In a triumph for cell biology, researchers have assembled the first high-resolution, 3D maps of entire folded genomes and found a structural basis for gene regulation—a kind of "genomic origami" that allows the same genome to produce different types of cells. The research appears online on December 11, 2014 in Cell. A central goal of the five-year project, a collaboration among researchers at Harvard University, Baylor College of Medicine, Rice University, and the Broad Institute of Harvard and MIT, was to identify the loops in the human genome. Loops form when two bits of DNA that are far apart in the genome sequence end up in close contact in the folded version of the genome in a cell's nucleus. Researchers used a technology called "in situ Hi-C" to collect billions of snippets of DNA that were later analyzed for signs of loops. The team found that loops and other genome folding patterns are an essential part of genetic regulation. "More and more, we're realizing that folding is regulation," said study co-first author Suhas Rao, a researcher at Baylor's Center for Genome Architecture and a 2012 graduate of Harvard College. "When you see genes turn on or off, what lies behind that is a change in folding. It's a different way of thinking about how cells work." Co-first author Miriam Huntley, a doctoral student at the Harvard School of Engineering and Applied Sciences (SEAS), said, "Our maps of looping have revealed thousands of hidden switches that scientists didn't know about before. In the case of genes that can cause cancer or other diseases, knowing where these switches are is vital."
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