title: Changes in mitochondrial carriers exhibit stress-specific signatures in INS-1Eβ-cells exposed to glucose versus fatty acids.
abstract: Chronic exposure of β-cells to metabolic stresses impairs their function and potentially induces apoptosis. Mitochondria play a central role in coupling glucose metabolism to insulin secretion. However, little is known on mitochondrial responses to specific stresses; i.e. low versus high glucose, saturated versus unsaturated fatty acids, or oxidative stress. INS-1E cells were exposed for 3 days to 5.6 mM glucose, 25 mM glucose, 0.4 mM palmitate, and 0.4 mM oleate. Culture at standard 11.1 mM glucose served as no-stress control and transient oxidative stress (200 µM H2O2 for 10 min at day 0) served as positive stressful condition. Mito-array analyzed transcripts of 60 mitochondrion-associated genes with special focus on members of the Slc25 family. Transcripts of interest were evaluated at the protein level by immunoblotting. Bioinformatics analyzed the expression profiles to delineate comprehensive networks. Chronic exposure to the different metabolic stresses impaired glucose-stimulated insulin secretion; revealing glucotoxicity and lipo-dysfunction. Both saturated and unsaturated fatty acids increased expression of the carnitine/acylcarnitine carrier CAC, whereas the citrate carrier CIC and energy sensor SIRT1 were specifically upregulated by palmitate and oleate, respectively. High glucose upregulated CIC, the dicarboxylate carrier DIC and glutamate carrier GC1. Conversely, it reduced expression of energy sensors (AMPK, SIRT1, SIRT4), metabolic genes, transcription factor PDX1, and anti-apoptotic Bcl2. This was associated with caspase-3 cleavage and cell death. Expression levels of GC1 and SIRT4 exhibited positive and negative glucose dose-response, respectively. Expression profiles of energy sensors and mitochondrial carriers were selectively modified by the different conditions, exhibiting stress-specific signatures.
authors.affiliation: Department of Cell Physiology and Metabolism, University of Geneva, Medical Center, Geneva, Switzerland.
authors.forename: Thierry
authors.initials: T
authors.lastname: Brun
authors.affiliation: Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Scarcia
authors.affiliation: Department of Cell Physiology and Metabolism, University of Geneva, Medical Center, Geneva, Switzerland.
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.affiliation: Swiss Institute of Bioinformatics (SIB) and University of Geneva, Medical Center, Geneva, Switzerland.
authors.forename: Pascale
authors.initials: P
authors.lastname: Gaudet
authors.affiliation: Department of Cell Physiology and Metabolism, University of Geneva, Medical Center, Geneva, Switzerland.
authors.forename: Dominique
authors.initials: D
authors.lastname: Duhamel
authors.affiliation: Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy ; Center of Excellence in Comparative Genomics (CEGBA), University of Bari, Bari, Italy.
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Palmieri
authors.affiliation: Department of Cell Physiology and Metabolism, University of Geneva, Medical Center, Geneva, Switzerland.
authors.forename: Pierre
authors.initials: P
authors.lastname: Maechler
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001692:Biological Transport / Q000187:drug effects / Q000235:genetics; D002331:Carnitine / Q000031:analogs & derivatives / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D004247:DNA / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects / Q000235:genetics; D004734:Energy Metabolism / Q000187:drug effects / Q000235:genetics; D005227:Fatty Acids / Q000494:pharmacology*; D020869:Gene Expression Profiling; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism; D050356:Lipid Metabolism / Q000187:drug effects / Q000235:genetics; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D010085:Oxidative Phosphorylation / Q000187:drug effects; D021122:Protein Subunits / Q000378:metabolism; D020543:Proteome / Q000378:metabolism; D051381:Rats; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism; D059467:Transcriptome / Q000235:genetics
chemical_list: D005227:Fatty Acids; D007328:Insulin; D024101:Mitochondrial Proteins; D021122:Protein Subunits; D020543:Proteome; D014157:Transcription Factors; C116917:acylcarnitine; D004247:DNA; D005947:Glucose; D002331:Carnitine