NADPH oxidase 2-derived reactive oxygen species are involved in dysfunction and apoptosis of pancreatic β-cells induced by low density lipoprotein.
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 β-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 β-cell function, insulin content, cell apoptosis and ROS production were measured in pancreatic islets of apoE(-/-)mice and mouse pancreatic β-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 β-cells through JNK and p53 pathways.
The Key Laboratory of Geriatrics, Beijing Hospital & Beijing Institute of Geriatrics, Ministry of Health, No. 1 Dahua Road, Dong Dan, Beijing, China.
Miao
M
Li
Lin
L
Dou
Juan
J
Jiao
Yonggang
Y
Lu
Han-Bang
HB
Guo
Yong
Y
Man
Shu
S
Wang
Jian
J
Li
D000818:Animals; D001057:Apolipoproteins E / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D002784:Cholesterol / Q000097:blood / Q000378:metabolism; D059305:Diet, High-Fat; D007328:Insulin / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000097:blood / Q000494:pharmacology; D008297:Male; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D001057:Apolipoproteins E; D007328:Insulin; D008077:Lipoproteins, LDL; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; D002784:Cholesterol; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D048031:JNK Mitogen-Activated Protein Kinases