Systems and Chemical Biology Approaches for the Study of Innate Immune Signaling Pathways

Abstract

The innate immune system is equipped with several signaling pathways that detect for signs of pathogens. Upon recognition of a pathogenic associated molecular pattern (PAMP), these signaling pathways elicit a tailored response that provides critical defense. These pathways are finely tuned to maintain immune homeostasis, and dysregulation has been linked to several classes of disease. Hypoactivity has been linked to susceptibility to infection as well as cancer, while hyperactivation has been linked to several types autoimmune and inflammatory disease. The critical roles these pathways play in host defense, as well as their relevance in disease, has generated an enormous interest in identification of pathway regulators as well as chemical probes that modulate pathway activity. We developed a high content screening assay to measure activity of pro-inflammatory pathways. Using this assay, we screened a collection of bioactive small molecules, and identified several kinase inhibitors that antagonize the anti-viral STING signaling pathway. Further follow-up suggested that the kinase, MAPKAPK5, might be involved in STING signal transduction. This project is described in chapter two. In chapter three, we discuss adapting the high content assay for a screen to identify viral proteins that suppress innate immune pathways. In chapter four of this thesis, we focus on a new question of how anti-mitotic drugs activate innate immune signaling. We identify some anti-mitotic drugs that activate STING signaling, and also propose mechanisms for how paclitaxel activates inflammatory signaling in THP-1 cells.