Role of NF-kβ factor Rel2 during Plasmodium falciparum and bacterial infection in Anopheles dirus

Abstract

BackgroundAnopheles mosquitoes transmit malaria which is one of the world’s most threatening diseases. Anopheles dirus (sensu stricto) is among the main vectors of malaria in South East Asia. The mosquito innate immune response is the first line of defence against malaria parasites during its development. The immune deficiency (IMD) pathway, a conserved immune signaling pathway, influences anti-Plasmodium falciparum activity in Anopheles gambiae, An. stephensi and An. albimanus. The aim of the study was to determine the role of Rel2, an IMD pathway-controlled NF-kappaβ transcription factor, in An. dirus.MethodsRACE (Rapid amplification of cDNA ends) was performed on the Rel2 gene. Double-stranded Rel2 was constructed and injected into the thorax of female mosquitoes. The injected mosquitoes were fed on a P. falciparum gametocyte culture and dissected on day 7–9 post-feeding in order to count the oocysts. A survival analysis was conducted by exposing the dsRNA injected mosquitoes to Gram-positive and Gram-negative bacteria.ResultsThis study demonstrated that the Rel2 gene in An. dirus has two isoforms, short length and full length. RNA interference-mediated gene silencing of Rel2 showed that the latter is involved in protection against P. falciparum, Gram-positive bacteria (Micrococcus luteus) with Lys-type peptidoglycan and Gram-negative bacteria (Escherichia coli) with DAP-type peptidoglycan.ConclusionThis study suggested that there are similarities in the splicing events and functionality of the Rel2 gene, between the Anopheles species. Among all the important anophelines, the immunity of only a few has been thoroughly investigated. In order to develop novel vector-based control strategies and restrict malaria transmission, the immune pathways of these important vectors should be thoroughly investigated.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1810-0) contains supplementary material, which is available to authorized users.

The IMD and JNK pathways drive the functional integration of the immune and circulatory systems of mosquitoes

“…Moreover, two downstream molecules – LRP1 and BINT2 – are transmembrane proteins that in mammals and insects have overlapping functions in phagocytosis and adhesion (Mantuano, Jo, Gonias, & Campana, 2010; Moita, Vriend, Mahairaki, Louis, & Kafatos, 2006; Rabiej et al, 2016), and therefore, likely facilitate the adhesion of hemocytes to the heart. In this study, we also confirmed the positive role that REL2 plays in pathogen killing (Dekmak, Yang, Zu Dohna, Buchon, & Osta, 2021; Dong et al, 2011; Dong, Simões, & Dimopoulos, 2020; Frolet et al, 2006; Kambris et al, 2010; Khan, Liew, Leong, & Lau, 2016; Meister et al, 2009; Meister et al, 2005; Mitri et al, 2009; Schnitger, Kafatos, & Osta, 2007). When we systemically knocked down the expression of rel2 , bacteria proliferated uncontrollably during the later stages of infection.…”

“…Moreover, two downstream molecules -the low-densitylipoprotein-receptor-related protein LRP1 and the beta integrin BINT2 -are transmembrane proteins that in mammals and insects have overlapping functions in phagocytosis and adhesion (69)(70)(71), and therefore, likely facilitate the adhesion of hemocytes to the heart. In this study, we also confirmed the positive role that REL2 plays in pathogen killing (29,44,68,(72)(73)(74)(75)(76)(77)(78). When we systemically knocked down the expression of rel2, bacteria proliferated uncontrollably during the later stages of infection.…”

The immune deficiency and c-Jun N-terminal kinase pathways drive the functional integration of the immune and circulatory systems of mosquitoes

“…Moreover, two downstream molecules-the low-density-lipoproteinreceptor-related protein LRP1 and the beta integrin BINT2are transmembrane proteins that in mammals and insects have overlapping functions in phagocytosis and adhesion [69][70][71], and therefore, likely facilitate the adhesion of haemocytes to the heart. In this study, we also confirmed the positive role that REL2 plays in pathogen killing [29,44,68,[72][73][74][75][76][77][78]. When we systemically knocked down the expression of rel2, bacteria proliferated uncontrollably during the later stages of infection.…”

Mosquito Trilogy: Microbiota, Immunity and Pathogens, and Their Implications for the Control of Disease Transmission

“…gambiae genome encodes two isoforms of the Relish homolog (i.e., REL-2); the short isoform, REL-2S, is involved in the response against Gram-negative bacteria, while the long isoform, REL-2F, against Gram-positives (Meister et al, 2005). It has been demonstrated that in Anopheles dirus REL-2F is involved in protection against both Gram-positive (with Lys-type peptidoglycan) and Gram-negative bacteria (with DAP-type peptidoglycan) (Khan et al, 2016). Relish, in turn, induces the expression of antimicrobial peptides (AMPs).…”