Brown fat cells, scientifically called brown adipocytes, play a crucial role in regulating body temperature by transforming calorie-dense nutrients into heat. This mechanism helps prevent excessive weight gain and reduces the risk of metabolic diseases. An international research team, led by Professor Alexander Bartelt from the Institute for Cardiovascular Prevention (IPEK), has uncovered a new process that boosts the respiration and metabolic functions of these brown fat cells. The researchers are optimistic that this finding will pave the way for innovative strategies to leverage brown fat in the fight against metabolic disorders. Their findings were recently published in The EMBO Journal.
Brown fat cells combat fat reserves
Activating these fat-burning cells helps individuals lose weight. In colder temperatures, brown adipocytes derive their energy from stored fat, as thermogenesis—heat production—demands a significant calorie expenditure. “Individuals who regularly expose their bodies to cold conditions tend to be slimmer and are less susceptible to diabetes and heart diseases,” states Bartelt. Brown fat cells contain a high number of mitochondria, which are essential for cellular respiration. However, the mechanisms through which brown fat cells enhance metabolism are still not fully understood, hindering the development of new treatments.
Cold triggers heat production
The key to the function of brown fat cells lies in a protein called uncoupling protein-1, which enables the generation of heat instead of ATP, the usual product of cellular respiration. Bartelt notes, “The elevated metabolic activity of brown fat cells likely also affects ATP production,” leading them to postulate that this activity is influenced by temperature. In collaboration with Brazilian colleagues from São Paulo, the researchers discovered “inhibitory factor 1,” a protein that ensures ATP production is prioritized over thermogenesis. As temperatures drop, levels of inhibitory factor 1 decrease, allowing thermogenesis to occur. When this factor is artificially raised, it hinders the activation of brown fat in cooler environments.
These results were obtained through studies involving isolated mitochondria, cultured cells, and animal models. “While we have identified a significant piece of the thermogenesis puzzle, we are still a long way from clinical applications,” explains Dr. Henver Brunetta, who was part of the research team. The authors suggest that many individuals underutilize their brown fat, leading to its inactivity. This new research indicates that there are molecular switches available that can enhance the function of mitochondria in brown fat cells. Bartelt and his team plan to further investigate this discovery. “Ideally, our findings will guide us toward methods to also restore the efficiency of mitochondria in white fat cells, which most people have in abundance, if not excess,” concludes Bartelt.
