Immune signaling pathways regulating bacterial and malaria parasite infection of the mosquito Anopheles gambiae

Abstract

We show that, in the malaria vector Anopheles gambiae, expression of Cecropin 1 is regulated by REL2, an NF-B-like transcription factor orthologous to Drosophila Relish. Through alternative splicing, REL2 produces a full-length (REL2-F) and a shorter (REL2-S) protein isoform lacking the inhibitory ankyrin repeats and death domain. RNA interference experiments show that, in contrast to Drosophila Relish, which responds solely to Gram-negative bacteria, the Anopheles REL2-F and REL2-S isoforms are involved in defense against the Gram-positive Staphylococcus aureus and the Gram-negative Escherichia coli bacteria, respectively. REL2-F also regulates the intensity of mosquito infection with the malaria parasite, Plasmodium berghei. The adaptor IMD shares the same activities as REL2-F. Microarray analysis identified 10 additional genes regulated by REL2, including CEC3, GAM1, and LRIM1.innate immunity ͉ NF-B ͉ Relish ͉ Cecropin ͉ Imd

Correlation of Differential Expression of Silkworm Antimicrobial Peptide Genes with Different Amounts of Rel Family Proteins and Their Gene Transcriptional Activity

“…The other is that BmRelish1 has a higher ability to enhance the promoter activity of AMP genes than BmRels. Dorsal and Relish homologs have also been found in other insects, such as Anopheles gambiae, 36,37) Aedes aegypti, 38,39) and Tribolium castaneum, 40) but differences in the amounts of Rel family proteins have not yet been reported in other insects. Whether this phenomenon is silkworm-or Lepidoptera-specific ought to be elucidated.…”

Plasmodium falciparum evades mosquito immunity by disrupting JNK-mediated apoptosis of invaded midgut cells

“…Other immune signaling cascades, such as the immune deficiency (IMD), Toll, and JAK/STAT pathways, have also been implicated in antiplasmodial responses in the mosquito (28)(29)(30)(31). For example, activation of the Toll pathway is more effective against the rodent malaria parasite, P. berghei (28), whereas the IMD pathway is more effective against the human malaria parasite, P. falciparum (30).…”

Nuclear factor-kappa B pathways in Drosophila

“…In A. gambiae the Relish homolog functions in the defense against Gram-positive and Gram-negative bacteria (Meister et al, 2005).…”