Chemical Tagging of Metabolites for Quantitative Metabolomics and Determining Structures of Metabolites Using Informative Fragmentation Tagging.

Since metabolites are a diverse group of compounds with a variety of functionalities including hydroxyl, amine, thiol and carboxyl functional groups investigating them using mass spectrometry has variable signal depending on which functional groups the metabolite contains. In order to overcome this difficulty in quantitation, we are developing a derivatization method that allows analysis of most common metabolites. By tagging each functional group with the same high proton affinity moiety, competing ionization will be diminished and signal intensity optimized. This technology will serve in our efforts of uncovering novel pathways and biomarkers in cancer, diabetes, neurological diseases, and heart disease.

Identifying metabolites is limited by fragmentation quality. Using a piperidine based tag, we can fragment analytes primarily across their C-C bond. Computational modeling and synthetic approaches are being developed for identifying previously credentialed metabolites and identification of new metabolites.

Funded by NIH/NIGMS R01GM134081, “Universal Metabolite Tagging”

Discovery of Ligands for Orphan G Protein-Coupled Receptors for the Treatment of Neuropathic Pain and Chemotherapy-Induced Neuropathic Pain

Neuropathic pain conditions arising from nervous system injuries due to trauma, disease (i.e., diabetes) or neurotoxins (i.e. chemotherapy) are severe, debilitating and difficult to treat. Opioids are widely used to treat chronic pain but limited by severe side effects and strong abuse liability. With over 15-20 million people in the US suffering neuropathic pain and a profound annual economic burden for treatment, there is a high priority for developing novel non-opioid based analgesics.

Using unbiased analyses of a model of traumatic nerve-injury induced neuropathic pain our collaborators have found significant increases in several orphan G-protein coupled receptors (GPCRs). Since most of these orphan receptors do not have known ligands, we have begun drug discovery efforts on several receptors. Thus far, we have successfully designed and synthesized four compounds that can inhibit neuropathic pain in mice. Since these are non-opioid based, and do not interact with opioid receptors, they may not have same severe side effects and abuse liability.

Funded by NIH/NINDS R01NS128004, “Uncovering the roles of oxysterols in neuropathic pain”

Illustrating rapid receptor-specific estrogen signaling.

Historically, estrogen receptor α and β have been connected to estrogen signaling on both genomic and non-genomic levels. Further evidence for estrogens’ involvement in rapid non-genomic signaling arose with the characterization consequent studies of a G protein-coupled estrogen receptor (GPER) which bound estrogen and subsequently induced downstream signaling. Through virtual screening and high-throughput analysis, several selective ligands have been discovered and shown possible physiological roles of GPER. Studies have revealed that this new mechanism of estrogen signaling may prove to be important in the treatment of estrogen sensitive cancers, gallstone disease and vital in neurodevelopment.

The long-term goal of this research is to design ligands that bind to GPER, identify selective agonists and antagonists, characterize their interactions with the receptor, analyze those interactions to develop selective ligands which can modulate receptor functions, and determine their therapeutic potential. Additionally, proteolysis targeting chimera (PROTACs) for GPER have been designed and synthesized (these are currently being commercialized by Starling Biosciences, Inc). These studies are significant because further understanding of the receptor-ligand interaction could ultimately lead to new therapeutics and better understanding of several types of cancers, gallstone disease, and the neurodevelopment effects of estrogens.