Gene editing in humans using CRISPR may still be a far-fetched idea, but a new breakthrough method CRISPRainbow could be a game changer in terms of tracking and labeling DNA, researchers have found.

University of Massachusetts Medical School scientists used CRISPR/Cas9 method to develop CRISPRainbow, which allow tracking and tagging of up to seven different chromosome loci in live cells, which can be an important tool in terms of studying the genomic structures in real time.

Previous studies have used CRISPR/Cas9 as a gene-editing tool, but their team, on the other hand, used the method to identify the precise genomic location in live cells, which provide a better understanding of the dynamics of chromosomes, said Hanhui Ma, a research specialist at the UMass and a postdoctoral fellow at Pederson Lab. Ma worked with Thoru Pederson, a professor of biochemistry and molecular pharmacology.

With the CRISPR/Cas9 method, labeling of specific locations in the genome was done by deactivating the nuclease so it only binds to and not cut the genome. Once bound to the genome, the researchers used a guide RNA to incorporate three primary fluorescent proteins: blue, green or red and observed under a microscope in real time.

To observe more genomic locations, a second fluorescent protein was added to the guide RNA producing three more labels: magenta, cyan and yellow. Combining all the primary colors produced the white label as its seventh label. Through the CRISPRainbow, the researchers were able to identify seven genomic locations.

The researchers explained that DNA positioning in a packed nucleus is crucial in embryonic development to cancer. Through the said method, tracking and labeling genes in a chromosome is much easier to transcribe and express. Present techniques only allow for a maximum of three genomic location tagging.

By using the technique in living cells, real-time genomic movements can be observed and applied in biological studies.

Real time visualization of several chromosomes at different points allows researchers to study structural changes during gene expression and relate them to diseases.

Job Dekker, professor and co-director at the Center for 3D structure and Physics of the Genome, is enthusiastic about the breakthrough method. He said that instead of just predicting and assuming the genomic structure as it responds to something, scientists can now look at the structure in real time, which is very important in studying diseases and genetic response.

"This system allows one to follow this over real time. I think it's a really important new technology," said Dekker.

The study was published in Nature Biotechnology.

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