Enteropathogenic E. coli (EPEC), an intestinal pathogen that causes diarrhea, is responsible for significant morbidity and mortality, especially among children below 5 years of age in developing countries. The precise mechanism(s) by which EPEC causes diarrhea is currently not known. The bacteria elaborate a syringe-like type III secretion system that delivers key virulence factors directly into host intestinal epithelial cells. During the initial phase of infection, EPEC appears to specifically limit the death of the underlying epithelial cells. The focus of this proposal is the suppression of host cell death by the type III-secreted protein EspZ, which is unique to EPEC and related pathogens. Strains lacking EspZ are highly impaired for colonization and disease in animal models of infection. We hypothesize that EspZ interacts with host proteins to suppress premature death of infected enterocytes and, thereby, plays a key role in intestinal colonization by A/E pathogens. We propose to (1) validate the interaction of EspZ with host cell partners, define EspZ interaction domains, and generate specific EspZ mutants deficient for interaction(s), (2) characterize the role of EspZ and its interaction partners in activating signaling pathways that contribute to the survival of host cells, and (3) define the role of EspZ and its interaction partners in pathogenesis using animal models of infection. Understanding the key role of EspZ, and of host survival to pathogenesis, could lead to future efforts to inhibit EspZ function, and thereby control EPEC-associated diarrhea.

Public Health Relevance

Enteropathogenic Escherichia coli is a diarrhea-causing organism responsible for significant morbidity and mortality in children. This proposal explores the role of host cell survival in Enteropathogenic Escherichia coli colonization and pathogenesis. The eventual goal is to define the critical processes in pathogenesis that can subsequently be targeted for therapeutic purposes.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI081742-03
Application #
8489250
Study Section
Gastrointestinal Mucosal Pathobiology Study Section (GMPB)
Program Officer
Baqar, Shahida
Project Start
2011-07-01
Project End
2016-06-30
Budget Start
2013-07-01
Budget End
2014-06-30
Support Year
3
Fiscal Year
2013
Total Cost
$380,237
Indirect Cost
$121,102
Name
University of Arizona
Department
Veterinary Sciences
Type
Schools of Earth Sciences/Natur
DUNS #
806345617
City
Tucson
State
AZ
Country
United States
Zip Code
85721
Roxas, Jennifer Lising; Viswanathan, V K (2018) Modulation of Intestinal Paracellular Transport by Bacterial Pathogens. Compr Physiol 8:823-842
Roxas, Jennifer Lising; Monasky, Ross Calvin; Roxas, Bryan Angelo P et al. (2018) Enteropathogenic Escherichia coli EspH-Mediated Rho GTPase Inhibition Results in Desmosomal Perturbations. Cell Mol Gastroenterol Hepatol 6:163-180
Wilbur, John Scott; Byrd, Wyatt; Ramamurthy, Shylaja et al. (2015) The secreted effector protein EspZ is essential for virulence of rabbit enteropathogenic Escherichia coli. Infect Immun 83:1139-49
Roxas, Jennifer Lising; Ryan, Katheryn; Vedantam, Gayatri et al. (2014) Enteropathogenic Escherichia coli dynamically regulates EGFR signaling in intestinal epithelial cells. Am J Physiol Gastrointest Liver Physiol 307:G374-80
McQuade, Rebecca; Roxas, Bryan; Viswanathan, V K et al. (2012) Clostridium difficile clinical isolates exhibit variable susceptibility and proteome alterations upon exposure to mammalian cationic antimicrobial peptides. Anaerobe 18:614-20
Roxas, Jennifer Lising; Wilbur, John Scott; Zhang, Xiangfeng et al. (2012) The enteropathogenic Escherichia coli-secreted protein EspZ inhibits host cell apoptosis. Infect Immun 80:3850-7
Vedantam, Gayatri; Clark, Andrew; Chu, Michele et al. (2012) Clostridium difficile infection: toxins and non-toxin virulence factors, and their contributions to disease establishment and host response. Gut Microbes 3:121-34