A CRISPR ‘revolution’

CRISPR-Cas is pretty popular with those wanting a relatively quick and easy way to delete, replace or modify single genes in cells. More recently, it’s been used to systematically increase or decrease the activity of individual genes. 

The problem, say Swiss researchers, is that it can only modify one gene at a time.

Now, a team led by Randall Platt from ETH Zurich in Basel says it has raised the bar by developing and demonstrating in experiments a process that can modify 25 target sites within genes in a cell at once. 

“Our method enables us, for the first time, to systematically modify entire gene networks in a single step,” Platt says.

Moreover, he adds, it paves the way for complex, large-scale cell programming. 

The CRISPR-Cas method requires an enzyme known as a Cas and a small RNA molecule. Its sequence of nucleobases serves as an “address label”, directing the enzyme with utmost precision to its designated site of action on the chromosomes. 

Platt and colleagues say they created a plasmid, or a circular DNA molecule, that stores the blueprint of the Cas enzyme and numerous RNA address molecules, arranged in sequences: in other words, a longer address list. 

In their experiments, they inserted this plasmid into human cells, demonstrating , they say, that several genes can be modified and regulated simultaneously.

The findings are reported in the journal Nature Methods.