Iron Absorption in Drosophila melanogaster

Abstract

The way in which Drosophila melanogaster acquires iron from the diet remains poorly understood despite iron absorption being of vital significance for larval growth. To describe the process of organismal iron absorption, consideration needs to be given to cellular iron import, storage, export and how intestinal epithelial cells sense and respond to iron availability. Here we review studies on the Divalent Metal Transporter-1 homolog Malvolio (iron import), the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (iron export) and the role of ferritin in the process of iron acquisition (iron storage). We also describe what is known about iron regulation in insect cells. We then draw upon knowledge from mammalian iron homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, systemic iron regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal iron uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to iron sequestration.

Mitoferrin modulates iron toxicity in a Drosophila model of Friedreich׳s ataxia

“…Notably, the main components of cellular iron homeostasis pathways are conserved throughout evolution and indeed most fly orthologs have been discovered and characterized (reviewed in [25]), with the exceptions of the transferrin receptor, ferroportin and hepcidin. Drosophila expresses three different ferritin genes, named Fer1HCH, Fer2LCH, and Fer3HCH.…”

The Digestive Tract of Drosophila melanogaster

“…Iron uptake is, in part, mediated by the divalent transporter ion transporter 1 (DMT1) homolog Malvolio (11). In addition to their role in iron storage, ferritins also mediate iron export from the midgut to the hemolymph (107,181). Finally, zinc absorption is mediated by ZIP transporters, whereas zinc efflux from the cytoplasm to the hemolymph is mediated by ZnT transporters.…”

Zinc storage granules in the Malpighian tubules ofDrosophila melanogaster

“…At the cellular level, cytosolic iron deficiency results in the stabilization of the transferrin receptor for iron uptake from circulation and in the translational inhibition of ferritin for iron storage through the action of iron regulatory proteins; the opposite effects occur under cytosolic iron overload, and these processes can be viewed as a balancing act (HENTZE et al 2004;ZHANG et al 2014;KUHN 2015). The similarities and differences between iron regulation in Drosophila melanogaster and mammals have been reviewed (MANDILARAS et al 2013;TANG and ZHOU 2013). In Drosophila, iron availability is linked to key developmental signals, such as ecdysone synthesis (LLORENS et al 2015;PALANDRI et al 2015), and to processes such as the formation of epithelial septate junctions (TIKLOVA et al 2010), the functionality of the circadian clock (MANDILARAS and MISSIRLIS 2012), and the induction of mitotic events (LI 2010).…”