For a long time, scientists have dreamt of converting undesirable white fat cells into brown fat cells and thus simply have excess pounds melt away. Researchers at the University of Bonn have now gotten a step closer to this goal: They decoded a "toggle switch" in mice which can significantly stimulate fat burning. The results are now being presented in the scientifc journal "Nature Communications".
Many people not only in industrialized nations struggle with excess weight - but all fat is not alike. "Love handles" in particular contain troublesome white fat cells which store excess food. Brown fat cells are the exact opposite: they burn excess energy as the desirable "heaters" of the body. Scientists at the University of Bonn working with Prof. Dr. Alexander Pfeifer, Director of the Institute for Pharmacology and Toxicology, have spent years using animal models to explore how the undesirable white fat can be converted into sought-after brown fat. "In this way, excess pounds may be able to simply be melted away and obesity combated", says Prof. Pfeifer.
A kind of "trigger switch" spurs fat burning
The researchers have now decoded a "microRNA switch" in mice which is important for brown fat cells. Micro-RNAs are located in the genome of cells and very quickly and efficiently regulate gene activity. The researchers studied a specific microRNA: microRNA 155. The gene regulator micro-RNA 155 inhibits a certain transcription factor, that controls brown fat cell function. Surprisingly, Prof. Pfeifer and his team found that the transcription factor also regulates the levels microRNA 155 establishing a tight feed-back loop that works like a toggle switch: When the microRNA is highly expressed brown fat cell differentiation is blocked; conversely, if the transcription factor wins the upper hand, brown fat is produced at an increased level and this in turn boosts fat burning in the body.
In knockout mice, the gene for Micro-RNA 155 was silent