Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Relish and the Regulation of Antimicrobial Peptides in Drosophila melanogaster
Stockholm University, Faculty of Science, The Wenner-Gren Institute .
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The fruit fly Drosophila melanogaster has been a powerful model system in which to study the immune response. When microorganisms breach the mechanical barrier of the insect, phagocytosing cells and a battery of induced antimicrobial molecules rapidly attack them. These antimicrobial peptides can reach micromolar concentrations within a few hours. This immediate response is reminiscent of the mammalian innate immune response and utilizes transcription factors of the NF-κB family.

We have generated loss-of-function mutants of the NF-κB-like transcription factor Relish in order to investigate Relish's role in the Drosophila immune response to microbes. Relish mutant flies have a severely impaired immune response to Gram-negative (G-) bacteria and some Gram-positive (G+) bacteria and fungi and succumb to an otherwise harmless infection. The main reason for the high susceptibility to infection is that these mutant flies fail to induce the antimicrobial peptide genes. The cellular responses appear to be normal.

Relish is retained in the cytoplasm in an inactive state. We designed a set of expression plasmids to investigate the requirements for activation of Relish in a hemocyte cell line after stimulation with bacterial lipopolysaccharide. Signal-induced phosphorylation of Relish followed by endoproteolytic processing at the caspase-like target motif in the linker region released the inhibitory ankyrin-repeat (ANK) domain from the DNA binding Rel homology domain (RHD). Separation from the ANK domain allowed the RHD to move into the nucleus and initiate transcription of target genes like those that encode the inducible antimicrobial peptides, likely by binding to κB-like sites in the promoter region.

By studying the immune response of the Relish mutant flies in combination with mutants for another NF-κB-like protein, Dorsal-related immunity factor (Dif), we found that the Drosophila immune system can distinguish between various microbes and generate a differential response by activating the Toll/Dif and Imd/Relish pathways. The recognition of foreign microorganisms is believed to occur through pattern recognition receptors (PRRs) that have affinity for selective pathogen-associated molecular patterns (PAMPs). We found that the Drosophila PRRs can recognize G- bacteria as a group. Interestingly, the PRRs are specific enough to distinguish between peptidoglycans from G+ bacteria such as Micrococcus luteus and Bacillus megaterium and fungal PAMPs from Beauveria bassiana and Geotrichum candidum.

This thesis also investigates the expression of the antimicrobial peptide genes, Diptericin B and Attacin C, and the putative intracellular antimicrobial peptide gene Attacin D, and explores a potential evolutionary link between them.

Place, publisher, year, edition, pages
Stockholm: The Wenner-Gren Institute, Stockholm University , 2004. , 49 p.
Keyword [en]
Drosophila immunity, NF-kappaB, Relish, antimicrobial peptides
National Category
Developmental Biology
Identifiers
URN: urn:nbn:se:su:diva-170ISBN: 91-7265-897-5 (print)OAI: oai:DiVA.org:su-170DiVA: diva2:190445
Public defence
2004-06-02, hörsalen, Frescati backe, Svante Arrhenius väg 21 A, Stockholm, 13:00
Opponent
Supervisors
Available from: 2004-05-13 Created: 2004-05-13 Last updated: 2011-03-28Bibliographically approved
List of papers
1. Relish, a central factor in the control of humoral but not cellular immunity in Drosophila
Open this publication in new window or tab >>Relish, a central factor in the control of humoral but not cellular immunity in Drosophila
Show others...
1999 (English)In: Molecular cell, ISSN 1097-2765, Vol. 4, no 5, 827-37 p.Article in journal (Refereed) Published
Abstract [en]

The NF-κB-like Relish gene is complex, with four transcripts that are all located within an intron of the Nmdmc gene. Using deletion mutants, we show that Relish is specifically required for the induction of the humoral immune response, including both antibacterial and antifungal peptides. As a result, the Relish mutants are very sensitive to infection. A single cell of E. cloacae is sufficient to kill a mutant fly, and the mutants show increased susceptibility to fungal infection. In contrast, the blood cell population, the hematopoietic organs, and the phagocytic, encapsulation, and melanization responses are normal. Our results illustrate the importance of the humoral response in Drosophila immunity and demonstrate that Relish plays a key role in this response.

Place, publisher, year, edition, pages
Elsevier, 1999
National Category
Cell Biology
Research subject
Cellbiology
Identifiers
urn:nbn:se:su:diva-23156 (URN)10.1016/S1097-2765(00)80392-5 (DOI)
Note
Part of urn:nbn:se:su:diva-170Available from: 2004-05-13 Created: 2004-05-13 Last updated: 2009-12-22Bibliographically approved
2. Expression and evolution of the Drosophila attacin/diptericin gene family
Open this publication in new window or tab >>Expression and evolution of the Drosophila attacin/diptericin gene family
2000 (English)In: Biochemical and Biophysical Research Communications, ISSN 0006-291X, Vol. 279, no 2, 574-81 p.Article in journal (Refereed) Published
Abstract [en]

We describe the genes for three new glycine-rich antimicrobial peptides in (support the proposal that these glycine-rich antimicrobial peptides evolved from a common ancestor and are probably also related to proline-rich peptides such as drosocin. Drosophila, two attacinsAttC and AttD) and one diptericin (DptB). Their structuresAttC is similar to the nearby  AttA on a different chromosome. Intriguingly, and AttB genes. AttD is more divergent and locatedAttD  may encode an intracellular attacin tandem to the closely related DptB is linked inDiptericin. However, the  DptB and may be processed in an attacin-like fashion. All attacin and diptericin genes are induced after bacterial challenge. This induction is reduced in and unexpectedly also in gene product contains a furin-like cleavage siteimd mutants,Tl2 mutants. The 18w  mutation particularly affects the induction of AttC,  which may be a useful marker for 18w signaling.

