CRISPRainbow Uses Gene-Editing Technology To Locate DNA In Live Cells

Experts from the University of Massachusetts (UMass) Medical School has built up a CRISPR/Cas9 technology called CRISPRainbow. It enables researchers to identify seven genomic locations in live cells.

"Most people are using CRISPR for editing genomes," said Hanhui Ma, UMass research specialist and co-author of the study. "We are using it to label DNA and track the movement of DNA in live cells."

Identifying the genomic elements in live cells is important in order to understand chromosome dynamics because the genes guiding our biology and health act in a three-dimensional space. The location of DNA is placed in the nucleus and wields a large role in various biological processes.

However, technology at present can just follow three genomic locations at one time in live cells. To track further, cells have to be sheathed in formaldehyde, which will take them to death and prevent scientists from studying chromosome's structural changes over a period.

Ma and his team created a Cas9 mutation inactivate the nucleus, just binding it to DNA, without cutting the genome. Researchers can program a guide RNA to bring the deactivated CRISPR/Cas9 element to some particular genomic spots.

The guide RNA was engineered with one of three primary fluorescent proteins---red, green or blue. It was enabled so that the team could track the modified complex. With the help of microscopes, the proteins can be located and watched. Moreover, when a second fluorescent protein is attached to the guide RNA, the team could create three more colors---cyan, magenta and yellow.

"Computers cooperating with spectral filters in the microscope read out combinations of colors and display them as a color that you request," said Thoru Pederson, professor of biochemistry and molecular pharmacology at UMass and co-author of the study. "For example, red and green can be yellow. Using the three primary colors and this approach called computational coloring we can generate additional three colors."

With its modern technology, the team could locate seven different DNA sites simultaneously. Each was given a unique hue, which enabled the experts to keep track of dynamic, topological genome movements that play a vital role in our biological functioning.

"With this technology, we can visualize different chromosome loci at different points in time," said Li-Chun Tu, an assistant professor of biochemistry and pharmacology at UMass and co-author of the study. "And we can monitor them to see how far and fast these loci move. With this, we can see how these structural changes affect the genes being expressed and their relation to health and disease."

The findings were published in the April 18 issue of the journal Nature.