Scientists map the human loop-ome, revealing a new form of genetic regulation

PUBLIC RELEASE DATE:

11-Dec-2014

Contact: Glenna Picton picton@bcm.edu 713-798-4710 Baylor College of Medicine @bcmhouston

EMBARGOED for release Thursday, Dec. 11, 2014, at 12 p.m. ET

HOUSTON - (Dec. 11, 2014) - The ancient Japanese art of origami is based on the idea that nearly any design - a crane, an insect, a samurai warrior - can be made by taking the same blank sheet of paper and folding it in different ways.

The human body faces a similar problem. The genome inside every cell of the body is identical, but the body needs each cell to be different -an immune cell fights off infection; a cone cell helps the eye detect light; the heart's myocytes must beat endlessly.

Appearing online this week in the journal Cell, researchers at Baylor College of Medicine, Rice University, the Broad Institute of MIT and Harvard, and Harvard University describe the results of a five-year effort to map, in unprecedented detail, how the 2-meter long human genome folds inside the nucleus of a cell. Their results show that the cell-- like a microscopic origamist - modulates its function by folding the genome into an almost limitless variety of shapes.

A centerpiece of the new study is the first reliable catalog of loops spanning the entire human genome. For decades, scientists have examined the regions in the close vicinity of a gene to understand how it is regulated. But as the genome folds, sequences far from a gene loop back and come in contact with those nearby elements.

Looping has been a blind spot for modern biology. "For over a century, scientists have known that DNA forms loops inside of cells, and that knowing where the loops are is incredibly important," said co-first author Suhas Rao, a researcher at the Center for Genome Architecture at Baylor. "But mapping the positions of all those loops was long thought to be an insurmountable challenge."

The researchers showed that the 3 billion DNA letters of the human genome are partitioned into roughly 10,000 loops, a surprisingly small number. (Prior work on loops had suggested that the genome contains over a million.)

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Scientists map the human loop-ome, revealing a new form of genetic regulation