Limits...
Functional characterization of the infection-inducible peptide Edin in Drosophila melanogaster.

Vanha-Aho LM, Kleino A, Kaustio M, Ulvila J, Wilke B, Hultmark D, Valanne S, Rämet M - PLoS ONE (2012)

Bottom Line: In addition, the immune signaling cascades found in Drosophila are evolutionarily conserved.In our experiments, Edin did not bind microbes, nor did it possess antimicrobial activity to tested microbial strains in vitro or in vivo.Furthermore, edin RNAi did not significantly affect the expression of AMPs in vitro or in vivo.

View Article: PubMed Central - PubMed

Affiliation: BioMediTech and Institute of Biomedical Technology, University of Tampere, Tampere, Finland.

ABSTRACT
Drosophila is a well-established model organism for studying innate immunity because of its high resistance against microbial infections and lack of adaptive immunity. In addition, the immune signaling cascades found in Drosophila are evolutionarily conserved. Upon infection, activation of the immune signaling pathways, Toll and Imd, leads to the expression of multiple immune response genes, such as the antimicrobial peptides (AMPs). Previously, we identified an uncharacterized gene edin among the genes, which were strongly induced upon stimulation with Escherichia coli in Drosophila S2 cells. Edin has been associated with resistance against Listeria monocytogenes, but its role in Drosophila immunity remains elusive. In this study, we examined the role of Edin in the immune response of Drosophila both in vitro and in vivo. We report that edin expression is dependent on the Imd-pathway NF-κB transcription factor Relish and that it is expressed upon infection both in vitro and in vivo. Edin encodes a pro-protein, which is further processed in S2 cells. In our experiments, Edin did not bind microbes, nor did it possess antimicrobial activity to tested microbial strains in vitro or in vivo. Furthermore, edin RNAi did not significantly affect the expression of AMPs in vitro or in vivo. However, edin RNAi flies showed modestly impaired resistance to E. faecalis infection. We conclude that Edin has no potent antimicrobial properties but it appears to be important for E. faecalis infection via an uncharacterized mechanism. Further studies are still required to elucidate the exact role of Edin in the Drosophila immune response.

Show MeSH

Related in: MedlinePlus

Edin RNAi impairs survival in vivo after E. faecalis infection.A–C. Healthy adult flies were pricked with a needle dipped either into a culture of E. cloacae, E. faecalis or L. monocytogenes and the survival of the flies was monitored. RelE20 mutants and/or MyD88 RNAi flies were used as positive controls. (A) Effect of edin RNAi after E. cloacae infection. Data are pooled from 3 independent experiments which showed similar trends, n = 112–117 for each cross. (B) Edin RNAi flies crossed with the C564-GAL4 driver are more susceptible to E. faecalis infection than uninduced edin RNAi flies crossed with w1118. Data are pooled from 2 independent experiments which showed similar trends n = 81–87 for each cross. For MyD88 RNAi crossed to w1118 and C564, data represents one experiment and n = 35 for both crosses. (C) Edin RNAi does not have a significant effect on fly survival against L. monocytogenes challenge. Data are pooled from 3 independent experiments which showed similar trends, n = 78–90 for each cross.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3351453&req=5

pone-0037153-g008: Edin RNAi impairs survival in vivo after E. faecalis infection.A–C. Healthy adult flies were pricked with a needle dipped either into a culture of E. cloacae, E. faecalis or L. monocytogenes and the survival of the flies was monitored. RelE20 mutants and/or MyD88 RNAi flies were used as positive controls. (A) Effect of edin RNAi after E. cloacae infection. Data are pooled from 3 independent experiments which showed similar trends, n = 112–117 for each cross. (B) Edin RNAi flies crossed with the C564-GAL4 driver are more susceptible to E. faecalis infection than uninduced edin RNAi flies crossed with w1118. Data are pooled from 2 independent experiments which showed similar trends n = 81–87 for each cross. For MyD88 RNAi crossed to w1118 and C564, data represents one experiment and n = 35 for both crosses. (C) Edin RNAi does not have a significant effect on fly survival against L. monocytogenes challenge. Data are pooled from 3 independent experiments which showed similar trends, n = 78–90 for each cross.

Mentions: Next, we investigated whether Edin is required for normal resistance against septic infection. To this end edin RNAi flies were crossed with the C564-GAL4 driver or w1118 flies as a control, and the one-week-old offspring were infected with E. cloacae, E faecalis or L. monocytogenes. RelE20 mutant flies were used as a positive control in the E. cloacae and L. monocytogenes infection model, and UAS-MyD88 RNAi flies crossed with the C564-GAL4 driver as a positive control in the E. faecalis infection model. When infected with the Gram-negative bacterium E. cloacae, RelE20 mutant flies succumbed to the infection within 24 h. Edin RNAi flies crossed with C564-GAL4 flies showed a mild decrease in survival after E. cloacae infection compared to edin RNAi flies crossed with w1118 (Figure 8A) but this it not significant because the C564-GAL4 driver flies crossed to w1118 are more susceptible to the infection. However, a decrease in survival was observed in edin RNAi flies infected with the Gram-positive bacterium E. faecalis (Figure 8B). However, no statistically significant difference in survival was seen after an L. monocytogenes infection (Figure 8C), although a similar trend in survival could be observed, which is in line with the results by Gordon et al. [15]. These results imply that the expression of edin might be required for normal resistance against some bacterial infections.


