Making connections in insect innate immunity

Kingsolver, Megan B.; Hardy, Richard W.

doi:10.1073/pnas.1216736109

Cited by 56 publications

(58 citation statements)

References 18 publications

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“…Because RNAi acts intracellularly, there may be greater opportunities for the symbiont to manipulate its expression than for pathways like JAK/STAT. However, while cross talk has been demonstrated between JAK/STAT and Toll70, such interactions have not yet been shown between RNAi and other pathways that may respond directly to bacterial effectors. A previous study has shown that Wolbachia has the capacity to affect intracellular localization of AGO-1, a member of the miRNA pathway within RNAi71.…”

Section: Discussionmentioning

confidence: 99%

The RNAi pathway plays a small part in Wolbachia-mediated blocking of dengue virus in mosquito cells

Terradas

Joubert

McGraw

2017

Sci Rep

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Wolbachia pipientis is an insect endosymbiont known to limit the replication of viruses including dengue and Zika in their primary mosquito vector, Aedes aegypti. Wolbachia is being released into mosquito populations globally in a bid to control the diseases caused by these viruses. It is theorized that Wolbachia’s priming of the insect immune system may confer protection against subsequent viral infection. Other hypotheses posit a role for competition between Wolbachia and viruses for host cellular resources. Using an A. aegypti cell line infected with Wolbachia, we tested the effects of targeting siRNAs against the major innate immune pathways on dengue virus loads. We show that while Wolbachia infection induces genes in the Toll, JAK/STAT and RNAi pathways, only reduced expression of RNAi leads to a rebound of dengue virus loads in Wolbachia-infected cells. The magnitude of the effect explained less than 10% of the total DENV load, demonstrating that blocking must be dependent on other factors in addition to the expression of RNAi. The findings bode well for the long-term stability of blocking given that immunity gene expression would likely be highly plastic and susceptible to rapid evolution.

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Section: Discussionmentioning

confidence: 99%

The RNAi pathway plays a small part in Wolbachia-mediated blocking of dengue virus in mosquito cells

Terradas

Joubert

McGraw

2017

Sci Rep

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“…Those changes identified in common, up or down, could reflect general physiological responses of intestinal cell exposure to dsRNA, such as stress or innate immune responses, as suggested for insect cells (Kingsolver and Hardy, 2012; Nunes et al, 2013). However, of the eight genes upregulated by both hsiRNA treatments in both the anterior and posterior intestine, there was no evidence of immune response or stress gene responses.…”

Section: Resultsmentioning

confidence: 88%

Direct experimental manipulation of intestinal cells in Ascaris suum , with minor influences on the global transcriptome

Rosa

McNulty

Mitreva

et al. 2017

International Journal for Parasitology

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Ascaris suum provides a powerful model for studying parasitic nematodes, including individual tissues such as the intestine, an established target for anthelmintic treatments. Here, we add a valuable experimental component to our existing functional, proteomic, transcriptomic and phylogenomic studies of the Ascaris suum intestine, by developing a method to manipulate intestinal cell functions via direct delivery of experimental treatments (in this case, double-stranded (ds)RNA) to the apical intestinal membrane. We developed an intestinal perfusion method for direct, controlled delivery of dsRNA/heterogeneous small interfering (hsi) RNA into the intestinal lumen for experimentation. RNA-Seq (22 samples) was used to assess influences of the method on global intestinal gene expression. Successful mRNA-specific knockdown in intestinal cells of adult A. suum was accomplished with this new experimental method. Global transcriptional profiling confirmed that targeted transcripts were knocked down more significantly than any others, with only 12 (0.07% of all genes) or 238 (1.3%) off-target gene transcripts consistently differentially regulated by dsRNA treatment or the perfusion experimental design, respectively (after 24 h). The system supports controlled, effective delivery of treatments (dsRNA/hsiRNA) to the apical intestinal membrane with relatively minor off-target effects, and builds on our experimental model to dissect A. suum intestinal cell functions with broad relevance to parasitic nematodes.

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“…Melanization of invading microbes is one important strategy that protects insects against infection123. In melanization cascade, prophenoloxidase (PPO)-activating protease (PAP) functions as the terminal protease to convert PPO into active phenoloxidase (PO)1213152021.…”

Section: Discussionmentioning

confidence: 99%

“…Most insects lack a typical adaptive immune system and mainly rely on the innate immune response for defense against the infection of pathogens or parasites123. Insect innate immune response has striking similarities to mammalian innate immune response, and also consists of humoral and cellular responses4.…”

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confidence: 99%

Serine protease SP105 activates prophenoloxidase in Asian corn borer melanization, and is regulated by serpin-3

Cheng

Fang

Liu

et al. 2017

Sci Rep

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Melanization reaction, resulting from the activation of prophenoloxidase, is a vital immune response in insects for encapsulating and killing the invasive organisms. Prophenoloxidase needs to be proteolytically activated by its upstream prophenoloxidase-activating protease (PAP) in melanization. Identification and characterization of PAPs facilitates the understanding of the molecular mechanisms involved in insect immunity. We here cloned a full-length cDNA for a serine protease, named as SP105, from Asian corn borer, Ostrinia furnacalis (Guenée). The open reading frame of SP105 encodes 424-amino acid residue protein with a 19-residue signal peptide. Sequence comparison indicates that SP105 is most similar to Manduca sexta PAP3, a defined prophenoloxidase-activating protease. qRT-PCR analysis showed that SP105 mRNA levels increased significantly after a bacterial injection. Recombinant SP105 directly cleaved and activated Asian corn borer prophenoloxidase and therefore acted as the prophenoloxidase-activating protease. Additionally, SP105 formed SDS-stable complexes with a serine protease inhibitor, serpin-3, and its activity in activating prophenoloxidase was efficiently inhibited by serpin-3. Our work thus illustrated a prophenoloxidase-activating protease and revealed its regulation by serpin-3. The results would allow further advances in the understanding of the melanization in Asian corn borer and other insects.

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Making connections in insect innate immunity

Cited by 56 publications

References 18 publications

The RNAi pathway plays a small part in Wolbachia-mediated blocking of dengue virus in mosquito cells

The RNAi pathway plays a small part in Wolbachia-mediated blocking of dengue virus in mosquito cells

Direct experimental manipulation of intestinal cells in Ascaris suum , with minor influences on the global transcriptome

Serine protease SP105 activates prophenoloxidase in Asian corn borer melanization, and is regulated by serpin-3

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