scholarly journals Burkholderia cenocepacia –host cell contact controls the transcription activity of the trimeric autotransporter adhesin BCAM2418 gene

2020 ◽  
Vol 9 (4) ◽  
Author(s):  
Andreia I. Pimenta ◽  
Dalila Mil‐Homens ◽  
Arsenio M. Fialho
Keyword(s):  
Host Cell ◽  
Burkholderia Cenocepacia ◽  
Cell Contact ◽  
Transcription Activity ◽  
Trimeric Autotransporter Adhesin

scholarly journals Temperature Shift and Host Cell Contact Up-Regulate Sporozoite Expression of Plasmodium falciparum Genes Involved in Hepatocyte Infection

2008 ◽  
Vol 4 (8) ◽  
pp. e1000121 ◽  
Author(s):  
Anthony Siau ◽  
Olivier Silvie ◽  
Jean-François Franetich ◽  
Samir Yalaoui ◽  
Carine Marinach ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Host Cell ◽  
Temperature Shift ◽  
Cell Contact

scholarly journals RpoH Mediates the Expression of Some, but Not All, Genes Induced in Neisseria gonorrhoeae Adherent to Epithelial Cells

2006 ◽  
Vol 74 (5) ◽  
pp. 2767-2776 ◽  
Author(s):  
Ying Du ◽  
Cindy Grove Arvidson
Keyword(s):  
Epithelial Cells ◽  
Neisseria Gonorrhoeae ◽  
Host Cell ◽  
Infection Process ◽  
Host Cells ◽  
Cell Contact ◽  
Transmitted Infection ◽  
New Host ◽  
Sexually Transmitted ◽  
Cell Induction

ABSTRACT Neisseria gonorrhoeae (gonococcus [GC]), is highly adapted to the human host, the only known reservoir for gonococcal infection. However, since it is sexually transmitted, infection of a new host likely requires a regulatory response on the part of the gonococcus to respond to this significant change in environment. We previously showed that adherence of gonococci to epithelial cells results in changes of gene expression in the bacteria that presumably prepare them for subsequent steps in the infection process. Expression of the heat shock sigma factor gene, rpoH, was shown to be important for the invasion step, as gonococci depleted for rpoH were reduced in their ability to invade epithelial cells. Here, we show that of the genes induced in adherent gonococci, two are part of the gonococcal RpoH regulon. When RpoH is depleted, expression of these genes is no longer induced by host cell contact, indicating that RpoH is mediating the host cell induction response of these genes. One RpoH-dependent gene, NGO0376, is shown to be important for invasion of epithelial cells, consistent with earlier observations that RpoH is necessary for this step of infection. Two genes, NGO1684 and NGO0340, while greatly induced by host cell contact, were found to be RpoH independent, indicating that more than one regulator is involved in the response to host cell contact. Furthermore, NGO0340, but not NGO1684, was shown to be important for both adherence and invasion of epithelial cells, suggesting a complex regulatory network in the response of gonococci to contact with host cells.

scholarly journals Efficient Translocation of EspC into Epithelial Cells Depends on Enteropathogenic Escherichia coli and Host Cell Contact

2006 ◽  
Vol 74 (4) ◽  
pp. 2293-2303 ◽  
Author(s):  
Jorge E. Vidal ◽  
Fernando Navarro-García
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Host Cell ◽  
Cytopathic Effect ◽  
Cell Interaction ◽  
Cell Contact ◽  
Internalization Mechanism ◽  
Cell Cytosol ◽  
Cytoskeletal Disruption

ABSTRACT EspC is an autotransporter protein secreted by enteropathogenic Escherichia coli (EPEC). The pathogenic role of EspC in EPEC infection is unknown. We have shown that the purified EspC produces enterotoxicity and cytotoxicity; for the latter effect, EspC must be internalized. However, the internalization mechanism is unknown. Here we show that azithromycin (an inhibitor of pinocytosis), but not drugs affecting caveole-, clathrin-, or receptor-mediated endocytosis, inhibited purified EspC internalization and cytoskeletal disruption, suggesting that purified EspC is internalized by pinocytosis. Furthermore, unlike in cholera toxin, we were unable to detect a receptor on epithelial cells by pretreatment at 4°C. Upon EspC entry, it is delivered directly into the cell cytosol, as shown by the fact that drugs that inhibit intracellular trafficking had no effect on cytoskeletal disruption. All these data suggest that purified EspC internalization is not a physiological internalization mechanism; hence, we explored EspC internalization during the infection of epithelial cells by EPEC. Like other EPEC virulence factors, EspC secretion is stimulated by EPEC when it is grown in cell culture medium and enhanced by the presence of epithelial cells. Physiologically secreted EspC was efficiently internalized during EPEC and host cell interaction. Additionally, the lack of EspC internalization caused by using an isogenic mutant prevented the cytopathic effect caused by EPEC. These data suggest that EPEC uses an efficient mechanism to internalize milieu-secreted EspC into epithelial cells; once inside the cells, EspC is able to induce the cytopathic effect caused by EPEC.

scholarly journals Defining the Mechanical Determinants of Kingella kingae Adherence to Host Cells

2017 ◽  
Vol 199 (23) ◽  
Author(s):  
Brad K. Kern ◽  
Eric A. Porsch ◽  
Joseph W. St. Geme
Keyword(s):  
Host Cell ◽  
High Strength ◽  
Type Iv Pili ◽  
Host Cells ◽  
Initial Contact ◽  
Kingella Kingae ◽  
Content Type ◽  
Type Iv ◽  
Transmission Electron ◽  
Trimeric Autotransporter Adhesin

ABSTRACT Kingella kingae is an important pathogen in young children and initiates infection by colonizing the posterior pharynx. Adherence to pharyngeal epithelial cells is an important first step in the process of colonization. In the present study, we sought to elucidate the interplay of type IV pili (T4P), a trimeric autotransporter adhesin called Knh, and the polysaccharide capsule in K. kingae adherence to host cells. Using adherence assays performed under shear stress, we observed that a strain expressing only Knh was capable of higher levels of adherence than a strain expressing only T4P. Using atomic force microscopy and transmission electron microscopy (TEM), we established that the capsule had a mean depth of 700 nm and that Knh was approximately 110 nm long. Using cationic ferritin capsule staining and thin-section transmission electron microscopy, we found that when bacteria expressing retractile T4P were in close contact with host cells, the capsule was absent at the point of contact between the bacterium and the host cell membrane. In a T4P retraction-deficient mutant, the capsule depth remained intact and adherence levels were markedly reduced. These results support the following model: T4P make initial contact with the host cell and mediate low-strength adherence. T4P retract, pulling the organism closer to the host cell and displacing the capsule, allowing Knh to be exposed and mediate high-strength, tight adherence to the host cell surface. This report provides the first description of the mechanical displacement of capsule enabling intimate bacterial adherence to host cells. IMPORTANCE Adherence to host cells is an important first step in bacterial colonization and pathogenicity. Kingella kingae has three surface factors that are involved in adherence: type IV pili (T4P), a trimeric autotransporter adhesin called Knh, and a polysaccharide capsule. Our results suggest that T4P mediate initial contact and low-strength adherence to host cells. T4P retraction draws the bacterium closer to the host cell and causes the displacement of capsule. This displacement exposes Knh and allows Knh to mediate high-strength adherence to the host cell. This work provides new insight into the interplay of T4P, a nonpilus adhesin, and a capsule and their effects on bacterial adherence to host cells.

Gene Expression Profile inNeisseria meningitidisandNeisseria lactamicaupon Host-Cell Contact

2002 ◽  
Vol 975 (1) ◽  
pp. 202-216 ◽  
Author(s):  
R. GRIFANTINI ◽  
E. BARTOLINI ◽  
A. MUZZI ◽  
M. DRAGHI ◽  
E. FRIGIMELICA ◽  
...  
Keyword(s):  
Gene Expression ◽  
Host Cell ◽  
Gene Expression Profile ◽  
Expression Profile ◽  
Cell Contact

scholarly journals Baculovirus induces host cell aggregation via a Rho/Rok-dependent mechanism

2014 ◽  
Vol 95 (10) ◽  
pp. 2310-2320 ◽  
Author(s):  
Zihao Deng ◽  
Zhihong Huang ◽  
Meijin Yuan ◽  
Kai Yang ◽  
Yi Pang
Keyword(s):  
Rna Interference ◽  
Host Cell ◽  
Actin Polymerization ◽  
Cell Aggregation ◽  
Small Gtpases ◽  
Dominant Negative ◽  
Cell Contact ◽  
Amoeboid Movement ◽  
Pathway Inhibition

Several baculoviruses can induce host cell aggregation during infection; however, the molecular basis remains unknown. The Rho family of small GTPases, including Rho1, Racs and Cdc42, plays important roles in cell migration and cell–cell contact. Activated GTPases target actin polymerization to discrete sites on the plasma membrane, thereby inducing membrane protrusions. In this study, we demonstrated that Spodoptera litura nucleopolyhedrovirus (SpltNPV) infection induced the amoeboid movement and aggregation of SpLi-221 cells in vitro. The amount of Rho1-GTP increased in the infected cells, which suggested that Rho1 was activated upon infection. RNA interference and superinfection of dominant-negative recombinants revealed that the SpltNPV-induced SpLi-221 cell aggregation was dependent on the Rho1, but not Racs or Cdc42, signalling pathway. Inhibition of Rho-associated protein kinase (Rok) activity by the inhibitor Y-27632 significantly reduced SpLi-221 cell aggregation. Silencing Rho1 expression with RNA interference decreased SpltNPV propagation by approximately 40 % in vitro, when SpLi-221 cells were infected at a low, but not high, m.o.i., suggesting that the SpltNPV-induced cell aggregation may benefit SpltNPV spread.

scholarly journals Host Cell Contact-Induced Transcription of the Type IV Fimbria Gene Cluster of Actinobacillus pleuropneumoniae

2004 ◽  
Vol 72 (2) ◽  
pp. 691-700 ◽  
Author(s):  
Bouke K. H. L. Boekema ◽  
Jos P. M. Van Putten ◽  
Norbert Stockhofe-Zurwieden ◽  
Hilde E. Smith
Keyword(s):  
Epithelial Cells ◽  
Host Cell ◽  
Gene Cluster ◽  
Promoter Activity ◽  
Actinobacillus Pleuropneumoniae ◽  
Lung Epithelial Cells ◽  
Cell Contact ◽  
Variable Expression ◽  
Type Iv

ABSTRACT Type IV pili (Tfp) of gram-negative species share many characteristics, including a common architecture and conserved biogenesis pathway. Much less is known about the regulation of Tfp expression in response to changing environmental conditions. We investigated the diversity of Tfp regulatory systems by searching for the molecular basis of the reported variable expression of the Tfp gene cluster of the pathogen Actinobacillus pleuropneumoniae. Despite the presence of an intact Tfp gene cluster consisting of four genes, apfABCD, no Tfp were formed under standard growth conditions. Sequence analysis of the predicted major subunit protein ApfA showed an atypical alanine residue at position −1 from the prepilin peptidase cleavage site in 42 strains. This alanine deviates from the consensus glycine at this position in Tfp from other species. Yet, cloning of the apfABCD genes under a constitutive promoter in A. pleuropneumoniae resulted in pilin and Tfp assembly. Tfp promoter-luxAB reporter gene fusions demonstrated that the Tfp promoter was intact but tightly regulated. Promoter activity varied with bacterial growth phase and was detected only when bacteria were grown in chemically defined medium. Infection experiments with cultured epithelial cells demonstrated that Tfp promoter activity was upregulated upon adherence of the pathogen to primary cultures of lung epithelial cells. Nonadherent bacteria in the culture supernatant exhibited virtually no promoter activity. A similar upregulation of Tfp promoter activity was observed in vivo during experimental infection of pigs. The host cell contact-induced and in vivo-upregulated Tfp promoter activity in A. pleuropneumoniae adds a new dimension to the diversity of Tfp regulation.

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