title: Uncoupling protein-2 attenuates palmitoleate protection against the cytotoxic production of mitochondrial reactive oxygen species in INS-1E insulinoma cells.
abstract: High glucose and fatty acid levels impair pancreatic beta cell function. We have recently shown that palmitate-induced loss of INS-1E insulinoma cells is related to increased reactive oxygen species (ROS) production as both toxic effects are prevented by palmitoleate. Here we show that palmitate-induced ROS are mostly mitochondrial: oxidation of MitoSOX, a mitochondria-targeted superoxide probe, is increased by palmitate, whilst oxidation of the equivalent non-targeted probe is unaffected. Moreover, mitochondrial respiratory inhibition with antimycin A stimulates palmitate-induced MitoSOX oxidation. We also show that palmitate does not change the level of mitochondrial uncoupling protein-2 (UCP2) and that UCP2 knockdown does not affect palmitate-induced MitoSOX oxidation. Palmitoleate does not influence MitoSOX oxidation in INS-1E cells ±UCP2 and largely prevents the palmitate-induced effects. Importantly, UCP2 knockdown amplifies the preventive effect of palmitoleate on palmitate-induced ROS. Consistently, viability effects of palmitate and palmitoleate are similar between cells ±UCP2, but UCP2 knockdown significantly augments the palmitoleate protection against palmitate-induced cell loss at high glucose. We conclude that UCP2 neither mediates palmitate-induced mitochondrial ROS generation and the associated cell loss, nor protects against these deleterious effects. Instead, UCP2 dampens palmitoleate protection against palmitate toxicity.
authors.affiliation: School of Biomedical and Healthcare Sciences, Plymouth University, Drake Circus, Plymouth PL4 8AA, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Barlow
authors.affiliation: School of Biomedical and Healthcare Sciences, Plymouth University, Drake Circus, Plymouth PL4 8AA, UK.
authors.forename: Verena
authors.initials: V
authors.lastname: Hirschberg Jensen
authors.affiliation: School of Biomedical and Healthcare Sciences, Plymouth University, Drake Circus, Plymouth PL4 8AA, UK. Electronic address: charles.affourtit@plymouth.ac.uk.
authors.forename: Charles
authors.initials: C
authors.lastname: Affourtit
mesh_terms: D000968:Antimycin A / Q000008:administration & dosage; D002452:Cell Count; D045744:Cell Line, Tumor; D005229:Fatty Acids, Monounsaturated / Q000633:toxicity; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000378:metabolism / Q000473:pathology; D007340:Insulinoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D007473:Ion Channels / Q000235:genetics* / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D017382:Reactive Oxygen Species / Q000378:metabolism / Q000633:toxicity; D000071246:Uncoupling Protein 2
chemical_list: D005229:Fatty Acids, Monounsaturated; D007328:Insulin; D007473:Ion Channels; D024101:Mitochondrial Proteins; D017382:Reactive Oxygen Species; C000604389:UCP2 protein, human; D000071246:Uncoupling Protein 2; C008757:palmitoleic acid; D000968:Antimycin A; D005947:Glucose
keywords: Cytoprotection; Glucolipotoxicity; INS-1E insulinoma cells; Mitochondrial dysfunction; Non-esterified fatty acids; Obesity; Pancreatic beta cells; Reactive oxygen species; Type 2 diabetes; Uncoupling protein-2 (UCP2)