title: Vitamin C enters mitochondria via facilitative glucose transporter 1 (Glut1) and confers mitochondrial protection against oxidative injury.
abstract: Reactive oxygen species (ROS)-induced mitochondrial abnormalities may have important consequences in the pathogenesis of degenerative diseases and cancer. Vitamin C is an important antioxidant known to quench ROS, but its mitochondrial transport and functions are poorly understood. We found that the oxidized form of vitamin C, dehydroascorbic acid (DHA), enters mitochondria via facilitative glucose transporter 1 (Glut1) and accumulates mitochondrially as ascorbic acid (mtAA). The stereo-selective mitochondrial uptake of D-glucose, with its ability to inhibit mitochondrial DHA uptake, indicated the presence of mitochondrial Glut. Computational analysis of N-termini of human Glut isoforms indicated that Glut1 had the highest probability of mitochondrial localization, which was experimentally verified via mitochondrial expression of Glut1-EGFP. In vitro mitochondrial import of Glut1, immunoblot analysis of mitochondrial proteins, and cellular immunolocalization studies indicated that Glut1 localizes to mitochondria. Loading mitochondria with AA quenched mitochondrial ROS and inhibited oxidative mitochondrial DNA damage. mtAA inhibited oxidative stress resulting from rotenone-induced disruption of the mitochondrial respiratory chain and prevented mitochondrial membrane depolarization in response to a protonophore, CCCP. Our results show that analogous to the cellular uptake, vitamin C enters mitochondria in its oxidized form via Glut1 and protects mitochondria from oxidative injury. Since mitochondria contribute significantly to intracellular ROS, protection of the mitochondrial genome and membrane may have pharmacological implications against a variety of ROS-mediated disorders.
authors.affiliation: Department of Pharmacology, Weill Medical College, Cornell University, New York, New York 10021, USA.
authors.forename: Sagan
authors.initials: S
authors.lastname: KC
authors.forename: Juan M
authors.initials: JM
authors.lastname: Cárcamo
authors.forename: David W
authors.initials: DW
authors.lastname: Golde
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology; D001205:Ascorbic Acid / Q000378:metabolism / Q000502:physiology*; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D004249:DNA Damage; D004272:DNA, Mitochondrial / Q000378:metabolism; D003683:Dehydroascorbic Acid / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004579:Electron Transport; D016678:Genome; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1 / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D015151:Immunoblotting; D008564:Membrane Potentials; D051379:Mice; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism* / Q000473:pathology*; D008954:Models, Biological; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism*; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D017382:Reactive Oxygen Species; D012402:Rotenone / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D012984:Software
chemical_list: D000975:Antioxidants; D004272:DNA, Mitochondrial; D051272:Glucose Transporter Type 1; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D012402:Rotenone; D049452:Green Fluorescent Proteins; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D005947:Glucose; D001205:Ascorbic Acid; D010100:Oxygen; D003683:Dehydroascorbic Acid