Signal transduction between enteropathogenic Escherichia coli (EPEC) and epithelial cells: EPEC induces tyrosine phosphorylation of host cell proteins to initiate cytoskeletal rearrangement and bacterial uptake.

Enteropathogenic Escherichia coli (EPEC) is a bacterial pathogen that causes diarrhea in infants by adhering to intestinal epithelial cells. EPEC induces host cell protein phosphorylation and increases intracellular calcium levels that may function to initiate cytoskeletal rearrangement. We found that EPEC triggers the release of inositol phosphates (IPs) after adherence of bacteria to cultured epithelial cells. We also demonstrated that the EPEC-induced flux of IPs precedes actin rearrangement and bacterial invasion. EPEC mutants and tyrosine protein kinase inhibitors were used to establish that formation of IPs is dependent on tyrosine phosphorylation of a 90-kD HeLa protein. Collectively these results suggest that EPEC-induced tyrosine phosphorylation of a host cell substrate(s) leads to release of IPs, which may then trigger cytoskeletal rearrangement.

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Enterohemorrhagic Escherichia coli O157:H7 Disrupts Stat1-Mediated Gamma Interferon Signal Transduction in Epithelial Cells

Infection and Immunity ◽

10.1128/iai.71.3.1396-1404.2003 ◽

2003 ◽

Vol 71 (3) ◽

pp. 1396-1404 ◽

Cited By ~ 30

Author(s):

Peter J. M. Ceponis ◽

Derek M. McKay ◽

Joyce C. Y. Ching ◽

Perpetual Pereira ◽

Philip M. Sherman

Keyword(s):

Escherichia Coli ◽

Signal Transduction ◽

Epithelial Cells ◽

Host Cell ◽

Tyrosine Phosphorylation ◽

Gamma Interferon ◽

Enterohemorrhagic Escherichia Coli ◽

Cell Protein ◽

E Coli ◽

Ifn Γ

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a clinically important bacterial enteropathogen that manipulates a variety of host cell signal transduction cascades to establish infection. However, the effect of EHEC O157:H7 on Jak/Stat signaling is unknown. To define the effect of EHEC infection on epithelial gamma interferon (IFN-γ)-Stat1 signaling, human T84 and HEp-2 epithelial cells were infected with EHEC O157:H7 and then stimulated with recombinant human IFN-γ. Cells were also infected with different EHEC strains, heat-killed EHEC, enteropathogenic E. coli (EPEC) O127:H6, and the commensal strain E. coli HB101. Nuclear and whole-cell protein extracts were prepared and were assayed by an electrophoretic mobility shift assay (EMSA) and by Western blotting, respectively. Cells were also processed for immunofluorescence to detect the subcellular localization of Stat1. The EMSA revealed inducible, but not constitutive, Stat1 activation upon IFN-γ treatment of both cell lines. The EMSA also showed that 6 h of EHEC O157:H7 infection, but not 30 min of EHEC O157:H7 infection, prevented subsequent Stat1 DNA binding induced by IFN-γ, whereas infection with EPEC did not. Immunoblotting showed that infection with EHEC, but not infection with EPEC, eliminated IFN-γ-induced Stat1 tyrosine phosphorylation in both dose- and time-dependent fashions and disrupted inducible protein expression of the Stat1-dependent gene interferon regulatory factor 1. Immunofluorescence revealed that EHEC infection did not prevent nuclear accumulation of Stat1 after IFN-γ treatment. Also, Stat1 tyrosine phosphorylation was suppressed by different EHEC isolates, including intimin-, type III secretion- and plasmid-deficient strains, but not by HB101 and heat-killed EHEC. These findings indicate the novel disruption of host cell signaling caused by EHEC infection but not by EPEC infection.

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Internalization of Escherichia coli by human renal epithelial cells is associated with tyrosine phosphorylation of specific host cell proteins.

