Study cold can not break down fat

Fat cells as "cogeneration plants": Researchers at BioTechMed-Graz decipher energy supply
People need to keep their body at body temperature when it is cold. For this, the organism must draw energy. This fat should be burned. Previous opinion was that the degradation of the enzyme ATGL in "brown" fat cells is important so that sufficient energy is produced. This teaching view has now been refuted by a recent study by the Medical University of Graz.

White fat makes up the majority of body fat and is responsible, among other things, for storing excess nutritional energy. In contrast, energy is converted into brown adipose tissue in the form of heat energy. It sits mainly in the neck, on the sternum and on the spine. In infants, the brown fat ensures the maintenance of body temperature, since the body surface is large and the muscle mass is still low.

Presentation: fat cells. Picture: fotoliaxrender-fotolia

The scientists refute in their publication the previous assumption that the degradation of fat by the fat-cleaving enzyme adipose triglyceride lipase (ATGL) in so-called brown fat cells is crucial to generate sufficient fuel and thus maintain the body temperature in the cold in the range of five degrees to be able to get.

Now it has been demonstrated in the animal model that the lack of ATGL in the brown fat cells is compensated by increased supply of energy from other fat deposits. "However, if the ATGL is missing in these too, energy must be additionally supplied through the diet," explains Dr. med. Renate Schreiber, the first author of the study.

The enzyme in the heart plays an essential role in ensuring the distribution of heat in the body. "If the ATGL is missing in this organ, it is deadly," says Assoz.-Prof. Dr. Simon Sedej from the Medical University of Graz.

Brown fat cells, originally described only in neonates, were also identified as central "combustion engines" in adults a few years ago. "The current work makes an important contribution to the understanding of the physiological processes in these" cogeneration plants ", which are indispensable for the development of therapeutic approaches in the treatment of obesity," says Schreiber.

The study of the Graz scientists, who worked together with colleagues from the Universities of Maastricht (NL) and Pittsburgh (USA), was funded by the Foundation Leducq, the European Research Council (ERC), and the Austrian Science Fund FWF.

publication
Cold-induced thermogenesis depends on ATGL-mediated lipolysis in cardiac muscle but not brown adipose tissue
Renate Schreiber, Clemens Diwoky, Gabriele Schoiswohl, Ursula Feiler, Nuttaporn Wongsiriroj, Mahmoud Abdellatif, Dagmar Kolb, Joris Hoeks, Erin E. Kershaw, Simon Sedej, Patrick Schrauwen, Günter Haemmerle, Rudolf Zechner
DOI: 10.1016 / j.cmet.2017.09.004