutations.
Single nucleotide polymorphisms, or snips (from the English single nucleotide polymorphism, SNP) are the most common type of variation in the human genome. More than 10 million snips are known, many of which are associated with such common diseases as Alzheimer's disease, diabetes mellitus and others.
To prove the involvement of one particular snip in the development of the disease, it is necessary to compare a pair of cells whose genetic information is almost completely the same. Such cells are called isogenic. Ideally, it is necessary to compare isogenic "twins" – cells whose genetic information is absolutely identical and differs only in the studied snip.
Creating such twin cells is not an easy task. Japanese scientists have developed a new genome editing technology that allows you to insert a snip together with a fluorescent reporter gene that acts as an identification signal to identify altered cells.
On the left and right sides of the reporter gene, the authors placed short identical DNA sequences - microhomologists. Unique sections of DNA were added to this system, which acted as targets for the CRISPR enzyme that cuts off genes.
The cell's own DNA repair system, consisting in connecting two microhomologists with cutting out the sequence located between them, was thus directed by scientists to remove the fluorescent reporter gene while preserving the snip. Comparing such cells with normal ones is the essence of an effective method of isogenic twins.
The authors called the new method of genome editing MhAX (Microhomology-Assisted eXcision). Using it, they created mutations in the HPRT and APRT genes responsible for the development of gout and kidney disease. Biochemical analyses showed that there were metabolic disorders characteristic of gout in cells with a mutation in the HPRT gene, while there were no disorders in the twin cells obtained in this experiment.
The APRT gene mutation, which is often found in patients with acute renal failure, also demonstrated the high effectiveness of the MhAX method, since it was necessary to study the influence of genes from the mother and father.
Researchers have already started using the new development to create and correct models of other diseases: they are currently studying the genetic causes of severe diabetes mellitus. A deep understanding of the mechanisms of the disease, achieved using MhAX, will one day give an impetus to its cure.
Article by S. Kim et al. Microhomology-assisted scarless genome editing in human iPSCs is published in the journal Nature Communications.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on EurekAlert materials: Stem cell 'twins' to study disease.