Place, publisher, year, edition, pages
Elsevier, 2000
National Category
Cell Biology
Research subject
Cellbiology
Identifiers
urn:nbn:se:su:diva-23157 (URN)10.1006/bbrc.2000.3988 (DOI)
Note
Part of urn:nbn:se:su:diva-170Available from: 2004-05-13 Created: 2004-05-13 Last updated: 2009-12-22Bibliographically approved
3. Differential activation of the NF-kappaB-like factors Relish and Dif in Drosophila melanogaster by fungi and gram-positive bacteria
Open this publication in new window or tab >>Differential activation of the NF-kappaB-like factors Relish and Dif in Drosophila melanogaster by fungi and gram-positive bacteria
Show others...
2004 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, Vol. 279, no 20, 21121-7 p.Article in journal (Refereed) Published
Abstract [en]

The current model of immune activation in Drosophila melanogaster suggests that fungi and Gram-positive (G+) bacteria activate the Toll/Dif pathway and that Gram-negative (G-) bacteria activate the Imd/Relish pathway. To test this model, we examined the response of Relish and Dif (Dorsal-related immunity factor) mutants to challenge by various fungi and G+ and G- bacteria. In Relish mutants, the Cecropin A gene was induced by the G+ bacteria Micrococcus luteus and Staphylococcus aureus, but not by other G+ or G- bacteria. This Relish-independent Cecropin A induction was blocked in Dif/Relish double mutant flies. Induction of the Cecropin A1 gene by M. luteus required Relish, whereas induction of the Cecropin A2 gene required Dif. Intact peptidoglycan (PG) was necessary for this differential induction of Cecropin A. PG extracted from M. luteus induced Cecropin A in Relish mutants, whereas PGs from the G+ bacteria Bacillus megaterium and Bacillus subtilis did not, suggesting that the Drosophila immune system can distinguish PGs from various G+ bacteria. Various fungi stimulated antimicrobial peptides through at least two different pathways requiring Relish and/or Dif. Induction of Attacin A by Geotrichum candidum required Relish, whereas activation by Beauvaria bassiana required Dif, suggesting that the Drosophila immune system can distinguish between at least these two fungi. We conclude that the Drosophila immune system is more complex than the current model. We propose a new model to account for this immune system complexity, incorporating distinct pattern recognition receptors of the Drosophila immune system, which can distinguish between various fungi and G+ bacteria, thereby leading to selective induction of antimicrobial peptides via differential activation of Relish and Dif.

Place, publisher, year, edition, pages
American Society for Biochemistry and Molecular Biology, 2004
National Category
Cell Biology
Research subject
Cellbiology
Identifiers
urn:nbn:se:su:diva-23158 (URN)10.1074/jbc.M313856200 (DOI)
Note
Part of urn:nbn:se:su:diva-170Available from: 2004-05-13 Created: 2004-05-13 Last updated: 2009-12-22Bibliographically approved
4. Caspase-mediated processing of the Drosophila NF-κB factor Relish
Open this publication in new window or tab >>Caspase-mediated processing of the Drosophila NF-κB factor Relish
Show others...
2003 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 100, no 10, 5991-5996 p.Article in journal (Refereed) Published
Abstract [en]

The NF-κB-like transcription factor Relish plays a central role in the innate immune response of Drosophila. Unlike other NF-κB proteins, Relish is activated by endoproteolytic cleavage to generate a DNA-binding Rel homology domain and a stable IκB-like fragment. This signal-induced endoproteolysis requires the activity of several gene products, including the IκB kinase complex and the caspase Dredd. Here we used mutational analysis and protein microsequencing to demonstrate that a caspase target site, located in the linker region between the Rel and the IκB-like domain, is the site of signal-dependent cleavage. We also show physical interaction between Relish and Dredd, suggesting that Dredd indeed is the Relish endoprotease. In addition to the caspase target site, the C-terminal 107 aa of Relish are required for endoproteolysis and signal-dependent phosphorylation by the Drosophila IκB kinase β. Finally, an N-terminal serine-rich region in Relish and the PEST domain were found to negatively regulate Relish activation.

National Category
Natural Sciences
Identifiers
urn:nbn:se:su:diva-24103 (URN)10.1073/pnas.1035902100 (DOI)
Available from: 2007-02-01 Created: 2007-02-01 Last updated: 2017-12-13Bibliographically approved

Open Access in DiVA

fulltext(3101 kB)1656 downloads
File information
File name FULLTEXT01.pdfFile size 3101 kBChecksum SHA-1
fbf9e9054915b2a8ddeec420f42cb614b140f82de819212c5703c299ba48831202205baa
Type fulltextMimetype application/pdf

By organisation
The Wenner-Gren Institute
Developmental Biology

Search outside of DiVA

GoogleGoogle Scholar
Total: 1656 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 559 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf