Plant-Produced Chimeric VHH-sIgA Against Enterohemorrhagic E. coli Intimin Shows Cross-Serotype Inhibition of BacterialAdhesion to Epithelial Cells
Showing 2/2: Image_2_Plant-Produced Chimeric VHH-sIgA Against Enterohemorrhagic E. coli Intimin Shows Cross-Serotype Inhibition of BacterialAdhesion to Epithelial.TIF
The gastrointestinal (GI) tract of cattle is considered the primary reservoir of EHEC and can contaminate various food or water supplies via excreted fecal matter or after slaughter during processing of the carcass ( Montenegro et al., 1990 ; Beutin et al., 1993 ). Indeed, cattle density has been identiﬁed as a primary risk factor for the incidence of local EHEC infections ( Brehony et al., 2018 ). In accord with the “One Health” framework, virtually all strategic interventions to prevent EHEC transmission to humans have focused on minimizing colonization of cattle reducing the risk of contamination from fecal shedding or at harvest. In cattle, EHEC principally adheres to and colonizes the lymphoid follicle- dense mucosa at the terminal rectum known as the rectoanal junction ( Phillips et al., 2000 ; Naylor et al., 2003 ; Lim et al., 2007 ). The adhesin protein known as intimin mediates interaction of the bacteria with uninfected host epithelial cells and is a necessary prerequisite for intimate bacterialadhesion and colonization
Figure 4. CLSM observations of three bacterial strains from Atlantic Ocean (Bacillus sp. 4J6), Indian Ocean (Shewanella sp. MVV1) and Mediterranean Sea (Pseudoalteromonas lipolytica TC8), with or without an extract from the P-78 strain (50 µg mL −1 ).
To observe possible clusterization of the different extracts depending on their activities on all the bacterial strains, a principal component analysis (PCA) was realized. It was based on the capacity of microalgal extracts to inhibit bacterialadhesion. The resulting plots showed that the two first components of this statistical model accounted for 57.52% (38.02% for the first component axis and 19.50% for the second one) of the total variance of the dataset (Figure 5 ). Thus, the first axis accounted for 38.02% and the second axis 19.50%. On the resulting score plot (Figure 5 A), the first dimension allowed a gross discrimination between dinoflagellates extracts (excepted for P-59), positively correlated with the first axis, and the major part of the other extracts (excepted C-59, P-59, and P-89), negatively correlated with the first axis. Moreover, by comparison with Table 2 , the most and the least active strains were situated positively and negatively on this first axis, respectively.
Figure 1. Schematic representation of the exopolymeric matrix (EPM) in E. coli biofilm. By analogy with the extracellular matrix (ECM) in mammalian tissue, the EPM in bacterial biofilm can be further discriminated between (i) the EPM closely associated with the bacterial cells, i.e. the cell-associated EPM (caEPM) (purple shade background), and (ii) the interstitial EPM (iEPM) (white background). Molecular determinants of the caEPM are attached, anchored or linked to the bacterial cell surface. Besides cell-surface proteinaceous determinants including monomeric proteins (not depicted in the picture) and supramolecular protein structures, such the flagella and pili, molecular components of caEPM further comprise extracellular polysaccharides (EPS), namely, some lipopolysaccharides (LPS) as well as poly- β-1,6-N-acetyl-
In Vivo Animal Models
A relatively low number of in vivo/ex vivo studies (i.e., biopsy samples) have been conducted to confirm the muco-adhesive phenotype of L. lactis in “real” environmental conditions (Figure 1). Application of such methods seems to be the next step, as shown for lactobacilli ( Da Silva et al., 2015 ; Walsham et al., 2016 ). Nevertheless, first experimental evidence has been provided for lactococci. In mice, the GFP-labeled L. lactis WH- C1 strain was found to adhere to the gut mucosa ( Wang et al., 2011 ). In another study in rats, in ex vivo and in vivo experiments, AggL protein was found to confer adhesive properties to L. lactis BGKP1 to colonic tissue through non-specific hydrophobic interactions. In contrast, for this particular strain, the MbpL protein did not contribute to bacterialadhesion to colonic tissues but was rather involved in gastric mucin binding ( Lukic et al., 2012 ). More recently, it was shown that the cell-wall proteinase PrtP, albeit contributing to in vitro muco-adhesion of L. lactis IBB477, probably through non-specific interactions, could not confer a selective advantage to this strain in the gut of conventional C57BL/6 mice ( Radziwill-Bienkowska et al., 2017 ).
Listeria exploit this conversion for cellular invasion.
Pathogens that adhere to host cells during infection often target proteins involved in cell adhesion such as integrins and E-cadherin [2-4]. In the case of pathogens that invade cells, these receptors are also hijacked for entry using a clathrin- and actin-dependent mechanism [6,7,14]. We recently reported that bacterial infections trigger the formation of clathrin-coated pits at bacterial/cell contact sites and that the formation of clathrin-coated pits precedes and is required for the rearrangements of actin needed for bacterialadhesion or uptake . Here we show that the process of cell-cell adhesion triggers the same sequence of intracellular events that occur during bacterial infections. These include tyrosine- phosphorylation of CHC, as well as recruitment of the clathrin adaptor Dab2, the actin-binding protein Hip1R and the motor protein Myosin VI. In addition, we used siRNA to deplete cells of endogenous CHC and we show that clathrin recruitment at cell-cell contacts is required for subsequent reorganization of actin during the maturation of AJs. Because E-cadherin-coated beads bound to cells also recruit clathrin and actin and their uptake depends on these proteins, we propose that the actin alterations at the AJ following clathrin depletion result from direct interference with pathways triggered by transcellular E-cadherin complexes. We therefore suggest a novel role for clathrin as an actin organizer during the initiation of AJ formation that is independent of endocytosis and therefore distinct from clathrin-mediated E-cadherin internalization that occurs during AJ disruption [31,32].
Focal adhesion kinase (FAK), a multifunctional protein
Focal adhesion kinase (FAK) is a cytoplasmic protein tyrosine kinase localized to regions called focal adhe- sions. Many stimuli can induce tyrosine phosphorylation and activation of FAK, including integrins and growth factors. The major site of autophosphorylation, tyrosine 397, is a docking site for the SH2 domains of Src family proteins. The other sites of phosphorylation are phos- phorylated by Src kinases. Phosphorylated FAK binds proteins of focal adhesion and can activate them directly or indirectly by phosphorylation. These activa- ted proteins forming the FAK complex facilitate the generation of downstream signals necessary to regulate cell functions, like motility, survival and proliferation. Dysregulation of FAK could participate in the develop- ment of cancer. This review will focus upon the mecha- nisms by which FAK transmits biochemical signals and elicits biological effects. ◊
3 Statistical mechanics of active suspensions: the emergence of an ”active fluid”
3.1 A simple kinetic model for dilute active suspensions : the ”bacterial gas” There are different view points suited to handle the hydrodynamics of active fluids. First the macroscopic phenomenology approach as exposed for example in the review by Marchetti et al. . In a nut shell, this type of approach identifies the relevant terms in the momentum and density transport equations stemming from general symmetry argument. It couples generically these fields with some relevant order parameters such as the polar direction of motion or the nematic alignment tensor. To close the theory, dynamical equations for the order parameter fields are added to the description. The second approach is more ”bottom-up” or “micro/macro” in the statistical mechanics jargon, as it describes the microscopic behaviour and possible interactions between the swimmers to obtained by averaging, the macroscopic contributions to transport (see review by Marenduzzo et al. [?] in this series for a more complete picture). At the end, both approaches should provide similar macroscopic outcome, however the mi- cro/macro path is clearly more difficult to handle when multiple interactions become significant. On the other hand, it provides testable predictions for the constitutive relations involving microscopic scale parameters.
We anticipate that the topic of field-activated MR fluid adhesion will be a rich source of both scientific and en- gineering development in the future. Many unexplored parameters still exist for the problem of field-responsive magnetorheological fluid adhesion, such as substrate ma- terial, surface roughness, fluid thickness, magnetic field orientation, and other modes of adhesive failure such as peeling. Furthermore, a number of interesting phenom- ena can be explored in more detail in the future. This includes the stick/slip sawtooth waves observed in the force vs. displacement curves with strong magnetic fields (Fig. 8). This phenomenon can be examined by varying the instrument compliance, and is motivated by the pos- sibility that the sawtooth wave may indicate the proxim- ity to adhesive failure in a functional device. Additional phenomena include the over-prediction of peak forces for strong magnetic fields (Fig. 10) and the “flower” instabil- ity which is observed at moderate magnetic field strength [URL will be inserted by AIP].
The decreased adhesion activity of the antisense-Dp71 cells on laminin, fibronectin and collagen correlates with impairment in their ability to develop neurites in response to NGF. Since adhesion of growth cones to the substrate is essential for growth cone movement and directionality [11,25], it is likely that the deficiencies of antisense-Dp71 cells in b1-integrin-mediated cell adhesion and neurite outgrowth are functionality linked. Hence, an initial instability of the multiprotein adhesion complex in the antisense-Dp71 cells, due to the reduced levels of Dp71, could cause a further failure in the protrusive activity of the growth cone leading to neurite outgrowth inhibition. However, in spite of showing unaltered adhesion activity on poly-D-lysine, the antisense-Dp71 cells failed to extend neurites upon NGF treatment. These results might indicate that regardless of the ECM influence on neuritogenesis, the machinery and signaling pathway relevant to neurite extension are affected per se in the antisense-Dp71 cells.
10). The ultimate goal is to predict the adhesion of the bituminous material to the
substrate, such as HMA, aggregates, or model aggregates as glass or aluminum (2, 10-
Given the importance of pavement maintenance and the emphasis to extend the service life of aging roadways, efforts have been directed towards better understanding crack sealing and bituminous crack sealants, including characterization their adhesion in sub-zero temperatures (12, 13). Sealants are complex mixtures (3) for which adhesion has been related to viscosity or temperature (11, 12, 13, 15); but given the few sealants studied, it is generally impossible to predict sealant adhesion.
Adhesion-GPCRs, a novel family of G protein-coupled receptors (GPCRs), are characterized by
an extended extracellular region linked to a seven-pass transmembrane moiety via GPCR proteolytic site (GPS)-containing stalk region known as GAIN domain. The name adhesion refers to the presence of functional domains in the extracellular region that commonly mediate cell-cell and cell-matrix interactions in various contexts. Recently, many genome-scale analyses of genetic alterations across diverse cancer types have revealed significant alterations (copy number and mutational) in adhesion-GPCRs, yet no comprehensive examination of their roles in cancer biology exists. Through a systematic screening for all adhesion-GPCRs by RT-qPCR in murine mammary carcinoma cell lines with varying metastatic abilities as well as tumor samples of different grades, I have identified several candidate genes with possible roles in breast cancer progression and metastasis. Based on these analyses and cross-referencing with the published gene expression data on human breast cancer cell lines and patient samples, I chose two candidate genes, CELSR2 and GPR126, for more detailed investigation. To elucidate their functions in cancer biology, I investigated the effects of their perturbations using RNAi (loss-of-function) methods both in vitro and in vivo. The results from my work reveal that loss of CELSR2 affects neither tumor growth nor lung metastasis in a xenograft mouse model of breast cancer, despite enhancing invadopodial activity in vitro. I also show that highly metastatic breast cancer and melanoma cells have elevated levels of GPR126, and confirm the significance of this result by revealing (a) reduction in pulmonary metastasis without affecting primary tumor growth in a spontaneous metastasis model of breast cancer, and (b) reduction in lung metastasis in three different experimental metastasis models of breast cancer and melanoma, upon shRNA-mediated knockdown of GPR126. After probing the different steps in the metastatic cascade to investigate how GPR126 promotes metastasis, I demonstrate that GPR126 specifically affects extravasation, most likely through its engagement with type IV collagen in the sub-endothelial basement membrane. Thus, the work described in this thesis contributes to our overall understanding of the perplexing problem of cancer metastasis via identification of novel regulators of distinct steps along the ominous path of malignant cells from primary sites to distant organs.
Adhesion loss due to internal strain
Croll, S. G.
L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.
ABSTRACT Cell adhesion plays a central role in multicellular organisms helping to maintain their integrity and homeostasis. This complex process involves many different types of adhesion proteins, and synergetic behavior of these proteins during cell adhesion is frequently observed in experiments. A well-known example is the cooperation of rolling and stationary adhesion proteins during the leukocytes extravasation. Despite the fact that such cooperation is vital for proper functioning of the immune system, its origin is not fully understood. In this study we constructed a simple analytic model of the interaction between a leuko- cyte and the blood vessel wall in shear flow. The model predicts existence of cell adhesion bistability, which results from a tug-of- war between two kinetic processes taking place in the cell-wall contact area—bond formation and rupture. Based on the model results, we suggest an interpretation of several cytoadhesion experiments and propose a simple explanation of the existing synergy between rolling and stationary adhesion proteins, which is vital for effective cell adherence to the blood vessel walls in living organisms.
The performance of bituminous sealants in the field is partly controlled by the properties and strength of the sealant- aggregate interface. The thermodynamic work of adhesion represents the energy required for reversible separation of the two materials at the interface. The work of fracture includes the energy required for both reversible and irreversible processes during separation. The excess of work of facture over work of adhesion represents the energy consumed by irreversible processes in the specimen during loading and fracture. In addition, the adhesion strength is related to the properties of the constitutive components. The objective of this study is to measure or predict the adhesion of hot- poured bituminous-based sealant to aggregates of different chemical composition. In order to accomplish this, the work of fracture and the thermodynamic work of adhesion were estimated for 14 hot-poured bituminous-based sealants with two types of aggregate: limestone and quartzite. The work of adhesion for each sealant-aggregate system was