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Docs get the skinny on mice

November 9, 2005

By Holly Lake
The Ottawa Sun

A group of Ottawa researchers has found the controls for the fat that keep mice skinny.

It turns out mice lacking a gene called p107 have half as much fat as normal mice and the fat they do have is not the conventional type.

Mice, like humans, have two types of fat: Brown and white. White fat is like a storage depot that tucks energy away to draw on in the event of a food shortage.

Rather than storing fat, brown fat burns it. Both types start from the same parent cell.

"The cell has to decide what it's going to be when it grows up and we've found the mechanism by which it makes the decision," said Dr. Michael Rudnicki, director of molecular medicine at the Ottawa Health Research Institute.

His team of scientists from the University of Ottawa and OHRI, specifically post-doctoral fellow and lead author Dr. Anthony Scime, have shown that when p107 is not present, these parent cells are unable to make white fat and instead make brown.

Despite eating about the same as normal mice, those without the gene were thinner.

"These mice are quite slim and healthy looking. The excess food they eat is turned into heat," Rudnicki said.

Although humans are born with about 5% brown fat, most is lost shortly after birth. Now that scientists know what controls the creation of white fat, it's possible drugs can be developed to inhibit the body from making it.

'REALM OF SCIENCE FICTION'

"Now we're entering into the realm of science fiction. This would be an important addition to the toolbox of drugs to treat obesity," Rudnicki said. "As all of us know (white fat) shows up all over -- places where we don't want it to show up. And right now we don't have any way of getting rid of white cells. Once they're there they stay there."

Although his team hasn't studied this further, they believe it might be possible to interfere with the gene in mature white cells, leaving them incapable of working as a fat cell.

The findings appear in this month's issue of Cell Metabolism.

Note: Reproduced with permission from the Ottawa Sun.