A new CRISPR class could expand gene editing capabilitiesPublished: September 25, 2019
Duke University researchers have demonstrated the use of a new class of CRISPR technology in editing human genome. The new approach, researchers hope, would dramatically expand the CRISPR-based tools, opening up new avenues for cell and gene therapies.
CRISPR-Cas is an antiviral defense mechanism that evolved in bacteria to destroy the DNA of invading viruses. CRISPR-Cas9, the most commonly used genome editing tool today, is categorized as a Class 2 CRISPR system. Class 2 systems are less common in bacteria, but as they rely on only one Cas protein to target and cleave DNA, it is simpler to work with compared to Class 1 systems which rely on multiple proteins. These proteins work together in a complex called Cascade (CRISPR-associated complex for antiviral defense) to target DNA and after binding, Cascade recruits a Cas3 protein to cut the DNA.
In the present study published in Nature Biotechnology, Dr Charles Gersbach and team at Duke University explored the Class 1 system and discovered that CRISPR-Cas3 could edit the epigenome in cells.
The team were able to attach gene activators to the Cascade complex and positively regulate the expression of genes in cells and by attaching a repressor, they could turn genes off.
The team plans to explore the Class 1 CRISPR technology further and one of their aims is to determine if the Class 1 system could help solve some of the limitations of CRISPR-Cas9 in addressing human diseases, including the risk of immune responses. The team will also investigate whether the approach could be used to perform many different genome editing tasks simultaneously.
Dr Gersbach commented: “We know CRISPR could have a big impact on human health. But we’re still at the very beginning of understanding how CRISPR is going to be used, what it can do, and what systems are available to us. We expect that this new tool will enable new areas of genome engineering.”
Source: Targeted transcriptional modulation with type I CRISPR–Cas systems in human cells. Pickar-Oliver et al., Nature Biotechnology, September 2019. DOI