scholarly journals A chemotactic sensor controls Salmonella-host cell interaction

2021 ◽  
Author(s):  
Stefanie Hoffmann ◽  
Kathrin Gendera ◽  
Christiane Schmidt ◽  
Peter Kirchweger ◽  
Axel Imhof ◽  
...  
Keyword(s):  
Surface Expression ◽  
Cell Interaction ◽  
Secretion System ◽  
Cell Contact ◽  
Signaling Mechanism ◽  
Bacterial Surface ◽  
Type Three Secretion System ◽  
Polarized Cells ◽  
Spatio Temporal ◽  
Key Steps

Intimate cell contact and subsequent type three secretion system-dependent cell invasion are key steps in host colonization of Salmonella. Adhesion to complex glycostructures at the apical membrane of polarized cells is mediated by the giant adhesin SiiE. This protein is secreted by a type 1 secretion system (T1SS) and needs to be retained at the bacterial surface to exert its adhesive function. Here, we show that SiiE surface expression was linked to the presence of L aspartate sensed by the Salmonella-specific methyl-accepting chemotaxis protein CheM. Bacteria lacking CheM were attenuated for invasion of polarized cells, whereas increased invasion was seen with Salmonella exposed to the non-metabolizable aspartate analog α methyl-D, L aspartate (MeAsp). While components of the chemotaxis phosphorelay or functional flagella were dispensable for the increased invasion, CheM directly interacted with proteins associated with the SiiE T1SS arguing for a novel non-canonical signaling mechanism. As a result, CheM attractant signaling caused a shift from secreted to surface-retained and adhesion-competent SiiE. Thus, CheM controls the virulence function of SiiE in a precise spatio-temporal fashion depending on the host micro-milieu.

An inhibitory mechanism of action of coiled‐coil peptides against type three secretion system from enteropathogenicEscherichia coli

2019 ◽  
Vol 25 (3) ◽  
Author(s):  
Mariano Larzábal ◽  
Hector A. Baldoni ◽  
Fernando D. Suvire ◽  
Lucrecia M. Curto ◽  
Gabriela E. Gomez ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
Coiled Coil ◽  
Secretion System ◽  
Inhibitory Mechanism ◽  
Type Three Secretion System ◽  
Type Three Secretion

scholarly journals Plasmid composition in Aeromonas salmonicida subsp. salmonicida 01-B526 unravels unsuspected type three secretion system loss patterns

BMC Genomics ◽  
2017 ◽  
Vol 18 (1) ◽  
Author(s):  
Katherine H. Tanaka ◽  
Antony T. Vincent ◽  
Jean-Guillaume Emond-Rheault ◽  
Marcin Adamczuk ◽  
Michel Frenette ◽  
...  
Keyword(s):  
Secretion System ◽  
Aeromonas Salmonicida ◽  
Type Three Secretion System ◽  
Type Three Secretion

Inhibition of neutrophil L-selectin shedding: a potential anti-inflammatory effect of aprotinin

Perfusion ◽  
2000 ◽  
Vol 15 (6) ◽  
pp. 495-499 ◽  
Author(s):  
George Asimakopoulos ◽  
Kenneth M Taylor ◽  
Dorian O Haskard ◽  
R Clive Landis
Keyword(s):  
Endothelial Cell ◽  
Venous Blood ◽  
Platelet Activating Factor ◽  
Surface Expression ◽  
Cell Interaction ◽  
Dose Dependent Fashion ◽  
Anti Inflammatory ◽  
Dose Dependent ◽  
Inflammatory Action ◽  
Inflammatory Effect

The cardiopulmonary bypass (CPB)-related inflammatory response involves leucocyte activation and increased leucocyte-endothelial cell interaction. L-selectin is an adhesion molecule expressed on the surface of leucocytes which participates in the initial rolling step of the leucocyte-endothelial cell adhesion cascade. L-selectin is proteolytically cleaved off the surface of leucocytes when they become activated, an event that is regarded as a marker of leucocyte activation. Aprotinin is a protease inhibitor that has been used in cardiac surgery as a haemostatic agent and also exhibits certain anti-inflammatory properties. In this study, peripheral venous blood from volunteers was pre-incubated with aprotinin at 200, 800 and 1600 kallikrein inhibiting units (kiu)/ml and stimulated with the chemoattractants N-formyl-methyl-leucyl-phenylalanine (fMLP) or platelet activating factor (PAF). Surface expression of L-selectin on neutrophils was measured using a monoclonal antibody and flow cytometry. The results demonstrate that aprotinin inhibits shedding of L-selectin in a dose-dependent fashion ( p=0.0278 and 0.0005, respectively, at 800 and 1600 kiu/ml for fMLP-stimulated shedding; p=0.0017 and 0.0010, respectively, at 200 and 800 kiu/ml for PAF-stimulated shedding). This effect may be of significance with respect to the anti-inflammatory action of aprotinin in patients undergoing CPB.

