Ferritin regulates organismal energy balance and thermogenesis.

Objective: The ferritin heavy/heart chain (FTH) gene encodes the ferroxidase component of the iron (Fe) sequestering ferritin complex, which plays a central role in the regulation of cellular Fe metabolism. Here we tested the hypothesis that ferritin regulates organismal Fe metabolism in a manner that impacts energy balance and thermal homeostasis.

Methods: We developed a mouse strain, referred herein as Fth, expressing a tamoxifen-inducible Cre recombinase under the control of the Rosa26 (R26) promoter and carrying two LoxP (fl) sites: one at the 5'end of the Fth promoter and another the 3' end of the first Fth exon. Tamoxifen administration induces global deletion of Fth in adult Fth mice, testing whether FTH is required for maintenance of organismal homeostasis.

Results: Under standard nutritional Fe supply, Fth deletion in adult Fth mice led to a profound deregulation of organismal Fe metabolism, oxidative stress, inflammation, and multi-organ damage, culminating in death. Unexpectedly, Fth deletion was also associated with a profound atrophy of white and brown adipose tissue as well as with collapse of energy expenditure and thermogenesis. This was attributed mechanistically to mitochondrial dysfunction, as assessed in the liver and in adipose tissue.

Conclusion: The FTH component of ferritin acts as a master regulator of organismal Fe homeostasis, coupling nutritional Fe supply to organismal redox homeostasis, energy expenditure and thermoregulation.