Ricin and Shiga toxin share a unique mode of action, causing irreversible damage to host ribosomal RNA. Our understanding of how these bioterror agents cause tissue damage is incomplete and no medications exist to prevent or treat intoxication with these agents. Shiga toxin- or ricin-mediated ribosomal damage results in inhibition of protein synthesis as well as profound changes in host cell signal transduction. This phenomenon, called the """"""""ribotoxic stress response"""""""", is poorly understood. This proposal is focused on understanding: 1) what initiates the ribotoxic stress response; 2) which signal transduction pathways are involved; and 3) what are the downstream effects that may contribute to disease pathogenesis. Our preliminary data indicate that ricin and Shiga toxin activate host stress activated protein kinase (SAPK) and mitogen activated protein kinase (MAPK) pathways. We hypothesize that activation of these pathways contributes to intestinal and other tissue damage observed following intoxication with these agents. Effects of ricin and Shiga toxins on these pathways will be studied using cultured intestinal epithelial cells and an infant rabbit model of oral intoxication. The mechanism(s) by which these signal transduction pathways are stimulated will be assessed using Shiga toxin mutants and isolated Shiga toxin subunits. Direct effects of ricin and Shiga toxin on host cell signal transduction will be studied using phosphorylation-specific antibodies and immunoprecipitation kinase assays. Transfection of dominant negative constructs, RNA interference, and specific chemical inhibitors of signal transduction pathways will be used to dissect the mechanisms by which ricin and Shiga toxin alter cell physiology. Our work has revealed that oral administration of purified Shiga toxin 2 induces gut damage. In the infant rabbit model, SAPKinase-blocking compounds will be tested for their effect on preventing the gut damage that occurs following oral administration of Shiga toxin or ricin. This work will provide new insight into the ribotoxic stress response. Understanding how Shiga toxin and ricin cause damage to host cells should reveal potential therapeutic targets. These findings will be relevant to either accidental or intentional intoxication with ricin or Shiga toxin, and may prove generalizable to other host target organs affected by these toxins.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI059509-02
Application #
7071716
Study Section
Host Interactions with Bacterial Pathogens Study Section (HIBP)
Program Officer
Schmitt, Clare K
Project Start
2005-06-15
Project End
2010-02-28
Budget Start
2006-03-01
Budget End
2007-02-28
Support Year
2
Fiscal Year
2006
Total Cost
$318,339
Indirect Cost
Name
Tufts University
Department
Type
DUNS #
079532263
City
Boston
State
MA
Country
United States
Zip Code
02111
Jandhyala, Dakshina M; Ahluwalia, Amrita; Schimmel, Jennifer J et al. (2016) Activation of the Classical Mitogen-Activated Protein Kinases Is Part of the Shiga Toxin-Induced Ribotoxic Stress Response and May Contribute to Shiga Toxin-Induced Inflammation. Infect Immun 84:138-48
Jandhyala, Dakshina M; Thorpe, Cheleste M; Magun, Bruce (2012) Ricin and Shiga toxins: effects on host cell signal transduction. Curr Top Microbiol Immunol 357:41-65
Stone, Samuel M; Thorpe, Cheleste M; Ahluwalia, Amrita et al. (2012) Shiga toxin 2-induced intestinal pathology in infant rabbits is A-subunit dependent and responsive to the tyrosine kinase and potential ZAK inhibitor imatinib. Front Cell Infect Microbiol 2:135
Jandhyala, Dakshina M; Rogers, Trisha J; Kane, Anne et al. (2010) Shiga toxin 2 and flagellin from shiga-toxigenic Escherichia coli superinduce interleukin-8 through synergistic effects on host stress-activated protein kinase activation. Infect Immun 78:2984-94
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Jandhyala, Dakshina M; Ahluwalia, Amrita; Obrig, Tom et al. (2008) ZAK: a MAP3Kinase that transduces Shiga toxin- and ricin-induced proinflammatory cytokine expression. Cell Microbiol 10:1468-77
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Johnson, Kristine E; Thorpe, Cheleste M; Sears, Cynthia L (2006) The emerging clinical importance of non-O157 Shiga toxin-producing Escherichia coli. Clin Infect Dis 43:1587-95