| 1. |
- Pasupuleti, Mukesh, et al.
(author)
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Preservation of Antimicrobial Properties of Complement Peptide C3a, from Invertebrates to Humans
- 2007
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In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 282:4, s. 2520-2528
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Journal article (peer-reviewed)abstract
- The human anaphylatoxin peptide C3a, generated during complement activation, exerts antimicrobial effects. Phylogenetic analysis, sequence analyses, and structural modeling studies paired with antimicrobial assays of peptides from known C3a sequences showed that, in particular in vertebrate C3a, crucial structural determinants governing antimicrobial activity have been conserved during the evolution of C3a. Thus, regions of the ancient C3a from Carcinoscorpius rotundicauda as well as corresponding parts of human C3a exhibited helical structures upon binding to bacterial lipopolysaccharide permeabilized liposomes and were antimicrobial against Gram-negative and Gram-positive bacteria. Human C3a and C4a (but not C5a) were antimicrobial, in concert with the separate evolutionary development of the chemotactic C5a. Thus, the results demonstrate that, notwithstanding a significant sequence variation, functional and structural constraints imposed on C3a during evolution have preserved critical properties governing antimicrobial activity.
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| 2. |
- Holmberg, Anna, et al.
(author)
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Biofilm formation by Propionibacterium acnes is a characteristic of invasive isolates
- 2009
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In: Clinical Microbiology and Infection. - : Elsevier BV. - 1198-743X .- 1469-0691. ; 15:8, s. 787-795
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Journal article (peer-reviewed)abstract
- Propionibacterium acnes is a common and probably underestimated cause of delayed joint prosthesis infection. Bacterial biofilm formation is central in the pathogenesis of infections related to foreign material, and P. acnes has been shown to form biofilm both in vitro and in vivo. Here, biofilm formation by 93 P. acnes isolates, either from invasive infections (n = 45) or from the skin of healthy people (n = 48), was analysed. The majority of isolates from deep infections produced biofilm in a microtitre model of biofilm formation, whereas the skin isolates were poor biofilm producers (p <0.001 for a difference). This indicates a role for biofilm formation in P. acnes virulence. The type distribution, as determined by sequencing of recA, was similar among isolates isolated from skin and from deep infections, demonstrating that P. acnes isolates with different genetic backgrounds have pathogenic potential. The biofilm formed on plastic and on bone cement was analysed by scanning electron microscopy (EM) and by transmission EM. The biofilm was seen as a 10-mum-thick layer covering the bacteria and was composed of filamentous as well as more amorphous structures. Interestingly, the presence of human plasma in solution or at the plastic surface inhibits biofilm formation, which could explain why P. acnes primarily infect plasma-poor environments of, for example, joint prostheses and cerebrospinal shunts. This work underlines the importance of biofilm formation in P. acnes pathogenesis, and shows that biofilm formation should be considered in the diagnosis and treatment of invasive P. acnes infections.
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| 3. |
- Tomašić, Nikica, et al.
(author)
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Fasting reveals largely intact systemic lipid mobilization mechanisms in respiratory chain complex III deficient mice
- 2020
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In: Biochimica et Biophysica Acta - Molecular Basis of Disease. - Amsterdam : ELSEVIER. - 0925-4439 .- 1879-260X. ; 1866:1
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Journal article (peer-reviewed)abstract
- Mice homozygous for the human GRACILE syndrome mutation (Bcs1l (c.A232G)) display decreased respiratory chain complex III activity, liver dysfunction, hypoglycemia, rapid loss of white adipose tissue and early death. To assess the underlying mechanism of the lipodystrophy in homozygous mice (Bcs1l(p.S)(78G)), these and wild-type control mice were subjected to a short 4-hour fast. The homozygotes had low baseline blood glucose values, but a similar decrease in response to fasting as in wild-type mice, resulting in hypoglycemia in the majority. Despite the already depleted glycogen and increased triacylglycerol content in the mutant livers, the mice responded to fasting by further depletion and increase, respectively. Increased plasma free fatty acids (FAs) upon fasting suggested normal capacity for mobilization of lipids from white adipose tissue into circulation. Strikingly, however, serum glycerol concentration was not increased concomitantly with free FM, suggesting its rapid uptake into the liver and utilization for fuel or gluconeogenesis in the mutants. The mutant hepatocyte mitochondria were capable of responding to fasting by appropriate morphological changes, as analyzed by electron microscopy, and by increasing respiration. Mutants showed increased hepatic gene expression of major metabolic controllers typically associated with fasting response (Ppargc1a, Fgf21, Cd36) already in the fed state, suggesting a chronic starvation-like metabolic condition. Despite this, the mutant mice responded largely normally to fasting by increasing hepatic respiration and switching to FA utilization, indicating that the mechanisms driving these adaptations are not compromised by the CIII dysfunction. Summary statement: Bcs1l mutant mice with severe CIII deficiency, energy deprivation and post-weaning lipolysis respond to fasting similarly to wild-type mice, suggesting largely normal systemic lipid mobilization and utilization mechanisms.
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| 4. |
- Sonesson, Andreas, et al.
