Abstract P1078: Early Trypanosoma Cruzi Infection Of Heart Endothelial Cells Modulates Hippo And Wnt Signaling Pathways In TSP-1 Dependent Manner

Trypanosoma cruzi , an obligate intracellular protozoan parasite, is the etiological agent of Chagas Disease. Due to globalization, the disease is now present in all economically advanced countries of the world. About 40% of T. cruzi infected individuals will develop cardiac, neurological, and/or gastrointestinal pathology, with Chagasic Cardiomyopathy being the most prevalent pathology. During transportation, the molecular mechanisms by which the parasite signals and interact with host endothelial cells (EC), especially heart endothelium is currently unknown. Previous studies in our lab showed that the parasite dysregulates the expression of host genes, such as Thrombospondin-1 (TSP-1), to facilitate infection. Hippo and Wnt signaling pathways, in particular, have been implicated in cardiac development and disease pathogenesis. Here, we aim to evaluate the significance of TSP-1 in Hippo and Wnt signaling during the course of early T. cruzi infection. We challenged mouse heart endothelial cells (MHEC) from wild type (WT) and TSP1 knockout mice with T. cruzi and evaluated Wnt signaling by immunoblotting, YAP/β-catenin crosstalk via immunofluorescence assays, and parasite infectivity using β-catenin inhibitor. We found that in the absence of TSP1, the parasite induced the expression of Wnt-5a and enhanced the activation of GSK-3β simultaneously. In WT MHEC, the levels of Wnt-5a, p-GSK-3β were decreased compared to uninfected control. We also observed a continuous significant increase in the nuclear colocalization of β-catenin/YAP in TSP1 KO MHEC. Interestingly in WT MHEC, nuclear colocalization of β-catenin/YAP remained steady and reduced during later parasite challenge. Importantly, dysregulation of this crosstalk by pre-incubation of WT MHEC with a β-catenin inhibitor, endo-IWR 1, dramatically reduced the level of infection of WT MHEC. Parasite infectivity of inhibitor-treated WT MHEC was similar to the level of infection of TSP1 KO MHEC. These results indicate that TSP1 plays an important role in regulating Wnt/Hippo crosstalk and may be important potential therapeutic targets.