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!
Historical rainfall levels are significant in carbon emissions from soil
30.05.2017 | University of Texas at Austin
3D printer inks from the woods
30.05.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt
Scientists have developed a new method of characterizing graphene’s properties without applying disruptive electrical contacts, allowing them to investigate both the resistance and quantum capacitance of graphene and other two-dimensional materials. Researchers from the Swiss Nanoscience Institute and the University of Basel’s Department of Physics reported their findings in the journal Physical Review Applied.
Graphene consists of a single layer of carbon atoms. It is transparent, harder than diamond and stronger than steel, yet flexible, and a significantly better...
The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.
The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
30.05.2017 | Life Sciences
30.05.2017 | Life Sciences
30.05.2017 | Physics and Astronomy