Iron Metabolism in Insects

Abstract

Like other organisms, insects must balance two properties of ionic iron, that of an essential nutrient and a potent toxin. Iron must be acquired to provide catalysis for oxidative metabolism, but it must be controlled to avoid destructive oxidative reactions. Insects have evolved distinctive forms of the serum iron transport protein, transferrin, and the storage protein, ferritin. These proteins may serve different functions in insects than they do in other organisms. A form of translational control of protein synthesis by iron in insects is similar to that of vertebrates. The Drosophila melanogaster genome contains many genes that may encode other proteins involved in iron metabolism.

Highly specific host-pathogen interactions influence Metarhizium brunneum blastospore virulence against Culex quinquefasciatus larvae

“…quinquefasciatus during activation of the immune response [51]. Transferrin is an iron-binding protein involved in iron transport, however in insects it also inhibits the growth of bacteria and other invading organisms by sequestering iron [52,53]. The results of the current study showed that the antimicrobial genes; Cecropin A, Defensin A and Gambicin were significantly up-regulated in both larvae infected with either blastospores or conidia.…”

Identification of iron-loaded ferritin as an essential mitogen for cell proliferation and postembryonic development in Drosophila

“…The growth factor activity of ferritin described here is reminiscent of that of mammalian transferrin, which is also a secreted protein that is often supplemented as a growth factor for many mammalian cell lines [27,28]. However, whether and how transferrin functions in maintaining iron homeostasis in insects is unclear, and a homologue of mammalian transferrin receptor is not present in Drosophila and other insect genomes [22,29]. Future studies will shed light on how ferritin and transferrin function in concert to maintain iron homeostasis in Drosophila and other insects.…”

“…Unlike mammalian ferritins, which are predominantly cytoplasmic iron storage proteins [14], insect ferritins are primarily secreted proteins and their protein sequences include recognizable signal peptides [13]. Thus, it has long been speculated that insect ferritins may be involved in processes beyond iron storage [22]. My identification of ferritin as a growth factor for cultured Drosophila cells supports this hypothesis.…”

Identity and transfer of male reproductive gland proteins of the dengue vector mosquito, Aedes aegypti: Potential tools for control of female feeding and reproduction

“…aegypti mRGPs are predicted to play a role in either iron regulation or blood clotting. In addition to its potential immunityrelated function described in section 3.5.E, insect transferrin (AAEL015458/15639/ Supp_Aedes05593) helps to regulate iron levels and to transport iron into developing oocytes (Nichol et al, 2002). Iron regulation is especially important in blood-feeding animals since iron is consumed in large amounts and can be toxic when ingested in excess (Nichol et al, 2002).…”

“…In addition to its potential immunityrelated function described in section 3.5.E, insect transferrin (AAEL015458/15639/ Supp_Aedes05593) helps to regulate iron levels and to transport iron into developing oocytes (Nichol et al, 2002). Iron regulation is especially important in blood-feeding animals since iron is consumed in large amounts and can be toxic when ingested in excess (Nichol et al, 2002). To our knowledge, transferrin has only been reported from the male reproductive tissues of one other insect, the tsetse fly (Glossina morsitans morsitans; (Strickler-Dinglasan et al, 2006), which also feeds on blood.…”