A fresh category of fat cells aids in enhancing health. These cells utilize energy and generate warmth through seemingly pointless chemical processes.
Fat cells can be classified into three colors: white, brown, and beige. White fat cells act as energy reserves by storing fat in our bodies. While these cells are necessary, having an excessive amount can lead to health issues. Brown fat cells are particularly active in infants, generating heat to help maintain their body temperature. Unfortunately, the amount of brown fat decreases as a person ages, resulting in adults having minimal brown adipose tissue. Lastly, there are beige fat cells; these also produce heat, though not as effectively as brown fat cells. In adults, beige fat cells are found interspersed within white fat tissue, mainly in the neck and shoulder regions, aiding in burning off excess energy.
A team of international researchers has identified and analyzed a new variant of beige fat cells, distinct from previously recognized types. “This new beige-type fat cells significantly influence energy metabolism in the human body and have a beneficial impact on metabolic disorders and obesity,” explains Anand Sharma, a postdoctoral researcher within ETH Professor Christian Wolfrum’s team and a co-author of the research. “Understanding how these cells function is therefore crucial.” The investigation was spearheaded by ETH Zurich, collaborating with the University of Basel, University of Leipzig Medical Center, and the Dana-Farber Cancer Institute in Boston, along with various other hospitals and research institutions globally.
Not reliant on a known protein
The previously known beige fat cells produce heat similarly to brown fat cells, using a specific protein called UCP1. This protein is found in the inner of the two membranes encasing the mitochondria—often deemed the cell’s powerhouse. During their regular function, mitochondria expel protons into the area between these two membranes. Protons, which are electrically charged particles, are essential in the cellular energy conversion processes. Both brown fat and traditional beige fat cells contain the UCP1 protein, which forms a narrow passage within the inner membrane that enables protons to flow back into the mitochondria, generating warmth through friction.
In recent years, researchers have revealed the existence of beige fat cells that lack the UCP1 protein yet still consume energy and produce heat. The research group from ETH Zurich, alongside other establishments, has meticulously characterized this new category of beige fat cells and explained their functioning through a “Sisyphus mechanism.”
Here’s how it operates: All chemical processes inside cells invariably produce some heat. The newly identified beige fat cells exploit this by allowing certain processes to run continuously in opposite directions, appearing purposeless. This mainly involves two metabolic pathways. In one pathway, the cells rapidly break down fats into their basic components, fatty acids, only to promptly reassemble them into new fats. In the other, an enzyme transforms creatine molecules into creatine phosphate, a related compound, and then switches it back into creatine. Scientists define these back-and-forth processes as “futile cycles.” While they do not contribute positively to the overall biochemical balance, they consume energy and generate heat.
Reducing risks of diabetes and obesity
The research team initially identified this new form of beige fat cells in mice, then investigated human adipose tissue and confirmed their presence there too. Although less than half of the population has the previously identified classical beige fat cells, almost everyone possesses the new futile-cycle type, albeit in varying amounts.
The researchers discovered that individuals with a higher quantity of beige fat cells—whether of the older version or this newly identified type—are generally leaner and exhibit better metabolic health, making them less vulnerable to obesity and metabolic illnesses such as diabetes. “Since beige fat cells convert energy into heat, they assist in breaking down excess fat,” states Tongtong Wang, an ETH doctoral student in Professor Wolfrum’s team and the study’s lead author.
Additionally, the researchers discussed potential medical applications for these findings in the future. One possibility is transplanting beige fat cells into individuals who have low amounts and suffer from metabolic illnesses or weight-related issues. It could also be possible to create medications to activate often dormant beige fat cells. Such treatments could assist individuals with elevated blood sugar levels or those who have lost weight through surgery or other means. “Stimulating their beige fat cells may help them sustain their reduced body weight over time,” Sharma remarks.
