Abstract Only about 2% of the mammalian genome contains genes that are translated into proteins. Yet, the vast majority of the genome is transcribed as RNA and lncRNAs account for most of these transcripts. Emerging evidence from our lab and others has defined long non-coding RNAs (lncRNAs) as important regulators of immunity providing a new perspective on gene regulation in the immune system. To date, our studies have focused on murine macrophages and studies in animals. This R21 proposal will advance our understanding of lncRNAs with immunomodulatory functions in human cells, specifically dendritic cells. We will focus on an intergenic lincRNA- Lucat-1; which we identified as a dynamically regulated gene in human monocyte derived dendritic cells exposed to Influenza virus, Herpes Simplex virus and lipopolysaccharide. Using loss and gain of function CRISPr/Cas9-based genome editing approaches we have found that lucat-1 acts as a negative feedback regulator of type I interferon and interferon stimulated gene expression in human dendritic cells. Aim 1 will advance our understanding of this lincRNA by exploring its role in controlling immune gene expression, defining its genomic targets and identifying its protein binding partners. Aim 2 will characterize the role of lucat-1 in controlling Influenza virus infection using newly generated lucat-1 KO mice. The underlying hypothesis to be explored in this proposal is that lucat1 represents a conserved regulatory component of the anti-viral response that acts to shut down the type I IFN response in infected cells. We propose that nuclear localized chromatin associated lncRNAs such as Lucat-1 bind the genome to regulate the expression of anti-viral genes. The versatility of these molecules and their ability to engage protein complexes with gene regulatory capacity endows these lncRNAs with the capacity to alter the immune response. Detailed mechanistic studies of how Lucat-1 impact ISG expression in human cells and animals could unveil novel drug targets that could potentially lead to the development of improved therapeutics for diseases associated with excessive production of type I IFNs such as lupus.