title: Oleate-induced beta cell dysfunction and apoptosis: a proteomic approach to glucolipotoxicity by an unsaturated fatty acid.
abstract: High levels of fatty acids contribute to loss of functional beta cell mass in type 2 diabetes, in particular in combination with high glucose levels. The aim of this study was to elucidate the role of the unsaturated free fatty acid oleate in glucolipotoxicity and to unravel the molecular pathways involved. INS-1E cells were exposed to 0.5 mM oleate, combined or not with 25 mM glucose, for 24 h. Protein profiling of INS-1E cells was done by 2D-DIGE, covering pH ranges 4-7 and 6-9 (n = 4). Identification of differentially expressed proteins (P < 0.05) was based on MALDI-TOF analysis using Peptide Mass Fingerprint (PMF) and fragmentation (MS/MS) of the most intense peaks of PMF and proteomic results were confirmed by functional assays. Oleate impaired glucose-stimulated insulin secretion and decreased insulin content. 2D-DIGE analysis revealed 53 and 54 differentially expressed proteins for oleate and the combination of oleate and high glucose, respectively. Exposure to oleate down-regulated chaperones, hampered insulin processing and ubiquitin-related proteasomal degradation, and induced perturbations in vesicle transport and budding. In combination with high glucose, shunting of excess amounts of glucose toward reactive oxygen species production worsened beta cell death. The present findings provide new insights in oleate-induced beta cell dysfunction and identify target proteins for preservation of functional beta cell mass in type 2 diabetes.
authors.affiliation: Laboratory for Experimental Medicine and Endocrinology (LEGENDO), Herestraat 49, Catholic University of Leuven, Leuven, Belgium.
authors.forename: Michael
authors.initials: M
authors.lastname: Maris
authors.forename: Etienne
authors.initials: E
authors.lastname: Waelkens
authors.forename: Miriam
authors.initials: M
authors.lastname: Cnop
authors.forename: Wannes
authors.initials: W
authors.lastname: D'Hertog
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Cunha
authors.forename: Hannelie
authors.initials: H
authors.lastname: Korf
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Koike
authors.forename: Lut
authors.initials: L
authors.lastname: Overbergh
authors.forename: Chantal
authors.initials: C
authors.lastname: Mathieu
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D015180:Electrophoresis, Gel, Two-Dimensional; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D005947:Glucose / Q000633:toxicity*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D008055:Lipids / Q000633:toxicity*; D019301:Oleic Acid / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D040901:Proteomics; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D017931:DNA Primers; D005231:Fatty Acids, Unsaturated; D007328:Insulin; D008055:Lipids; D017382:Reactive Oxygen Species; D019301:Oleic Acid; D000255:Adenosine Triphosphate; D005947:Glucose