Brown fat and obesity: light at the end of the tunnel?
According to the US National Institute of Oncology, approximately 68% of the adult population of the country is obese or overweight, which increases the risk of developing cancer, cardiovascular diseases, diabetes and a number of other chronic diseases.
Perhaps researchers at Virginia Commonwealth University, working under the guidance of Dr. Andrew Larner, have found a solution to this problem. They found that the enzyme tyrosine-specific protein kinase-2 (Tyk2), involved in the differentiation of cells of a special type of adipose tissue known as brown fat, is involved in ensuring the normal functioning of adipose tissue in mice and humans. In experiments, scientists managed to cure mice from obesity by manipulating the synthesis of Tyk2.
Unlike the so-called white fat, which acts as an energy reservoir in the mammalian body, brown fat performs the function of maintaining a constant body temperature. Until recently, it was believed that brown fat is only in the body of infants, but the results of research in recent years have shown that it also participates in the regulation of energy consumption of the adult body. Moreover, it turned out that the reduced activity of brown fat is associated with metabolic syndrome – a complex of medical abnormalities that increase the risk of developing diseases of the cardiovascular system and diabetes.
As an animal model, the authors used Tyk2-free mice with progressively developing obesity. The body weight of the animals decreased to normal values by restoring the expression of Tyk2, or by increasing the expression of transcription activator protein-3 (Stat3). This protein provides expression of a number of genes regulating a wide range of cellular processes, and also interacts with the protein PRDM16 (PR domain containing 16), which is the main regulator of brown fat cell differentiation.
The authors also found that the level of Tyk2 protein in the body of mice is regulated by the diet. At the same time, the analysis of human tissue samples showed that with obesity, Tyk2 levels do not even reach 50% of the norm.
All the data obtained indicate that Tyk2 and Stat3 are important components of the mechanism of formation of brown adipose tissue, and a change in the concentration of Tyk2 in the body is associated with obesity in both humans and rodents. The researchers plan to continue studying the functions of Tyk2 and Stat3 in order to gain a more complete understanding of the mechanisms of formation of brown adipose tissue. They hope that their work will provide new targets not only for the treatment of obesity, but also for the prevention of associated diseases, including cancer, diseases of the cardiovascular system and diabetes.
The article by Marta Derecka et al. Tyk2 and Stat3 Regulate Brown Adipose Tissue Differentiation and Obesity is published in the journal Cell Metabolism.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Virginia Commonwealth University:
Scientists Discover Mechanism That Could Reduce Obesity.
07.12.2012