Peroxiredoxin6 Is a Novel Promoter of Pancreatic Beta-Cell Survival

Background: Diabetes is a multifactorial disease with low levels of inflammation and loss of functional pancreatic β-cell mass. Pancreatic β-cells have a reduced antioxidant capacity with an increased vulnerability to oxidative stress. Pro-inflammatory cytokines increasing reactive oxygen species production lead to cell death. Peroxiredoxin6 (Prdx6), an antioxidant enzyme, is highly expressed in beta cells compared to other antioxidants. We previously reported as Prdx6 knockout (Prdx6-/-) mice have a mild diabetes mellitus phenotype due to a reduction of pancreatic β-cell mass. Moreover, the higher levels of TNFα in Prdx6-/- mice may induce β-cell loss, contributing to the reduction in β-cell mass. However, the intracellular apoptotic pathway leading to cell death have not been investigated, yet. Aims and Results: The objective of this study was to analyze the role of Prdx6 in the modulation of apoptosis in response to TNFα. To achieve this goal, Prdx6 was stably silenced (Prdx6KD) in murine pancreatic beta cell line (βTC6), and, the activation of intrinsic and/or extrinsic apoptotic pathway in response TNFα was analyzed in Prdx6KD and control (Scramble) cell lines. We demonstrated that TNFα administration (50 ng/ml for 24h), induced a two folds increase in apoptosis evaluated by FACS analysis, in Prdx6KD cells compared to scramble cells. Furthermore, by using ELISA assay, we measured the activity of caspase 2, 8, and 10 for the extrinsic pathway and caspase 9 for the intrinsic one. We found that after TNFα treatment, Prdx6KD cells exhibited significant higher levels (p<0.05) of caspase 8 and 9 compared to control cells. Moreover, also the activation of caspase 3 and PARP1 cleavage were significantly augmented in Prdx6KD cells compared to scramble cells, both treated with TNF-α as reported above. Conclusion: These results suggest that Prdx6 can regulate pancreatic β-cells apoptosis. In conclusion, Prdx6 can be considered a novel potential therapeutic target for diabetes, preserving pancreatic β-cells survival.