Adipose knockout of H-ferritin improves energy metabolism in mice

Objective: Ferritin, the principal iron storage protein, is essential to iron homeostasis. How iron homeostasis affects the adipose tissue is not well understood. We investigated the role of ferritin heavy chain in adipocytes in energy metabolism.

Methods: We generated adipocyte-specific ferritin heavy chain (Fth, also known as Fth1) knockout mice, herein referred to as Fth^AKO. These mice were analyzed for iron homeostasis, oxidative stress, mitochondrial biogenesis and activity, adaptive thermogenesis, insulin sensitivity, and metabolic measurements. Mouse embryonic fibroblasts and primary mouse adipocytes were used for in vitro experiments.

Results: In Fth^AKO mice, the adipose iron homeostasis was disrupted, accompanied by elevated expression of adipokines, dramatically induced heme oxygenase 1(Hmox1) expression, and a notable decrease in the mitochondrial ROS level. Cytosolic ROS elevation in the adipose tissue of Fth^AKO mice was very mild, and we only observed this in the brown adipose tissue (BAT) but not in the white adipose tissue (WAT). Fth^AKO mice presented an altered metabolic profile and showed increased insulin sensitivity, glucose tolerance, and improved adaptive thermogenesis. Interestingly, loss of ferritin resulted in enhanced mitochondrial respiration capacity and a preference for lipid metabolism.

Conclusions: These findings indicate that ferritin in adipocytes is indispensable to intracellular iron homeostasis and regulates systemic lipid and glucose metabolism.