AICAR potentiates ROS production induced by chronic high glucose: roles of AMPK in pancreatic beta-cell apoptosis.
We previously demonstrated that chronic high glucose (33.3 mM) induced beta-cell dysfunction and apoptosis through glucokinase (GCK) downregulation, but the exact mechanisms involved remain unclear. Here, we show that prolonged exposure of 5-aminoimidazole-4-carboxamide (AICA)-riboside potentiated apoptosis induced by high glucose in MIN6N8 pancreatic beta-cells, correlating with enhanced GCK downregulation and decreased production of ATP and insulin. These events are potentiated in AMPK-overexpressing cells, but are prevented in cells transfected with mutant dominant-negative AMPK (AMPK-K45R). Furthermore, AMPK activation increases production of reactive oxygen species (ROS) and loss of mitochondria membrane potential induced by high glucose, which is significantly inhibited by treatment with compound C or by AMPK-K45R overexpression. Overexpression of GCK prevents apoptosis; decreased cellular ATP and insulin secretion, and ROS production enhanced by AICAR, but does not affect AMPK activation. Similar results are obtained using isolated primary islet cells. Collectively, these data demonstrate that AMPK activation potentiates beta-cell apoptosis induced by chronic high glucose through augmented GCK downregulation mediated by enhanced ROS production.
Kim
Won-Ho
WH
Division of Metabolic Diseases, Center for Biomedical Sciences, National Institutes of Health, 194 Tongillo, Eunpyeong-Gu, Seoul, South Korea.
Lee
June Woo
JW
Suh
Young Ho
YH
Lee
Hyun Jung
HJ
Lee
Seung Hee
SH
Oh
Yeo Kyoung
YK
Gao
Bin
B
Jung
Myeong Ho
MH
D055372:AMP-Activated Protein Kinases; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002461:Cell Line, Transformed; D015536:Down-Regulation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D005941:Glucokinase / Q000235:genetics / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology*; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D009097:Multienzyme Complexes / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012265:Ribonucleotides / Q000494:pharmacology*
D009097:Multienzyme Complexes; D011506:Proteins; D017382:Reactive Oxygen Species; D012265:Ribonucleotides; D000620:Aminoimidazole Carboxamide; D005941:Glucokinase; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide; D005947:Glucose