ASEMV 2017—Exosomal miRNAs As Potential Biomarkers for Energy Expenditure by Human Brown Fat

On Tuesday morning, October 10, Alexander Pfeifer, PhD, Institute of Pharmacology and Toxicology, University of Bonn, addressed the interesting topic of exosomal miRNAs, energy expenditure, and brown fat. He began by noting the brown adipose tissue (BAT) is essential for non-shivering thermogenesis and regulates whole-body metabolism. He said brown fat activity correlates with leanness and has, therefore, received significant attention as a potential target for anti-obesity therapies. However, he noted, there is presently a lack of BAT diagnostics, and that novel diagnostic tools are need to develop BAT-centered therapies. In the current work, Dr. Pfeifer focused on exosomes released from BAT in order to identify biomarkers of BAT activity. Exosomes were isolated from brown adipocytes, explanted brown fat depots, and also from serum of mice. Brown adipocytes released exosomes in an activation-dependent manner. Physiologically, norepinephrine (NE) induces BAT energy expenditure by activating the cyclic AMP signaling pathway in brown adipocytes. Increasing cyclic AMP levels resulted in activation of brown adipocytes and induced a five-fold increase in exosome release. In addition, BAT isolated from mice exposed to cold released nine-fold more exosomes than BAT from mice kept at room temperature. The conclusion drawn is that exosome release is increased after activation of BAT. In order to identify potential biomarkers of BAT activity, the scientists focused on miRNAs.
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