scholarly journals Type Three Secretion System-Dependent Microvascular Thrombosis and Ischemic Enteritis in Human Gut Xenografts Infected with Enteropathogenic Escherichia coli

2017 ◽  
Vol 85 (11) ◽  
Author(s):  
Einat Nissim-Eliraz ◽  
Eilam Nir ◽  
Irit Shoval ◽  
Noga Marsiano ◽  
Israel Nissan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Blood Vessels ◽  
Secretion System ◽  
Infection Model ◽  
Apical Surface ◽  
Muscularis Mucosa ◽  
Human Gut ◽  
Type Three Secretion System ◽  
Type Three Secretion ◽  
Ischemic Enteritis

ABSTRACT Enteropathogenic Escherichia coli (EPEC) is a leading cause of severe intestinal disease and infant mortality in developing countries. Virulence is mediated by a type three secretion system (T3SS), causing the hallmark attaching and effacing (AE) lesions and actin-rich pedestal formation beneath the infecting bacteria on the apical surface of enterocytes. EPEC is a human-specific pathogen whose pathogenesis cannot be studied in animal models. We therefore established an EPEC infection model in human gut xenografts in SCID mice and used it to study the role of T3SS in the pathogenesis of the disease. Following EPEC O127:H6 strain E2348/69 infection, T3SS-dependent AE lesions and pedestals were demonstrated in all infected xenografts. We report here the development of T3SS-dependent intestinal thrombotic microangiopathy (iTMA) and ischemic enteritis in ∼50% of infected human gut xenografts. Using species-specific CD31 immunostaining, we showed that iTMA was limited to the larger human-mouse chimeric blood vessels, which are located between the muscularis mucosa and circular muscular layer of the human gut. These blood vessels were massively invaded by bacteria, which adhered to and formed pedestals on endothelial cells and aggregated with mouse neutrophils in the lumen. We conclude that endothelial infection, iTMA, and ischemic enteritis might be central mechanisms underlying severe EPEC-mediated disease.

scholarly journals Purification of pseudopodia from polarized cells reveals redistribution and activation of Rac through assembly of a CAS/Crk scaffold

2002 ◽  
Vol 156 (4) ◽  
pp. 725-736 ◽  
Author(s):  
Samuel Y. Cho ◽  
Richard L. Klemke
Keyword(s):  
Focal Adhesion ◽  
Feedback Loop ◽  
Kinase Activity ◽  
Cell Polarization ◽  
Molecular Scaffold ◽  
Rac1 Activity ◽  
Polarized Cells ◽  
Focal Adhesion Kinase Activity ◽  
Spatio Temporal ◽  
Temporal Localization

Initiation of cell migration requires morphological polarization with formation of a dominant leading pseudopodium and rear compartment. A molecular understanding of this process has been limited, due to the inability to biochemically separate the leading pseudopodium from the rear of the cell. Here we examine the spatio-temporal localization and activation of cytoskeletal-associated signals in purified pseudopodia directed to undergo growth or retraction. Pseudopodia growth requires assembly of a p130Crk-associated substrate (CAS)/c-CrkII (Crk) scaffold, which facilitates translocation and activation of Rac1. Interestingly, Rac1 activation then serves as a positive-feedback loop to maintain CAS/Crk coupling and pseudopodia extension. Conversely, disassembly of this molecular scaffold is critical for export and down regulation of Rac1 activity and induction of pseudopodia retraction. Surprisingly, the uncoupling of Crk from CAS during pseudopodium retraction is independent of changes in focal adhesion kinase activity and CAS tyrosine phosphorylation. These findings establish CAS/Crk as an essential scaffold for Rac1-mediated pseudopodia growth and retraction, and illustrate spatio-temporal segregation of cytoskeletal signals during cell polarization.

