Multicopper oxidase-1 is required for iron homeostasis in Malpighian tubules of Helicoverpa armigera

Abstract

Multicopper oxidases (MCOs) are enzymes that contain 10 conserved histidine residues and 1 cysteine residue. MCO1 has been extensively investigated in the midgut because this MCO is implicated in ascorbate oxidation, iron homeostasis and immune responses. However, information regarding the action of MCO1 in Malpighian tubules is limited. In this study, Helicoverpa armigera was used as a model to investigate the function of MCO1 in Malpighian tubules. Sequence analysis results revealed that HaMCO1 exhibits typical MCO characteristics, with 10 histidine and 1 cysteine residues for copper ion binding. HaMCO1 was also found to be highly abundant in Malpighian tubules. Temporal expression patterns indicated that HaMCO1 is mainly expressed during larval molting stages. Hormone treatments [the molting hormone 20-hydroxyecdysone (20E) and juvenile hormone (JH)] revealed that 20E inhibits HaMCO1 transcript expression via its heterodimer receptor, which consists of ecdysone receptor (EcR) and ultraspiracle (USP), and that JH counteracts the action of 20E to activate HaMCO1 transcript expression via its intracellular receptor methoprene-tolerant (Met). HaMCO1 knockdown caused a significant decrease in iron accumulation and also significantly reduced transferrin and ferritin transcript expression. Therefore, HaMCO1 is coordinately regulated by 20E and JH and is required for iron homeostasis in Malpighian tubules.

Ironing out the Details: Exploring the Role of Iron and Heme in Blood-Sucking Arthropods

“…dMCO1's role in iron homeostasis was confirmed by RNAi knockdown experiments yielding increased longevity when flies fed on high iron food and a decreased iron accumulation in the body. The MCO gene family is conserved in coleopterans, lepidopterans and dipterans (Lang et al, 2012 ; Liu et al, 2015 ; Peng et al, 2015 ; Ye et al, 2015 ). An.…”

RNAi-Mediated Suppression of Laccase2 Impairs Cuticle Tanning and Molting in the Cotton Boll Weevil (Anthonomus grandis)

“…Two main Laccase genes, Laccase1 ( Lac1 / MCO1 ), and Laccase2 ( Lac2 / MCO2 ), have been described in insects. Lac1 is expressed in tissues such as salivary glands, midgut and Malpighian tubules and has been implicated in lignocellulose digestion, detoxification of secondary plant compounds, ascorbate and iron homeostasis, and immune defense in insects ( Gorman et al, 2008 ; Coy et al, 2010 ; Lang et al, 2012 ; Liu et al, 2015 ; Peng et al, 2015 ; Yang C.-H. et al, 2017 ; Wang et al, 2018 ; Zhang et al, 2018 ), while Lac2 is expressed primarily in the epidermis and has been associated with insect cuticular pigmentation and hardening as well as melanization immune response ( Arakane et al, 2005 ; Elias-Neto et al, 2010 ; Futahashi et al, 2011 ; Ye et al, 2015 ; Du et al, 2017 ; Nishide et al, 2020 ). Further, Lac2 has been related to mechanisms of insecticide cuticular resistance.…”

Characterization of multicopper oxidase genes in the green rice leafhopper, Nephotettix cincticeps (Hemiptera: Cicadellidae), with focus on salivary gland‐specific genes

“…Two types of MCOs have been identified in various insect species. MCO1s are expressed generally in a number of organs in Manduca sexta , Drosophila melanogaster , Nephottetix cincticeps , Helicoverpa armigera , Nilaparvata lugens , and Triboleum castaneum (Dittmer et al, ; Hattori et al, ; Lang, Braun, Kanost, & Gorman, ; Liu et al, ; Peng et al, ; Ye, Pan, Kang, Lu, & Zhang, ), with associated ascorbate oxidase activities identified in several of these species (Peng et al, ). Meanwhile, MCO2s are laccases that are highly expressed in integument.…”