ABSTRACT
In type 2 diabetes, pancreatic ß-cells cannot secret enough insulin compensate for insulin resistance, which are often accompanied by abnormality in lipid metabolism such as hypertriglyceridemia. It is reported that oxidative stress is involved in pancreatic ß-cell dysfunction. However, molecular mechanisms linking between excessive generations of reactive oxygen species (ROS) and ß-cell dysfunction and apoptosis induced by high levels of very low-density lipoprotein (VLDL) are poorly understood. In this study, we test the hypothesis that NADPH oxidase 2 (NOX2)-derived ROS may play a key role in dysfunction and apoptosis of pancreatic ß-cell induced by VLDL. Our results show that the ApoCIII transgenic mice displayed increased serum TG levels, enhanced generation of ROS and impaired insulin content in pancreatic ß-cells. In vitro, the treatment of pancreatic NIT-1 cells with 1 mg/ml VLDL for 12 h stimulated NOX2-derived ROS generation, decreased expression and secretion of insulin. Furthermore, we found that VLDL induced dysfunction and apoptosis of pancreatic ß-cells through JNK and p53 pathways, which were rescued by siRNA-mediated NOX2 reduction. In conclusion, our data demonstrate a critical role of NOX2-derived ROS in dysfunction and apoptosis through JNK and p53 pathways in pancreatic ß-cells induced by VLDL.
Subject(s)
Apoptosis/drug effects , Insulin-Secreting Cells/enzymology , Insulin-Secreting Cells/pathology , Lipoproteins, VLDL/pharmacology , Membrane Glycoproteins/metabolism , NADPH Oxidases/metabolism , Animals , Cell Line , Enzyme Activation/drug effects , Insulin/metabolism , Insulin Secretion , Insulin-Secreting Cells/drug effects , JNK Mitogen-Activated Protein Kinases/metabolism , Mice , Mice, Transgenic , NADPH Oxidase 2 , NF-kappa B/metabolism , Proto-Oncogene Proteins c-akt/antagonists & inhibitors , Proto-Oncogene Proteins c-akt/metabolism , Reactive Oxygen Species/metabolism , Triglycerides/blood , Tumor Suppressor Protein p53/metabolismABSTRACT
BACKGROUND: Increased levels of plasma cholesterol are a common feature of patient of type 2 diabetes. However, the links between elevated levels of low-density lipoprotein (LDL) and dysfunction of ß-cells are still unclear. METHODS: The apoE(-/-)mice were fed with a high-fat, cholesterol-rich diet for 8 weeks. Blood samples were collected from the mice for measurement of plasma glucose, lipids. The pancreas were embedded in OCT compound and frozen immediately in liquid nitrogen for further analysis. To examine the effects of LDL on ß-cell function, insulin content, cell apoptosis and ROS production were measured in pancreatic islets of apoE(-/-)mice and mouse pancreatic ß-cell line NIT-1. Relative cell signal pathways were determined by Western blot. RESULTS: Decreased insulin content and increased apoptosis and ROS production were found in pancreatic islets of apoE(-/-)mice, accompanied by elevated plasma LDL. The ROS levels were significantly enhanced in NIT-1 cells exposed to LDL. Reduced insulin synthesis and glucose-stimulated insulin secretion and elevated apoptosis were reversed by suppression of NOX2 expression. Moreover, LDL induced dysfunction and apoptosis of pancreatic NIT-1 cells through JNK and p53 pathways, which were rescued by siRNA-mediated NOX2 reduction. CONCLUSIONS: NOX2-derived ROS may play a key role in LDL-induced dysfunction and apoptosis of pancreatic ß-cells through JNK and p53 pathways.
Subject(s)
Insulin-Secreting Cells/metabolism , Membrane Glycoproteins/metabolism , NADPH Oxidases/metabolism , Reactive Oxygen Species/metabolism , Animals , Apolipoproteins E/deficiency , Apolipoproteins E/genetics , Apolipoproteins E/metabolism , Apoptosis/drug effects , Cell Line , Cholesterol/blood , Cholesterol/metabolism , Diet, High-Fat , Insulin/metabolism , Insulin-Secreting Cells/cytology , JNK Mitogen-Activated Protein Kinases/metabolism , Lipoproteins, LDL/blood , Lipoproteins, LDL/pharmacology , Male , Membrane Glycoproteins/antagonists & inhibitors , Membrane Glycoproteins/genetics , Mice , Mice, Inbred C57BL , Mice, Knockout , NADPH Oxidase 2 , NADPH Oxidases/antagonists & inhibitors , NADPH Oxidases/genetics , NF-kappa B/metabolism , Proto-Oncogene Proteins c-bcl-2/metabolism , RNA Interference , RNA, Small Interfering/metabolism , Signal Transduction/drug effects , Tumor Suppressor Protein p53/metabolismABSTRACT
OBJECTIVE: To assess the relationship between fractional esterification rate of high density lipoprotein cholesterol (FER(HDL)) and coronary artery disease. METHODS: A total of 131 hospitalized patients underwent coronary angiography due to chest pain were included in the study and patients were divided into CAD group (n = 76) and non CAD group (n = 55) according to coronary angiogram. Clinical and laboratory data including biochemical laboratory, FER(HDL) and lipid subclasses were analyzed. RESULTS: The FER(HDL) value of CAD group was significantly higher than that of the non CAD group (21.70 ± 8.73 vs. 18.65 ± 6.26, P < 0.05). There was an increased trend of FER(HDL) with numbers of diseased coronary arteries, significant difference was evidenced between non CAD group and 3-vessel group (18.65 ± 6.26 vs. 24.00 ± 9.22, P < 0.05). FER(HDL) was positively correlated with TG (r = 0.647, P < 0.001), LDLb-C(r = 0.441, P < 0.001) and negatively correlated with HDL-C (r = -0.708, P < 0.001) and HDL(2)-C (r = -0.748, P < 0.001). CONCLUSION: Our data showed that the values of FER(HDL) were significantly increased in CAD patients and correlated with the severity of the CAD.