(author)
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Antifungal activity of C3a and C3a-derived peptides against Candida
- 2007
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In: Biochimica et Biophysica Acta - Biomembranes. - : Elsevier BV. - 0005-2736 .- 1879-2642. ; 1768:2, s. 346-353
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Journal article (peer-reviewed)abstract
- Antimicrobial peptides are generated during activation of the complement system [Nordahl et al. Proc. Natl. Acad. Sci. U. S. A. 2004, 101:16879-16884]. Here we show that the anaphylatoxin C3a exerts antimicrobial effects against the yeast Candida. Fluorescence microscopy and electron microscopy analysis demonstrated that C3a-derived peptides bound to the cell surface of Candida, and induced membrane perturbations and release of extracellular material. Various Candida isolates were found to induce complement degradation, leading to generation of C3a. Arginine residues were found to be critical for the antifungal and membrane breaking activity of a C3a-derived antimicrobial peptide, CNY21 (C3a; Cys57–Arg77). A CNY21 variant with increased positive net charge displayed enhanced antifungal activity. Thus, C3a-derived peptides can be utilized as templates in the development of peptide-based antifungal therapies.
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| 5. |
- Singh, Birendra, et al.
(author)
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A fine-tuned interaction between the trimeric autotransporter Haemophilus surface fibrils and vitronectin leads to serum resistance and adherence to respiratory epithelial cells.
- 2014
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In: Infection and Immunity. - 1098-5522. ; 82:6, s. 2378-2389
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Journal article (peer-reviewed)abstract
- Haemophilus influenzae type b (Hib) escapes the host immune system by recruitment of the complement regulator vitronectin that inhibits the formation of the membrane attack complex (MAC) by inhibiting C5b-C7 complex formation and C9 polymerization. We previously reported that Hib acquires vitronectin at the surface by using Haemophilus surface fibrils (Hsf). Here we studied in detail the interaction between Hsf and vitronectin and its role in inhibition of MAC formation and invasion of lung epithelial cells. The vitronectin-binding region of Hsf was defined at the N-terminal comprising amino acids Hsf 429-652. Moreover, the Hsf recognition site on vitronectin consisted of the C-terminal amino acids 352-374. H. influenzae was killed more rapidly in vitronectin-depleted serum when compared to normal human serum (NHS), and an increased MAC deposition was observed at the surface of an Hsf-deficient H. influenzae mutant. In parallel, Hsf-expressing E. coli selectively acquired vitronectin from serum that resulted in significant inhibition of the MAC. Moreover, when vitronectin was bound to Hsf an increased bacterial adherence and internalization of epithelial cells was observed. Taken together, we have defined a fine-tuned protein-protein interaction between Hsf and vitronectin that may contribute to an increased virulence of Hib.
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| 6. |
- Oohashi, T, et al.
(author)
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Mouse ten-m/Odz is a new family of dimeric type II transmembrane proteins expressed in many tissues
- 1999
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In: Journal of Cell Biology. - 0021-9525. ; 145:3, s. 563-577
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Journal article (peer-reviewed)abstract
- The Drosophila gene ten-m/odz is the only pair rule gene identified to date which is not a transcription factor. In an attempt to analyze the structure and the function of ten-m/odz in mouse, we isolated four murine ten-m cDNAs which code for proteins of 2,700-2, 800 amino acids. All four proteins (Ten-m1-4) lack signal peptides at the NH2 terminus, but contain a short hydrophobic domain characteristic of transmembrane proteins, 300-400 amino acids after the NH2 terminus. About 200 amino acids COOH-terminal to this hydrophobic region are eight consecutive EGF-like domains. Cell transfection, biochemical, and electronmicroscopic studies suggest that Ten-m1 is a dimeric type II transmembrane protein. Expression of fusion proteins composed of the NH2-terminal and hydrophobic domain of ten-m1 attached to the alkaline phosphatase reporter gene resulted in membrane-associated staining of the alkaline phosphatase. Electronmicroscopic and electrophoretic analysis of a secreted form of the extracellular domain of Ten-m1 showed that Ten-m1 is a disulfide-linked dimer and that the dimerization is mediated by EGF-like modules 2 and 5 which contain an odd number of cysteines. Northern blot and immunohistochemical analyses revealed widespread expression of mouse ten-m genes, with most prominent expression in brain. All four ten-m genes can be expressed in variously spliced mRNA isoforms. The extracellular domain of Ten-m1 fused to an alkaline phosphatase reporter bound to specific regions in many tissues which were partially overlapping with the Ten-m1 immunostaining. Far Western assays and electronmicroscopy demonstrated that Ten-m1 can bind to itself.
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| 7. |
- Melin Fürst, Camilla, et al.
(author)
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The C-type lectin of the aggrecan g3 domain activates complement.
