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  • 1
    Online Resource
    Online Resource
    3D correlative electron microscopy reveals continuity of Brucella -containing vacuoles with the endoplasmic reticulum
    The Company of Biologists ; 2018
    In:  Journal of Cell Science
    Details
    In: Journal of Cell Science, The Company of Biologists
    Abstract: Entry of the facultative intracellular pathogen Brucella into host cells results in the formation of endosomal Brucella-containing vacuoles (eBCVs) that initially traffic along the endocytic pathway. eBCV acidification triggers the expression of a type IV secretion system that translocates bacterial effector proteins into host cells. This interferes with lysosomal fusion of eBCVs and supports their maturation to replicative Brucella-containing vacuoles (rBCVs). Bacteria replicate in rBCVs to large numbers, eventually occupying most of the cytoplasmic volume. As rBCV membranes tightly wrap each individual bacterium, they are constantly being expanded and remodeled during exponential bacterial growth. rBCVs are known to carry endoplasmic reticulum (ER) markers, however, the relationship of the vacuole to the genuine ER has remained elusive. We have reconstructed the 3-dimensional ultrastructure of rBCVs and associated ER by correlative structured illumination microscopy (SIM) and focused ion beam/scanning electron microscopic tomography (FIB/SEM). Studying B. abortus-infected HeLa cells and trophoblasts derived from B. melitensis-infected mice, we demonstrate that rBCVs are complex and interconnected compartments that are continuous with neighboring ER cisternae, thus supporting a model that rBCVs are extensions of genuine ER.
    Type of Medium: Online Resource
    ISSN: 1477-9137 , 0021-9533
    URL: Article
    DOI: 10.1242/jcs.210799
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2018
    detail.hit.zdb_id: 219171-4
    detail.hit.zdb_id: 1483099-1
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Interaction of Bartonella henselae with endothelial cells results in bacterial aggregation on the cell surface and the subsequent engulfment and internalisation of the bacterial aggregate by a unique structure, the invasome
    The Company of Biologists ; 1997
    In:  Journal of Cell Science Vol. 110, No. 18 ( 1997-09-15), p. 2141-2154
    Details
    In: Journal of Cell Science, The Company of Biologists, Vol. 110, No. 18 ( 1997-09-15), p. 2141-2154
    Abstract: Vascular colonisation by Bartonella henselae may cause vaso-proliferative tumour growth with clumps of bacteria found in close association with proliferating endothelial cells. By using B. henselae-infected human umbilical vein endothelial cells as an in vitro model for endothelial colonisation, we report here on a novel mechanism of cellular invasion by bacteria. First, the leading lamella of endothelial cells establishes cellular contact to sedimented bacteria and mediates bacterial aggregation by rearward transport on the cell surface. Subsequently, the formed bacterial aggregate is engulfed and internalised by a unique host cellular structure, the invasome. Completion of this sequence of events requires 24 hours. Cortical F-actin, intercellular adhesion molecule-1 and phosphotyrosine are highly enriched in the membrane protrusions entrapping the bacterial aggregate. Actin stress fibres, which are anchored to the numerous focal adhesion plaques associated with the invasome structure, are typically found to be twisted around its basal part. The formation of invasomes was found to be inhibited by cytochalasin D but virtually unaffected by nocodazole, colchicine or taxol, indicating that invasome-mediated invasion is an actin-dependent and microtubuli-independent process. Bacterial internalisation via the invasome was consistently observed with several clinical isolates of B. henselae, while a spontaneous mutant obtained from one of these isolates was impaired in invasome-mediated invasion. Instead, this mutant showed increased uptake of bacteria into perinuclear localising phagosomes, suggesting that invasome-formation may interfere with this alternative mechanism of bacterial internalisation. Internalisation via the invasome represents a novel paradigm for the invasion of bacteria into host cells which may serve as a cellular colonisation mechanism in vivo, e.g. on proliferating and migrating endothelial cells during Bartonella-induced vaso-proliferative tumour growth.
    Type of Medium: Online Resource
    ISSN: 0021-9533 , 1477-9137
    URL: Article
    DOI: 10.1242/jcs.110.18.2141
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 1997
    detail.hit.zdb_id: 219171-4
    detail.hit.zdb_id: 1483099-1
    SSG: 12
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Bartonella henselae engages inside-out and outside-in signaling by integrin β1 and talin1 during invasome-mediated bacterial uptake
    The Company of Biologists ; 2011
    In:  Journal of Cell Science Vol. 124, No. 21 ( 2011-11-01), p. 3591-3602
    Details
    In: Journal of Cell Science, The Company of Biologists, Vol. 124, No. 21 ( 2011-11-01), p. 3591-3602
    Abstract: The VirB/D4 type IV secretion system (T4SS) of the bacterial pathogen Bartonella henselae (Bhe) translocates seven effector proteins (BepA–BepG) into human cells that subvert host cellular functions. Two redundant pathways dependent on BepG or the combination of BepC and BepF trigger the formation of a bacterial uptake structure termed the invasome. Invasome formation is a multi-step process consisting of bacterial adherence, effector translocation, aggregation of bacteria on the cell surface and engulfment, and eventually, complete internalization of the bacterial aggregate occurs in an F-actin-dependent manner. In the present study, we show that Bhe-triggered invasome formation depends on integrin-β1-mediated signaling cascades that enable assembly of the F-actin invasome structure. We demonstrate that Bhe interacts with integrin β1 in a fibronectin- and VirB/D4 T4SS-independent manner and that activated integrin β1 is essential for both effector translocation and the actin rearrangements leading to invasome formation. Furthermore, we show that talin1, but not talin2, is required for inside-out activation of integrin β1 during invasome formation. Finally, integrin-β1-mediated outside-in signaling by FAK, Src, paxillin and vinculin is necessary for invasome formation. This is the first example of a bacterial entry process that fully exploits the bi-directional signaling capacity of integrin receptors in a talin1-specific manner.
    Type of Medium: Online Resource
    ISSN: 1477-9137 , 0021-9533
    URL: Article
    DOI: 10.1242/jcs.084459
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2011
    detail.hit.zdb_id: 219171-4
    detail.hit.zdb_id: 1483099-1
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
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