Induction of copper and iron in acute cold-stimulated brown adipose tissues

Copper (Cu) and iron (Fe), the enzymatic cofactors required for various biochemical processes, have been recently linked to lipid metabolism. Adipose tissues play central roles in energy balance and whether copper and iron homeostasis is involved in cold-stimulated energy metabolism remains unknown. In this study, the Cu and Fe contents in interscapular brown adipose tissue (BAT) and subcutaneous white adipose tissue (subWAT) from mice at different developmental stages were measured. Our results revealed the dynamic changes of Cu and Fe levels during development, suggesting their potential roles in energy homeostasis. Furthermore, the significantly increased Cu and Fe contents and the markedly up-regulated CTR1 and ATP7A expression in acute cold-stimulated BAT indicates the involvement of both Cu and Fe in the BAT-mediated thermogenesis. Comparably, no change in the Cu and Fe levels in cold-stimulated subWAT was observed at the indicated time points, suggesting that both metals are not involved in the cellular process of cold-induced WAT browning. Taken together, these data demonstrate the induction of Cu and Fe in acute cold-stimulated BAT activation, thus providing the direct evidences of the involvement of copper and iron homeostasis in BAT-mediated non-shivering energy metabolism.