Wouters, Fred Silvester

[["dc.bibliographiccitation.firstpage","461"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Molecular Microbiology"],["dc.bibliographiccitation.lastpage","477"],["dc.bibliographiccitation.volume","71"],["dc.contributor.author","Iliev, Asparouh I."],["dc.contributor.author","Djannatian, Jasmin Roya"],["dc.contributor.author","Opazo, Felipe"],["dc.contributor.author","Gerber, Joachim"],["dc.contributor.author","Nau, Roland"],["dc.contributor.author","Mitchell, Timothy J."],["dc.contributor.author","Wouters, Fred S."],["dc.date.accessioned","2018-11-07T08:35:08Z"],["dc.date.available","2018-11-07T08:35:08Z"],["dc.date.issued","2009"],["dc.description.abstract","Streptococcus pneumoniae is the most frequent cause of bacterial meningitis, leading to permanent neurological damage in 30% and lethal outcome in 25% of patients. The cholesterol-dependent cytolysin pneumolysin is a major virulence factor of S. pneumoniae. It produces rapid cell lysis at higher concentrations or apoptosis at lower concentrations. Here, we show that sublytic amounts of pneumolysin produce rapid bundling and increased acetylation of microtubules (signs of excessive microtubule stabilization) in various types of cells - neuroblastoma cells, fibroblasts and primary astrocytes. The bundling started perinuclearly and extended peripherally towards the membrane. The effect was not connected to pneumolysin's capacity to mediate calcium influx, macropore formation, apoptosis, or RhoA and Rac1 activation. Cellular cholesterol depletion and neutralization of the toxin by pre-incubation with cholesterol completely inhibited the microtubule phenotype. Pharmacological inhibition of Src-family kinases diminished microtubule bundling, suggesting their involvement in the process. The relevance of microtubule stabilization to meningitis was confirmed in an experimental pneumococcal meningitis animal model, where increased acetylation was observed. Live imaging experiments demonstrated a decrease in organelle motility after toxin challenge in a manner comparable to the microtubule-stabilizing agent taxol, thus proposing a possible pathogenic mechanism that might contribute to the CNS damage in pneumococcal meningitis."],["dc.identifier.doi","10.1111/j.1365-2958.2008.06538.x"],["dc.identifier.isi","000262304400014"],["dc.identifier.pmid","19040644"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/17989"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-blackwell Publishing, Inc"],["dc.relation.issn","0950-382X"],["dc.title","Rapid microtubule bundling and stabilization by the Streptococcus pneumoniae neurotoxin pneumolysin in a cholesterol-dependent, non-lytic and Src-kinase dependent manner inhibits intracellular trafficking"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2897"],["dc.bibliographiccitation.issue","8"],["dc.bibliographiccitation.journal","PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA"],["dc.bibliographiccitation.lastpage","2902"],["dc.bibliographiccitation.volume","104"],["dc.contributor.author","Iliev, Asparouh I."],["dc.contributor.author","Djannatian, Jasmin Roya"],["dc.contributor.author","Nau, Roland"],["dc.contributor.author","Mitchell, Timothy J."],["dc.contributor.author","Wouters, Fred S."],["dc.date.accessioned","2018-11-07T11:04:55Z"],["dc.date.available","2018-11-07T11:04:55Z"],["dc.date.issued","2007"],["dc.description.abstract","The Streptococcus pneumoniae toxin pneumolysin belongs to the group of cholesterol-dependent cytolysins. It produces rapid cell lysis at higher concentrations or apoptosis at lower concentrations. In cell membranes, it forms prepores and pores. Here, we show that sublytic concentrations of pneumolysin produce rapid activation of Rho and Rac GTPases and formation of actin stress fibers, filopodia, and lamellipodia. That Rac1-specific and Rho-associated kinase (ROCK)specific inhibitors reverted the formation of lamellipodia and stress fibers, respectively, identifies RhoA and Rac1 as key toxin effectors. Live imaging excluded macropore formation (as judged by membrane impermeability toward calcein) but indicated very early membrane depolarization [as judged by bis-(1,3-dibutylbarbituric acid)trimethine oxanol staining], indicative of formation