Green tea polyphenols require the mitochondrial iron transporter, mitoferrin, for lifespan extension in Drosophila melanogaster

Green tea has been found to increase the lifespan of various experimental animal models including the fruit fly, Drosophila melanogaster. High in polyphenolic content, green tea has been shown to reduce oxidative stress in part by its ability to bind free iron, a micronutrient that is both essential for and toxic to all living organisms. Due to green tea's iron-binding properties, we questioned whether green tea acts to increase the lifespan of the fruit fly by modulating iron regulators, specifically, mitoferrin, a mitochondrial iron transporter, and transferrin, found in the hemolymph of flies. Publicly available hypomorph mutants for these iron regulators were utilized to investigate the effect of green tea on lifespan and fertility. We identified that green tea could not increase the lifespan of mitoferrin mutants but did rescue the reduced male fertility phenotype. The effect of green tea on transferrin mutant lifespan and fertility were comparable to w(1118) flies, as observed in our previous studies, in which green tea increased male fly lifespan and reduced male fertility. Expression levels in both w(1118) flies and mutant flies, supplemented with green tea, showed an upregulation of mitoferrin but not transferrin. Total body and mitochondrial iron levels were significantly reduced by green tea supplementation in w(1118) and mitoferrin mutants but not transferrin mutant flies. Our results demonstrate that green tea may act to increase the lifespan of Drosophila in part by the regulation of mitoferrin and reduction of mitochondrial iron.