Project Summary Conventional dendritic cells (CDC) play a central role in protective immunity by connecting innate and adaptive immune responses. CDCs can distinguish `self' from `non-self' (example pathogen) or `altered-self' (example cancer) through specialized pattern recognition receptors and help orchestrate the appropriate adaptive immune response. CDC1 and CDC2 are the two major subsets of CDCs with CDC1s having the unique capacity to cross- present antigens that is critical for immunity against viruses and cancer. Circulating precursors of CDCs (Pre- CDCs) infiltrate tissue where they differentiate into CDC1 and CDC2. The relative distribution of these CDC subsets differ between tissue types and under pathological conditions, suggesting a role of tissue microenvironment in Pre-CDC differentiation. What factors in the tissue microenvironment might regulate this process, however, remains poorly understood. Our preliminary studies show that CDC1 differentiation is regulated by local availability of the amino acid glutamine through its metabolic conversion into glutamate. Glutamine uptake and utilization increases significantly in rapidly proliferating cells or during catabolic stress, potentially creating a glutamine deficient local microenvironment. Hence, we hypothesize that metabolic adaptations in tissue alters local CDC1 differentiation by modulating glutamine levels. In this proposal, we seek to understand which steps of CDC1 differentiation is regulated by glutamate and its underlying molecular mechanism. We will focus on epigenetic regulation of gene expression and oxidative stress as potential pathways by which glutamate mediates this effect. Findings from the proposed work can potentially open new lines of research linking tissue metabolic adaptations to its immune microenvironment.