of micropores with ion channel properties. That Rac1-dependent lamellipodia formation was reverted by the voltage-gated calcium channel inhibitor SKF96365 and by toxin exposure in calcium-free medium suggests a role for calcium influx via endogenous calcium channels in the Rac1 activation. Cellular cholesterol depletion by methyl-beta-cyclodextrin or incubation of the toxin with cholesterol before cell treatment eliminated its membrane binding and the subsequent GTPase activation. Thus, that our experiments show small GTPase activation by a cholesterol-dependent cytolysin suggests a membrane cholesterol-dependent activation mechanism."],["dc.description.sponsorship","Wellcome Trust"],["dc.identifier.doi","10.1073/pnas.0608213104"],["dc.identifier.isi","000244511200060"],["dc.identifier.pmid","17301241"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/51952"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Natl Acad Sciences"],["dc.relation.issn","0027-8424"],["dc.title","Cholesterol-dependent actin remodeling via RhoA and Rac1 activation by the Streptococcus pneumoniae toxin pneumolysin"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","39"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Journal of Neuroscience Methods"],["dc.bibliographiccitation.lastpage","46"],["dc.bibliographiccitation.volume","161"],["dc.contributor.author","Iliev, Asparouh I."],["dc.contributor.author","Wouters, Fred S."],["dc.date.accessioned","2018-11-07T11:03:59Z"],["dc.date.available","2018-11-07T11:03:59Z"],["dc.date.issued","2007"],["dc.description.abstract","The directionality of axonal transport represents an important question in neurophysiological and neuropathological research. Various approaches such as videomicroscopy, radioisotopic and fluorescence-based techniques are used. Recently, a novel FRAP-based (fluorescent recovery after photobleaching) technique using synaptophysin-EGFP expression in primary neurons was applied, allowing reliable and sensitive evaluation of gross axonal transport changes using confocal live-imaging microscopy. Here, we describe a novel FLIP-based (fluorescence loss in photobleaching) approach using a synaptophysin-EGFP probe that allows the differential evaluation of the ante- and retrograde transport parameters. Furthermore, we improved the sensitivity of the probe by substituting EGFP with an ECFP/VenusYFP fusion FRET (fluorescence resonance energy transfer) pair. The use of this FRET couple improves the precision of axonal transport measurements by combining FLIP and FLAP (fluorescence localization after photobleaching) techniques and eliminating the need for pre-bleaching images and thus pixel shifts between various exposures, and by reducing the deleterious effect of photobleaching. (c) 2006 Elsevier B.V. All rights reserved."],["dc.identifier.doi","10.1016/j.jneumeth.2006.10.010"],["dc.identifier.isi","000245490900006"],["dc.identifier.pmid","17123628"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/51735"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Bv"],["dc.relation.issn","0165-0270"],["dc.title","Application of simple photobleaching microscopy techniques for the determination of the balance between anterograde and retrograde axonal transport"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.journal","Naunyn-Schmiedeberg s Archives of Pharmacology"],["dc.bibliographiccitation.volume","379"],["dc.contributor.author","Djannatian, Jasmin Roya"],["dc.contributor.author","Wouters, Fred S."],["dc.contributor.author","Iliev, Asparouh I."],["dc.date.accessioned","2018-11-07T08:31:18Z"],["dc.date.available","2018-11-07T08:31:18Z"],["dc.date.issued","2009"],["dc.format.extent","46"],["dc.identifier.isi","000266563200212"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/17092"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.publisher.place","New york"],["dc.relation.conference","50th Annual Meeting of the Deutsche-Gesellschaft-fur-Experimentelle-und-Klinische-Pharmakologie-und Toxikologie"],["dc.relation.eventlocation","Mainz, GERMANY"],["dc.relation.issn","0028-1298"],["dc.title","Lithium modulates pneumolysin-induced rapid loss of mitochondrial potential"],["dc.type","conference_abstract"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]