Manganese Transport and Toxicity

Harvard School Of Public Health, Boston MA

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Abstract

DESCRIPTION (provided by applicant): We advance the hypothesis that hepcidin regulates manganese metabolism. Accumulating evidence from in vitro studies suggests that ferroportin, the target of hepcidin regulation, plays a role in the transport of manganese. Our in vivo studies of Hfe-/- mice strongly support this idea. We will directly test its function in manganese metabolism using flatiron (ffe+/-) mice as a genetic model of ferroportin deficiency. While ferroportin function in iron export by intestinal enterocytes and macrophages of the reticuloendothelial system has been established, its activity has yet-to-be fully explored in hepatocytes where the exporter also is highly expressed. We hypothesize that in the liver, ferroportin functions in biliary excretion of manganese, a known homeostatic pathway that clears excess metal from the body. Based on our model, we speculate that circulating manganese levels are suppressed during inflammation by hepcidin, an idea that is well-supported by known host-pathogen interactions. Finally, we will determine the mechanism responsible for increased olfactory manganese absorption we have observed in Hfe knockout mice. The original new ideas forming the basis of our research will have a powerful sustaining influence on the field of metal metabolism by creating new paradigms to explain the molecular basis for manganese homeostasis.