TALEN vs. CRISPR

By Anna Rose Welch, Editorial & Community Director, Advancing RNA

No, this isn’t another Transformers movie, folks.

In a study recently completed at The University of Illinois Urbana-Champaign, TALEN (transcription activator-like effector nuclease) was found to be five times more effective than CRISPR Cas-9 in editing the heterochromatin — or condensed DNA — regions of the genome. Defects in the heterochromatin can be the cause of several genetic diseases being targeted by gene therapies, including Fragile X syndrome, sickle cell anemia, and beta-thalassemia. 

In an experiment using single-molecule fluorescence microscopy, the researchers were able to determine how quickly TALENS and CRISPR technologies were able to navigate mammalian cell DNA, find their target, and cut it. According to the researchers:

‘We found that CRISPR works better in the less-tightly wound regions of the genome, but TALEN can access those genes in the heterochromatin region better than CRISPR,’ Zhao said. ‘We also saw that TALEN can have higher editing efficiency than CRISPR. It can cut the DNA and then make changes more efficiently than CRISPR.’

In light of this, researchers concluding that next steps, in addition to simply relying on TALEN for specific projects, could be to home in on CRISPR and improve the tool’s ability to navigate the heterochromatin.