Scientists at the Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC) have identified a protein that holds promise as a target for therapies to reduce obesity. The work was published yesterday in Nature Communications.
There are two types of fat. White adipose tissue is used to store excess calories and then there is brown adipose tissue, which is considered as a "good" fat because it burns lipids to maintain body temperature. Brown fat can be activated by the cold to "generate heat instead of storing fat," explained group leader Guadalupe Sabio, Ph.D. But the most interesting observation is that "white adipose tissue can be converted into brown adipose tissue, thus increasing body temperature."
In this new study, Sabio's team analyzed fat tissue samples from obese patients and found high levels of protein MKK6. They learned that MKK6 can actually stop the conversion of white fat to brown fat. Therefore, these obese patients were not able to take advantage of this particular pathway of losing excess weight due to MKK6.
The researchers then used animal models to further investigate MKK6's role. They found that mice that lacked MKK6 had more brown fat than mice with MKK6, showing that MKK6 does, in fact, prevent the conversion of white fat into brown fat. The research also demonstrated that eliminating MKK6 after mice had become obese stopped the further development of obesity and led to a drop in body weight.
With all of this data, the team believes that MKK6 could be a potential therapeutic target against obesity.
Image: Thermal imaging of a mouse, with white indicating the location of brown fat (maximum heat generation). Image courtesy of Nuria Matesanz, CNIC.