Human genetic studies have identified T NIP 1 as a susceptibility locus to systemic lupus erythematosus (SLE). T NIP 1 encodes the protein ABIN-I, which was originally identified as binding to the ubiquitin-modifying enzyme A20 another SLE associated risk gene. Our hypothesis is that ABIN-I regulates homeostatic signals that prevent autoimmunity. To dissect ABIN-I’s functions in autoimmunity, we generated conditional knockout ABIN-1 mice in which ABIN-I is specifically deleted in dendritic cells, and discovered that ABIN-I expression is required for maintaining tolerance and protection against autoimmunity. We will test the cellular and molecular regulatory pathways that are disrupted in dendritic cells and in the mice. We will also ask how ABIN-I collaborates with A20 to prevent SLE. These studies will validate ABIN-I as a true susceptibility gene for SLE and reveal cellular and molecular insights into how ABIN-I might contribute to SLE risk, providing new opportunities for targeting new therapeutics.