title: Aminoglycosides decrease glutathione peroxidase-1 activity by interfering with selenocysteine incorporation.
abstract: Cellular glutathione peroxidase is a key intracellular antioxidant enzyme that contains a selenocysteine residue at its active site. Selenium, a selenocysteine incorporation sequence in the 3'-untranslated region of the glutathione peroxidase mRNA, and other translational cofactors are necessary for "read-through" of a UGA stop codon that specifies selenocysteine incorporation. Aminoglycoside antibiotics facilitate read-through of premature stop codons in prokayotes and eukaryotes. We studied the effects of G418, an aminoglycoside, on cellular glutathione peroxidase expression and function in mammalian cells. Insertion of a selenocysteine incorporation element along with a UGA codon into a reporter construct allows for read-through only in the presence of selenium. G418 increased read-through in selenium-replete cells as well as in the absence of selenium. G418 treatment increased immunodetectable endogenous or recombinant glutathione peroxidase but reduced the specific activity of the enzyme. Tandem mass spectrometry experiments indicated that G418 caused a substitution of l-arginine for selenocysteine. These data show that G418 can affect the biosynthesis of this key antioxidant enzyme by promoting substitution at the UGA codon.
authors.affiliation: Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA. dhandy@rics.bwh.harvard.edu
authors.forename: Diane E
authors.initials: DE
authors.lastname: Handy
authors.forename: Gaozhen
authors.initials: G
authors.lastname: Hang
authors.forename: John
authors.initials: J
authors.lastname: Scolaro
authors.forename: Nicole
authors.initials: N
authors.lastname: Metes
authors.forename: Nadia
authors.initials: N
authors.lastname: Razaq
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.forename: Joseph
authors.initials: J
authors.lastname: Loscalzo
mesh_terms: D020413:3' Untranslated Regions; D000563:Amebicides / Q000494:pharmacology; D000617:Aminoglycosides / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D000975:Antioxidants / Q000737:chemistry; D001011:Aorta / Q000166:cytology; D001120:Arginine / Q000737:chemistry; D015153:Blotting, Western; D019556:COS Cells; D002417:Cattle; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D003062:Codon; D018388:Codon, Terminator; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000166:cytology; D017930:Genes, Reporter; D005822:Genetic Vectors; D005979:Glutathione Peroxidase / Q000378:metabolism*; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D013058:Mass Spectrometry; D009154:Mutation; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D012643:Selenium / Q000378:metabolism; D017279:Selenocysteine / Q000737:chemistry / Q000378:metabolism*; D051140:Selenoproteins / Q000737:chemistry; D014162:Transfection; D000094765:Glutathione Peroxidase GPX1
chemical_list: D020413:3' Untranslated Regions; D000563:Amebicides; D000617:Aminoglycosides; D000975:Antioxidants; D003062:Codon; D018388:Codon, Terminator; D018076:DNA, Complementary; D012333:RNA, Messenger; D011994:Recombinant Proteins; D051140:Selenoproteins; D017279:Selenocysteine; D001120:Arginine; D005979:Glutathione Peroxidase; D008156:Luciferases; D012643:Selenium; D000094765:Glutathione Peroxidase GPX1