Aedes aegypti ferritin

Abstract

Diseases transmitted by hematophagous (blood-feeding) insects are responsible for millions of human deaths worldwide. In hematophagous insects, the blood meal is important for regulating egg maturation. Although a high concentration of iron is toxic for most organisms, hematophagous insects seem unaffected by the iron load in a blood meal. One means by which hematophagous insects handle this iron load is, perhaps, by the expression of iron-binding proteins, specifically the iron storage protein ferritin. In vertebrates, ferritin is an oligomer composed of two types of subunits called heavy and light chains, and is part of the constitutive antioxidant response. Previously, we found that the insect midgut, a main site of iron load, is also a primary site of ferritin expression and that, in the yellow fever mosquito, Aedes aegypti, the expression of the ferritin heavy-chain homologue (HCH) is induced following blood feeding. We now show that the expression of the Aedes ferritin light-chain homologue (LCH) is also induced with blood-feeding, and that the genes of the LCH and HCH are tightly clustered. mRNA levels for both LCH-and HCH-genes increase with iron, H 2 O 2 and hemin treatment, and the temporal expression of the genes is very similar. These results confirm that ferritin could serve as the cytotoxic protector in mosquitoes against the oxidative challenge of the bloodmeal. Finally, although the Aedes LCH has no iron responsive element (IRE) at its 5¢-untranslated region (UTR), the 5¢-UTR contains several introns that are alternatively spliced, and this alternative splicing event is different from any ferritin message seen to date.

Increasing genomic information in bivalves through new EST collections in four species: Development of new genetic markers for environmental studies and genome evolution

“…They have also been shown to play a role in biomineralisation in the bivalve Pinctada fucata (Zhang et al, 2003). Ferritins are known to be regulated by many factors, including anoxia (Larade and Storey, 2004;Geiser et al, 2003). Recent results also suggest a role of ferritins as a protector against oxygen free radical-mediated damage (Orino et al, 1997), and acting in cellular proliferation (Le and Richarson, 2002).…”

Insect iron binding proteins: Insights from the genomes

“…The Fer1HCH-3 and Fer1HCH-4 sequences are 91% and 94% identical to Fer1HCH-2. The deduced amino acid sequence of the published Fer2LCH-1 (Geiser et al, 2003) is 57%, 56%, and 46% identical to the Fer2LCH-2, Fer2LCH-3, and Fer2LCH-4, respectively. The same sequence is 49% identical to its A. gambiae ortholog.…”

Molecular characterization of iron binding proteins from Glossina morsitans morsitans (Diptera: Glossinidae)

“…With the exception of the unusual placement of an Nglycosylation site at the beginning of the Ae. aegypti mature LCH peptide (Asp22/23) (Geiser et al, 2003), known dipteran LCH homologues lack glycosylation, including G. m. morsitans (Lind et al, 1998a). Previously published alignments of insect LCHs, including that of D. melanogaster, maintain conservation of three Cys residues (Kim et al, 2004b, Kim et al, 2004a.…”

“…The lack of an IRE in the GmmFer2LCH cDNA sequence is in agreement with LCH homologues characterized from two other dipteran species, D. melanogaster and Ae. aegypti , Geiser et al, 2003.…”

“…The IRE is indicated by a string of karats '∧' and the consensus loop is in bold and double-underlined. The signal peptide sequence is underlined, the polyadenylation signal is indicated by a string of asterisks ' * ', and the putative non-canonical polyadenylation signals , Geiser et al, 2003 are indicated by a string of colons ':'. The oligonucleotide sequences used in the tissue-specific semi-quantitative RT-PCR analysis are in bold and labeled as FHC942F (forward primer) and FHC1418R (reverse primer).…”