Researchers at the University of North Carolina at Chapel Hill have developed a procedure that tracks the breakdown in DNA chromosomes, a step they say could lead to future therapeutic treatments to repair the damage.

“This is the first paper that distinguishes breaks in chromosomes versus breaks in DNA,” said Kerry Bloom, a professor of biology. “Chromosomal breaks are important in many diseases that stem from chromosomal translocation, in which genes get switched around.

“Our new system allows for visualizing DNA ends at the site of a double-stranded break in living cells. We showed that a protein complex we call RMX holds broken ends of DNA together and counteracts forces that can be destructive to damaged chromosomes.”

Chromosome damage triggers many fatal or debilitating illnesses, including cancer, Bloom said. Bloom is part of the Lineberger Comprehensive Cancer Center staff.

“In the course of this work, we discovered that when breaks occur in either one or both strands of DNA, which is a complex, double-stranded, helical molecule, the chromosomes do not fragment,” Bloom said. “Proteins are recruited very quickly to the sites of DNA damage, and they keep the chromosome intact. This was hypothesized but never shown before. We also identified some of those specific proteins.”

The research is reported in the new issue of Current Biology.
Also involved in the research was Kirill Lobachev, formerly of the National Institute of Environmental Health Sciences’ Laboratory of Molecular Genetics who works at the Georgia Institute of Technology; biology graduate students Eric Vitriol of UNC and Jennifer Stemple of the University of Southern California; and Michael Resnick of National Institute of Environmental Health Sciences. Vitriol and Stemple were UNC undergraduates.

The research was funded by the National Institutes of Health and the U.S. Department of Energy.