title: A novel giant peroxisomal superoxide dismutase motif-containing protein.
abstract: Oxidative glutamate toxicity in the neuronal cell line HT22 is a model for neuronal cell death by oxidative stress. In this model, extracellular glutamate blocks cystine uptake via the glutamate/cystine antiporter system x(c)(), eventually leading to depletion of the antioxidant glutathione and cell death. We used subtractive suppression hybridization and a screening procedure using various HT22 sublines to identify transcripts relevantly upregulated in resistance to oxidative glutamate toxicity. One of these coded for a novel protein of 3440 amino acids comprising a superoxide dismutase (SOD) motif, which we named TIGR for "transcript increased in glutamate resistance." TIGR is mainly expressed in the nervous system in cortical pyramidal and hippocampal neurons. Intracellularly, TIGR colocalizes with catalase, strongly suggesting a peroxisomal localization. Overexpression of TIGR but not of a mutant lacking two conserved histidine residues in the SOD motif increased SOD activity and protected against oxidative stress in mammalian cells, but had no direct SOD activity in yeast. We conclude that this novel giant peroxisomal protein is implicated in resistance to oxidative stress. Despite the presence of a SOD motif, which is necessary for protection in mammalian cells, the protein is not a functional SOD, but might be involved in SOD activity.
authors.affiliation: Neurologische Klinik, Universitätsklinikum Düsseldorf, D-40225 Düsseldorf, Germany.
authors.forename: Diamandis
authors.initials: D
authors.lastname: Toutzaris
authors.forename: Jan
authors.initials: J
authors.lastname: Lewerenz
authors.forename: Philipp
authors.initials: P
authors.lastname: Albrecht
authors.forename: Laran T
authors.initials: LT
authors.lastname: Jensen
authors.forename: Julia
authors.initials: J
authors.lastname: Letz
authors.forename: Andreas
authors.initials: A
authors.lastname: Geerts
authors.forename: Stefan
authors.initials: S
authors.lastname: Golz
authors.forename: Axel
authors.initials: A
authors.lastname: Methner
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D018698:Glutamic Acid / Q000633:toxicity; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018384:Oxidative Stress / Q000187:drug effects; D020675:Peroxisomes / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000378:metabolism*; D000099179:Myocilin
chemical_list: D003598:Cytoskeletal Proteins; D005136:Eye Proteins; D018698:Glutamic Acid; D006023:Glycoproteins; D012333:RNA, Messenger; D013482:Superoxide Dismutase; D000099179:Myocilin