Cellular heterogeneity in brown adipose tissue.

Brown adipose tissue (BAT) contains mitochondria-enriched thermogenic fat cells (brown adipocytes) that play a crucial role in the regulation of energy metabolism and systemic glucose homeostasis. It was presumed that brown adipocytes are composed of a homogeneous cell population. In this issue of the JCI, however, Song and colleagues report a previously uncharacterized subpopulation of brown adipocytes that display distinct characteristics from the conventional brown adipocytes in their molecular signature, regulation, and fuel utilization. The present study provides novel insight into our understanding of cellular heterogeneity in adipose tissues.