Scientists Find Way to Make 'Good' Brown Fat
WEDNESDAY July 29, 2009 -- Boston scientists have succeeded in making brown fat out of mouse and human cells, a feat that takes scientists a step closer to victory in the fight against obesity and type 2 diabetes.
Brown fat is "good" fat because it burns energy, acting as a furnace, to help regulate body temperature by generating heat. The more of this fat you have, the leaner you tend to be.
"Brown fat is necessary for thermogenesis [heat production], to prevent shivering. It basically burns off calories," explained Dr. Jacob Warman, chief of endocrinology at The Brooklyn Hospital Center in New York City. "It's healthy. It keeps your weight down. Thinner people have larger amounts of brown fat."
White fat, on the other hand, stores calories and contributes to obesity.
"This could be very important research if it pans out," said Dr. Spyros Mezitis, an endocrinologist with Lenox Hill Hospital in New York City. "It could provide a lot of opportunities for new therapeutics. We don't have any drugs that really work well to control weight gain."
The paper appears online July 29 in the journal Nature.
A 2007 paper, also published in Nature by the same team, discovered that the protein PRDM16 could transform immature cells into brown fat.
Earlier this year, three separate groups of scientists on two continents independently verified that adult humans possess this slimming form of fat, which was thought only to be present in children and rodents.
"Several papers found that humans have a lot of brown fat, contrary to previous reports," said study senior author Dr. Bruce Spiegelman, a professor of cell biology at Dana-Farber Cancer Institute in Boston.
Now the team reports that PRDM16 has a collaborator, the protein C/EBP-beta. The two work together to propel various types of cells (including adult mouse and human skin cells) to morph into brown fat. Once transplanted into mice, these galvanized cells turned into energy-burning brown fat.
"We have our hands on a molecule that can turn cells into brown fat," Spiegelman said, and the findings could eventually lead to a couple of different treatment possibilities.
One would be to take cells from an actual patient, "treat" it with the PRDM16 and C/EBP-beta combination, then inject it back into the patient with the hope that it would promote the creation of brown fat.
Another possibility would be to create a drug that would make brown fat. "That's a more conventional route," Spiegelman said.
"A combination of genes [proteins] are playing a role. It's not just one gene," Mezitis said. "We need to understand the pattern. We know the individual genes that may play a role, but we don't know the pattern."
The U.S. Centers for Disease Control and Prevention has more on obesity.
Posted: July 2009