| 1. |
- Huang, TS, et al.
(författare)
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A cell adhesion protein from the crayfish Pacifastacus leniusculus, a serine proteinase homologue similar to Drosophila masquerade
- 2000
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 275:14, s. 9996-10001
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Tidskriftsartikel (refereegranskat)abstract
- A cDNA encoding a protein resembling masquerade, a serine proteinase homologue expressed during embryogenesis, larval, and pupal development in Drosophila melanogaster, was identified in hemocytes of the adult freshwater crayfish, Pacifastacus leniusculus. The crayfish protein is similar to Drosophila masquerade in the following aspects: (a) overall sequence of the serine proteinase domain, such as the position of three putative disulfide bridges, glycine in the place of the catalytic serine residue, and the presence of a substrate-lining pocket typical for trypsins; (b) the presence of several copies of a disulfide-knotted motif in the putative propeptide. This masquerade-like protein is cleaved into a 27-kDa fragment, which could be detected by immunoblot analysis using an affinity-purified antibody against a synthetic peptide in the C-terminal domain of the protein. The 27-kDa protein could be immunoaffinity-purified from hemocyte lysate supernatant and exhibited cell adhesion activity in vitro, indicating that the C-terminal domain of the crayfish masquerade-like protein mediates cell adhesion.
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| 2. |
- Johansson, Karin C, et al.
(författare)
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Diptericin expression in bacteria infected Drosophila mbn-2 cells - effect of infection dose and phagocytosis.
- 2006
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Ingår i: Insect molecular biology (Print). - : Wiley. - 0962-1075 .- 1365-2583. ; 15:1, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- Drosophila haemocytes play a key role in defence against microbial aggression. Their capacity to sense and dispose of bacteria and also to signal to other immune tissues is probably vital to overcome an infection. In this work we used the haemocyte-like mbn-2 cell line to investigate how expression of the antimicrobial peptide diptericin is affected after a high dose bacterial challenge with diaminopimelic acid (DAP)-peptidoglycan Gram-positive and Gram-negative bacteria. We report that diptericin expression is negatively affected by high infection dose and rapid bacterial growth regardless of the type of infection and bacterial virulence and occurs in the absence of mbn-2 cell death. Furthermore we show that the mbn-2 cell population is heterogeneous, containing both phagocytic and nonphagocytic cells and that contact with large numbers of bacteria decreases diptericin expression in the phagocytic cell population.
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| 3. |
- Johansson, Karin C, et al.
(författare)
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Microarray analysis of immune challenged Drosophila hemocytes
- 2005
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 305:1, s. 145-155
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Tidskriftsartikel (refereegranskat)abstract
- nsect hemocytes play multiple roles in immunity and carry out cellular responses like phagocytosis, encapsulation and melanization as well as producing humoral effector proteins in the first line of defense after injury and invasion of microorganisms. In this work, we used the Drosophila melanogaster hemocyte-like cell line mbn-2 and Affymetrix Drosophila GeneChips to investigate the transcriptome of a single type of immune competent tissue exposed to Gram-negative cell wall components (crude LPS) or high dose infection with live Escherichia coli. We found that gene expression profiles of both treatments overlap but show important differences in expression levels of several genes involved in immunity. In addition, cell morphology during infection was monitored and revealed distinct alterations in cell shape and adhesion. Presence of large numbers of bacteria also increased the number of cells taking on crystal cell fate. Taken together, our results indicate that hemocytes sense and respond differently to purified bacterial surface molecules and infection with live and actively growing bacteria both at the level of gene expression and in cell behavior.
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| 4. |
- Johansson, Karin C, et al.
(författare)
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Pefabloc : A sulfonyl fluoride serine protease inhibitor blocks induction of Diptericin in Drosophila l(2)mbn cells
- 2012
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Ingår i: Insect Science. - : Wiley. - 1672-9609 .- 1744-7917. ; 19:4, s. 472-476
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Tidskriftsartikel (refereegranskat)abstract
- Insects protect themselves against microbial infection by an efficient innate immune system that is activated by recognition of invariant microbial surface molecules. In the fruit fly Drosophila melanogaster the presence of bacteria is associated with expression of antimicrobial peptides in host immune-competent tissues. Host receptors detect infection and relay the signal to mount the appropriate immune response. In Drosophila hemocyte-like l(2)mbn cells pre-infection treatment with Pefabloc, a commonly used serine protease inhibitor, induced two major effects: it blocked expression of the antibacterial peptide Diptericin in response to live Gram-negative bacteria and bacterial surface molecules (crude lipopolysaccharide contaminated by peptidoglycans) and it induced morphological changes.
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| 5. |
- Lindmark, H, et al.
(författare)
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Enteric bacteria counteract lipopolysaccharide induction of antimicrobial peptide genes.
- 2001
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Ingår i: J Immunol. - 0022-1767. ; 167, s. 6920-6923
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Tidskriftsartikel (refereegranskat)abstract
- The humoral immunity of Drosophila involves the production of antimicrobial peptides, which are induced by evolutionary conserved microbial molecules, like LPS. By using Drosophila mbn-2 cells, we found that live bacteria, including E. coli, Salmonella typhimurium, Erwinia carotovora, and Pseudomonas aeruginosa, prevented LPS from inducing antimicrobial peptide genes, while Micrococcus luteus and Streptococcus equi did not. The inhibitory effect was seen at bacterial levels from 20 per mbn-2 cell, while antimicrobial peptides were induced at lower bacterial concentrations (< or =2 bacteria per cell) also in the absence of added LPS. Gel shift experiment suggests that the inhibitory effect is upstream or at the level of the activation of the transcription factor Relish, a member of the NF-kappaB/Rel family. The bacteria have to be in physical contact with the cells, but not phagocytosed, to prevent LPS induction. Interestingly, the inhibiting mechanism is, at least for E. coli, independent of the type III secretion system, indicating that the inhibitory mechanism is unrelated to the one earlier described for YopJ from Yersinia.
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