Type 1 diabetes (T1D) is caused by the immune destruction of insulin producing cells in the pancreas. The disease cannot be prevented, and the only treatment available is a life-long use of insulin injected multiple times a day. Insulin-producing beta cells can now be generated from pluripotent stem cells in the laboratory. This recent achievement has raised the prospect of restoring insulin production in patients by beta cell transplantation. However, the autoimmunity underlying T1D is long-lasting and will destroy new beta cells if they are transplanted without immunosuppression. A new therapy that protects beta cells is urgently needed not only enable curative beta cell replacement in patients but also to prevent diabetes in individuals at risk of developing the disease. To discover genetic targets for such a therapy, we performed a genome-wide search using CRIPSR-Cas9 genome editing in a mouse model for T1D. This broad unbiased search identified the gene Renalase (RNLS). Significantly, RNLS had previously been associated with the overall risk and the age- of-onset of T1D by human genome-wide association studies (GWAS), suggesting a role for RNLS in diabetes pathogenesis. We went on to confirm that deleting RNLS protected mouse beta cells against cellular stress and autoimmunity. We corroborated the protective effect of RNLS deletion in human stem cell-derived beta cells. Based on these findings, we hypothesized that a small molecule inhibitor of RNLS would also protect. Using structure-based molecular modeling, we identified the FDA-approved drug pargyline as a potential RNLS inhibitor. We showed that pargyline treatment replicated the protective effects of RNLS deletion, making this drug a potential candidate for a preventive treatment for T1D. Now, we aim to better understand how RNLS deficiency protects beta cells against cellular stress and autoimmunity. Further, we aim to more extensively test the therapeutic potential of pargyline. To these ends, we will pursue three Specific Aims. First, we will evaluate metabolic plasticity as a possible mechanistic basis for the protection of RNLS deficient cells. Second, we will quantify and delineate the immunogenicity of Rnls deficient beta cells in vitro and in mouse models for T1D. Third, we will evaluate the therapeutic utility of pargyline as a mimic of Rnls deletion, both at the cellular level and in the context of autoimmune diabetes in mice. Completing the first two Aims will help explain the mechanism by which RNLS modifies beta cell vulnerability and the risk of type 1 diabetes.
The third Aim will support the translation of our discoveries into a clinical application by testing the therapeutic value of drug we identified as a RNLS inhibitor. Our research team is composed of experts in immunology, beta cell biology and stem cell differentiation. We are ideally positioned to explore the role of RNLS in T1D from perspectives that range from cellular biology to systemic autoimmunity, with the prospect of improving our understanding of disease pathology and developing a preventive drug. Our research will utilize both a well characterized mouse model for T1D and human beta cells to ascertain the relevance of our findings for human disease.
We have performed a genome-wide screen for gene modifications that protect beta cells against immune- mediated killing in a mouse model for type 1 diabetes. This powerful and stringent screen identified the type 1 diabetes-associated gene RNLS that we have now extensively validated for its effect on beta cell resistance in both mouse islet cells and human stem cell-derived beta cells. This research aims to further understand how RNLS deletion protects beta cells against autoimmunity and whether targeting this gene pharmacologically could provide a new avenue for the prevention of type 1 diabetes.
