Researchers invent a new gene editing tool

Researchers at the University of Illinois at Chicago have discovered a new gene-editing technique that allows sequential cuts – or changes – to be programmed over time.

CRISPR is a gene editing tool that allows scientists to modify DNA sequences in cells and sometimes add desired sequence or genes. CRISPR uses an enzyme called Cas9 that acts like scissors to cut precisely at a desired location in DNA. Once the cleavage is made, the way in which cells repair the DNA breakage can be influenced to cause different changes or modifications to the DNA sequence.

The discovery of the gene-editing capabilities of the CRISPR system was first described in the early 2010s. In just a few short years, scientists fell in love with the ease of guiding CRISPR to target almost any DNA sequence in a cell or to target many different sites in a cell in one experiment.

“A downside to the CRISPR-based editing systems currently available is that all edits or cuts are done at once. There is no way to guide them so that they happen sequentially,” one after the other, “said Bradley of UIC. Merrill, associate professor of biochemistry and molecular genetics at the College of Medicine and lead author of the article.

Merrill and his colleagues’ new process involves the use of special molecules called guide RNAs that carry the Cas9 enzyme into the cell and determine the precise DNA sequence at which Cas9 will cut. They call their specially designed guide RNA molecules “proGuides”, and the molecules enable programmed sequential editing of DNA using Cas9.

Their results are published in the journal Molecular cell.

While proGuide is still in the prototype phase, Merrill and his colleagues plan to develop their concept further and hope researchers can use the technique soon.

“The ability to preprogram the sequential activation of Cas9 at multiple sites introduces a new tool for biological research and genetic engineering,” Merrill said. “The time factor is a critical component of human development and disease progression, but current methods to genetically study these processes do not work effectively with the time component. Our system enables preprogrammed gene editing, allowing researchers to better study time-sensitive processes like how cancer grows from a few genetic mutations and how the order in which these mutations occur can affect disease. ”