"Researchers at the Dana-Farber Cancer Institute in Boston said they used a single molecular switch to turn immature muscle cells into brown fat cells in the lab, suggesting that brown fat may be more akin to muscle cells than conventional white fat cells.
A second team from the Joslin Diabetes Center in Boston, found a protein important for bone growth helped promote the development of brown fat tissue in mice.
Spiegelman said his team previously found that PRDM16, a kind of genetic switch called a gene transcription factor, appears to regulate the development of brown fat cells.
When Spiegelman's team removed PRDM16 from immature brown fat cells in the lab, something strange happened.
"The dish filled up with muscle," Spiegelman said. "What it means is that muscle cells are precursor cells to brown fat cells."
In a separate finding, a team led by Yu-Hua Tseng of the Joslin Diabetes Center found the protein BMP-7, known for inducing bone growth, can also promote the development of brown fat cells.
When Tseng's team delivered this protein into mice through a virus, the mice made more brown fat tissue."
OBESITY IN THE US:
* 12 percent in 1991
* to 18 percent in 1998
* to 34 percent in 2006