PROJECT SUMMARY/ABSTRACT Targeting neuropeptide and peptide hormone signaling is a promising strategy to treat a wide range of human diseases, including neurodegenerative diseases, diabetes, osteoporosis, and cancer. A rigorous molecular-level understanding of how specific peptide molecules signal in disease provides valuable information that can directly inform the design of therapeutic compounds. However, there remain a large number of bioactive and disease- relevant endogenous peptides whose signaling pathways are not understood. Because of the importance of peptide-receptor interactions in normal physiology and disease, there is a critical need for new tools and approaches to fully interrogate and modulate these signaling systems. The long-term goal of my research program is to rigorously identify and evaluate novel molecular signaling pathways as therapeutic targets. To achieve this goal, my research program pursues a highly interdisciplinary approach, with expertise in the design, synthesis, and implementation of novel chemical probes and peptidomimetics, protein and peptide mass spectrometry, and analysis of peptide-receptor interactions on cells. Over the next five years, we are motivated by three broad research questions. 1) What are the receptors for a given disease-related bioactive peptide? Our goal is to develop and implement new and unbiased chemical approaches to directly detect peptide-receptor interactions without the need to genetically or chemically modify the receptor prior to interaction. We will implement these approaches to identify receptors for three specific peptide hormones with roles in obesity and diabetes. 2) How does peptide abundance and post-translational processing influence disease? Our goal is to identify neuropeptide and peptide hormone interactions that can be targeted to benefit human health. We are developing and applying mass spectrometry-based methods to uncover the full complement of neuropeptides and peptide hormones in understudied disease-relevant physiologies, including characterization of all post-translational modifications and rigorous quantitation. We will use our strengths in chemical probe and peptidomimetic design to evaluate these new targets after initial identification. 3) Are there new “non-traditional” approaches to modulating cell-cell signaling waiting to be uncovered? Our goal is to explore naturally occurring peptide-receptor systems that function outside of the traditional agonist/antagonist paradigm. Information gained from this research area will be utilized to develop new chemical probes to better understand signaling events, and to inform the design of novel therapeutic routes that may provide advantages over traditional modulators. Overall, this research program will develop new tools and strategies to fully understand and modulate peptide signaling pathways. This work will impact biomedical research by a) significantly advancing understanding of neuropeptides and hormones in...