Functional characterization of the infection-inducible peptide Edin in Drosophila melanogaster.

Vanha-Aho LM, Kleino A, Kaustio M, Ulvila J, Wilke B, Hultmark D, Valanne S, Rämet M - PLoS ONE (2012)

Edin RNAi impairs survival in vivo after E. faecalis infection.A–C. Healthy adult flies were pricked with a needle dipped either into a culture of E. cloacae, E. faecalis or L. monocytogenes and the survival of the flies was monitored. RelE20 mutants and/or MyD88 RNAi flies were used as positive controls. (A) Effect of edin RNAi after E. cloacae infection. Data are pooled from 3 independent experiments which showed similar trends, n = 112–117 for each cross. (B) Edin RNAi flies crossed with the C564-GAL4 driver are more susceptible to E. faecalis infection than uninduced edin RNAi flies crossed with w1118. Data are pooled from 2 independent experiments which showed similar trends n = 81–87 for each cross. For MyD88 RNAi crossed to w1118 and C564, data represents one experiment and n = 35 for both crosses. (C) Edin RNAi does not have a significant effect on fly survival against L. monocytogenes challenge. Data are pooled from 3 independent experiments which showed similar trends, n = 78–90 for each cross.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3351453&req=5

pone-0037153-g008: Edin RNAi impairs survival in vivo after E. faecalis infection.A–C. Healthy adult flies were pricked with a needle dipped either into a culture of E. cloacae, E. faecalis or L. monocytogenes and the survival of the flies was monitored. RelE20 mutants and/or MyD88 RNAi flies were used as positive controls. (A) Effect of edin RNAi after E. cloacae infection. Data are pooled from 3 independent experiments which showed similar trends, n = 112–117 for each cross. (B) Edin RNAi flies crossed with the C564-GAL4 driver are more susceptible to E. faecalis infection than uninduced edin RNAi flies crossed with w1118. Data are pooled from 2 independent experiments which showed similar trends n = 81–87 for each cross. For MyD88 RNAi crossed to w1118 and C564, data represents one experiment and n = 35 for both crosses. (C) Edin RNAi does not have a significant effect on fly survival against L. monocytogenes challenge. Data are pooled from 3 independent experiments which showed similar trends, n = 78–90 for each cross.
Mentions: Next, we investigated whether Edin is required for normal resistance against septic infection. To this end edin RNAi flies were crossed with the C564-GAL4 driver or w1118 flies as a control, and the one-week-old offspring were infected with E. cloacae, E faecalis or L. monocytogenes. RelE20 mutant flies were used as a positive control in the E. cloacae and L. monocytogenes infection model, and UAS-MyD88 RNAi flies crossed with the C564-GAL4 driver as a positive control in the E. faecalis infection model. When infected with the Gram-negative bacterium E. cloacae, RelE20 mutant flies succumbed to the infection within 24 h. Edin RNAi flies crossed with C564-GAL4 flies showed a mild decrease in survival after E. cloacae infection compared to edin RNAi flies crossed with w1118 (Figure 8A) but this it not significant because the C564-GAL4 driver flies crossed to w1118 are more susceptible to the infection. However, a decrease in survival was observed in edin RNAi flies infected with the Gram-positive bacterium E. faecalis (Figure 8B). However, no statistically significant difference in survival was seen after an L. monocytogenes infection (Figure 8C), although a similar trend in survival could be observed, which is in line with the results by Gordon et al. [15]. These results imply that the expression of edin might be required for normal resistance against some bacterial infections.

Bottom Line: In addition, the immune signaling cascades found in Drosophila are evolutionarily conserved.In our experiments, Edin did not bind microbes, nor did it possess antimicrobial activity to tested microbial strains in vitro or in vivo.Furthermore, edin RNAi did not significantly affect the expression of AMPs in vitro or in vivo.

View Article: PubMed Central - PubMed

Affiliation: BioMediTech and Institute of Biomedical Technology, University of Tampere, Tampere, Finland.

ABSTRACT
Drosophila is a well-established model organism for studying innate immunity because of its high resistance against microbial infections and lack of adaptive immunity. In addition, the immune signaling cascades found in Drosophila are evolutionarily conserved. Upon infection, activation of the immune signaling pathways, Toll and Imd, leads to the expression of multiple immune response genes, such as the antimicrobial peptides (AMPs). Previously, we identified an uncharacterized gene edin among the genes, which were strongly induced upon stimulation with Escherichia coli in Drosophila S2 cells. Edin has been associated with resistance against Listeria monocytogenes, but its role in Drosophila immunity remains elusive. In this study, we examined the role of Edin in the immune response of Drosophila both in vitro and in vivo. We report that edin expression is dependent on the Imd-pathway NF-κB transcription factor Relish and that it is expressed upon infection both in vitro and in vivo. Edin encodes a pro-protein, which is further processed in S2 cells. In our experiments, Edin did not bind microbes, nor did it possess antimicrobial activity to tested microbial strains in vitro or in vivo. Furthermore, edin RNAi did not significantly affect the expression of AMPs in vitro or in vivo. However, edin RNAi flies showed modestly impaired resistance to E. faecalis infection. We conclude that Edin has no potent antimicrobial properties but it appears to be important for E. faecalis infection via an uncharacterized mechanism. Further studies are still required to elucidate the exact role of Edin in the Drosophila immune response.

Show MeSH
Related in: MedlinePlus