Project summary My laboratory discovers metabolic adaptations required for cells to function, proliferate, and survive in low-nutrient metabolic environments, identifies small molecule inhibitors that target these metabolic vulnerabilities, and develops techniques to discover new metabolites and metabolic pathways. Cells require nutrients to make biomolecules required for growth and proliferation, and restricted availability of these nutrients prevents cell growth. Nutrient limits are imposed by the extracellular environment, such as the brain interstitial fluid, which maintains low levels of amino acids such as serine and glycine. These amino acids serve as neurotransmitters, and are needed to make proteins, nucleotides, and antioxidants. Cells also make some metabolites, such as coenzymes, in limiting quantities. Coenzymes are organic cofactors required for all metabolic pathways, and in unicellular organisms are made in a “just-in-time” manner to match cell growth. In addition to carbon and nitrogen-based nutrients, most of the human body, including the brain and bone marrow, maintains physiologic oxygen tensions below ambient oxygen availability. Oxygen is used for cellular respiration, but also is the substrate for a variety of enzymes, such as the dioxygenases, that synthesize metabolites and maintain epigenetic homeostasis. Both acute and chronic nutrient depletion and hypoxia contribute to the pathogenesis of many diseases including autoimmune disease, cardiac disease, and cancer. Cells entering, growing, or proliferating in the brain or other low-nutrient environments must find other sources of serine, glycine, and coenzymes or synthesize their own, and prioritize the efficient use of nutrients and oxygen. Over the next five years, we will identify the metabolic adaptations needed for cells to enter the brain, determine if cells acquire these adaptations before they enter the brain or adapt following entry into the brain, and target these adaptations with small molecule inhibitors. These studies will reveal metabolic targets whose inhibition could prevent diseases caused by cells inappropriately entering the brain, and offer proof of concept that targeting these adaptations would be of therapeutic value in diseases ranging from autoimmune disease to brain metastases. We also will define the enzymes, intermediates, and regulatory mechanisms of the mammalian Coenzyme Q10 headgroup synthesis pathway, which we recently discovered, and determine how cells produce the precise quantities of coenzymes needed for cell growth. Finally, we have developed novel techniques for tracing isotopically labeled gases into metabolites. We will use these techniques to discover metabolic pathways critical for the survival of cells in low-oxygen environments. These pathways have evaded discovery due to metabolic pathway redundancy or metabolite sharing. These projects will address longstanding unanswered questions in metabolic adaptation, reveal coenzyme-dep...