Joslin scientists have identified the key mechanism that regulates the production of brown fat.

Joslin scientists in the Tseng Laboratory of the Section on Integrative Physiology and Metabolism previously discovered that one type of bone morphogenetic protein, BMP-7, plays a key role in the control of brown fat formation and its heat-producing activity, which regulates whole body metabolism. In the present study, the scientists created a genetically mutant mouse model deficient in type 1A BMP-receptor (BMPR1A), a key receptor for BMP-7 which has been shown to be associated with obesity in human populations.
Mice have two types of BAT: constitutive BAT (cBAT), which develops before birth; and recruitable BAT (rBAT), which is found in WAT and skeletal muscle. Humans may also have two types of BAT.
The mice lacking BMPR1A were born with a deficiency of cBAT. Despite their lack of cBAT, the mutant mice were able to "maintain their body temperature perfectly," says senior author Yu-Hua Tseng, Ph.D., Assistant Professor of Medicine at Harvard Medical School, Principal Faculty of the Harvard Stem Cell Institute and an Investigator in the Section on Integrative Physiology and Metabolism.
The scientists discovered that when cBAT is deficient, cBAT cells send a signal through the sympathetic nervous system to increase production of rBAT within white fat. This study is the first to report this cross-talk between these two types of brown fat. The increased rBAT was sufficient to maintain normal body temperature and also protect against diet-induced obesity: When the control and mutant mice were fed a high-fat diet, the mutant mice did not gain more weight than the control mice.
Until this study, it was not known why a body needs two types of BAT and how they interact with each other. "These results show us that brown fat is essential for normal functioning. When one type of brown fat is deficient, the body has a sophisticated system for inducing development of the other type of brown fat to maintain body temperature and metabolism," says Dr. Tseng.
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Source-Eurekalert