Biology and Biomedical Sciences: Molecular Microbiology and Microbial Pathogenesis
Date of Award
Doctor of Philosophy (PhD)
Chair and Committee
Infection with Shiga toxin-producing bacteria can place patients at risk of developing hemolytic uremic syndrome, a toxemic condition characterized by hemolytic anemia, thrombocytopenia, and acute renal failure. Though hemolytic uremic syndrome remains the leading cause of acute renal failure in children under the age of 5, treatment of this disease remains purely supportive. In order to limit the systemic effects of Shiga toxin, efforts must be undertaken to target intoxicated cells. To this end, we have focused on two aspects of Shiga toxin pathogenesis. One approach relied on a high-throughput screen of a small compound library to identify potential inhibitors of Shiga toxin intracellular transport, as Shiga toxin is known to undergo a stepwise progression through host cells following endocytosis. This screen identified three compounds with distinct effects on Shiga toxin transport. A detailed characterization of one of these inhibitory compounds, golgicide A, shed insight into the role of a guanine nucleotide exchange factor, GBF1, in coordinating bidirectional transport through the Golgi. Golgicide A was found to be a potent and specific inhibitor of GBF1 and represents a novel tool for probing intra-Golgi transport. Our second approach adapted a siRNA screen of the human kinome to a high-throughput format. In an effort to identify human kinases involved in Shiga toxin pathogenesis, we identified the mitogen-activated protein kinase-activated protein kinase 2: MK2) as a kinase involved in the host stress response to Shiga toxin. MK2 was activated following ribotoxic stress and contributed to the Shiga toxin-induced acute inflammatory response. Genetic and chemical inhibition of MK2 significantly reduced the expression of the inflammatory cytokines IL-6 and TNF├í following Shiga toxin exposure. MK2 thus represents a therapeutic alternative for treating the immunopathological response to Shiga toxin, and future efforts at dissecting its role in an in vivo mouse model of hemolytic uremic syndrome will help elucidate the contribution of the inflammatory response to Shiga toxin-mediated disease.
Saenz, Jose, "Genetic and Chemical Genetic Approaches to Shiga Toxin Inhibition" (2011). All Theses and Dissertations (ETDs). 304.