GDF15 Is Induced by T1D-Associated Cytokines and ER Stress and Promotes Beta-Cell Apoptosis

Type 1 diabetes (T1D) is characterized by T-cell and cytokine-mediated pancreatic beta cell loss, but some of the mechanisms involved are still unknown. Growth differentiation factor 15 (GDF15), which is a distant member of the transforming growth factor β (TGFβ) family, has been shown to be increased in various diseases including cancer, heart failure and type 2 diabetes and to promote cancer cell apoptosis. Although we found that GDF15 is highly expressed in adult human beta cells, its role in beta cells and T1D has not been studied. In the present study, we found that GDF15 is significantly elevated in the islets of diabetic female NOD mice compared to nondiabetic female NOR and male NOD mice. In addition, by using human islets, Akita beta cells and INS-1 beta cells, we found that the expression and content of GDF15 are significantly increased by T1D-associated cytokines and thapsigargin/ER stress. Furthermore, we demonstrated that GDF15 knockdown significantly blunts cytokines-induced beta cell apoptosis, while GDF15 overexpression exacerbates T1D-associated cytokines-induced beta cell apoptosis. Taken together, these findings suggest that GDF15 is induced by cytokine-induced ER-stress in beta cells and might contribute to the beta cell loss in T1D. Targeting beta cell GDF15 may therefore represent a novel strategy to inhibit beta cell loss in T1D.