JNK1 protects against glucolipotoxicity-mediated beta-cell apoptosis.
Pancreatic β-cell dysfunction is central to type 2 diabetes pathogenesis. Prolonged elevated levels of circulating free-fatty acids and hyperglycemia, also termed glucolipotoxicity, mediate β-cell dysfunction and apoptosis associated with increased c-Jun N-terminal Kinase (JNK) activity. Endoplasmic reticulum (ER) and oxidative stress are elicited by palmitate and high glucose concentrations further potentiating JNK activity. Our aim was to determine the role of the JNK subtypes JNK1, JNK2 and JNK3 in palmitate and high glucose-induced β-cell apoptosis. We established insulin-producing INS1 cell lines stably expressing JNK subtype specific shRNAs to understand the differential roles of the individual JNK isoforms. JNK activity was increased after 3 h of palmitate and high glucose exposure associated with increased expression of ER and mitochondrial stress markers. JNK1 shRNA expressing INS1 cells showed increased apoptosis and cleaved caspase 9 and 3 compared to non-sense shRNA expressing control INS1 cells when exposed to palmitate and high glucose associated with increased CHOP expression, ROS formation and Puma mRNA expression. JNK2 shRNA expressing INS1 cells did not affect palmitate and high glucose induced apoptosis or ER stress markers, but increased Puma mRNA expression compared to non-sense shRNA expressing INS1 cells. Finally, JNK3 shRNA expressing INS1 cells did not induce apoptosis compared to non-sense shRNA expressing INS1 cells when exposed to palmitate and high glucose but showed increased caspase 9 and 3 cleavage associated with increased DP5 and Puma mRNA expression. These data suggest that JNK1 protects against palmitate and high glucose-induced β-cell apoptosis associated with reduced ER and mitochondrial stress.
Endocrinology Research Section, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
Michala
M
Prause
Endocrinology Research Section, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
Dan Ploug
DP
Christensen
Section of Cellular and Metabolic Research, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
Nils
N
Billestrup
Endocrinology Research Section, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark ; Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden.
Thomas
T
Mandrup-Poulsen
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D053453:Caspase 9 / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D005786:Gene Expression Regulation; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D050417:Insulin-Secreting Cells / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D048057:Mitogen-Activated Protein Kinase 10 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D048055:Mitogen-Activated Protein Kinase 8 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D048056:Mitogen-Activated Protein Kinase 9 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D019308:Palmitic Acid / Q000494:pharmacology*; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction; D051742:Transcription Factor CHOP / Q000235:genetics / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; C533952:Bbc3 protein, rat; C497251:Ddit3 protein, rat; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D051742:Transcription Factor CHOP; D019308:Palmitic Acid; D048057:Mitogen-Activated Protein Kinase 10; D048056:Mitogen-Activated Protein Kinase 9; D048055:Mitogen-Activated Protein Kinase 8; D053148:Caspase 3; D053453:Caspase 9; D005947:Glucose