Expression Profiles and RNAi Silencing of Inhibitor of Apoptosis Transcripts inAedes,Anopheles, andCulexMosquitoes (Diptera: Culicidae)

Abstract

Effective mosquito control is vital to curtail the devastating health effects of many vectored diseases. RNA interference (RNAi)-mediated control of mosquitoes is an attractive alternative to conventional chemical pesticides. Previous studies have suggested that transcripts for inhibitors of apoptosis (IAPs) may be good RNAi targets. To revisit and extend previous reports, we examined the expression of Aedes aegypti (L.) IAPs (AaeIAPs) 1, 2, 5, 6, 9, and a viral IAP-associated factor (vIAF) as well as Anopheles quadrimaculatus Say and Culex quinquefasciatus Say IAP1 homologs (AquIAP1 and CquIAP1) in adult females. Expression profiles of IAPs suggested that some older female mosquitoes had significantly higher IAP mRNA levels when compared to the youngest ones. Minor differences in expression of AaeIAPs were observed in mosquitoes that imbibed a bloodmeal, but the majority of the time points (up to 48 h) were not significantly different. Although in vitro experiments with the Ae. aegypti Aag-2 cell line demonstrated that the various AaeIAPs could be effectively knocked down within one day after dsRNA treatment, only Aag-2 cells treated with dsIAP1 displayed apoptotic morphology. Gene silencing and mortality were also evaluated after topical application and microinjection of the same dsRNAs into female Ae. aegypti. In contrast to previous reports, topical administration of dsRNA against AaeIAP1 did not yield a significant reduction in gene expression or increased mortality. Knockdown of IAP1 and other IAPs by microinjection did not result in significant mortality. In toto, our findings suggest that IAPs may not be suitable RNAi targets for controlling adult mosquito populations.

Apoptosis-related genes control autophagy and influence DENV-2 infection in the mosquito vector, Aedes aegypti

“…However, we also observed programmed autophagy at this time. In addition, we and others (Bonizzoni et al , 2012a; Puglise et al , 2015) observed upregulation of several apoptosis-related genes, some of which control autophagy in insects (Accorsi et al , 2015; Denton et al , 2012b). While these genes may indeed be activated in response to pathogen infection, our finding that Aedronc knockdown reduces infection suggests that apoptosis-related genes may have additional roles.…”

“…This complements and confirms other transcription studies where autophagic and IAP genes were upregulated in other strains of Ae. aegypti following blood feeding (Bonizzonni et al , 2011; Bonizzoni et al , 2012b; Puglise et al , 2015). In this study, we present a model where caspases are involved with the control of programmed autophagy post meal meal (Fig 9B).…”

Solute carriers affect Anopheles stephensi survival and Plasmodium berghei infection in the salivary glands

“…Apoptosis, i.e., programmed cell death, is a crucial cellular mechanism for tissue homeostasis and normal immune system functioning, which is highly regulated by a variety of caspases, Bcl-2 proteins, and inhibitors of apoptosis (IAPs) 47 . Studies using P. berghei reveal the induction of cell death and apoptosis during infection 48, 49 .…”

RNA Interference for Mosquito and Mosquito-Borne Disease Control

“…In Ae. aegypti , knockdown of IAP1 by RNAi results in activation of apoptosis and rapid mortality both in vitro and in vivo, making the gene a key target for insecticidal RNAi [10,52,53,54,55]. Mortality induced by IAP1 silencing can be reversed if initiator caspases such as Ae.…”