Infection and Immunity ◽

10.1128/iai.65.7.2570-2575.1997 ◽

1997 ◽

Vol 65 (7) ◽

pp. 2570-2575 ◽

Cited By ~ 26

Author(s):

L M Palmer ◽

T J Reilly ◽

S J Utsalo ◽

M S Donnenberg

Keyword(s):

Escherichia Coli ◽

Epithelial Cells ◽

Host Cell ◽

Tyrosine Phosphorylation ◽

Renal Epithelial Cells ◽

Host Cell Proteins ◽

Specific Host

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Interactions Between Salmonella Typhimurium, Enteropathogenic Escherichia Coli (EPEC), and Host Epithelial Cells

Advances in Dental Research ◽

10.1177/08959374950090010601 ◽

1995 ◽

Vol 9 (1) ◽

pp. 31-36 ◽

Cited By ~ 5

Author(s):

B.B. Finlay

Keyword(s):

Escherichia Coli ◽

Epithelial Cells ◽

Salmonella Typhimurium ◽

Host Cell ◽

Inositol Phosphate ◽

Enteric Pathogens ◽

Host Protein ◽

Host Cells ◽

Enteropathogenic Escherichia Coli ◽

Sequence Of Events

The interactions that occur between pathogenic micro-organisms and their host cells are complex and intimate. We have used two enteric pathogens, Salmonella typhimurium and enteropathogenic Escherichia coli (EPEC), to examine the interactions that occur between these organisms and epithelial cells. Although these are enteric pathogens, the knowledge and techniques developed from these systems may be applied to the study of dental pathogens. Both S. typhimurium and EPEC disrupt epithelial monolayer integrity, although by different mechanisms. Both pathogens cause loss of microvilli and re-arrangement of the underlying host cytoskeleton. Despite these similarities, both organisms send different signals into the host cell. EPEC signal transduction involves generation of intracellular calcium and inositol phosphate fluxes, and activation of host tyrosine kinases that results in tyrosine phosphorylation of a 90-kDa host protein. Bacterial mutants have been identifed that are deficient in signaling to the host. We propose a sequence of events that occur when EPEC interacts with epithelial cells. Once inside a host cell, S. typhimurium remains within a vacuole. To define some of the parameters of the intracellular environment, we constructed genetic fusions of known genes with lacZ, and used these fusions as reporter probes of the intracellular vacuolar environment. We have also begun to examine the bacterial and host cell factors necessary for S. typhimurium to multiply within epithelial cells. We found that this organism triggers the formation of novel tubular lysosomes, and these structures are linked with intracellular replication.

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Divergent Signal Transduction Responses to Infection with Attaching and Effacing Escherichia coli

Infection and Immunity ◽

10.1128/iai.66.4.1688-1696.1998 ◽

1998 ◽

Vol 66 (4) ◽

pp. 1688-1696 ◽

Cited By ~ 14

Author(s):

Arif Ismaili ◽

Elaine McWhirter ◽

Michelle Y. C. Handelsman ◽

James L. Brunton ◽

Philip M. Sherman

Keyword(s):

Escherichia Coli ◽

Signal Transduction ◽

Epithelial Cells ◽

Shiga Toxin ◽

Cytoskeletal Proteins ◽

Epec Strain ◽

E Coli ◽

Phosphorylated Proteins ◽

Host Cell Proteins ◽

Uremic Syndrome

ABSTRACT Shiga toxin-producing Escherichia coli (STEC) O157:H7 is an attaching and effacing pathogen that causes hemorrhagic colitis and the hemolytic-uremic syndrome. Although this organism causes adhesion pedestals, the cellular signals responsible for the formation of these lesions have not been clearly defined. We have shown previously that STEC O157:H7 does not induce detectable tyrosine phosphorylation of host cell proteins upon binding to eukaryotic cells and is not internalized into nonphagocytic epithelial cells. In the present study, tyrosine-phosphorylated proteins were detected under adherent STEC O157:H7 when coincubated with the non-intimately adhering, intimin-deficient, enteropathogenic E. coli(EPEC) strain CVD206. The ability to be internalized into epithelial cells was also conferred on STEC O157:H7 when coincubated with CVD206 ([158 ± 21] % of control). Neither the ability to rearrange phosphotyrosine proteins nor that to be internalized into epithelial cells was evident following coincubation with another STEC O157:H7 strain or with the nonsignaling espB mutant of EPEC.E. coli JM101(pMH34/pSSS1C), which overproduces surface-localized O157 intimin, also rearranged tyrosine-phosphorylated and cytoskeletal proteins when coincubated with CVD206. In contrast, JM101(pMH34/pSSS1C) demonstrated rearrangement of cytoskeletal proteins, but not tyrosine-phosphorylated proteins, when coincubated with intimin-deficient STEC (strains CL8KO1 and CL15). These findings indicate that STEC O157:H7 forms adhesion pedestals by mechanisms that are distinct from those in attaching and effacing EPEC. Taken together, these findings point to diverging signal transduction responses to infection with attaching and effacing bacterial enteropathogens.

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