Monday, 7 January 2013

Using a Protein To Stimulate Brown Fat and Reduce Obesity

Most of the fat in our body is the familiar white kind. It contains cells called adipocytes that store fat molecules, or triglycerides. These triglycerides can act as an energy source in the future, but if we don’t need the energy the triglycerides stay in place, resulting in fat buildup and weight gain.

Brown fat is darker in color than white fat and has a different function. It actually promotes weight loss instead of weight gain. Instead of storing triglycerides, brown fat adipocytes break triglycerides  down to produce heat. Newborn human babies and small animals have brown fat to keep them warm, since they are susceptible to heat loss. It was once thought that adult humans had no brown fat, but recently it’s been discovered that we do have a few isolated patches of brown fat in our body.

Mice have brown fat: photo by gracey at
Some scientists suspect that the main cause of obesity is a problem with a process inside the body instead of simply poor food choices and lack of exercise. Scientists at the Sanford-Burnham Medical Research Institute may have found evidence that this is true.

The researchers have shown that when a mouse’s fat lacks a protein called p62 the activity of their brown fat is inhibited and the activity of their white fat is stimulated, triggering weight gain. They theorize that  obese people also lack p62. If this is shown to be true, it may be possible to help people lose weight by giving them the missing protein.

The researchers produced a group of mice that couldn’t make p62. All the mice were obese. They also had diabetes and a high level of inflammation in their bodies, conditions that often accompany obesity.

Next, the scientists produced groups of mice that lacked p62 only in certain parts of their bodies, such as in the liver, the muscles or the central nervous system. These mice weren’t obese.

Finally a group of mice unable to make p62 in their fat was produced. These mice were obese, just like the mice that couldn’t make any p62. The researchers discovered that p62 stimulates an enzyme in brown fat and inhibits an enzyme in white fat, which may be how it promotes brown fat activity and reduces obesity.

Processes that take place in a mouse’s body often (but not always) take place in a human’s as well. It would be wonderful if p62 helps reverse the increasing cases of obesity that are appearing in some parts of the world, such as in North America.