New strategy to tackle obesity
Scientists at Washington University School of Medicine have found a way to turn bad fat into good fat. The discovery would lead to new preventive strategies for overweight, obesity, and related disorders like diabetes.
Fat is an important tissue in our bodies. There are two major types of fat, white fat and brown fat, which have different functions. White fat functions as heat insulation, as mechanical cushioning, and as an energy source. The accumulation of white fat causes obesity, a growing problem worldwide. For this reason, white fat is also known as bad fat. Brown fat, which is less plentiful than white fat, is recognized as good fat because it burns calories to make heat. Converting white fat into brown fat has been suggested as a strategy to prevent and treat obesity.
Recent studies have identified a previously unknown fat type -- beige fat. Beige fat is an intermediary between white fat and brown fat, but it functions more like brown fat and provides a defense against cold and obesity.
Dr. Irfan Lodhi, assistant professor of medicine at Washington University School of Medicine, and his team set out to find ways to tackle obesity. Previously, they found that a protein called PexRAP regulates the formation of fat tissue. In this work, they further explored the role of the protein.
Using the method of Western blot, the team examined PexRAP expression in different fat tissues of mice. The results revealed that PexRAP was relatively high in white fat but was very low in brown fat. Besides, PexRAP levels were decreased in white fat after the mice were exposed to cold.
Cold exposure induces brown and beige fats to burn energy and produce heat, Dr. Lodhi explained.
Working with PexRAP-deficient mice, the team found that PexRAP inactivation resulted in browning of white fat. Specifically, blocking PexRAP caused white fat to brown into beige fat. PexRAP-deficient mice had more beige fat, were leaner, and burned more calories, compared with control mice. Furthermore, the team uncovered that PexRAP regulates the expression of genes implicated in the generation of heat.
Taken together, the data imply that PexRAP is a key regulator of fat tissue remodeling. Inhibition of PexRAP turns white fat into beige white, providing a way to treat obesity.
The study appears in the journal Cell Reports.
The prevalence of obesity has increased rapidly over the past several decades. Obesity affects people of all ages. In 2014, about 1.9 billion adults were overweight or obese. Obesity among children is also an increasing concern. Drugs that transform bad fat to good fat would help reduce obesity and various complications of obesity.