Hydra regeneration from recombined ectodermal and endodermal tissue. I. Epibolic ectodermal spreading is driven by cell intercalation

1996 ◽  
Vol 109 (4) ◽  
pp. 763-772 ◽  
Author(s):  
Y. Kishimoto ◽  
M. Murate ◽  
T. Sugiyama
Keyword(s):  
Contact Surface ◽  
Single Cells ◽  
Cell Interaction ◽  
Inhibitory Effect ◽  
Cell Aggregates ◽  
Signaling Mechanism ◽  
Initial Adhesion ◽  
Radial Cell ◽  
Epithelial Sheet ◽  
Cell Intercalation

Cell-cell interaction and cell rearrangement were examined in the process of epithelial sheet formation during regeneration from hydra cell aggregates. The ectodermal and endodermal epithelial cell layers of Hydra magnipapillata were separated by procaine treatment. Each of the separated layers was then dissociated into single cells and reaggregated to produce ectodermal or endodermal cell aggregates. When the two aggregate types were recombined, a firm adhesion was quickly established between them. This was followed by a vigorous spreading of the ectodermal epithelial cells as a thin layer over the endoderm in a manner similar to the ‘epiboly’ in some developing embryos. Cell movement in this spreading process was examined using fluorescent dyestaining. It revealed that cells initially located in the inside of the aggregate migrated to intercalate themselves among the cells originally present in the contact surface. This radial cell intercalation took place continuously in the contact surface of both the ectodermal and endodermal aggregates, and produced a rapid growth of the contact surface, eventually leading to complete envelopment of the entire endoderm by the ectoderm. The resulting structure was a small sphere having a two-layered epithelial organization as in normal hydra. This sphere regenerated into a complete hydra a few days later. A tryptic extract of hydra membrane fraction specifically inhibited the ectodermal spreading over the endoderm, but not the initial adhesion or the later regeneration processes. These observations suggest that radial cell intercalation at the contact surface plays a crucial role in producing ectodermal spreading and establishing epithelial sheet organization in the recombined aggregates. The intercalation is presumably activated by a signal exchange through the contact surface. The inhibitory effect of the membrane extract suggests that it contains a factor that is involved in some way in this signaling mechanism.

N-cadherin in adult rat cardiomyocytes in culture. II. Spatio-temporal appearance of proteins involved in cell-cell contact and communication. Formation of two distinct N-cadherin/catenin complexes

1996 ◽  
Vol 109 (1) ◽  
pp. 11-20 ◽  
Author(s):  
C.M. Hertig ◽  
S. Butz ◽  
S. Koch ◽  
M. Eppenberger-Eberhardt ◽  
R. Kemler ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Gap Junctions ◽  
Connexin 43 ◽  
Cell Contact ◽  
Beta Catenin ◽  
Rat Cardiomyocytes ◽  
Cell Contacts ◽  
Adult Rat ◽  
Spatio Temporal ◽  
Cell Cell

The spatio-temporal appearance and distribution of proteins forming the intercalated disc were investigated in adult rat cardiomyocytes (ARC). The ‘redifferentiation model’ of ARC involves extensive remodelling of the plasma membrane and of the myofibrillar apparatus. It represents a valuable system to elucidate the formation of cell-cell contact between cardiomyocytes and to assess the mechanisms by which different proteins involved in the cell-cell adhesion process are sorted in a precise manner to the sites of function. Appearance of N-cadherin, the catenins and connexin43 within newly formed adherens and gap junctions was studied. Here first evidence is provided for a formation of two distinct and separable N-cadherin/catenin complexes in cardiomyocytes. Both complexes are composed of N-cadherin and alpha-catenin which bind to either beta-catenin or plakoglobin in a mutually exclusive manner. The two N-cadherin/catenin complexes are assumed to be functionally involved in the formation of cell-cell contacts in ARC; however, the differential appearance and localization of the two types of complexes may also point to a specific role during ARC differentiation. The newly synthesized beta-catenin containing complex is more abundant during the first stages in culture after ARC isolation, while the newly synthesized plakoglobin containing complex progressively accumulates during the morphological changes of ARC. ARC formed a tissue-like pattern in culture whereby the new cell-cell contacts could be dissolved through Ca2+ depletion. Presence of cAMP and replenishment of Ca2+ content in the culture medium not only allowed reformation of cell-cell contacts but also affected the relative protein ratio between the two N-cadherin/catenin complexes, increasing the relative amount of newly synthesized beta-catenin over plakoglobin at a particular stage of ARC differentiation. The clustered N-cadherin/catenin complexes at the plasma membrane appear to be a prerequisite for the following gap junction formation; a temporal sequence of the appearance of adherens junction proteins and of gap junctions forming connexin-43 is suggested.

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