In an article now being published in the leading American journal PNAS, a research team led by Barbara Cannon and Jan Nedergaard at the Wenner-Gren Institute, Stockholm University in Sweden, together with British and American scientists, have managed to show for the first time that the cells that become the so-called brown or white fat tissue already know from the very beginning what sort of fat tissue they will be.
Humans and other mammals have two sorts of fatty tissue - white and brown. The white fat tissue is what is usually regarded as 'fat,' the kind many people feel they have too much of. The brown tissue, on the other hand, is a fatty tissue whose job is to burn fat, so that the energy is converted to heat either to keep us (as newborns) warm, or to balance an excessive energy intake.
"This is an answer to many years of discussion in the field, where two views have been put forward: that the cells can have two different fates, brown or white, or that they were predetermined to be one or the other, as this study now shows. An additional and highly unexpected finding was that it could be demonstrated that the very young cells that were to become brown fat cells had characteristics similar to those of young muscle cells," says Barbara Cannon, professor of physiology at the Wenner-Gren Institute, Stockholm University.
The discovery explains to some extent the property that primarily distinguishes brown fat from white fat, namely, its ability to use energy, which is something a muscle cell does in order to work.
Since there is an interest in being able to make use of the potential of brown fat to burn fat and thereby to perhaps help make fat people slim or primarily to counteract the development of obesity in the first place, this discovery is not only of significance in terms of our basic understanding of cell development.
"Our findings do not exclude the possibility of influencing young cells to develop in one direction or the other. It also seems as if there are dormant brown fat cells within the body that could be stimulated to develop and become active, fat-burning cells. Normally adult humans are seen as having rather little brown fat tissue, but new studies using new technologies are starting to challenge this view. We see new potential for understanding the mechanisms that make cells develop into different tissues. And new knowledge always paves the way for new possibilities," says Barbara Cannon.