title: Thioredoxin 1 and thioredoxin 2 have opposed regulatory functions on hypoxia-inducible factor-1alpha.
abstract: Hypoxia inducible factor 1 (HIF-1), a key regulator for adaptation to hypoxia, is composed of HIF-1alpha and HIF-1beta. In this study, we present evidence that overexpression of mitochondria-located thioredoxin 2 (Trx2) attenuated hypoxia-evoked HIF-1alpha accumulation, whereas cytosolic thioredoxin 1 (Trx1) enhanced HIF-1alpha protein amount. Transactivation of HIF-1 is decreased by overexpression of Trx2 but stimulated by Trx1. Inhibition of proteasomal degradation of HIF-1alpha in Trx2-overexpressing cells did not fully restore HIF-1alpha protein levels, while HIF-1alpha accumulation was enhanced in Trx1-overexpressing cells. Reporter assays showed that cap-dependent translation is increased by Trx1 and decreased by Trx2, whereas HIF-1alpha mRNA levels remained unaltered. These data suggest that thioredoxins affect the synthesis of HIF-1alpha. Trx1 facilitated synthesis of HIF-1alpha by activating Akt, p70S6K, and eIF-4E, known to control cap-dependent translation. In contrast, Trx2 attenuated activities of Akt, p70S6K, and eIF-4E and provoked an increase in mitochondrial reactive oxygen species production. MitoQ, a mitochondria specific antioxidant, reversed HIF-1alpha accumulation as well as Akt activation under hypoxia in Trx2 cells, supporting the notion of translation control mechanisms in affecting HIF-1alpha protein accumulation.
authors.affiliation: Institute of Biochemistry I, Faculty of Medicine, Johann Wolfgang Goethe-University Frankfurt, 60590 Frankfurt, Germany.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhou
authors.forename: Anastassios E
authors.initials: AE
authors.lastname: Damdimopoulos
authors.forename: Giannis
authors.initials: G
authors.lastname: Spyrou
authors.forename: Bernhard
authors.initials: B
authors.lastname: Brüne
mesh_terms: D002478:Cells, Cultured; D039561:Eukaryotic Initiation Factor-4E / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000502:physiology*; D010766:Phosphorylation; D014176:Protein Biosynthesis; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017382:Reactive Oxygen Species; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism*
chemical_list: D039561:Eukaryotic Initiation Factor-4E; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D024101:Mitochondrial Proteins; D017382:Reactive Oxygen Species; C491203:TXN protein, human; C467002:TXN2 protein, human; D013879:Thioredoxins; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa