title: Selective protection of nuclear thioredoxin-1 and glutathione redox systems against oxidation during glucose and glutamine deficiency in human colonic epithelial cells.
abstract: Little is known about the relative sensitivities of antioxidant systems in nuclei, mitochondria, and cytoplasm. The present study examined the oxidation of the thiol-dependent antioxidant systems in these subcellular compartments under conditions of limited energy supply of human colonic epithelial HT-29 cells induced by depletion of glucose (Glc) and glutamine (Gln) from the culture medium. Increased oxidation of dichlorofluoroscein (DCF) indicated an increased level of reactive oxygen species (ROS). Redox Western blot analysis showed oxidation of cytosolic thioredoxin-1 (Trx1) and mitochondrial thioredoxin-2 (Trx2) by 24 h, but little oxidation of nuclear Trx1. The Trx1 substrate, redox factor-1 (Ref-1), was also oxidized in cytosol but was reduced in nuclei. Protein S-glutathionylation (PrSSG), expressed as a ratio of protein thiol (PrSH), was also increased in the cytosol, while nuclear PrSSG/PrSH was not. Taken together, the data show that oxidative stress induced by depletion of Glc and Gln affects the redox states of proteins in the cytoplasm and mitochondria more than those in the nucleus. These results indicate that the nuclear compartment has better protection against oxidative stress than cytoplasm or mitochondria. These results further suggest that energy and/or substrate supply may contribute to sensitivity of mitochondrial and cytoplasmic systems to oxidative damage.
authors.affiliation: Division of Pulmonary Medicine, Emory University, Atlanta, GA 30322, USA.
authors.forename: Young-Mi
authors.initials: YM
authors.lastname: Go
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Ziegler
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Johnson
authors.forename: Li
authors.initials: L
authors.lastname: Gu
authors.forename: Jason M
authors.initials: JM
authors.lastname: Hansen
authors.forename: Dean P
authors.initials: DP
authors.lastname: Jones
mesh_terms: D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D003106:Colon / Q000166:cytology; D003600:Cytosol / Q000378:metabolism; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D005452:Fluoresceins; D005456:Fluorescent Dyes; D005947:Glucose / Q000172:deficiency*; D005973:Glutamine / Q000172:deficiency*; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism*
chemical_list: D005452:Fluoresceins; D005456:Fluorescent Dyes; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D017382:Reactive Oxygen Species; D013438:Sulfhydryl Compounds; C491203:TXN protein, human; D005973:Glutamine; D013879:Thioredoxins; C037631:2',7'-dichlorofluorescein; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D005978:Glutathione; D005947:Glucose