The researchers used single molecule imaging to compare the CRISPR-Cas9 and TALEN genome editing tools. Their experiments showed that TALEN is up to five times more efficient than CRISPR-Cas9 in densely packed parts of the genome – heterochromatin.
Fragile X syndrome, sickle cell anemia, beta thalassemia, and other diseases are the result of genetic defects in heterochromatin. After conducting the research, the scientists came to the conclusion that in such densely packed parts of the genome, the TALEN editing tool is more efficient to use than the traditional CRISPR / Cas9. Biologists report their findings in the journal Nature Communications.
According to Humin Zhao, a professor of chemical and biomolecular engineering at the University of Illinois at Urbana-Champaign who led the new study, the finding confirms that a broader range of genome editing tools are needed to cover all parts of the genome.
“CRISPR is a very powerful tool that revolutionized genetic engineering,” Zhao explains. “But he still has some limitations.”
Zhao and colleagues have used single-molecule fluorescence microscopy to directly observe how two genome editing tools work in living mammalian cells. The fluorescent tags allowed researchers to measure how long it took for CRISPR and TALEN to move along the DNA, as well as detect and cut out target regions.
“We found that CRISPR works better in less vulnerable regions of the genome, but TALEN can access these genes in the heterochromatic region better than CRISPR,” Zhao said. – We also saw that TALEN can have better editing efficiency than CRISPR. He can cut DNA and then make changes more efficiently. ”
In total, TALEN was five times more effective than CRISPR in several experiments. In any case, the results will lead to improved approaches to targeting different parts of the genome, Zhao concludes: “Either we can use TALEN for certain applications, or we can try to improve CRISPR performance with heterochromatin.””