scholarly journals The role of PI3K signaling in enteropathogenic escherichia coli induced apoptosis in epithelial cells

2021 ◽  
Author(s):  
Heather Park
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Integration Site ◽  
Pi3k Signaling ◽  
Enteropathogenic Escherichia Coli ◽  
Apoptotic Signaling ◽  
Signaling Protein ◽  
Infected Cells ◽  
Induced Apoptosis

Enteropathogenic Escherichia coli (EPEC) is a diarrheagic pathogen that has been the cause of severe and persistent infant diarrhea worldwide. EPEC invades the gastrointestinal tract where it hijacks host cell signaling and evades immune response long enough to cause the disease. This study was done to establish the role of PI3K signaling in EPEC induced apoptosis in epithelial cells. This report demonstrates that EPEC infected cells activate the anti-apoptotic signaling protein Akt via phosphorylation along with another anti-apoptotic signaling protein, Bcl-2. At the same time during EPEC infection the pro-aptoptotic protein Bax is inhibited. The activation of Akt was also observed with the addition of lipopolysaccharide (LPS) in the presence of serum. This thesis suggests that there are likely separate sensing mechanisms for EPEC, LPS and serum that are independent but synergistic and that Akt is the integration site of these signaling cascades.

scholarly journals The role of PI3K signaling in enteropathogenic escherichia coli induced apoptosis in epithelial cells

2021 ◽  
Author(s):  
Heather Park
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Integration Site ◽  
Pi3k Signaling ◽  
Enteropathogenic Escherichia Coli ◽  
Apoptotic Signaling ◽  
Signaling Protein ◽  
Infected Cells ◽  
Induced Apoptosis

Enteropathogenic Escherichia coli (EPEC) is a diarrheagic pathogen that has been the cause of severe and persistent infant diarrhea worldwide. EPEC invades the gastrointestinal tract where it hijacks host cell signaling and evades immune response long enough to cause the disease. This study was done to establish the role of PI3K signaling in EPEC induced apoptosis in epithelial cells. This report demonstrates that EPEC infected cells activate the anti-apoptotic signaling protein Akt via phosphorylation along with another anti-apoptotic signaling protein, Bcl-2. At the same time during EPEC infection the pro-aptoptotic protein Bax is inhibited. The activation of Akt was also observed with the addition of lipopolysaccharide (LPS) in the presence of serum. This thesis suggests that there are likely separate sensing mechanisms for EPEC, LPS and serum that are independent but synergistic and that Akt is the integration site of these signaling cascades.

Enteropathogenic Escherichia coli (EPEC) adhesion to intestinal epithelial cells: role of bundle-forming pili (BFP), EspA filaments and intimin

Microbiology ◽  
2004 ◽  
Vol 150 (3) ◽  
pp. 527-538 ◽  
Author(s):  
Jennifer Cleary ◽  
Li-Ching Lai ◽  
Robert K. Shaw ◽  
Anna Straatman-Iwanowska ◽  
Michael S. Donnenberg ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Intestinal Epithelial ◽  
Enteropathogenic Escherichia Coli

scholarly journals Two Enteropathogenic Escherichia coli Type III Secreted Proteins, EspA and EspB, Are Virulence Factors

1998 ◽  
Vol 188 (10) ◽  
pp. 1907-1916 ◽  
Author(s):  
Akio Abe ◽  
Ursula Heczko ◽  
Richard G. Hegele ◽  
B. Brett Finlay
Keyword(s):  
Escherichia Coli ◽  
Virulence Factors ◽  
Enterohemorrhagic Escherichia Coli ◽  
Laser Scanning Microscopy ◽  
Secreted Proteins ◽  
Confocal Laser ◽  
Infection Model ◽  
Enteropathogenic Escherichia Coli ◽  
Type Iii

Enteropathogenic Escherichia coli (EPEC) belongs to a family of related bacterial pathogens, including enterohemorrhagic Escherichia coli (EHEC) O157:H7 and other human and animal diarrheagenic pathogens that form attaching and effacing (A/E) lesions on host epithelial surfaces. Bacterial secreted Esp proteins and a type III secretion system are conserved among these pathogens and trigger host cell signal transduction pathways and cytoskeletal rearrangements, and mediate intimate bacterial adherence to epithelial cell surfaces in vitro. However, their role in pathogenesis is still unclear. To investigate the role of Esp proteins in disease, mutations in espA and espB were constructed in rabbit EPEC serotype O103 and infection characteristics were compared to that of the wild-type strain using histology, scanning and transmission electron microscopy, and confocal laser scanning microscopy in a weaned rabbit infection model. The virulence of EspA and EspB mutant strains was severely attenuated. Additionally, neither mutant strain formed A/E lesions, nor did either one cause cytoskeletal actin rearrangements beneath the attached bacteria in the rabbit intestine. Collectively, this study shows for the first time that the type III secreted proteins EspA and EspB are needed to form A/E lesions in vivo and are indeed virulence factors. It also confirms the role of A/E lesions in disease processes.

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

1995 ◽  
Vol 9 (1) ◽  
pp. 31-36 ◽  
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.

scholarly journals Dengue activates mTORC2 signaling to counteract apoptosis and maximize viral replication

2020 ◽  
Author(s):  
Christoph C. Carter ◽  
Jean Paul Olivier ◽  
Alexis Kaushansky ◽  
Fred D. Mast ◽  
John D. Aitchison
Keyword(s):  
Viral Replication ◽  
Cell Survival ◽  
Structural Protein ◽  
Protein Protein Interaction ◽  
Mechanistic Target Of Rapamycin ◽  
Promote Cell Survival ◽  
Important Regulator ◽  
Infected Cells ◽  
Induced Apoptosis

ABSTRACTThe mechanistic target of rapamycin (mTOR) functions in at least two distinct complexes: mTORC1, which regulates cellular anabolic-catabolic homeostasis, and mTORC2, which is an important regulator of cell survival and cytoskeletal maintenance. mTORC1 has been implicated in the pathogenesis of flaviviruses including dengue, where it contributes to the establishment of a pro-viral autophagic state. In contrast, the role of mTORC2 in viral pathogenesis is unknown. In this study, we explore the consequences of a physical protein-protein interaction between dengue non-structural protein 5 (NS5) and host cell mTOR proteins during infection. Using shRNA to differentially target mTORC1 and mTORC2 complexes, we show that mTORC2 is required for optimal dengue replication. Furthermore, we show that mTORC2 is activated during viral replication, and that mTORC2 counteracts virus-induced apoptosis, promoting the survival of infected cells. This work reveals a novel mechanism by which the dengue flavivirus can promote cell survival to maximize viral replication.

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