- 2013
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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:4
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Journal article (peer-reviewed)abstract
- Excessive complement activation contributes to joint diseases such as rheumatoid arthritis and osteoarthritis during which cartilage proteins are fragmented and released into the synovial fluid. Some of these proteins and fragments activate complement, which may sustain inflammation. The G3 domain of large cartilage proteoglycan aggrecan interacts with other extracellular matrix proteins, fibulins and tenascins, via its C-type lectin domain (CLD) and has important functions in matrix organization. Fragments containing G3 domain are released during normal aggrecan turnover, but increasingly so in disease. We now show that the aggrecan CLD part of the G3 domain activates the classical and to a lesser extent the alternative pathway of complement, via binding of C1q and C3, respectively. The complement control protein (CCP) domain adjacent to the CLD showed no effect on complement initiation. The binding of C1q to G3 depended on ionic interactions and was decreased in D2267N mutant G3. However, the observed complement activation was attenuated due to binding of complement inhibitor factor H to CLD and CCP domains. This was most apparent at the level of deposition of terminal complement components. Taken together our observations indicate aggrecan CLD as one factor involved in the sustained inflammation of the joint.
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| 8. |
- Oldberg, Åke, et al.
(author)
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Collagen-binding proteoglycan fibromodulin can determine stroma matrix structure and fluid balance in experimental carcinoma.
- 2007
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In: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 104:35, s. 13966-13971
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Journal article (peer-reviewed)abstract
- Research on the biology of the tumor stroma has the potential to lead to development of more effective treatment regimes enhancing the efficacy of drug-based treatment of solid malignancies. Tumor stroma is characterized by distorted blood vessels and activated connective tissue cells producing a collagen-rich matrix, which is accompanied by elevated interstitial fluid pressure (IFP), indicating a transport barrier between tumor tissue and blood. Here, we show that the collagen-binding proteoglycan fibromodulin controls stroma structure and fluid balance in experimental carcinoma. Gene ablation or inhibition of expression by anti-inflammatory agents showed that fibromodulin promoted the formation of a dense stroma and an elevated IFP. Fibromodulin-deficiency did not affect vasculature but increased the extracellular fluid volume and lowered IFP. Our data suggest that fibromodulin controls stroma matrix structure that in turn modulates fluid convection inside and out of the stroma. This finding is particularly important in relation to the demonstration that targeted modulations of the fluid balance in carcinoma can increase the response to cancer therapeutic agents.
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| 9. |
- Svensson, Katrin, et al.
(author)
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Exosome uptake depends on ERK1/2-heat shock protein 27 signalling and lipid raft-mediated endocytosis negatively regulated by caveolin-1.
- 2013
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In: Journal of Biological Chemistry. - 1083-351X. ; 288:24, s. 17713-17724
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Journal article (peer-reviewed)abstract
- The role of exosomes in cancer can be inferred from the observation that they transfer tumor cell derived genetic material and signalling proteins, resulting in e.g. increased tumor angiogenesis and metastasis. However, the membrane transport mechanisms and the signalling events involved in the uptake of these virus-like particles remain ill-defined. We now report that internalization of exosomes derived from glioblastoma (GBM) cells involves nonclassical, lipid raft-dependent endocytosis. Importantly, we show that the lipid raft associated protein caveolin-1 (CAV1), in analogy with its previously described role in virus uptake, negatively regulates the uptake of exosomes. We find that exosomes induce the phosphorylation of several downstream targets known to associate with lipid rafts as signalling and sorting platforms, such as extracellular signal-regulated kinase-1/2 (ERK1/2) and heat shock protein 27 (HSP27). Interestingly, exosome uptake appears dependent on unperturbed ERK1/2-HSP27 signalling, and ERK1/2 phosphorylation is under negative influence by CAV1 during internalization of exosomes. These findings significantly advance our general understanding of exosome-mediated uptake and offer potential strategies for how this pathway may be targeted through modulation of CAV1 expression and ERK1/2 signaling.
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| 10. |
- Li, Dai-Qing, et al.
(author)
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Suppression of sulfonylurea- and glucose-induced insulin secretion in vitro and in vivo in mice lacking the chloride transport protein ClC-3.
- 2009
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In: Cell metabolism. - : Elsevier BV. - 1932-7420 .- 1550-4131. ; 10:4, s. 309-15
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Journal article (peer-reviewed)abstract
- Priming of insulin secretory granules for release requires intragranular acidification and depends on vesicular Cl(-)-fluxes, but the identity of the chloride transporter/ion channel involved is unknown. We tested the hypothesis that the chloride transport protein ClC-3 fulfills these actions in pancreatic beta cells. In ClC-3(-/-) mice, insulin secretion evoked by membrane depolarization (high extracellular K(+), sulfonylureas), or glucose was >60% reduced compared to WT animals. This effect was mirrored by a approximately 80% reduction in depolarization-evoked beta cell exocytosis (monitored as increases in cell capacitance) in single ClC-3(-/-) beta cells, as well as a 44% reduction in proton transport across the granule membrane. ClC-3 expression in the insulin granule was demonstrated by immunoblotting, immunostaining, and negative immuno-EM in a high-purification fraction of large dense-core vesicles (LDCVs) obtained by phogrin-EGFP labeling. The data establish the importance of granular Cl(-) fluxes in granule priming and provide direct evidence for the involvement of ClC-3 in the process.
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