Scientists isolate new type of energy-burning fat cell

Both types of fat contain energy-burning organelles called mitochondria, which contain iron and are the cause of the brown and beige hues. A key difference is that brown fat cells express high levels of UCP1 - a protein required by mitochondria to burn calories and generate heat - while beige cells normally express low levels of it. Beige cells can, however, turn on high levels of UCP1 in response to cold or certain hormones like irisin, enabling beige fat to burn calories nearly as effectively as brown fat.

Spiegelman has published a series of discoveries about the different fat cell types. Brown fat cells, he found, are born from stem cells precursors that also produce muscle cells. Beige fat, however, forms within deposits of white fat cells from beige cell precursors.

Earlier this year, he reported the discovery of irisin, produced by muscular exercise, and which can convert white fat to brown fat. In the new Cell report, Spiegelman says that irisin specifically stimulates white fat to produce beige fate. Dana-Farber has licensed both discoveries to Ember Therapeutics, a biotech company founded by Spiegelman, which plans to develop irisin as a therapy for obesity and diabetes.

In addition to Spiegelman and Wu, authors include researchers from, Maastricht University Medical Center in the Netherlands, Goteborg University in Sweden, and the University of Turku in Finland.

The research was supported, in part, by grants from the National Institute of Health (DK31405 and DK90861) and the American Heart Association.

Spiegelman is a shareholder and consultant to Ember Therapeutics.

Source: Dana-Farber Cancer Institute