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The Role of ZAK in Shiga Toxin/Ricin-Induced Inflammation


Inflammatory responses are natural consequences of many infections and can be a key protective response. However, in some cases, inflammation can cause devastating effects on the host. Cases of inadvertent intoxication of humans with either Shiga toxins or ricin occur, with serious and sometimes fatal effects, thus they are considered potential bioterror agents. One effect of these toxins is to stimulate host inflammation that ultimately damages the host. There are no established treatments for the diseases resulting from intoxication.<P> To fully understand the unique intoxication syndromes associated with these protein synthesis inhibitors, it is essential to determine which aspects of disease pathogenesis are due to protein synthesis inhibition per se, and which aspects result from the novel immune activating properties now associated with these toxins.<P> Our overall goal is to investigate critical host proteins activated by Shiga toxins/ricin that result in host-damaging inflammation. These host proteins would be potential therapeutic targets to prevent or treat Shiga toxin/ricin-associated diseases. We are the first group to identify a MAP3Kinase (called 'ZAK') that is associated with the proinflammatory signaling cascade initiated by these toxins. <P>Our overall hypothesis is that Shiga toxin/ricin-induced ZAK activation contributes to overall host morbidity/mortality by causing host-damaging inflammation, and that ZAK may be a potential therapeutic target. To the best of our knowledge, we are the only group working on development of therapeutics for Shiga toxin/ricin-induced inflammation by targeting the MAP3Kinase(s) involved in the proinflammatory signaling cascade.<P> In this proposal, we will create a murine line with a targeted deletion in ZAK, for use in Shiga toxin/ricin challenge models in which the mechanisms underlying immune-mediated damage can be studied. We will initiate studies to determine ZAK localization in cells under basal or intoxicated conditions. We will identify potential ZAK-interacting molecules using several complementary approaches, and evaluate the interaction(s) between ZAK and its binding partners. These molecules may be new therapeutic targets.<P> PUBLIC HEALTH RELEVANCE: Inadvertent intoxication of humans with either Shiga toxins or ricin can cause serious and sometimes fatal effects. As a result, they are considered potential bioterror agents. There are no specific treatments for diseases caused these agents, so understanding how these toxins harm host cells is critical to understanding how to prevent illnesses that occur following inadvertent or intentional exposure.

Thorpe, Cheleste
Tufts Medical Center
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