Their work, using mice as a model organism, provides important new insights into the origin of brown fat cells, which is a prerequisite for the development of successful anti-obesity therapies.
Two types of fat cells can be found in mammals and hence in humans: White fat cells function mainly as highly flexible energy stores which are filled in times of calorie abundance. The fat is stored in the form of lipid droplets, which are mobilized when energy is needed. Diametrically opposed in function are the so-called brown adipocytes: These cells specialize in burning energy in the form of fat and sugar to produce heat. New-born babies possess substantial amounts of brown fat and utilize it to maintain body temperature. Since it was recently shown that brown adipocytes also exist in adult humans, research has focused on understanding how brown adipocytes are formed. The ultimate goal of these efforts is to increase brown adipocyte number and activity in obese humans, allowing them to burn excess calories and thus reduce weight.
Against the current belief
It is known that both humans and mice can adapt to cold temperatures by forming brown fat cells within their white fat depots. These cells are called "brite" fat cells (brown-in-white) and are less common at warmer versus colder temperatures. However, the origin of these special brown adipocytes has remained a matter of debate. The prevalent hypothesis was that brite cells are formed from special precursor cells and are removed when no longer needed. The alternate idea of a direct interconversion between white and brown fat cells gained less attention. By demonstrating that this interconversion does occur and is one of the main contributors to brite fat cell formation, the current belief has been challenged.
Genetically labelled fat cells
To demonstrate how brite fat cells are formed the researchers in the laboratory of Christian Wolfrum, a professor at the Institute of Food, Nutrition and Health, generated mice that allowed them to genetically label specific fat cells. These animals were kept in a changing environment: starting at 8°C for a week and for several weeks afterwards at normal room temperature. During the cold exposure, the mice formed brown adipocytes in their white fat depots – a process called "britening". After warm adaptation the fat tissue turned white again. Using the genetic markers the scientists concluded from these experiments that white fat cells can convert into brown fat cells and vice versa. As humans have the same type of cells as mice it is likely that the same process occurs in humans upon cold stimulation.
Treatments against obesity
"To develop new treatment strategies we need to find ways to convert white into brown adipocytes", says Wolfrum. Most of the research has focused on identifying the precursor cells for brown fat cells, an approach that may be insufficient. Future work will address the question of how to manipulate this interconversion process either by pharmacological or by nutritional means.
This approach would represent a novel strategy. "Current anti-obesity therapies target the energy intake side of the equation by controlling appetite and the uptake of nutrients", says Wolfrum. The pharmacological treatments that are available are not very efficient and usually are associated with side effects. In contrast, this novel approach to treat obesity would target the energy expenditure side of the equation by promoting brown fat formation.
Rosenwald M, Perdikari A, Rülicke T, Wolfrum C: Bi-directional interconversion of brite and white adipocytes. Nature Cell Biology 2013, Advance Online Publication, DOI: 10.1038/ncb2740
Christian Wolfrum | EurekAlert!
20.11.2017 | Washington University in St. Louis
Carefully crafted light pulses control neuron activity
20.11.2017 | University of Illinois at Urbana-Champaign
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
20.11.2017 | Life Sciences
20.11.2017 | Materials Sciences
20.11.2017 | Life Sciences