Zhichen Cai1, Shuqing Liu1, Yaxing Nie1, Bingzheng Dong2, Chenglin Li1, Jinyuan Zhang1, Chunya Xia1, Lei Du1, Xiaoxing Yin1, Jianyun Wang3. 1. Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, 221002, Jiangsu, China. 2. Department of Urology, Xuzhou Central Hospital, The Affiliated School of Clinical Medicine, Xuzhou Medical University, Xuzhou, 221009, Jiangsu, China. 3. Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, 221002, Jiangsu, China. wangjianyun@xzhmu.edu.cn.
Abstract
BACKGROUND: Reactive oxygen species (ROS) plays a vital role in the apoptosis of islet β-cells in type 2 diabetes mellitus (T2DM). Sirt3 (Sirtuin 3, a deacetylase) and FoxO1 (a transcription factor) might be involved in ROS production. This study was to investigate mechanism of ROS production and β-cell apoptosis in T2DM. METHODS: Oxidative stress and apoptosis in islets of db/db mice and high glucose cultured β-cells were observed by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay and western blotting. Then, H2O2 was used to ascertain the effect of ROS on the expression of Sirt3. Meanwhile, FoxO1, antioxidant enzymes - catalase (CAT) and manganese superoxide dismutase (MnSOD) and β-cell apoptosis were also determined by western blotting. Finally, Sirt3 was knocked down to evaluate the effect on oxidative stress and apoptosis of β-cells. RESULTS: Under high glucose environment, enhanced ROS made a decrease of Sirt3 expression, which increased acetylation of FoxO1, thus reduced the expression of its target proteins -MnSOD and CAT, and further significantly increased ROS levels. Increased ROS finally led to the apoptosis of β-cells. CONCLUSION: Down-regulation of Sirt3 plays an important role in the cyclic production of ROS and β-cell apoptosis. Targeting Sirt3 may be favorable for the treatment of T2DM.
BACKGROUND: Reactive oxygen species (ROS) plays a vital role in the apoptosis of islet β-cells in type 2 diabetes mellitus (T2DM). Sirt3 (Sirtuin 3, a deacetylase) and FoxO1 (a transcription factor) might be involved in ROS production. This study was to investigate mechanism of ROS production and β-cell apoptosis in T2DM. METHODS: Oxidative stress and apoptosis in islets of db/db mice and high glucose cultured β-cells were observed by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay and western blotting. Then, H2O2 was used to ascertain the effect of ROS on the expression of Sirt3. Meanwhile, FoxO1, antioxidant enzymes - catalase (CAT) and manganese superoxide dismutase (MnSOD) and β-cell apoptosis were also determined by western blotting. Finally, Sirt3 was knocked down to evaluate the effect on oxidative stress and apoptosis of β-cells. RESULTS: Under high glucose environment, enhanced ROS made a decrease of Sirt3 expression, which increased acetylation of FoxO1, thus reduced the expression of its target proteins -MnSOD and CAT, and further significantly increased ROS levels. Increased ROS finally led to the apoptosis of β-cells. CONCLUSION: Down-regulation of Sirt3 plays an important role in the cyclic production of ROS and β-cell apoptosis. Targeting Sirt3 may be favorable for the treatment of T2DM.